US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
241 PM EST Thu Jan 21 2021
Valid Sunday January 24 2021 - Thursday January 28 2021
- Heavy precipitation across portions of Southern California, the Central and Southern
Appalachians, the Mid-Atlantic, the Great Lakes, and the Ohio Valley, Mon-Tue, Jan 25-Jan 26.
- Heavy precipitation across portions of the Central Plains and the Middle Mississippi Valley, Mon,
- Heavy rain across portions of California, Wed-Thu, Jan 27-Jan 28.
- Heavy rain across portions of the Lower Mississippi Valley, the Central Appalachians, the
Tennessee Valley, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the
Southeast, the Southern Plains, and the Ohio Valley, Sun-Mon, Jan 24-Jan 25.
- Heavy snow across portions of the Pacific Northwest and the Northern Great Basin, Sun, Jan 24.
- Heavy snow across portions of California, the Central Great Basin, the Pacific Northwest, and the
Southwest, Sun-Mon, Jan 24-Jan 25 and Wed-Thu, Jan 27-Jan 28.
- Heavy snow across portions of the Central Great Basin and the Southwest, Mon-Tue, Jan 25-Jan 26.
- Severe weather across portions of the Lower Mississippi Valley and the Southern Plains, Sun, Jan
- High winds across portions of the Aleutians, Tue-Wed, Jan 26-Jan 27.
The medium range period (Sunday, January 24 to Thursday, January 28) will continue to feature a
fairly typical January weather pattern, with multiple areas of potentially impactful wintry
precipitation. Starting with the end of this upcoming weekend and early next week, upper-level
energy is expected to eject out of the Southwest and into the south-central United States. This
will help increase moisture transport from the eastern Pacific and western Gulf of Mexico. Combined
with an approaching cold front, the expected atmospheric set up will allow for potentially heavy
rain from far eastern sections of the Southern Plains, throughout much of the Tennessee and Ohio
valleys, as well as into the southern Appalachians. There are high probabilities of greater than 1
inch of rain for these areas, with potential local amounts greater than 2 inches. On the northern
periphery of the precipitation shield there is the potential for impactful snow and freezing rain.
This includes areas from the Midwest to Northeast. At the moment, confidence is highest across the
northern Mid-Atlantic and an area spreading from far northeast Kansas to northwest Illinois
regarding impactful wintry precipitation between Monday and Tuesday. A stripe of heavy snow could
also stretch between these regions across the Upper Ohio Valley and Lower Great Lakes, but
confidence is low on exactly where this occurs. Along and east of the central Appalachians, cold
air should remain in place long enough to support snow, sleet, and/or freezing rain from the
Shenandoah Valley to central Pennsylvania. Further north, the northern edge of the precipitation
shield will likely be sharp and snowfall amounts will drop off significantly across northern
Pennsylvania and the Tri-State Region. Be sure to check back for the latest forecast as slight
adjustments are likely over the next several days. By next Thursday, forecast models are starting
to converge on yet another winter storm threat that could impact the Ohio Valley and Mid-Atlantic.
Given it is still seven days out and confidence is low, no areas were added to the hazards chart
Much needed precipitation will continue to impact the Southwest and West Coast during the medium
range forecast period thanks to a persistent upper-level trough. Heavy snow will be found from the
Cascades to the Sierra Nevada between Sunday and Monday. Heavy precipitation will make it as far
south as Southern California, with rain along the coast and snow across the Transverse and
Peninsular ranges. Heavy snow will also be a concern Monday and Tuesday across the Mogollon Rim in
Arizona, as well as higher elevations in Utah and Nevada. By Wednesday, there is the potential for
an atmospheric river across northern California that may meander southward by Thursday. This could
lead to several feet of snow across the central and northern Sierra if forecast trends continue,
with 1 to 2 inches of rain possible in the lower elevations. There is still considerable spread
with the location and timing, as the axis of heavy precipitation could be delayed until late
Across Alaska, temperatures are forecast to remain well above average throughout western portions
of the state Sunday and Monday. By Tuesday, a potent low pressure system is expected to enter the
Bering Sea and could produce high winds along the Aleutian Islands through Wednesday.
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