Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
356 PM EDT Mon Mar 27 2023

Valid 00Z Tue Mar 28 2023 - 00Z Thu Mar 30 2023

...Heavy rain with the potential for flash flooding and severe weather
continues in the Southeast...

...Series of frontal systems increase precipitation chances for the
Northeast through Tuesday...

...Chilly temperatures and the chance for snow across portions of the
Plains and Great Lakes...

...Powerful storm system to bring yet another round of heavy snow/rainfall
to California with cooling temperatures...

A slowly-propagating cold frontal boundary currently located across
southern Alabama and central Georgia will slowly move across the southeast
over the next few days, triggering scattered showers and thunderstorms
along the boundary early this week. Anomalously high moisture continuing
to stream northward from the Gulf will help to induce heavy rain rates.
The quasi-stationary nature of the boundary may also lead to repeated,
overlapping storm development and motions, increasing the potential for
locations to see multiple rounds of heavy rain and higher rainfall totals.
A Slight Risk of Excessive Rainfall is in effect over the Florida
Panhandle and southeastern Alabama as these storms continue to produce
heavy rain over this region. Additionally, as a result of the moderate to
strongly buoyant airmass in place to the south of the boundary, there is
the potential for some storms to be severe. The Storm Prediction Center
has issued a Slight Risk for severe weather (level 2/5) over southern
Alabama and Georgia, with the primary severe threats being isolated
instances of strong winds and, with potential for isolated tornadoes. By
Tuesday, an upper-level shortwave will help to push a better organized
frontal system south towards the Gulf, helping to clear out the region and
create more progressive thunderstorms, limiting the severe flooding
threat. However, anomalously high moisture will still be present, helping
to retain the threat of higher rain rates and localized heavy rain. This
led to the upgrade to a Slight Risk of Excessive Rainfall (level 2/4) from
the Central Gulf Coast east into southern Georgia and northern Florida.
High temperatures will generally cool from northwest to southeast through
the early portion of this week across the Southeast. Highs will cool into
the mid-60s to low 70s for most of the region Tuesday as the front finally
pushes southward into the Gulf. The Florida peninsula will still be warmer
than average on Tuesday, with temperatures in the mid-80s before the cold
front pushes through by Wednesday.

The frontal system pushing through the South will also create
precipitation chances regionally for the Northeast. Light to moderate
showers are expected to clear out of the Mid-Atlantic as wintry
precipitation chances increase across the Interior Northeast. Little to no
accumulations of sleet/snow are expected, except for portions of higher
terrain across the Northeast. Highs will generally be seasonable for the
Interior Northeast/New England with 40s and 50s forecast through the early
portion of this week. Over the Midwest, energetic flow aloft will help to
encourage additional waves of low pressure along the Canadian front
trailing through the Great Lakes and into the Plains, increasing
precipitation chances for these regions as well. A few inches of
accumulating snow are forecast to move from the Central High Plains into
the Upper Great Lakes through Tuesday. On Wednesday, this frontal system
will push through the Great Lakes region and into the Interior Northeast
with embedded rain/snow showers and some lake-effect snow. Highs across
the Northern Plains and Midwest will generally be below average as high
temperatures remain in the 40s. Very chilly, much below average
temperatures are forecast for the Plains Monday with highs only in the 20s
and 30s. High temperatures will stay below average through Wednesday for
much of the northern Plains.

Meanwhile, a powerful Pacific storm system will approach the West Coast
Monday night with anomalously high Pacific moisture quickly overspreading
southern portions of the Pacific Northwest and California ahead of an
occluded frontal boundary, bringing yet another round of heavy
coastal/lower elevation rain and mountain snow. The heaviest rainfall is
expected Tuesday along coastal Central California. A Slight Risk of
Excessive Rainfall (level 2/4) is in effect along the terrain of the
coastal mountains, as incoming warmer air acts to raise snow levels and
increase the threat of runoff into downstream rivers, especially as the
entire region remains sensitive to the risk of flooding given very wet
antecedent conditions. Very heavy snow is forecast for higher elevations
of the northern Coastal Ranges and Sierra through Tuesday, with totals of
several feet possible. In addition to the precipitation, gusty winds are
also likely Monday along coastal California and the Sacramento Valley.
This system will remain progressive, and moisture will quickly spread
further inland into the Pacific Northwest and Great Basin on Tuesday. A
mix of rain and snow is expected for lower elevation valley locations with
accumulating snow for the Cascades, Blue Mountains of Oregon, and Sawtooth
Range of Idaho. On Wednesday, precipitation will then spread further into
the Great Basin, with chances of moderate accumulating snow over the
Monitor Range of Nevada as well as mountainous regions of Utah. Despite a
brief period of upper-level ridging expected on Tuesday, high temperatures
will continue to be below average for most of the West through Wednesday.
Highs will be in the 40s and 50s for the Great Basin and Northern/Central
Rockies; 50s and 60s for the Pacific Northwest, northern/central
California, and the Southern Rockies; and 70s to 80s for the Desert
Southwest. A strong frontal passage on Wednesday will reinforce cool
temperatures over portions of the West on Wednesday, cooling temperatures
back into the 40s and 50s across much of California and Nevada.

Putnam/Genz


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