Significant Warm Surge Follows Coldest April Open In Years For USA

untitledWhile April may bring one of the coldest openings in 20 years for parts of the Canadian Prairies and US, spring DOES appear to be on the horizon according to the models but it’s going to get colder before it get’s warmer. Patience has been key throughout March and in fact winter this year never really got going until February. What was lost in December, January was certainly made up for during February and March and when combining these two months, it wouldn’t surprise me if it’s the coldest period in many decades for central and eastern Canada and the US.

A Look Back At February-March

There have been plenty of cold February’s in the past 10-20 years especially back in the 1990s but the Marches have tended to be warmer than normal and combine a colder than normal February with an even colder March and this may be the coldest back end’s to winter since the 1970s. In terms of putting this March into perspective, March 1996 stands out, March 87 even more so and these may BOTH be beaten by March 2013 and so one has to likely go back to the 1970s to find a March which can compete with this year. Of course here in Europe it has been even worse with the coldest since 1962 in the UK and just this morning, a low of 9.5F was recorded in the village of Braemar, NE Scotland breaks the 1986 record for the UK’s coldest Easter Sunday on record.

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The bitter March on both sides of the Atlantic can be blamed on a deeply negative AO and NAO and to look even deeper as to what may have triggered these exceptionally low indexes, perhaps it’s down to the unusually low solar activity. The AO dislodged the motherlode of arctic air into the mid-latitudes and this exceptional late season cold has been directed right across Europe and central/eastern Canada and United States by a strongly negative NAO which produced a sold and prolonged blocking high over the North Atlantic and Greenland. The persistency has been quite remarkable.

While many of you are asking, when the heck will we see spring warmth? For those in the Desert Southwest, you see the warmth first, late weekend into next weekend (of course it’s been warm down here in recent days but this will be the warmest to date). As for the Plains and East, the warmth builds into the early part of the following week, starting April 8th.

However, we must get through the first half of this week and highs of 10-20 below normal.

Here’s the latest NCEP GFS 500mb ensemble mean out at 72 hours (Tuesday)

m500z_f072_ussm

The ECMWF 500mb and 850mb chart coincides well with this last gasp arctic blast.

Monday

Geopotential3250032hPa32and32Temperature32at3285032hPa_North32America_24

Tuesday

Geopotential3250032hPa32and32Temperature32at3285032hPa_North32America_48

Wednesday

Geopotential3250032hPa32and32Temperature32at3285032hPa_North32America_72

That is certainly a healthy blast of arctic air. This may well break early April records for both highs and lows but the good news is that as stated already, warmth is coming. It starts in the Southwest late next week with temperatures rising potentially into the 90s for Los Angeles, 100s for both Las Vegas and Phoenix. We may even see the first 110-degree reading in Death Valley.

It’s as a storm system and trough begins to push onto the West Coast next weekend that we begin to see this ‘build up’ of heat slide east. This setup will pump warmth from the Deserts across the southern Rockies and from Mexico into the Southern Plains and so we’re likely to see the first widespread 90s extend from Texas up through western Oklahoma and Kansas, perhaps extending into Nebraska. The first surge of 100s are likely for West Texas.

Between April 8 through 12, while the West Coast trough slides east into the Great Basin, heat across the Southwest lifts out and from Texas, late-spring, early summer warmth surges northeast into the Ohio Valley and eventually the East. Don’t be surprised to see 80s up through Kentucky, Ohio and the interior Mid-Atlantic, 70s for the Big Cities by mid to late week.

Here’s NCEP 500mb ensemble mean for April 9. Note the trough replaces warmth over the Southwest, shifts the warmth east, This is a complete reversal from what we’ll see this week and over the past few.

m500z_f240_ussm

Here’s the ECMWF chart for the week starting April 8th.

Monday April 8

Geopotential3250032hPa32and32Temperature32at3285032hPa_North32America_192

Tuesday

Geopotential3250032hPa32and32Temperature32at3285032hPa_North32America_216

Wednesday

Geopotential3250032hPa32and32Temperature32at3285032hPa_North32America_240

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