Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
357 PM EDT Tue Mar 28 2023

Valid 00Z Wed Mar 29 2023 - 00Z Fri Mar 31 2023

...Powerful storm system brings more heavy rainfall/mountain snow to the
West with cooling temperatures...

...Heavy rain with the potential for flash flooding tapers off across the
Southeast tonight...

...Chance for light snow across the Great Lakes, followed by a frigid
airmass...

...Snow squalls possible over the Interior Northeast on Wednesday
evening...

A powerful Pacific storm system currently impacting much of the Pacific
Northwest and northern California, bringing in moderate to heavy rain and
heavy snow to the higher elevations. Some areas of locally heavy rain may
impact portions of the central California coast through Tuesday night.
Therefore, a Slight Risk of Excessive Rainfall (level 2/4) has been issued
as terrain-enhanced rainfall will spread into the coastal ranges. This
will increase the risk for runoff into local rivers and the potential for
rapid onset flooding. Antecedent soil conditions also remain very wet
given the repeated rounds of heavy rainfall over the last few months.
Additionally, very heavy snow is forecast for higher elevations of the
northern coastal ranges and the Sierra, with storm-total snowfall likely
be upwards to 1-3 feet by late Wednesday. Winds will also remain rather
gusty Tuesday over portions of California, Nevada, southern Oregon, and
northwestern Arizona. Additional moisture spreading inland over the Great
Basin will bring moderate to locally heavy snow to the Blue Mountains of
Oregon, the Saw Tooth Range of Idaho, and higher elevations of the central
mountain ranges of Nevada. Little to no accumulating snow is expected for
lower elevation valley locations. High temperatures will continue to be
below average for much of the West Tuesday-Wednesday, with highs in the
30s and 40s for the Northern Rockies/Great Basin and the 50s for most of
California. Some high temperatures over the next few days in California
may break or tie the coldest maximum temperature for that date. Highs over
the Pacific Northwest will be closer to average for this time of year,
with much of the region's highs in the upper 50s. Warmer air flowing
northward ahead of the approaching Pacific front will push highs into the
60s and 70s for the Southern Rockies and the 80s for portions of the
Desert Southwest Wednesday. However, a cold front will push across the
region on Thursday, cooling temperatures over Arizona and Utah
significantly. Highs will be in the mid-60's in southern Arizona, and only
in the 30s and 40s to the north.

A quasi-stationary front lingering over the Southeast is forecast to
finally progress offshore overnight Tuesday/early Wednesday morning.
However, in the short term, heavy rain and thunderstorms capable of
producing flash flooding continue across the Southeast. Anomalously high
Gulf moisture residing along and south of the front is helping to fuel
heavy rain rates of 1-2" per hour. The quasi-stationary nature of the
front may result in overlapping storm development and motions that will
contribute to heavier rainfall totals across the region. A Slight Risk of
Excessive Rainfall is in effect for portions of the central Gulf Coast as
heavy rainfall from these storms overlap areas that have already seen
heavy rainfall previously, enhancing the flash flood risk. An upper-level
shortwave will help to push this front south over the Gulf overnight
Tuesday/early Wednesday morning, likely bringing an end to the showers and
thunderstorms that have plagued the region for days. A brief cooling trend
will keep high temperatures in the upper 60s to low 70s for much of the
Southeast before temperatures rise Wednesday into Thursday. In the
Tennessee and Ohio River Valleys, highs will be a bit cooler, with
temperatures in the upper 50s and low 60s expected. Temperatures over the
southern Plains will be similarly below average, before downsloping winds
east of the Rockies over the Southern High Plains will warm temperatures
up into the 70s on Wednesday.

An upper-level shortwave and associated surface frontal system will pass
over the Great Lakes Tuesday night and move over the Interior Northeast on
Wednesday. This front is forecast to strengthen over Michigan Tuesday
evening into Wednesday, with generally light snow accumulations expected
over the Great Lakes. When this system moves into the Northeast,
atmospheric conditions may be conducive to support snow and some snow
squalls across the region, especially Wednesday afternoon and evening. The
highest chances of snow squalls are across interior Upstate New York,
Vermont, and portions of New Hampshire. Brief periods of heavy snow and
gusty winds are possible, followed by rapid drop in temperature, which may
lead to icy conditions on roadways overnight. Toward the west, a cold,
Canadian airmass will push southward into the Central Plains/Upper Midwest
Wednesday following the passage of a cold front, bringing chilly, below
freezing high temperatures. Morning lows will be frigid and well below
average for late March, with temperatures dropping below zero over
portions of northern Montana, North Dakota, and Minnesota Wednesday
morning. Further east, temperatures will be more seasonable. Highs Tuesday
and Wednesday will be in the 40s for the Lower Great Lakes/Interior
Northeast/New England and upper 50s to low 60s for the Mid-Atlantic. The
cold frontal passage Wednesday evening will result in much cooler
conditions across the Northeast, with highs in the 30s and 40s across the
region on Thursday.

Putnam/Genz


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