تجزیه و تحلیل وضعیت جوی در سال زراعی 93-94 /فصل دوم( دي- بهمن-اسفند)

[Amir Mohsen]

جدیدترین آپدیت آنومالی و تجمعی بارش cfsv2 برای 5 روز آینده

و در انتهای خروجی 4 مدل اسمبل cfsv2 از ارتفاع تجمعی برف روی زمین تا 5 روز آینده

 

[heaven1]

 

[samann]

اینم سند که بر اساس دوره بلند مدت هست

حرف زدن راحته ولی حرف درست زدن سخته

پسر جان تو اصلا همین نقشه رو فهمیدی !!!معنی رنگ ابی یعنی چی؟ مگه مشهد تو رنگ ابی نیست!!!دقت این نقشه چقدره؟ مقیاسش به چه شکله!!
تو هیچ کدوم از اینا رو نفهمیدی . توفارسیشو خوندی که اره فاز + باعث افزایش بارش سواحل غربی
محسن دوست منه..ولی تو یکطوری حرف میزنی انگار حرفش خداست
اینو بدون در تحقیقات ایستگاهو مشخص میکنن مثلا ایستگاه مشهد با طول و عرض جغرافیایی فلان نه یک نقشه کلی ..
ببخشید صفاتتم به بقیه نده. حرف درستو تو نمیزنی.
دلیل اینکه من اینجا نظر میدم نه در پرشین تولز برخورد خیلی خوب تو و ...نیست. دلیلش همشهریا و هم استانیامن که اینجان

 

[morteza00]

 

[Amir Mohsen]

پسر جان تو اصلا همین نقشه رو فهمیدی !!!معنی رنگ ابی یعنی چی؟ مگه مشهد تو رنگ ابی نیست!!!دقت این نقشه چقدره؟ مقیاسش به چه شکله!!
تو هیچ کدوم از اینا رو نفهمیدی . توفارسیشو خوندی که اره فاز + باعث افزایش بارش سواحل غربی
محسن دوست منه..ولی تو یکطوری حرف میزنی انگار حرفش خداست
اینو بدون در تحقیقات ایستگاهو مشخص میکنن مثلا ایستگاه مشهد با طول و عرض جغرافیایی فلان نه یک نقشه کلی ..
ببخشید صفاتتم به بقیه نده. حرف درستو تو نمیزنی.
دلیل اینکه من اینجا نظر میدم نه در پرشین تولز برخورد خیلی خوب تو و ...نیست. دلیلش همشهریا و هم استانیامن که اینجان

سامان و هادی عزیز

خواهش میکنم با هم دوستانه و در غالب مباحث علمی مجادله کنید.
بخدا اینطوری مورد خطاب قرار دادن هم خیلی بد و دور از شان هست.
در خصوص رنگها در نقشه آنومالی بالا و اینکه تا چه حدودی مناطق مذکور دارای آنومالی مثبت بارش میشن سال گذشته با همراهی دکتر بهروز عزیز یک مطلب مهم با در نظر گرفتن داده های اماری هم در انجمن و هم در وب من قرار گرفت که حالا اگه پیداش کردم حتما میذارمش ولی اون رنگ آبی کم رنگ روی نقشه بر روی مشهد به معنای پر بارشی نیست و رنگهای تیره مناطق با دقت بالا هستند.
خواهشا با هم در کمال محبت و احترام متقابل بحث و مجادله کنید.

 

[Amir Mohsen]

ببخشید وسط حرف دوستان میپرم... من یک انتقاد دارم از روش برخورد تهاجمی هادی خان .. نمیدونم این سبک ادراه اینجا درسته یا ن؟؟!!

اصلا کسی جرات نداره بالای حرف دوستان حرفی بزنه چون بلافاصله با برخرود چکشی و حذفی جوابش داده میشه !!

آخه مطالبی ک دیشب من گذاشتم چ مشکلی داشت که تمام اونا حذف شد !!! من الان باید چ جوری این صحبتم رو ب ادمین برسونم ؟؟

من تو صحبتام ب کی و چی مگه توهین کردم یا حرف بدی زدن ک الان شاهد حذف پستام باشم !!!!

آقای احمد زاده خواهشا جوابگو من باشید !! یکجوراییخودرایی و دیکتاتوری راه افتاده تو بخش هواشناسی ... تمنا دارم جلوی این خودرای رو بگیرید !!!

حرفای ما حرف نیست فقط اینا میتونن حرف بزنن !!!!!

