Thursday, February 05, 2015

Winter and Spring Battle It Out


The forecast for the very minor snow event over northern Arkansas worked out well.  I'm very impressed with the performance of our new hi-res Futurecast. Our good snows never come from the north.  You must have cold air in place or cold air moving in as a surface low tracks south of the state.

I want to thank you for the feedback in the previous blog post.  It seems many want video blogs and a few like the written ones.  I will continue to do both and that will hopefully keep everyone happy.  I think a good snow for the entire state would be the best for raising every ones spirits.

The Pacific air I have been talking about will flood much of the western half of the country, including Arkansas this weekend, with warmer air.  While I do think temperatures will be well above average, I'm concerned a few clouds may prevent temperatures from reaching their maximum potential.  The models even show this at times with areas of cool in a sea of warmth.  Regardless, the weekend will feature highs in the 60s and maybe even lower 70s.  That enormous Pacific jet will bring almost 18 inches of rain to northern California into the Pacific Northwest.  That's where we want a ridge to be in place to deliver cold air here.  The models do relax that jet, and a ridge does build next week over that area. That will shut off the Pacific moisture and allow the jet to tap into colder Canadian and arctic air.  It does cool down next week, but nothing drastic.  I will watch next Thursday for a stronger cold front.  The GFS is very strong with it and brings in well below average temperatures while the Euro only brings in readings which would be a little below average.  Way too early to tell the strength of it.

Most of the following weather maps are courtesy of Weatherbell.







Surface temperature anomalies show much of the country will be well above average over the next 2-7 days.  All the cold air is locked up in Alaska and Canada.  Look how warm it is over the plains.  That's due to downsloping off the mountains with that strong Pacific jet.

That Pacific jet will scream and 7 day rain totals could reach 18 inches.  This may make news headlines.

In the 7-12 day period, surface temperatures will cool substantially over the eastern half of the country and warm in the western U.S. up to Alaska.  That's the Pacific Jet buckling and ridging taping into colder arctic air.  The cold air drains south and east, that's why we get colder.
11-16 day time period, when Alaska warms, we get cold and that's very evident here.  Temperature anomalies are well below average east and central.  Remember, ridging in the eastern Pacific/west coast is needed to tap into that colder air and that's what is happening here.
Highs Saturday afternoon area in the 60s.
Highs Sunday are in the 60s to near 70, but look at the cooler air south.  That MIGHT be due to some cloud cover.
As stated above, the western ridge goes up next week allowing winter to return.  The GFS here is more enthusiastic compared to the Euro for colder air.  This is late next Thursday with an arctic boundary in the state and a huge contrast from north to south.
This is the GFS and it's much colder than the Euro next Friday the 13th.  It only has highs in the low to mid 30s.  That's quite a change from the 60s this weekend!  It has everything to do with that jet stream changing configuration explained above.

No comments:

NOAA Winter Guidance