Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Mon Apr 10 2023

Valid 12Z Mon Apr 10 2023 - 12Z Wed Apr 12 2023

...Unsettled weather to linger over the Northwest; return to the Gulf
Coast by midweek...

...Widespread warm up across much of the Lower 48 ahead of the next cold
front Tuesday...

...Thunderstorm chances continue over the Central and Southern Plains...

As was the story 24 hours ago, rainy and unsettled conditions remain
across the Pacific Northwest as the pattern of moist onshore flow
continues on the northern flank of an upper-ridge building over the Four
Corners. Steady moderate to at-times heavy rainfall should persist across
the Northwest through midweek before northwest flow behind a cold front
brings cool and dry air over the region. Until then, however, additional
areal liquid precipitation totals upwards of 1-2" look like a good bet
across western portions of Washington and Oregon. The persistent rainfall
coupled with relatively high snow levels could support isolated instances
of flooding through tomorrow, where a Marginal Risk (level 1/4) of
excessive rainfall is in effect.

As the Northwest begins to dry out, our focus for the next area of heavy
rainfall shifts toward the Southeast and Gulf States tomorrow into
midweek, with initial locally heavy rains possible through Tuesday over
eastern Florida with post-frontal onshore flow in place. Meanwhile, to the
west, thunderstorm activity is expected to increase in the Central Gulf as
an area of low pressure forms along an old stationary front. By Wednesday,
a frontal system is forecast to lift northeast towards the coastline, with
the current forecast focusing the axis of heavy rain along the southeast
LA and southern MS coastline, although it should be noted a fair amount of
spread remains amongst model guidance with where and when this system
spins up. Regardless, at least isolated instances of flash flooding (level
1/4 on the WPC Excessive Rainfall Outlook) are possible with this system
along the Central Gulf Coast beginning later tomorrow into Wednesday. 

Rainfall aside, much of the Lower 48 will warm up considerably throughout
the week as a strong upper-ridge migrates into the Central U.S. In fact,
by tomorrow daytime high temperatures could near 15-25 degrees above
normal across a fair portion of the Intermountain West into the Plains
which could challenge a few daily records Tuesday and Wednesday. It does
look like this warm-up could be fairly short lived, however, as cooler air
spreads begins to spread southeast Wednesday behind a strong cold front
west of the Continental Divide. Until the cooler air arrives, the warm
weather combined with a few weak disturbances will support scattered
thunderstorm chances across the Plains through tomorrow. A few of these
storms today could be severe, with hail and wind being the main threats
with the activity this afternoon.

Asherman

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