| Welcome to Natural Hazards Forum. We hope you enjoy your visit. You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile, sending personal messages, and voting in polls. Registration is simple, fast, and completely free. Join our community! If you're already a member please log in to your account to access all of our features: |
| June 2012: First 10-15 Days Supports Trough/Chill But Could Warmth Return Mid-Month For E. North America & W. Europe? | |
|---|---|
| Tweet Topic Started: 3 Jun 2012, 06:21 PM (27 Views) | |
| Audi-Tek | 3 Jun 2012, 06:21 PM Post #1 |
|
June 2012: First 10-15 Days Supports Trough/Chill But Could Warmth Return Mid-Month For E. North America & W. Europe? .![]() This ECMWF NAO Bias chart off Policlimate.com shows the negative NAO but a forecast to turn more positive towards June 16th. JUNE COULD HAVE SIMILARITIES TO MAY WITH COOL, DAMP FIRST HALF, FOLLOWED BY A WARM SECOND HALF We’ve just came off a positive NAO (North Atlantic Oscillation) which followed a cold first 18 days of May on the heels of a super wet April. By glancing at the chart on the left off Policlimate.com we can clearly see the relationship between where the NAO went positive, which supported ridging and warmth and where it went negative, troughiness and cool/unsettled.Notice the strong positive in March, that of course was when western North America was cold while central and eastern areas was off the scale warm..We too here in the UK saw record warmth with Scotland experiencing three all-time record March highs in a row while it was very cold still over eastern Europe. Before this surge of stunning heat, check out the tanking into negative at the close of February. Remember the short return to winter in eastern North America but the super chill over Europe? There is many who debate why North America appeared to be the focal point of last winter’s warmth while large swaths of Asia extending into much of Europe which saw a bitter second half to winter 2011-12.Most recently you can see back to last month where it was cold to start and warm to end, this is reflected beautifully in the flip from a negative to positive NAO.The return positive following negative around May 16-20 meant for repositioning of the north Atlantic trough and ridging both over central/eastern North America as well as over Western Europe. We really did have a terrific spell between May 20-28 and this was actually the longest May warm spell since 1992 according to Nick Miller of the BBC. We all know, whether your here in the UK/Ireland or eastern North America that we’ve seen a return of the troublesome trough and cool, more unsettled weather, this looks set to stay for at least the first half of June given the NAO and forecast ensembles (an ensemble is a collection of various different models and their all blended together to create a general consenses).Many ask, when are we set to see a return to that glorious warm spell and the return to ridging over eastern North America? Well, given the fact we’ve seen decent warm and settled spells during postive NAO’s, well Id say we’re looking for a return to + and do we see that on the horizon? The ECMWF forecast for the NAO (left) does show a flip towards at least neautral by around mid-month, until then heights are stronger across the north while heights are lower underneath. Until you flip the balance, we here in Western Europe and eastern North America will continue to stay cool and periodically unsettled.During this period, any high pressure which visits in between and around areas of low pressure will be of the cool variety, therefore heights are low there will be a feed of chilly air out of the north, so despite sunshine it’s not going to be anything like what we saw last week. The good news is that it’s June and not March and with short nights and a high angle sun, it should feel warm though nights can get cool. If we get a return to a positive by June 16 onwards, we may see a return to positive heights over the mid-latitudes and negative heights further north. Notice in the below chart off the Penn State E-Wall site, showing current surface pressure and thicknesses for today. The strongest heights are over Greenland and the pole while lower heights are to the south, keeping W Europe, the central Atlantic and E North America unseasonably cool the low heights dominating the mid-latitudes including eastern US, central Atlantic and W Europe while strongest heights are over top. ![]() To summerise, I believe a cool and at times unsettled first 16 days of June could see a return of warmth and settled conditions for the last 10 days of the month which may even the monthly average to near normal following a below normal start over eastern NA and western Europe. Source ............... http://www.markvoganweather.com/europe/2012/06/03/1678/ |
![]() |
|
| 1 user reading this topic (1 Guest and 0 Anonymous) | |
| « Previous Topic · Forecasting Model Discussion · Next Topic » |








8:18 PM Jul 11