…A storm system over the central U.S. today will create chances for
severe thunderstorms, and gusty winds along the Gulf Coast…
…Heavy rain and flash flooding potential exists throughout the central
and eastern Gulf Coast over the next few days…
…Powerful Pacific low pressure system to impact the Northwest with high
winds and heavy mountain snow, while an atmospheric river takes aim at
northern California by Wednesday…
An amplified weather pattern and two separate strong storm systems will
impact the Nation during the first half of this week. First, a deep low
pressure system is ejecting northeastward across the Plains. Moderate to
heavy rain and gusty winds will occur across the Plains for the remainder
of Monday. The Storm Prediction Center has much of the Central Plains
under a Marginal Risk for severe thunderstorms as an isolated strong wind
gust or spin-up tornado remain possible. The south-central Gulf Coast has
a higher severe weather threat because of more favorable parameters such
as abundant moisture and instability; a Slight Risk for severe weather is
active and threats include strong winds and a couple of tornadoes. The
severe weather threat will shift eastward and lower to a Marginal Risk,
but much of the eastern to central Gulf Coast may have conditions to still
support a strong wind gust or a tornado or two.
Now for the flooding threat with this system, the highest risk areas will
be over Louisiana through Monday and the central and eastern Gulf Coast,
including the Florida Panhandle, on Tuesday. These regions are under a
Slight Risk for Excessive Rainfall as high precipitable water,
instability, and possible training of storms may yield 2-3 inches of
rainfall with the right set-up. Scattered flash floods are most likely
throughout low-lying and urban regions.
The second notable weather system will be the strong area of low pressure
across the Pacific Northwest. The Weather Prediction Center has the region
from the Pacific Northwest to northern California under a Marginal
Excessive Rainfall Outlook on Tuesday as a band of heavy rain moves in
along a cold front entering the region. On Wednesday, the flooding threat
greatly increases; a Moderate Risk for Excessive Rainfall is in effect as
flooding is likely. 6-8 inches of rainfall could fall alone on Wednesday
as a strong flux of moisture from the Pacific trains over the region due
to a nearly stationary area of strong low pressure out in the Pacific.
Areas in terrain may maximize QPF, some of which may be in the frozen
variety as mountain ranges in the Northern Rockies, northern California,
and the Cascades in Oregon and Washington could see feet of heavy,wet
snow. This snow may be impactful for hazards. The Winter Storm Severity
Index has some ranges in the Major to Extreme impacts, with power outages
and downed trees some of the specific hazards. Another notable threat with
the system is the strong winds associated with a deepening area of low
pressure. Many coastal regions are under a Storm Warning for wind gusts
over 70 mph and possible coastal flooding hazards.
As for the rest of the country outside these two dynamic systems, the east
coast should be relatively warm with temperatures about 10-15 degrees
above average into Wednesday. Highs go from the 50s in New England, the
60s and 70s across the Mid-Atlantic, and a progressively warmer and more
humid airmass in the Southeast and Florida with highs in the 70s and 80s.
Out west, a reinforcing shot of cold air will funnel in behind a cold
front clearing the Rockies this afternoon. High temperatures will be in
the 30s and 40s from the northern Plains to much of the intermountain West
and lows will fall to the single digits in this cold air mass in the
typical cold spots. The Desert Southwest and Southern California will much
warmer than their western neighbors, as highs should still manage to be
quite mild in the 70s.
Wilder
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
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