680
FXUS02 KWBC 051803
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
203 PM EDT Sat Apr 5 2025

Valid 12Z Tue Apr 08 2025 - 12Z Sat Apr 12 2025


...Guidance/Predictability Assessment...

The WPC medium range guidance suite was primarily derived from a
composite blend of seemingly reasonable and best clustered
guidance from the 00 UTC ECMWF/UKMET/Canadian models and
ECMWF/Canadian ensemble means. Forecast spread increases normally
through medium-range time scales and a composite of these overall
compatible guidance pieces tends to mitigate much of numerous
smaller scale system details as consistent with individual system
predictability. This plan maintains good WPC product continuity,
generally in line with machine learning guidance and the National
Blend of Models. Latest 12 UTC guidance overall is in line so far.

...Weather/Hazards Highlights...

Heavy rainfall potential decreases quite a bit going into the
Tuesday and Wednesday time period, with no risk areas necessary for
both the Day 4 and Day 5 excessive rainfall outlooks. With the
exception of some locally heavy showers across portions of the
central and southern Florida Peninsula, the threat of heavy
rainfall should end by Tuesday across the rest of the country.
However, lingering snow is likely across portions of northern New
England through Tuesday evening main surface low departure.

Elsewhere across the country, organzied rain and mountain snow
periods return to especially western Washington and Oregon
courtesy of onshore flow and an potentially amplified series of
shortwave trough passages all next week, but these don`t look like
major events at this time. With downstream propagation of these
troughs, light precipitation chances cross the Northwest then
Northern Plains and Midwest into mid-late next week, but there is
some risk for moderate amounts with runoff issues over the Ohio
Valley given inudated soils from currently ongoing rains. The next
good chance of enhanced rainfall settles over the East Friday and
next Saturday with potential surface low/coastal low development.

In terms of temperatures, much cooler conditions are coming for the
Eastern U.S. after the strong cold front exits the East Coast
by Monday morning. Afternoon highs are likely to be on the order
of 10 to 20 degrees below early April averages on Tuesday and
Wednesday from the Ohio Valley/Great Lakes to the Northeast U.S.,
compliments of the upper low overhead. Readings return closer to
average by late in the week for the East Coast states with the
upper trough lifting out of the region. Meanwhile, a warm pattern
is expected for the Western U.S. through the week with both daytime
highs and overnight lows about 10-20 degrees above average, with
the greatest anomalies over the Great Basin.

Hamrick/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














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