Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
156 AM EST Thu Mar 10 2022
Valid 12Z Sun Mar 13 2022 - 12Z Thu Mar 17 2022
...Overview...
An amplified trough and associated very deep cyclone will be
exiting the East Coast early Sunday with a modified but chilly
airmass behind. Meanwhile, an active pattern looks to return to
the Pacific Northwest with a couple of shortwaves -- the first
moving through on Sunday and the next one Monday into Tuesday. The
first wave will dive southeast to the Gulf Coast and shift across
the Southeast early to mid next week. The second, stronger wave,
will bring a quick atmospheric river to the region before becoming
more positively tilted and slowly make its way across the West
Wednesday into Thursday. In between, upper ridging will build
across the central U.S. and into the Midwest.
...Guidance Evaluation/Predictability Assessment...
Plenty of uncertainty continues surrounding the initial shortwave
into the Pacific Northwest early Sunday. Right off the bat, the
12z/Mar 9 CMC (most recent run at forecast issuance time) was much
flatter than the consensus, resulting in a quicker wave through
the central/eastern U.S., so it was excluded from the medium range
blend tonight. However, the new 00z run did come in looking more
amplified and usable. Models are beginning to come together on the
idea that this wave may split, with northern stream energy moving
into the Midwest/Northeast and amplifying southern stream energy
with a possible closed low over the Gulf Coast/Southeast mid-next
week. Despite this trend, there remains quite a bit of depth and
timing issues, with the GFS consistently the deepest/slowest of
the solutions (although also the first model to pick up on this
idea) and also significantly faster with the northern stream
energy. The ECMWF seems a little more reasonable and more in line
with recent ensembles. The next trough into the West early next
week continues to show ample run to run variability and timing,
but at least decent agreement on the larger scale.
The WPC blend tonight used a blend of the GFS and ECMWF, and
smaller amounts of the UKMET, through day 5. After this, began
increasing contributions from the ensemble means to help mitigate
the details with both the system in the Southeast and the West.
...Weather Highlights/Threats...
A departing and still rapidly deepening surface low out of the
Northeast should continue to bring some gusty winds to northern
New England into Sunday. An arctic airmass will still be in place
across the East through Sunday, with daytime highs Sunday
averaging 10-15 degrees below normal likely. Subfreezing
temperatures are likely Sunday morning as far south as the Gulf
Coast and northern Florida, with record lows possible in several
locations. After Sunday, temperatures in the East should rebound
back to more spring like weather with above normal temperatures
persisting through much of next week.
Meanwhile, rain and mountain snows will accompany the first
shortwave passage this week across the West. As the southern
stream energy amplifies into the Southeast next week, it should
tap Gulf moisture to bring increasing rain and thunderstorms
chances across the Gulf Coast and Southeast Monday-Tuesday, and
maybe into Wednesday depending on the progression of the upper
low/trough. Out West, the second trough early next week looks to
direct an atmospheric river into the Pacific Northwest, bringing
mostly beneficial rainfall and higher elevation snows to western
Washington/Oregon and northern California. Upper level ridging
between these troughs will build across the central U.S. with
daytime highs 10 to 25 degrees above normal by next
Tuesday-Wednesday for the northern/central Plains, which should be
a welcome relief to the very chilly weather there currently.
Santorelli
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