به نام آذادی بیان ادمین جواب من رو بدین ؟؟؟

مطالبی که شما دیشب مطرح کنید جزء محتوای اسپم محسوب میشد و قانون میگه که باید از صفحه اصلی منتقل بشن .

 

[ali_kermanshah]

بازگشت قدرتمندانه پرفشار سیبری

 

[DR WHO]

Home » Science & Research » Climate & Weather » Arctic Oscillation
Arctic Oscillation Analysis and Forecasts
AER scientists provide researchers and enthusiasts real-time insights on one of North America’s and Europe’s leading drivers for extreme and persistent temperature patterns. Authors Judah Cohen, Ph.D., and Jason Furtado, Ph.D., work at Atmospheric and Environmental Research (AER), a division of Verisk Climate.
Do you want to be notified when there's an update to this AO analysis? Use this form and put "AO updates" in the field labeled Requests or Comments.
[h=3]January 15, 2015[h=4]Summary

• A positive AO will continue for the next week along with a positive North Atlantic Oscillation (NAO). Meanwhile, higher in the atmosphere, the polar vortex remains perturbed following a sudden stratospheric warming (SSW) event which peaked a week ago. Further perturbation of the polar vortex is predicted, at least in the near term.
• Extreme cold over the Central and Eastern US in the near term should relax to seasonably mild by the end of the week into early next week. Overall mild temperatures will continue across northern Eurasia including Europe.
• The downward propagation of negative AO conditions in the stratosphere should begin to influence the tropospheric circulation in about a week. Therefore, we anticipate positive AO conditions to trend more negative the second half of January. This will promote more high latitude blocking and colder temperatures hemispherically for the remainder of the month. The biggest change should be felt across northern Eurasia including Europe, where temperatures should turn significantly colder from what has been observed so far this month.
• Prospects for a negative AO remain fairly high into February given the recent and ongoing weakening of the stratospheric polar vortex, though some uncertainty on timing and the eventual strength of the negative AO state still remains.

[h=4]ImpactsPositive AO conditions will weaken over for the next week as a negative trend in the AO has commenced. With the positive AO seasonably mild temperatures are expected in the near term for both Eurasia and eventually North America.
However after about a week we expect that the sudden stratospheric warming (SSW), which peaked the end of the first week of January but is still evolving in the polar stratosphere, to be an important influence on the tropospheric circulation. The SSW remains the current best predictor of the AO and therefore Northern Hemisphere surface temperatures next month and is heavily weighted in our winter forecast of surface temperature anomalies. The downward propagation of the negative AO conditions from the stratosphere into the troposphere should cause a shift in phase of the tropospheric AO. Timing of this change is now seen towards the middle of next week. There is uncertainty to the AO forecast mostly due to the persistence of low pressure in the Barents-Kara seas region. Still surface temperatures are predicted to respond as if the AO will turn negative with the biggest impact and change across northern Eurasia, including Europe. The exact location, amplitude and duration of the coldest temperatures are dependent on further distortions of the polar vortex.
[h=4]Recent and Very Near Term ConditionsThe AO is currently positive but will trend back towards neutral and even negative by next week before possibly turning positive once more based on the latest GFS forecasts (Figure 1). The North Atlantic Oscillation (NAO) will also have the same negative trend (not shown). We feel that the predicted negative trend is likely related to the ongoing SSW. Past research has shown that the surface AO turns negative approximately two weeks after the AO turns negative in the middle stratosphere (i.e., 10 hPa) so the timing of the predicted negative trend in the surface AO is consistent with past research.

In the near term with the AO still positive and the tropospheric polar cap heights (PCH) neutral to cold in the troposphere (Figure 2), there is an absence of high latitude blocking. Therefore temperatures look to be near seasonable across the Northern Hemisphere continents, as true Arctic air remains confined to high latitudes. Though slightly below normal temperatures will persist across the Eastern US with above normal temperatures across northern Eurasia including Europe.

