Heat Builds Out West, Migrates Into Plains, Frost/Freeze Threat For Ohio Valley, East

HeatwaveOver the next couple of days we’re going to see the Southern California system which brought record rains to such areas as Long Beach push into the Rockies and enhance the shower and thunderstorm activity there while on the backside, a ridge is set to build the heat back into the LA Basin northwards as well as out across the Deserts. Meanwhile, the rain and thundershower activity continues for the East with the big upper low, although weakening, will continue to deliver sizable amounts of rain with increased flood potential through the Mid-Atlantic and eventually up into the Northeast and New England.

The latest 5-day QPF model shows the enhanced precip over the Mid-Atlantic up into particularly the Northeast as the upper low pushes out by late week and the weekend but those rains back west into Texas and through the Central Plains is the result of the system now pushing out of California. Notice the drying which takes place over SOCAL. That may be the last ‘system’ rain for the San Fran – LA – San Diego corridor for quite some time and unfortunately the half inch of liquid which fell with nearer an inch in the Coastal Mtns, won’t make a whole lot of difference.

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The models show a large upper ridge developing this weekend which will build north but both GFS and ECMWF indicate a trough trying to dig into the PNW which rather than driving the heat all the way up through western Canada into Alaska, it forces it east, bringing potentially the first 100s to parts of Kansas, Nebraska, possibly even South Dakota early next week.

Another significant trough drops into the Upper Midwest and will drive another cold shot through the Great Lakes, Ohio Valley and eventually the Mid-Atlantic. The Canadian high with clear skies, light winds, cold 850s and dry air would support a significant late season frost and freeze and yet another threat of seeing some ‘coldest so late’ readings to such areas as the Mid-Atlantic and Northeast interior.

Here’s the GFS 500mb chart for Sunday.

Courtesy/Owned by AccuWeather

Courtesy/Owned by AccuWeather

Here’s the 850 temps for the same period (120 hr)

Courtesy/Owned by AccuWeather

Courtesy/Owned by AccuWeather

Given how warm the 850s are over the Great Basin, we’re likely to see record highs here while Sunday night we could see record lows quite easily over the Great Lakes with rural lows dropping well into the 20s.

The night to watch for a damaging frost and freeze threat is Monday night into Tuesday next week as the 850s are comfortably below freezing and with a cold high in place, we could easily see a freeze with lows in the 20s from Vermont, New York down through Pennsylvania, Maryland, western Virginia, West Virginia into the mountains of North Carolina and even Tennessee.

Check out the GFS 850s at 144 hrs.

Courtesy/Owned by AccuWeather

Courtesy/Owned by AccuWeather

While it’s the cold being watch across the interior East early next week. It’s the heat that will be noteworthy from the Desert Southwest, across the Central Rockies into the Central Plains where temperatures may approach 90 for the first time this year in Denver, possibly near 100 for portions of western Kansas up through Nebraska and into southwest South Dakota.

Here’s the ECMWF upper chart for next Monday. Check out how warm the 850s are from Los Angeles to Bismarck.

Geopotential3250032hPa32and32Temperature32at3285032hPa_North32America_144

This is a major early season hot blast if it occurs with 100s maybe even making it into North Dakota and a complete turnaround from earlier runs which pushed the heat all the way up into the Yukon due to a low pushing into Washington and BC. Will be interesting to see if the model holds to this idea because if it occurs, we could well be looking at some exceptionally low numbers over the East for so late in the season while some of the warmest Mid-May temperatures ever recorded may be approached at the same time in the Northern Plains.

Here’s Tuesday, notice the heat continues to get pushes east from the Great Basin into the heart of the Plains as a system drives a strong jet into the PNW.

Geopotential3250032hPa32and32Temperature32at3285032hPa_North32America_168

Will have more on early next week’s weather potential on Wednesday. Stay tuned.

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