Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
345 PM EDT Mon May 01 2023

Valid 00Z Tue May 02 2023 - 00Z Thu May 04 2023

...Heavy snow will persist across Upper Peninsula of Michigan through
early work week...

...Well-below-average temperatures spread from Great Lakes/Midwest into
Northeast/Mid-Atlantic on Wednesday, with snow chances in higher terrain...

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

A late-season snowstorm is currently ongoing across portions of the Upper
Great Lakes as a very strong, nearly stationary upper-level low pressure
system churns over the region. In addition to this system causing near
record-low pressures during the month of May, it is also responsible for
bringing a very cool airmass over the region. Surface temperatures under
this area of low pressure range from 10-20F below average, cold enough for
snow to fall over this area. Gusty, northerly flow on the backside of the
strong surface low in conjunction with cold air being pushed southward
will lead to additional snowfall of 4-8", locally 1+ feet over higher
elevations of Michigan's Upper Peninsula. Near-freezing surface
temperatures will result in falling snow being wet and heavy, which may
result in downed trees and power lines. On Tuesday, the snowfall coverage
will diminish as this system begins to weaken and exits toward the east.
Temperatures are expected to gradually warm throughout the week, with
seasonal temperatures expected for the area by late-week.

Conditions across the Mid-Atlantic and Northeast are expected to be drier,
but cooler after the widespread heavy rainfall over the weekend. The
heaviest axis of precipitation will progress northward from far northern
Maine into southern Quebec Monday night, leaving drier conditions in its
wake. However, the low pressure system located over the Great Lakes will
gradually propagate east-southeastward toward the Northeast this week,
bringing its very cool airmass along with it. While temperatures will be
below average to begin the week, it will get even colder. By Wednesday,
surface temperatures will be particularly cool as the upper-level low
slowly moves across Upstate New York. High temperatures will only in peak
in the 40s and 50s over much of the Northeast and Mid-Atlantic on
Wednesday, which is 15-20F below average. In addition to the cool
temperatures, the main band of precipitation is expected to wrap around
the south side of the upper-level low on Monday/Tuesday, bringing rain
chances into the Ohio River Valley and into portions of the
Mid-Atlantic/Northeast. While most of the precipitation will fall as rain,
some areas, particularly at higher elevations, are expected to see
accumulating snow as well. The Central Appalachians are expected to see
the most snow, with snowfall totals ranging from 6-10", with locally
higher amounts possible.

In the West, an unsettled weather pattern is entering the area as an
upper-level low pressure system propagates southward along the West Coast.
Initially, impacts will be confined to areas west of the Sierra Nevada and
portions of western Oregon/Washington. The main impacts will be well-below
average temperatures, scattered showers, and higher-elevation snow. This
system will progress southward along the West Coast during the early-week.
By mid-week, this system will begin propagating eastward into the Desert
Southwest and portions of the southern Rockies, cooling down temperatures
significantly across the region. For portions of the Intermountain West
and central/northern High Plains, well-above average temperatures are
expected this week, with many highs over the area in the 70s and 80s.
Conditions will be mostly dry across this region, minus a chance of
scattered thunderstorms over portions of the northern/central Rockies on
Tuesday. Regions in the Great Basin that are experiencing river flooding
due to rapid snow melt can expect more significant snowmelt this week
given the warm temperatures overspreading the region.


Genz


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