…Wet snow along the Sierra Nevada, parts of the Great Basin today, and
then the northern Rockies Sunday night into Monday…
…Heavy rainfall and snowmelt expected to raise concern of flooding for
portions of the northern High Plains of Montana today…
…Outbreak of severe weather, including strong tornadoes, expected for
portions of the Midwest/Plains Monday…
…Much below average temperatures across California, the Great Basin, and
the Southwest with much above average temperatures spreading from the
Plains into the Midwest/Southeast…
Our ongoing active Spring weather pattern across the U.S. will bring
increasingly active weather into the mid-section of the country as we head
into the new week. First of all, a low pressure system is slowing down
its forward motion across New England this morning. Colder air wrapping
around the slowly-departing system could change the rain to wet snow for
the higher elevation in the interior sections of northern New England
today. All precipitation should gradually taper off tonight as the system
moves farther away into the Canadian Maritimes. Meanwhile,
a more compact and energetic upper-level low moving onshore into
California this morning will kick the entire system inland, bringing
additional snowfall for the higher elevations of the Sierra Nevada
followed by mixed rain/snow across the Great Basin today. By Monday, the
upper low will head toward the northern Rockies and begin to interact with
a cold front dipping south from Canada into Montana. This interaction
will set off a period of snow mainly across southern Montana into northern
Wyoming from Sunday night into Monday where as much as 6-12″ of
accumulations can be expected. Accumulating snowfall should be limited to
higher elevations but heavy rain is also expected to fall over areas of
slightly lower elevations in close proximity, leading to concern of
snowmelt and flooding for portions of the northern High Plains of Montana.
From Monday into Tuesday morning, an elongated low pressure system is
forecast to track across the northern Plains. This system will result in
a blossoming area of rain and embedded thunderstorms across the region
this evening, spreading into the upper Midwest on Monday. A cold
northerly wind will become strong and gusty from Montana to North Dakota
while a warm and gusty southerly wind strengthens through much of the
southern and central Plains to the south of the system. The threat of
severe thunderstorms will be much increased tonight across the
northern-central Plains ahead of the intensifying system and a trailing
cold front. The Storm Prediction Center indicates a slight risk of severe
thunderstorms to extend from northern Texas through the central Plains,
increasing to a moderate risk across the upper Mississippi Valley where an
outbreak of severe weather, including strong tornadoes, is expected. A
broader Enhanced Risk extends into the Mid-Missouri Valley where very
large hail, damaging winds, and tornadoes will also be possible on Monday
and Monday night. By Tuesday morning, the low pressure system should
begin to exit the upper Great Lakes. Colder air surging south from Canada
could change the rain to wet snow across portions of the upper Great Lakes
along with gusty winds.
Elsewhere, very dry conditions, warm temperatures, and strong, gusty winds
have prompted concern of critical to extreme fire weather danger from New
Mexico to the southeast corner of Arizona and far western Texas. The deep
upper-level trough over the western U.S. as well as a corresponding
upper-level ridge intensifying over the central/eastern U.S. is leading to
an increasing dichotomy in well above average and below average
temperatures for the remainder of this weekend and into next week. Well
above average temperatures over the Plains today will expand eastward
across the Midwest and Southeast on Monday, with the
Northeast/Mid-Atlantic also seeing above average highs. California, the
Great Basin, and the Southwest will see another day of well below average
highs today before conditions moderate closer to average on Monday. Areas
of the Pacific Northwest and northern Great Basin will remain at or above
average.
Kong/Putnam
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
