Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1240 PM EST Sat Mar 12 2022
Valid 12Z Tue Mar 15 2022 - 12Z Sat Mar 19 2022
...Overview...
A few waves cross the lower 48 in a progressive pattern that is
active for the Pacific Northwest. A leading southern stream system
will shift east across the Deep South/Gulf Coast Tuesday into
Wednesday before lifting northeast over the Carolinas and off the
southern Mid-Atlantic coast Thursday. The next upper trough will
push inland over the Pacific Northwest Tuesday and dig a bit as it
shifts east over the southern Intermountain West Wednesday and the
southern Rockies Wednesday night before turning east-northeast and
to the Midwest/Great Lakes through Friday. This should make for a
return to wet weather for the south-central at the end of the work
week and the Midwest/Northeast next weekend.
...Guidance Evaluation/Predictability Assessment...
The 00Z ECMWF/UKMET/CMC and 06Z GFS are in excellent agreement
with the strength and timing of the leading southern stream system
through Wednesday before the 06Z GFS (and now the 12Z GFS) becomes
more progressive with the exit off Cape Hatteras Wednesday night.
The GFS remains farther north with the next wave over the southern
Rockies Wednesday night and then is more unified with the northern
and southern stream troughs as that wave shifts to the Midwest
while the 00Z ECMWF/CMC have notable separation. Therefore, a
blend of the four main global models for Days 3 and 4 becomes more
reliant on ensemble means on Day 5 and are majority ensemble means
for 6/7.
...Weather Highlights/Threats...
Ample Gulf moisture will be drawn ahead of the Deep South system
Tuesday into Wednesday, which should combine with sufficient
instability to bring widespread thunderstorms capable of producing
heavy rainfall and locally excessive rain, especially over north
Florida which is an area that received heavy rain over the past
day. Precipitation over the Intermountain West Tuesday
night/Wednesday will weaken as Pacific Moisture is cut off from
the wave. However, as the wave amplifies over the southern Rockies
a moderate return of moisture can be expected from the Gulf of
Mexico which will an emerging and expanding area of rain and
thunderstorms from the south-central to east-central U.S. Thursday
through Saturday, albeit in a pattern with increasing forecast
spread with the progression and strength determined by the
aforementioned interaction of the northern and southern stream
components.
Ridging between the Southeast and West systems will bring
temperatures 10 to 20 degrees above normal to the central/northern
Plains Tuesday. This warm airmass shifts east, reaching the
interior Northeast by Friday.
Jackson
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
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/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml