269
FXUS01 KWBC 030801
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Thu Apr 03 2025

Valid 12Z Thu Apr 03 2025 - 12Z Sat Apr 05 2025

...Life-threatening, catastrophic, and potentially historic flash
flood event continues across the Lower Ohio Valley and
Mid-South...

...A couple rounds of significant severe weather expected from the
Mid-South west through the Ozarks and ArkLaTex with very large
hail and strong tornadoes possible...

...Moderate to locally heavy snow showers expected for the
Rockies, with some snow showers spreading eastward into the High
and Northern/Central Plains...

...Well above average, very warm Spring temperatures to end the
week across the Southeast with numerous record-tying/breaking
highs possible...

A powerful Spring storm system will continue to bring the threat
of life-threatening flash flooding and significant severe weather
focused on the Ohio Valley west-southwest through the Middle
Mississippi Valley, Mid-South, and ArkLaTex. A leading upper-level
shortwave within a broader large-scale trough over the
western/central U.S. and accompanying surface low pressure/frontal
system will continue eastward over the Great Lakes and Northeast
today, with a trailing cold front stretching southwestward through
the Mid-Atlantic, Ohio Valley, Mid-South, and into the Southern
Plains. A building upper-level ridge over the Southeast has
brought the progress of this frontal boundary to a halt overnight,
with the boundary expected to remain quasi-stationary through the
region over the next few days. The blocking pattern has also
focused southerly flow of deep boundary layer moisture from the
Gulf along the front which will help to fuel continued rounds of
intense downpour-producing thunderstorms throughout the region,
but with a particular focus centered on the Lower Ohio Valley into
the Mid-South. Storm initiation and movement roughly parallel to
the boundary will lead to repeated rounds of rainfall over the
same areas, including those already hard hit on Wednesday, leading
to significant to extreme rainfall totals over increasingly
saturated soils. A High Risk of Excessive Rainfall (level 4/4) is
in effect Thursday from southwestern Kentucky into western
Tennessee and northeastern Arkansas where the greatest threat for
numerous instances of life-threatening flash flooding exists
following heavy rainfall over the same areas Wednesday. A broader
Moderate Risk (level 3/4) stretches from the Lower Ohio Valley
southwest through the Mid-South with a Slight Risk (level 2/4)
across the broader Ohio Valley southwest to the ArkLaTex where
additional scattered to numerous instances of flash flooding are
possible. Another Moderate Risk is in effect on Friday with the
focus shifting a bit northwestward over the Middle Mississippi
Valley southwest through the ArkLaTex, areas that have not been as
hard hit compared to the Lower Ohio Valley/Mid-South, but are
still expected to see significant heavy rainfall totals and
scattered to numerous instances of flash flooding. A Slight Risk
extends further northeast towards the Great Lakes as well as
southwest into portions of the southern Plains where additional
scattered instances of flash flooding will be possible. Then, on
Saturday, another High Risk is in effect as the focus shifts back
towards the hard hit Lower Ohio Valley/Mid-South. This is a
catastrophic, potentially historic heavy rainfall and flash flood
event, with some locations potentially seeing rainfall amounts as
high as 10-15"+ through the weekend. The additional rounds of
heavy rainfall each day will also raise the risk of catastrophic
river flooding from western Kentucky into northwest Tennessee, and
widespread significant river flooding from the Ozarks/ArkLaTex
through the Lower Ohio Valley. Communities in the region should
prepare for possible long duration and severe disruptions to daily
life.

In addition to the flash flood threat, significant severe weather
will also remain a concern for many of the same locations over the
next couple of days. Embeded shortwaves within the broader trough
will help to bring upper-level dynamic support amidst intense
low-level southerly flow and sufficient instability to support
supercells. The Storm Prediction Center has issued an Enhanced
Risk of severe weather (level 3/5) from the Mid-South west through
the ArkLaTex Thursday for the threat of a few tornadoes, some of
which could be strong, very large hail, and damaging winds. A
broader Slight Risk (level 2/5) extends along the boundary from
the Mid-Atlantic southwest though the Tennessee Valley/Mid-South
and into northern Texas for the threat of large hail, damaging
winds, and a few tornadoes. An Enhanced Risk is also in place
Friday across the Ozarks/ArkLaTex as another round of storms will
bring yet another threat for a few tornadoes, including strong
tornadoes, very large hail, and damaging winds. A Slight Risk
extends from the Middle/Lower Mississippi Valley southwest through
northern and central Texas mainly for the threat of large hail and
damaging winds.

A pair of upper waves and a passing cold front will help support
snow showers over the Rockies as well as bring the chance for some
wintry precipitation to the High and northern/central Plains the
next couple of days. To the north, a northern stream upper wave
dropping south from Canada and accompanying surface cold front
will bring moderate to heavy snows Thursday to the northern
Rockies, as well as a wintry mix of rain and snow spreading
eastward into portions of the northern/central Plains Thursday
into Friday. Accumulations are expected to remain light with any
snows over the Plains. To the south, an upper-level shortwave in
the broader western/central U.S. trough will pass over the Four
Corners region and central/southern Rockies as an area of low
pressure in the lee of the Rockies helps to focus upslope flow
along the mountains. Moderate to locally heavy snows are expected
Thursday into Friday for the regional mountain ranges, with the
potential for some snow for portions of the High Plains along the
Front Range. The cold front to the north will also pass southward
by late Friday and into the day Saturday, bringing renewed
post-frontal upslope flow and additional heavy snow for the
mountains of the Front Range. There is also an increasing
potential for accumulating snow spreading further east across the
Raton Mesa on Friday and across portions of the southern High
Plains on Saturday. Elsewhere, some showers and thunderstorms are
expected across the Northeast Thursday as the lead system passes
through the region. Wintry precipitation will remain possible
further north into northern Maine, with some light snow and ice
accumulations possible. Some lingering snow showers are expected
Thursday over portions of the western Great Basin and into the
Sierra Nevada, with rain showers for southern California.

The amplifying pattern will lead to expanding well above average,
warm Spring temperatures over portions of the eastern U.S. as the
upper-level ridge builds northward, while temperatures will remain
much cooler and below average under the upper-level trough over
most of the western/central U.S. Forecast highs the the next
couple days from southern Texas east through the Lower Mississippi
Valley and into the Southeast will be in the 80s to low 90s, with
numerous record-tying/breaking highs possible. Well above average
temperatures are also forecast from the Lower Great Lakes east
into the Mid-Atlantic/Northeast Thursday as highs rise into the
60s, 70s, and low 80s before a cold front brings more seasonable
temperature mainly in the 60s Friday. Forecast highs from the
Northern/Central Plains into the Interior West will be mostly well
below average, with 30s and 40s expected. Areas of the Southern
Plains outside of south Texas will cool from the 60s Thursday to
the 50s on Friday, while the Desert Southwest will see highs
mainly in the 60s to low 70s. The West Coast will see warmer,
above average temperatures compared to the rest of the West as a
ridge builds northward over the region, with highs in the 60s.

Putnam

Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
$$