Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
247 PM EDT Sun Mar 16 2025

Valid 12Z Wed Mar 19 2025 - 12Z Sun Mar 23 2025


...Snow storm forecast to impact areas from the Central Plains to
Upper Midwest/Great Lakes mid/late this week...

...Unsettled and wet weather forecast for the Northwest...


...Overview...

Over the course of the medium range period, a few different low
pressure systems will move west to east across the lower 48. The
first low pressure system will strengthen in the lee of the Rockies
and track towards the Upper Midwest mid-week, then move across the
Great Lakes and Northeast late this week. A swath of potentially
heavy snow and gusty winds are expected on the northern side of the
storm track from the Central Plains to the Upper Midwest, and
wintry weather is also expected in the Northeast, with the highest
chances in northern New England. Two other low pressure systems are
forecast to move west to east across the nation but be quite a bit
weaker than the first system. This pattern will favor unsettled
and wet weather in the West and periods of precipitation over the
Central and Eastern U.S..


...Guidance/Predictability Assessment...

Model guidance showed good agreement on the overall weather pattern
through the medium range period, with reasonably good agreement on
individual storm systems as well. Deterministic model spread did
increase over the last two days of the forecast period, but
ensemble means remained in good agreement. Overall, forecast
confidence is above average, but there is still some uncertainty in
details late in the period. WPCs afternoon forecast blend was
comprised of near even parts of the GFS/ECMWF/CMC/UKMET, with
slightly more weight on the GFS/ECMWF than the CMC/UKMET, for Days
3 and 4. For Days 5-7, CMC/UKMET contributions were reduced and
ensemble means from the GEFS/ECENS/CMCE were added in increasing
amounts, making up 60% of the forecast blend by Day 7.


...Weather/Hazards Highlights...

The main weather story in the medium range period is the growing
signal for a late season winter storm that may produce blizzard
conditions in the Central U.S. Tuesday and Wednesday. A deepening
low pressure system tracking from the Central Plains to the Upper
Midwest is expected to support a wrap-around heavy snow threat on
the northern side of the storm track, and the tight pressure
gradient around the system will likely produce strong gusty winds
that could create blizzard conditions. There may also be a band of
moderate rain over the Upper Midwest, displaced south of the axis
of heavy snow, but no Excessive Rainfall Outlook (ERO) threat area
has been introduced at this time. This system will push east across
the Great Lakes and the Northeast Thursday into Friday, and some
wintry weather can be expected mainly in northern New England, but
some wintry weather may be possible in the Central Appalachians as
well. The trailing cold front associated with this system will
likely produce showers from the Ohio and Tennessee Valleys to the
East Coast.

Upstream, a series of Pacific low pressure/frontal systems will
move into the West and trigger repeating rounds of precipitation
through next weekend. Moderately heavy rain and mountain snow are
likely in the Pacific Northwest where moisture will be channeled
onshore. While no WPC ERO threat area has been introduced, the
compounding effects of multiple days of precipitation may lead to
local runoff issues. The Pacific systems are forecast to move east
across the Central and Eastern U.S. Friday through the weekend and
may produce some modest precipitation chances.

Well above average temperatures, by 15-25 degrees, will precede
the initial mid-week low pressure system over the Midwest and
Central/Southern Plains. The focus will shift eastward with the
system into the Great Lakes and Northeast on Wednesday and could
linger into Thursday depending on the speed of the trailing cold
front. Temperatures from the Central to Eastern U.S. will be
briefly below average following the cold frontal passage, then
trend back to just slightly above average, by 5-10 degrees, next
weekend. In contrast, temperatures will begin below average across
much of the West then trend close to near average by next weekend.


Dolan/Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw