Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
410 AM EDT Fri Apr 04 2025
Valid 12Z Fri Apr 04 2025 - 12Z Sun Apr 06 2025
...Life-threatening, catastrophic, and potentially historic flash flood
event continues across the Lower Ohio Valley and Mid-South to Lower
Mississippi Valley...
...Additional episodes 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 into the High Plains through Saturday...
...Well above average, very warm Spring temperatures to end the week
across the Southeast with numerous record-tying/breaking highs possible...
Several developing waves of low pressure acting on a stalling frontal
boundary will continue to be the focus for the threat of life-threatening
flash flooding and significant severe weather from the Ohio Valley
west-southwest through the Middle/Lower Mississippi Valley, Mid-South, and
ArkLaTex the next couple of days. Deep moisture pooling along the front
combined with impressive dynamics will set the stage for persistent rounds
of intense thunderstorms capable of producing torrential downpours
throughout the region. This will especially be the case for the Lower Ohio
Valley into the Mid-South and Lower Mississippi Valley, where the
necessary ingredients of moisture, instability, forcing, and wind shear
best overlap. Storm initiation and movement roughly parallel to the
boundary will lead to repeated rounds of heavy rainfall over the same
areas, leading to significant to extreme, potentially historic, rainfall
totals over increasingly saturated soils. High Risks of Excessive Rainfall
(level 4/4) remain in effect through Saturday, highlighting an
increasingly dangerous and life-threatening situation. Outside of the High
Risk, Moderate and Slight Risks also continue to be in place over broader
areas of the Ohio Valley into the south-central U.S. through Saturday
where scattered to numerous instances of flash flooding can be expected.
As has been said repeatedly for the last several days, this has the
makings of 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 repeating rounds of heavy
rainfall each day will also raise the risk of widespread significant river
flooding, including potentially catastrophic major flooding, in the
Ozarks, portions of the Middle Mississippi Valley, and much of the Ohio
Valley. Thankfully, the heaviest rainfall should ease somewhat for the
hardest hit areas on Sunday as the frontal boundary finally begins to push
eastward into the Southeast and Mid-Atlantic; however, major river
flooding is likely to continue into early next week. With the front on the
move, the focus for heavy rainfall shifts eastward into parts of the
Carolinas southward to the Central Gulf Coast to round out the weekend. A
Slight Risk (level 2/4) remains in effect as a result.
In addition to the flash flood threat, additional bouts of significant
severe weather will also be in play for many of the same locations through
the weekend. The same ingredients of moisture, instability, forcing, and
wind shear that are conducive to intense downpour producing thunderstorms
are also supportive of supercells and severe weather. The Storm Prediction
Center has issued a Moderate Risk (level 4/5) for Friday from the ArkLaTex
into southeast Missouri for strong tornadoes, very large hail, and
damaging winds. A broader Slight Risk is in place from Texas through the
Lower Ohio Valley. On Saturday, Slight to Enhanced Risks are delineated
for the Lower Mississippi Valley through the Mid-South and Ohio Valley,
with severe thunderstorms capable of producing strong tornadoes, very
large hail, and damaging wind gusts above 70 mph. Similar to the flash
flood threat, the severe weather risk shifts eastward into parts of the
Mid-Atlantic, Southeast, and southern Appalachians on Sunday, with the
Storm Prediction Center issuing a Slight Risk for the potential for
damaging winds and possibly a few tornadoes.
Farther west, a passing cold front will help support snow showers over the
Rockies as well as portions of the High Plains the next couple of days.
Accumulations are expected to remain light with snows over the Plains,
though a corridor of a few inches of snow could focus in North Dakota. To
the south, an area of low pressure in the lee of the Rockies will help to
focus upslope flow along the mountains, resulting in moderate to locally
heavy snows for the regional mountain ranges on Friday, 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 to spread across portions of
New Mexico and into the southern High Plains later Friday into Saturday.
Drier weather returns on Sunday as high pressure takes control.
The highly amplified flow pattern will lead to well above average
temperatures across the Southeast as an upper-level ridge dominates the
region. Meanwhile, temperatures will remain much cooler and below average
under the upper-level trough over most of the western/central U.S. Highs
the next couple days across the Southeast are forecast to be in the 80s to
low 90s, with numerous record-tying/breaking highs possible. Farther
north, the Mid-Atlantic/Northeast will cool to the 50s and 60s for highs
on Friday, and a cool surface high will take hold in the Northeast
Saturday for below normal highs in the 40s. Some wintry weather can't be
ruled out across northern New England on Sunday either given persistently
cool temperatures on the north side of the front. Meanwhile, forecast
highs across the Plains into the Interior West will be mostly well below
average. Northern and central areas of the Rockies and Plains should see
high temperatures in the 30s and 40s on Friday, and southern Rockies/High
Plains can expect highs that are below average by 20-25 degrees by
Saturday with actual highs falling into the 40s. The West Coast can expect
warmer, above average temperatures compared to the rest of the West as a
ridge builds northward over the region, with highs in the 60s and 70s The
West will continue to warm up on Sunday while cooler air across the Plains
spreads eastward into the Ohio Valley, the Mid-South, and the Lower
Mississippi Valley.
Miller
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php