[h=4]Near Term
1-2 weekThe weakened stratospheric polar vortex is clearly visible in the PCH plot (Figure 2) with the dominance of high/warm PCH in the stratosphere this month. The SSW resulted from a strong upward pulse of Wave Activity Flux (WAF) in late December (Figure 3). The vertical WAF is predicted to be relatively quiet over the coming two weeks, but with the stratospheric polar vortex already perturbed it does not require much wave driving to keep the polar vortex perturbed. The GFS forecast of cold PCH throughout the stratosphere and troposphere predicted this period (Figure 2) is not consistent with past SSW events and we expect that forecast to change with future runs. Instead we expect that the circulation anomalies, which have already occurred in the stratosphere (i.e., warming near the pole and cooling in the mid-latitudes), to start manifesting in the troposphere this period. For comparison we composite the PCH from the surface to 10 hPa based on high minus low October Eurasian snow cover extent October through March (Figure 4). Based on extensive snow cover a SSW warming or stratospheric negative AO is favored in early January, which occurred this winter. Following the SSW a high/warm PCH and a negative AO are favored in the troposphere from late January through February.

The GFS mid-tropospheric circulation forecast for the period predicts below normal heights across northern Eurasia including Europe and higher heights across the North American Arctic, consistent with negative AO circulation anomalies (Figure 5). Further perturbation of the stratospheric polar vortex may yet still determine where the coldest temperatures occur.

The models predict that temperatures will turn briefly milder across the central and eastern US over the weekend before turning colder once again next week. However we feel that the most significant change in the sensible weather this period will be a significant cool down across northern Eurasia, including Europe. Northern Eurasia is the region with the strongest relationship to the phase of the AO. So far this month the AO has remained strongly positive and hence temperatures have been mild across northern Eurasia. However as the AO turns more negative next week, we expect the coldest weather of the winter season to commence across northern Eurasia, including Europe.

[h=4]3-4 weekTypically following a SSW, the AO turns more negative in the lower stratosphere and eventually throughout the troposphere within 2 weeks. The negative phase of the tropospheric AO is then favored for 1-2 months following a SSW. Though the warming is only defined as a minor SSW based on the WMO definition of SSWs, the SSW did result in a daily-record warm temperature in the stratospheric polar cap at 10 hPa and thus is a significant event in the stratosphere. The operational models predict that the polar vortex will remain perturbed in the near-term with recovery possible during this period. Therefore, we expect a negative bias in the near-surface AO, which should lead to increased frequency of high altitude blocking and cold temperatures across the Northern Hemisphere continents this period.
One caveat in this long-term AO forecast involves the current hemispheric circulation pattern. So far this winter, deep low pressure in the Barents-Kara seas has persisted, and models have had a very difficult time predicting its evolution. This feature is more associated with a positive AO/NAO than a negative AO. Hence, should this feature persist even longer, the transition to the negative phase of the near-surface AO would be difficult (it destructively interferes with a canonical negative AO circulation pattern). The models once again are predicting for the polar low in the Barents Kara seas to be absorbed into polar lows in the more climatologically favored regions of Eastern Siberia and Hudson Bay (Figure 5). We have seen this movie before with the Barents-Kara seas polar low only to return. However the ongoing SSW favors a change in the pattern more so going forward than has been observed so far this winter.
[h=4]Longer Term
30–dayBased on the SSW in early January, we continue to favor the negative state of the near-surface AO into middle and the end of February. This would increase the chances for more cold air outbreaks across northern Eurasia including Europe, and Central and Eastern North America during February. We have included our seasonal forecast for Northern Hemisphere temperature anomalies for January, February and March 2015 (Figure 6) that was issued in early December. We continue to favor the overall cold forecast as averaged for the season, though observed temperature anomalies can deviate regionally and temporally through the season (e.g., the anticipated cold spell coming to Europe following a seasonable to seasonably mild December and early January).

[h=4]Winter AO Outlook
Arctic Sea IceThe largest negative departures in Arctic sea ice extent continue to be observed in the Bering Sea (Figure 7). Sea ice continues to remain near normal extent in the Barents-Kara seas region or even slightly below normal. The ice anomalies have been concomitant with generally high pressure over the North Pacific and low pressure across the North Atlantic and Barents-Kara Seas area, respectively. Whether there is an ocean-atmosphere feedback in place is unknown, but so long as the atmospheric pattern remains as such, the contribution will be toward a more neutral AO state.

[h=4]El Niño/Southern Oscillation and the Pacific BasinWeak Central Pacific El Niño conditions persist (at least in the ocean – atmospheric coupling has been indiscernible with this event) with a positive PDO-like sea surface temperature (SST) pattern in the North Pacific (Figure 8). The El Niño event has peaked and is weakening now.

