Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
347 PM EDT Sun Apr 30 2023

Valid 00Z Mon May 01 2023 - 00Z Wed May 03 2023

...Heavy rainfall and flooding concerns linger across the Northeast into
early Monday morning...

...Significant and long-duration heavy snowfall event expected for the
U.P. of Michigan through Tuesday...

...Cool and unsettled weather spreads into the West Coast, while well
above average temperatures continue across the Intermountain West,
northern/central Rockies, and northern High Plains...

A deep upper-level trough over the Great Lakes and anomalously strong
surface low pressure system expected to swing from the Mid-Atlantic into
the Northeast tonight are forecast to produce unsettled weather into the
start of May from the Midwest to the East Coast. Heavy rain is likely
tonight for much of the Northeast as the strong low pressure system ushers
in a plentiful amount of atmospheric moisture from the Atlantic Ocean. 1
to 3 inches of rain over saturated ground could lead to scattered
instances of flash, urban, and small stream flooding. The greatest chances
for flooding concerns overnight reside over parts of New Hampshire and
southern Maine, where a Slight Risk (level 2/4) of Excessive Rainfall is
in effect. Heavy rain is also possible across eastern Pennsylvania, New
Jersey, the Delmarva Peninsula, and parts of southern New York State into
this evening. As this system pushes into southeast Ontario, Canada on
Monday, breezy, cool, and cloudy conditions are expected throughout the
Northeast into Wednesday. Additional showers are also possible, with the
higher upslope elevations of the central and northern Appalachians
experiencing at least a few inches of snow.

Speaking of snow, a significant spring snowfall event has begun across
parts of the Upper Great Lakes and is expected to continue through
Tuesday. Cold northerly winds on the western side of the powerful low
pressure system combined with a deep upper-level low supplying plenty of
cold air aloft will support additional bursts of heavy-wet snow throughout
the central/western U.P. of Michigan and far northern Wisconsin. Over 6
inches of snow has already accumulated through this morning, with a few
more feet of snow possible by Tuesday. Snow load and gusty winds could
lead to broken tree limbs and power outages. Winter Storm Warnings are in
effect.

Other weather conditions associated with this powerful Eastern U.S. spring
storm include gusty winds across the Midwest and well below average
temperatures throughout much of the eastern half of the Nation. Wind gusts
as high as 45 mph are possible this afternoon and again on Monday across
the Upper Midwest from Minnesota to western Illinois. Meanwhile, the core
of the below average temperatures on Monday and Tuesday is forecast across
the Great Lakes, Ohio Valley, and Interior Northeast. With numerous
clouds, showers, and breezy conditions in place, high temperatures will
struggle to reach out of the 40s in this region (20+ degrees below the
climatological average for the date).

For the western U.S., a cool and unsettled weather pattern is currently
spreading into the West Coast as an upper-level low is forecast to slide
into the region early this week. This will lead to shower and high
elevation snow chances, along with below average temperatures. Further
inland, gusty southerly winds and well above average temperatures are
anticipated for much of the Intermountain West, with warm weather also
spreading into the northern/central Rockies and northern High Plains.
Regions experiencing river flooding due to snow melt across the Great
Basin can expect more significant snowmelt into this week. Additionally,
scattered shower and thunderstorm chances will overspread much of the
Rockies by Tuesday as well.

Snell


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