The Weather Prediction Center

College Park, MD


Extended Forecast Discussion




Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
159 AM EST Fri Feb 03 2023

Valid 12Z Mon Feb 06 2023 - 12Z Fri Feb 10 2023

...Guidance/Predictability Assessment...

Guidance solutions only seem reasonably well clustered aloft into
Monday as an trough moves through the East and a stengthening
trough digs into the West, with ridging in between. Differences
grow quickly with the subsequent evolution of the western trough.
Two general forecast scenarios seem to exist in guidance with
recent GFS/Canadian runs showing run to run stream separation
leading to an upper low closing off in the Southwest/northern
Mexico Tuesday-Wednesday that is stronger then slower to eject
downstream through the east-central U.S. next week compared to the
ECMWF/UKMET. Ensemble members by and large showed similar
progression trends as their parent models with the
GEFS/Canadian/NAEFS ensemble means less progressive than the ECMWF
ensemble mean. This remains a difficult emerging split flow
forecast with low predictability, but still suspect that a
solution on the less progressive side of the full envelope of
guidance makes more sense given much guidance does develop a
separated southern stream system of which often are on the slow
side to eject. The WPC medium range product suite was accordingly
derived from a composite blend of the 18 UTC GEFS mean and 12 UTC
NAEFS/ECMWF ensemble means, given uncertainty of model details, to
accomodate this along with WPC continuity and the 01 UTC National
Blend of Models. The latest 00 UTC model runs do now show a
significant slowing trend from the ECMWF/UKMET, bolstering
forecast confidence to a degree.

...Weather/Hazard Highlights...

A couple of rounds of light precipitation are expected to pass
over the Midwest/Great Lakes into the Northeast early next week
with northern stream dominated shortwave passages and approaching
modest/lead frontal low/system. Areas downwind of the Lakes may
have higher amounts than surrounding locations due to lake
enhancement. Showers are possible along the Eastern Seaboard with
some moisture return by Sunday from Florida into the eastern
Carolinas and eastern parts of New England, but any heavier
amounts look to remain offshore.

For the western states, moderate precipitation is expected to
overspread the West Coast to portions of the Intermountain
West/Rockies by early next week. In general lower elevations
coastal areas will have rain while areas farther inland/higher
elevation will receive snow; with typical terrain enhancement
across the coastal ranges and the Sierra Nevada. Then
precipitation could overspread the central U.S. by Monday-Tuesday
along and ahead of a low pressure/frontal system. The details of
this precipitation including placement and precipitation type
remain uncertain given the model differences. The current forecast
shows enhanced rainfall amounts centered across the Southern
Plains and Lower Mississippi Valley and surrounding areas by
Tuesday-Wednesday with enhanced low/frontal system induced return
Gulf of Mexico moisture inflow. The WPC experimental excessive
rainfall outlook (ERO) will be highlighted by an emerging
"marginal" risk area Tuesday into Wednesday. There is also some
potential for snow/ice again on the northern periphery of the
expanding precipitation shield across portions of the southern
Plains to Midwest and interior Northeast next week, but this is
subject to change with future forecasts. Subsequent eastern
Pacific system approach Tuesday/Wednesday should offer modest
system amplitude and associated moisture/rainfall potential across
the Pacific Northwest along with terrain/mountain snows inland
from the Northwest through the northern Great Basin/Rockies.

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, experimental excessive rainfall
outlook, winter weather outlook probabilities and heat indices are
at:

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

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Last Updated: 159 AM EST FRI FEB 03 2023