More importantly, the MJO is presently in a very strong Phase 6 for this time of the year and expected to move into Phase 7 but weaken in magnitude (Figure 9). The response of this will be for a deepening trough across the Northeast Pacific and ridging over North America. Thereafter, the forecasted neutral MJO conditions at the end of the period will remove its influence on the jet stream, likely allowing for high latitude forcing to have more influence heading into February.
[h=4]

[h=4]Northern Hemisphere Snow CoverSnow cover extent is just off its highs for both North America and Eurasia and typical of this time of year (Figure 10). Hemispheric totals are higher than they were last year, thanks to growth in snow cover across Eastern Europe and even parts of North America. In the short term milder weather could result in a contraction of snow cover across the United States. However, with colder temperatures expected in a about a week for both continents, snow cover could extend further on both continents.
[h=4]

[h=4]Quasi Biennial Oscillation (QBO; unchanged from previous discussion)Winds in the lower tropical stratosphere (e.g., 50 hPa) continue to trend more negative (i.e., easterly) and should continue that trend over the next month or two, while the easterly winds have peaked in intensity at 30 hPa. The easterly QBO signature continues to be favorable for changing the tropospheric wave guide and keeping wave energy anomalously directed toward the polar stratosphere. This element was a factor in producing the minor SSW and may still play a role in any future wave driving if it materializes. Note that signs of the westerly phase of the QBO are already appearing higher in the stratosphere and will propagate downwards over the next 6-9 months.
[h=4]Temperature Anomaly AnimationBelow we show the daily temperature difference between those with observed high October Eurasian snow cover minus low October Eurasian snow cover from September 1 through February 28 in degrees Celsius. Temperature differences are shown in shading and those differences that are found to be statistically significant are outlined by a black contour. This is not meant to be a forecast but instead shows the general progression of the temperature anomalies across the Northern Hemisphere based on October Eurasian snow cover variability alone.

 

[DR WHO]

In the past, a combination of a positive PNA and negative AO has been a frequent one during 4 inch or greater snow storms that have impacted D.C. Below is a scatter diagram showing the PNA and AO indices for each 4 inch snowstorm from 1950 through 2010. Note that the majority occur when the PNA index is positive and AO is negative. With that in mind, I’ve leaned towards above normal snow chances for week that runs through Jan. 29.

​

The bottom line is that no prolonged warming is likely before the end of the month. However, next Thursday or Friday could climb into the 40s or even 50s if a storm tracks to our north or temperatures could remain seasonal or even a little below normal if that same low passes to our south. Once that low and its front passes by, the chances of getting another shot of Arctic air increases. If the mean patterns being forecast in the longer ranges by the European and NCEP ensemble are in the ball, always a big if, our snow chances should rise before the end of the month.

 

[golil]

امشب و فردا انشاء الله بارش خوبی در شمال شرق داشته باشیم همه چیز مهیا است هوا هم عالی برای بارش

 

[Amir Mohsen]

هشدار کاهش شدید دمای هوا
حداقل دمای 8- و 9- برای قوچان و بجنورد برای سردترین ساعات فردا توسط اپلیکیشن موبایلم.

 

[Amir Mohsen]

هشدار کاهش شدید دمای هوا
حداقل دمای 8- و 9- برای قوچان و بجنورد برای سردترین ساعات فردا توسط اپلیکیشن موبایلم.

 

[DR WHO]

Has warming Arctic made the jet stream wavier?

High above our heads an atmospheric river of air, known as the jet stream, directs the weather patterns down below. In recent years there’s been speculation that climate change is altering the movement of the jet stream. Now a US study supports the idea that the ​

jet stream has started to meander more as the Arctic has warmed

, and that this meandering increases the chances of persistent weather patterns and extreme events.​

 

[Amir Mohsen]

Has warming Arctic made the jet stream wavier?

High above our heads an atmospheric river of air, known as the jet stream, directs the weather patterns down below. In recent years there’s been speculation that climate change is altering the movement of the jet stream. Now a US study supports the idea that the ​

jet stream has started to meander more as the Arctic has warmed

, and that this meandering increases the chances of persistent weather patterns and extreme events.​

هرچه دمای هوا در قطب شمال گرمتر میشود جت استریم مواجتر میگردد و در نتیجه الگوهای آب و هوای و پدیده هلی اکستریم جوی تداوم بیشتری پیدا خواهند کرد.

 

[abtinT]

سال های ابی زیر هم مثل امسال هست. از اول مهر تا اخر دی بسیار کم بارش بود. (شهر تهران )
باید بگردم ببینم چه چیز مشترکی وجود داره .
این سال ها یک نکته هم داره در بعضی از سالها مثل سال 1340-1341 تا اخر دی فقط 33 میل بارش داشتیم ولی بهمن ماه 100 میل و فروردین 130 میل باریده و اون سال از خشکی در امده و پر بارش شده.
1334-1335
1340-1341
1341-1342
1344-1345
1345-1346
1346-1347
1375-1376
​

​

 

[DR WHO]

In Depth Winter Outlook 2014/2015

• A mean negative Arctic Oscillation (AO) throughout winter of around -1. (AO description here.)
• Positive height anomalies to the north leading to significant high latitude blocking.
• A weakened stratospheric vortex with a Sudden Stratospheric Warming (SSW) likely around the turn of the year leading to a very disturbed tropospheric polar vortex and negative NAO around this time.
• A southerly displaced jet stream. (Jet stream tutorial.)

Chart 1 Expected Winter NH 500hPA anomaly


Chart 2 Expected winter jet stream anomalies


Chart 3 Europe temperature anomalies


Chart 4 Europe precipitation anomalies


The key considerations that this forecast has been based upon are outlined below and will be discussed in more detail in turn. The detail here is pitched at the enthusiastic amateur level – those who would like further discussion please join the Netweather forum:

• Stratospheric Conditions – descending eQBO which should lead to a more responsive polar vortex especially when linked to:
• ENSO conditions – a weak to moderate El Nino likely.
• Eurasion Snow Cover Extent(SCE) and Snow Advance Index(SAI) relative to 60ºN during October – this is well above average leading to an increased likelihood of increased wave activity flux propagating into the stratosphere.
• Solar Output – Currently experiencing a reduced solar maximum compared to previous cycles but solar flux levels leading into winter uncertain.
• Autumn Arctic Sea Ice levels – slightly below average leading to slightly increased possibility of a negative AO.
• Pacific and Atlantic Sea Surface Temperature Anomalies (SST’s).
• GLAAM state – the atmosphere has shown El Nino tendencies that are likely to increase throughout the winter.
• Other factors that are currently being studied such as the experimental October Pressure Index (OPI) – likely to be negative which has a high correlation with a negative AO, the Taymyr Peninsular Circulation Anomaly (TCA) during October and the sea level pressure anomalies over the Pacific during October.

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[h=5]Stratospheric ConditionsKey Considerations - SSW highly likely this winter.
The stratosphere is the level of the atmosphere situated approximately 10-­‐50km above us and is known to influence the weather patterns experienced in the layer below – the troposphere – and therefore the type of weather that the Northern Hemisphere and we in the UK will experience. A basic tutorial can be found here. (And more advanced reading here)
The polar stratospheric conditions preceding and during winter are arguably the most important in determining the wintertime tropospheric conditions. There are a number of factors that contribute to the strength and position of the stratospheric vortex during winter. These range from tropospheric Eurasion snow conditions during the preceding autumn to the tropical stratospheric wind strength and direction and the solar activity. This year the tropical stratospheric wind – the Quasi Biennial Oscillation is in an easterly direction and is descending at peak strength towards the troposphere. These are very favourable conditions for warmer stratospheric conditions to persist in the polar stratosphere. A warmer polar stratosphere will lead to better tropospheric conditions for high latitude blocking to occur which increases the chances of cold pushed towards the UK. Occasionally a dramatic and severe warming of the stratosphere can occur – known as a Sudden Stratospheric Warming (SSW). When this occurs the stratospheric vortex can breakdown completely and this can lead to dramatic tropospheric affects with strong and prolonged high latitude blocking persisting for a period of time in the troposphere. This is when the most severe cold outbreaks can occur.

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[h=5]JanuaryJanuary is likely to start with the continued cold theme (or become cold if the stratospheric wave break hasn’t occurred yet). The risk of significant snowfall is most likely during these weeks of winter. The early winter Scandinavian block will fade as a more west based negative NAO becomes established. The cold will slowly fade in intensity as often in these situations, the block that prevented the westerly winds from reaching the UK moves west, allowing milder Atlantic air to break through. There still exists the possibility of further cold intrusions during this time before the stratospheric vortex reorganizes and influences the troposphere again.
Charts 36 and 37 Jan NH 500hPa heights and 850hpa temperature




The overall temperatures for January are likely to be below average for the start of the month before recovering later – I think that the better guides this year will be the 850 temps which show a below average month overall.
Charts 38 and 39 Euro temp and 850hPa temperature Jan




Precipitation is likely to be around average with the east coast wetter than the west - remember some of this is likely to fall as snow early in the month and the east is likely to hold onto the colder temperatures for longer than the west.
Chart 40 Euro Jan precipitation chart

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[h=5]FebruaryFebruary is probably the most difficult month to forecast. At this point there are indications that the Scandinavian block is likely to become re-established. If the stratospheric polar vortex is yet to reform in the lower part of the stratosphere, then the possibility remains that a further cold outbreak is possible as cold continental air will never be too far away. In fact, if it does then the possibility remains that any cold spell in this month could deliver the coldest conditions of the winter. This scenario can be highlighted by looking at the 500hPa anomaly chart below:
Chart 41 NH Feb 500hPa chart


However, if the stratospheric vortex is gaining strength at this time, then initially settled conditions should prevail before the westerlies become re-established.
Overall the temperatures will be around average and the month is likely to start be drier than average as any early cold spells are likely to be countered with later milder weather and more rainfall expected towards the end of the month.
Charts 42 and 43 Feb Euro temp and precipitation charts

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[h=5]Winter OverallOverall, we are likely to see a winter that starts off slowly, but gains momentum as the stratospheric vortex is destroyed by tropospheric wave activity. This will significantly increase the risk of a cold and snowy spell in the heart of winter, which will then slowly fade as the stratospheric vortex slowly recovers.
Final chart

 

[DR WHO]

The expected stratospheric conditions during winter can be determined by looking at previous years when similar conditions have also existed, but before we look at these it will be best to look other influences that can affect the stratosphere.
Already we are seeing the stratospheric vortex this autumn that has been highly disturbed and affected by tropospheric wave events. We consider it as if ripening up nicely for an SSW!

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[h=5]Eurasion Snow Cover Extent (SCE) and Snow Advance Index SAI during the month of October.Key Consideration - very high SAI and SCE values increase the chance of stratospheric feedback and the risk of a SSW
Through the work of Cohen et al, it has been shown that the amount of snow cover over the Eurasian land mass during the month of October and more importantly the rate of gain of this snow cover is important in determining the likely following winter pattern. This is due to a feedback mechanism where high SAI levels in particular, lead to high levels of wave activity flux activity transferred to the stratosphere, leading to a warmer stratosphere that is prone to a SSW from planetary wave breaking.
Typical 500 hPA anomaly patterns can be seen below:
Chart 5 High SAI years


Chart 6 Low SAI years


Chart 7 High SCE chart


Chart 8 Low SCE chart


This year we have seen an incredible gain of Eurasian snow cover coupled with the second highest SCE and SAI on record. This is likely to lead to increased planetary wave activity and and a disturbed tropospheric and stratospheric polar vortex. We have already seen evidence of this throughout November with numerous wave attacks on the polar vortex transmitted into the stratosphere.
Chart 9 SCE chart


Chart 10 Snow departure chart


Cohen has shown that high SAI years exhibit a November 500hPA anomaly pattern as seen below.
Chart 11 Cohen Nov pattern

Courtesy of Cohen paper JoC

This pattern matches the 500hPa anomalies that have been seen during November so that increases confidence moving forward that we are more likely to see a similar winter pattern similar to the high SAI years.

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[h=5]ENSO ConditionsKey Consideration – Neutral to weak El Nino conditions to persist with the atmosphere showing more El Nino charactersitics.
The temperature of the tropical body of water in the Pacific Ocean stretching from the Americas to Asia can fluctuate from year to year. When warmer water upwells from deeper in the Ocean then we have a phenomenom known as an El Nino and when colder water upwells we have a La Nina.
Chart 12 El Nino Pacific Diagram


This can affect the temperature locally to those areas, but also can alter the state of the whole global atmospheric circulatory pattern. The atmospheric component of the Southern Oscillation can be measured in an index (the SOI) and is computed from the fluctuations between the surface air pressures between Tahita and Darwin, Australia.
This year we are seeing conditions where warmer waters have upwelled and even though El Nino criteria have not been met, the atmospheric response is expected to behave as if an El Nino has occurred. The leads to tropospheric wave patterns that have a higher chance of occurring during the winter months and can also lead to stratospheric conditions more favourable for a SSW.
Charts 13 and 14 ENSO forecast chartsCharts 13 and 14 ENSO forecast charts

