Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
221 AM EDT Thu Mar 17 2022
Valid 12Z Sun Mar 20 2022 - 12Z Thu Mar 24 2022
***Strong low pressure system will likely produce heavy rain and
severe storms across portions of the southern U.S. by early next
week***
...Overview...
A rather active weather pattern will be developing across much of
the nation beginning this weekend, and particularly into the
beginning of next week as a deep upper level trough develops over
the Intermountain West as Pacific shortwave energy moves inland.
This will likely evolve into a closed upper low by Monday along
with an intensifying surface low over the central/southern Plains
that will eventually result in heavy rain and severe storms from
Texas to the Deep South by the middle of the week. There will
also be a well organized storm system exiting the Northeast U.S.
Sunday ahead of the central U.S. event.
...Guidance Evaluation/Predictability Assessment...
The 00Z model guidance suite is generally in above average
agreement through Monday night with the overall synoptic scale
pattern and the evolution of the main upper level trough/closed
low over the Rockies and Southern Plains. Model differences
become more apparent as the upper low begins lifting out and
evolving into a positively tilted open wave feature by the middle
of the week, with the CMC considerably slower and keeps the trough
axis in place longer across the Plains, whereas the GFS and ECMWF
indicate a northern stream shortwave amplifying the trough over
the Great Lakes and Ohio Valley region by Thursday. The models
are still struggling with the arrival of shortwave energy crossing
the northern periphery of the upper ridge over the West Coast
later in the period that would affect the Pacific Northwest, with
the past few runs of the GFS differing the most from the model
consensus.
Taking these factors into account, the WPC forecast was primarily
based on a multi-deterministic model blend as a starting point
through Tuesday morning, and then incorporated more of the
ensemble means whilst still maintaining smaller contributions from
the ECMWF/GFS/CMC going forward through Thursday.
...Weather Highlights/Threats...
The surface low over the Northeast on Sunday will likely be
accompanied by some lingering snow showers across northern
portions of New England, and then drier weather commences for this
region in time for the beginning of the work week. Attention then
turns to the Plains and Gulf Coast region as a surface low becomes
better organized by late Monday over northern Texas/Oklahoma and
taps into a surge of Gulf moisture across Texas and the central
Gulf Coast region. There is a strong model signal for episodes of
heavy rainfall that could result in instances of flash flooding,
mainly later in the day Monday and especially into Tuesday and
persisting into early Wednesday. The best prospects for this
would be from the ArkLaTex region to the southern Appalachians.
There is also an increasing threat of severe thunderstorms with
favorable dynamics and instability parameters in place, mainly
across eastern Texas and the lower Mississippi River valley. The
Storm Prediction Center has additional information pertaining to
the severe weather potential.
In terms of temperatures, highs are expected to be well above
average across most of the central and northern Plains and
Midwest, with highs up to 25 degrees above average on Sunday.
There will also be a surge of humidity across the Gulf Coast
region ahead of the cold front from the central U.S. low. Warm
weather returns to the West Coast region for the Tuesday through
Thursday time period as an upper ridge builds in behind the
departing trough. Some below average readings are likely across
the Rockies and western High Plains for early in the week in
association with the upper trough, but no major surges of arctic
air are expected.
Hamrick
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml