Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
342 AM EDT Mon Mar 13 2023

Valid 12Z Mon Mar 13 2023 - 12Z Wed Mar 15 2023

...There is a Moderate Risk of excessive rainfall over parts of
California...

...Heavy snow over parts of the Northeast and the highest elevations of
the Cascades, Sierra Nevada, and the Northern Rockies...

...A Nor Easter will develop along the Northeast Coast...

Upper-level energy over the Great Lakes will move eastward off
Mid-Atlantic Coast by Tuesday. The system will produce light to moderate
snow across portions of the Great Lakes, Ohio Valley, and the Central
Appalachians through late Tuesday afternoon.

Meanwhile, low pressure off the southern Mid-Atlantic Coast will deepen
rapidly as the Great Lake s upper-level energy moves towards the coast. As
a result, the storm will produce rain over parts of the Mid-Atlantic Coast
and showers/strong to severe thunderstorms over parts of the Southeast.
Therefore, the SPC has issued a Marginal Risk of strong to severe
thunderstorms over parts of the Florida Peninsula. The hazards associated
with these thunderstorms are frequent lightning, severe thunderstorm wind
gusts, hail, and a minimal threat of tornadoes. The rain ends along the
Mid-Atlantic Coast and the thunderstorms over the Southeast overnight
Monday.

Furthermore, overnight Monday, a coastal low pressure will strengthen
rapidly into a major Nor Easter that significantly impacts the Northeast
beginning later Monday night through Wednesday. Heavy snow rates (2 inches
plus per hour) and strong winds will produce dangerous to impossible
travel. The heavy-wet nature of the snow, combined with max wind gusts up
to 50 mph, will result in scattered to widespread power outages and tree
damage. Similar impacts could be felt along the I-95 corridor from New
York City to Boston. In addition, March Nor Easters tend to favor the more
elevated terrain for receiving the heaviest snowfall totals. Snowfall
totals greater than 12 inches are expected in the Catskills and southern
Adirondacks in New York State, Berkshires and Worcester Hills in
Massachusetts, Monadnocks and White Mountains in New Hampshire, and
southern Green Mountains in Vermont. Localized maximum totals of 24-30
inches are possible. Widespread minor coastal flooding and beach erosion
may be possible through Wednesday as the low pressure stalls and deepens
off the coast of New England.

In the meantime, onshore flow will produce coastal rain and highest
elevation snow over parts of California and the Pacific Northwest through
Wednesday. The storm will produce rain in low elevations and foothills and
snow at high elevations from Northern to Central California and northwest
Nevada and Oregon. The rain and snow will intensify late Monday into
Wednesday, creating considerable flooding impacts below 5000 feet
elevation across much of the California Coast and Central Valley and over
the southern Sierra Nevada foothills into Wednesday.

The additional heavy rain and snowmelt will result in more widespread
flooding from Tuesday into Wednesday, particularly in low elevations and
areas with increasing temperatures impacting snowpack. Creeks and streams
will continue to be vulnerable to flooding from additional rain and
snowmelt. Another round of heavy snow, measuring in feet in the higher
elevations in California, particularly the Sierra Nevada, will further
compound snow load impacts and issues.

As a result of the heavy rain, the WPC has issued a Moderate Risk of
excessive rainfall over portions of Northern California and southwestern
Oregon through Tuesday morning. The associated heavy rain will create
numerous areas of flash flooding. Furthermore, many streams may flood,
potentially affecting larger rivers.

On Tuesday, the heavy rain continues. Therefore, the WPC has issued a
Moderate Risk of excessive rainfall over parts of Central/Southern
California through Wednesday morning. The associated heavy rain will
create numerous areas of flash flooding. Furthermore, many streams may
flood, potentially affecting larger rivers.

Moreover, on Monday, a front will move onshore over the Pacific Northwest
and inland to the Upper Midwest by Wednesday. As the front passes, the
snow levels will low over the Northwest and snow will move into parts of
the Northern Intermountain Region and parts of the Northern Rockies
overnight Monday into Tuesday. The storm will create heavy snow over the
highest elevations of the Cascades, Sierra Nevada, and the Northern
Rockies through Wednesday.


Ziegenfelder


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