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[h=5]Autumn Arctic Sea Ice LevelsKey consideration – below average ice will reinforce any meridional pattern
One of the latest areas of research involves how the autumn minimum extent of Arctic sea ice can affect the possible pressure patterns in the following winter. Lower arctic sea ice minimums have become more prevalent in the last twenty years and it has been suggested that the jet stream takes a more meridional course in years when this is so. Composite anomaly charts show a significant difference between years when Arctic sea ice is comparatively high when compared to years when Arctic ice is close to record low. This year has been another with well below average Arctic sea ice when compared to the average.
Chart 15 Graph of Arctic Sea Ice Extent


This is likely to lead to a pressure pattern over the Arctic during winter similar to the low ice year chart below and somewhat reinforces a picture already being painted.
Chart 16 Low Arctic Sea Ice years


Chart 17 Arctic High Sea ice years

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[h=5]Solar OutputKey Consideration – Solar maximum of cycle 24 just peaked, but maximum sunspot activity vastly reduced when compared to previous cycles.
The sun is the earth’s source of energy and the energy that the sun gives out varies over an 11 year cycle, known as the solar cycle. These cycles can vary in intensity with differing peaks and troughs. Currently we are in and have just passed the peak of cycle 24. This cycle is very much less intense than other recent cycles, with lower sunspot numbers and reduced intense solar flux.
The mechanisms regarding how the intensity of a solar cycle can affect the climate and short term weather patterns are still being explored, but previously, longer term minimum solar outputs have coincided with colder periods. The intensity of the solar flux over a shorter term has also been explored and has been shown to affect the stratospheric ozone circulatory pattern – the Brewer Dobson Circulation. This is the mechanism that contributes to the amount of polar wintertime stratospheric ozone– increased levels of ozone lead to a warmer stratosphere and this to a less pronounced polar stratospheric vortex. There has been a link proposed that bursts of increased solar radiation may affect the top levels of the stratosphere by energetic particle forcing and that this can result in an increase in strength of the polar vortex. The levels of solar activity when linked with the ENSO and stratospheric state can given an indicator of how responsive the stratosphere will be to warming mechanisms and a possible SSW. Currently solar activity is slightly higher than one would expect to trigger a SSW, however, this signal is likely to be overridden by others being discussed that are highly suggestive of a SSW.
Chart 18 Solar Cycle 24

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[h=5]Atlantic Sea Surface TemperaturesKey Consideration -Atlantic tripole set up is conducive to –ve NAO
Studies have shown that the surface temperature anomalies of the Atlantic Ocean during October can influence the following winters pattern. This year we have seen the following pattern over the North Atlantic with an area of slightly cooler surface water sandwiched between warmer areas. Perhaps the hint of a tripole!
Chart 19 Atlantic Current SST pattern anomaliesChart 19 Atlantic Current SST pattern anomalies


This type of tripole pattern is slightly more conducive to a negative NAO and won’t be antagonistic to a high latitude block in a position. A negative NAO is more conducive to cold air reaching the UK.
Chart 20 Negative NAO pattern

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[h=5]Pacific SST'sAutumnal Pacific SST's and pressure patterns and suggest that a negative EPO and positive PDO are likely to become established during the winter. This type of pattern would be favourable to a more meridional flow leaving the Eastern Seaboard of the US. This would reinforce any blocking in the Atlantic sector.

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[h=5]Global Wind Oscillation (GWO)The forecast weak El Nino is likely to engage with the atmosphere in the coming weeks. This has been seen by rising tendency in global AAM in the last 3 months which will help deliver a base El Nino state that is expected this winter.

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[h=5]October Pressure Index (OPI) patternKey Consideration – Negative OPI leads to negative AO pattern.
It has been proposed by a group of Italian Scientists that the tropospheric pressure and wave pattern during October can have a bearing on the following winter pressure and wave pattern. They have created a formula known as the October Pressure Index that measures both the pressures and wave angulation across the northern hemisphere during October. The value of this index can then be applied to the AO of the following winter and has a proposed very high correlation rate. This winter the OPI has a value of -2.12. Projections of negative OPI years suggest the following pattern:
Chart 21 Negative OPI chart


Chart 22 Neutral/Positive OPI


This research is yet to be peer reviewed and until it is, it should be treated with some amount of caution, however, it should be noted that the OPI has a strong relationship with the SAI index and has a similar methodology to the Taymyr peninsular Circulation Anomaly. The above chart suggests a winter with a strongly negative AO and southerly displaced jet stream.

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[h=5]The Taymyr Peninsula Circulation Anomaly (TCA)Key Consideration - Negative AO favoured
A recent study into the pressure anomalies experienced over the Taymyr peninsular of north Russia has shown a linkage between these anomalies and the following winter AO. Less storm tracks crossing this area during the month of October (shown as positive 500hPa anomalies) have been shown to lead to a winter with a more negative AO.
As we can see from the following anomaly chart there has been a positive anomaly over the area and this is likely to again reinforce the idea of a negative AO this winter.
Chart 23 October 500hPa anomaly chart

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[h=4]Forecast ElementSo we can now start to put all the information together and start to formulate anomaly charts that can cover the winter period in a little more detail.
We shall start with the stratosphere. To recap we have seen during October strong Eurasian snow gain that is already feeding back to the stratosphere through vertical wave flux activity (WAF). This is likely to lead to warm stratosphere and culminate in a SSW. The timing of the SSW is not precise and we would propose that it is likely around the end of December or the start of January. However, the WAF is forecast to be so strong that it is not beyond the realms of possibilities that an even earlier SSW could be experienced.
The late December/ early January SSW thought is supported by the comparable year analog composites. We see December start with an already compromised vortex and warmer stratosphere when looking at the 30hPa level and this continues through to January. It takes until February before the stratospheric temperatures finally drop below average with the vortex finally regaining strength and shape.
Charts 24 and 25 Dec 30hPa temp and height anomaly charts




Charts 26 and 27 Jan 30hPa temp and height anomaly charts




Charts 28 and 29 Feb 30hPa temp and height anomaly charts

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[h=5]So how do the stratospheric conditions transfer through to the troposphere month by month?Before looking at the individual winter months it is worth looking at what pattern would we have expected this November and is it shaping up to expectations. Here is the latest (at the time of writing) November 500hPa anomaly chart:
Chart 30 Nov 14 to date


We can see that a four wave pattern exists, with positive height anomalies over Alaska and Scandinavia.
Chart 31 Forecast Analog Nov 500hPa anomalies


When looking at our chosen comparable years and also the Cohen November anomaly chart above we see that there is a good match and I think that this will improve further with the expected pattern throughout the rest of November.
So if we forward this pattern then we can forecast what is likely to occur overall for winter and the expected pattern each month.

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[h=5]DecemberDecember is likely to start with a similar pattern that is being experienced during November but with some subtle differences. The Scandinavian block is set to continue to dominate during the first part of the month though is likely to retreat slightly more into Russia. However, the jet stream is likely to veer further south as the month progresses elongating and stretching the North Atlantic polar field. This will then slowly allow heights to build further north to the northwest of the UK until eventually a block is formed in this area. This will create an environment for any wave breaking into the stratosphere to create a SSW. At that point towards the end of the month, the UK will be at the mercy of polar air and a cold spell will develop. The length and timing of the cold spell will be determined by the extent of the stratosphere polar vortex collapse but at this point it is expected to last well into January. A negative NAO will eventually become established.
One can see when looking at the December 500hPa anomaly chart the overall pattern to be expected.
Charts 32 and 33 Dec NH 500hPa heights and NH 850hPa Temperature




Troughing is expected to dominate initially over and then to the south of the UK and this will dig further south towards the end of the month. Overall the temperature of the month is likely to be around average - any colder spells will be tempered by the above average temperatures forecast for the start of the month.
Chart 34 Euro Dec temp chart


Precipitation is likely to be above average for the south and below average for the north.
Chart 35 Euro Dec precipitation chart


The one proviso here is that this likely pattern could be accelerated or delayed depending upon the success of the stratospheric wave break. Any significant wind events are likely to be early enough the month as the jet stream becomes invigorated prior to the stratospheric changes.

 

[نیما 68]

سلام دوستان :گل:
بارش باران همینک

 

[entezar59]

الان که در منطقه خواجه ربیع ، امام حسین، رسالت که بودم باران می بارید .

 

[heaven1]

وضع هوای مشهد

هوای حاضر ساعت: ۱۹:۴۵
پیش بینی ۳ روز آینده​

۴° c بارش باران جهت باد: جنوب شرقی​	هوای حاضر | شنبه ۲۷ دی سرعت باد: ۴ متر بر ثانیه, ۱۴ کیلومتر بر ساعت نم نسبی: % ۸۷ دید افقی: بیش از ۱۰ کیلومتر بارندگی 24 ساعت گذشته: صفر میلیمتر بیشینه دما در 24 ساعت گذشته: ۱۱° c کمینه دما در 24 ساعت گذشته: ۲° c
آخرین بروز رسانی: ۱۳۹۳/۱۰/۲۷ ۱۹:۳۰

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