Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
148 AM EST Fri Jan 17 2020
Valid 12Z Mon Jan 20 2020 - 12Z Fri Jan 24 2020
...Overview...
Progressive upper pattern will take the western/eastern
ridge/trough couplet eastward next week which will bring back
ridging to the East later in the week. A system will push through
the Pacific Northwest Tuesday and reorganize over the southern
Plains by Thursday and into the Lower Mississippi Valley next
Friday. This could increase the threat of some heavier rain to the
region in an otherwise quieter pattern between storms.
...Guidance/Predictability Assessment...
The flow out of the Pacific continues to be hard to resolve in the
shorter wavelengths, most evident in the GFS and its lack of
consistency. Even in the other models, none has been much better
than average. The ensembles, at least, have shown better
continuity but at the expense of detail. The ECMWF ensemble mean
has been less prone to changes than the GEFS mean, but both have
shown trends in recent runs toward a more amplified yet still
progressive pattern. Preferred the ECMWF-led cluster of solutions
rather than the GFS, which was close to the GEFS members, stemming
from 1) a different handling of the Pacific flow and therefore
downstream shortwave timing and 2) a sharper flow out of eastern
Canada in the GFS vs others. GFS did come back into general
agreement by next Thu/Fri with a system in the southern Plains
though on the northern side of the multi-center ensemble spread.
...Weather/Hazard Highlights...
Troughing east of the Rockies early in the week will favor below
normal temperatures especially over the Upper Midwest/Corn Belt
(owing to new snowfall in the short term) but also to the Gulf
region and through Florida. Above normal temperatures in the West
and Rockies Mon/Tue will slide eastward to the Plains on Wednesday
then Great Lakes/Midwest Thursday and to the East Coast Friday.
Precipitation will be limited in the East to around the Great
Lakes and across southern Florida early in the period as the
system comes into WA/OR and northern California. Modest lower
elevation rain/higher elevation snow Tuesday will be followed by
lighter precipitation Wednesday before increasing again next
Thu-Fri with another Pacific front. By next Wed-Thu, Gulf moisture
should increase rain chances over Texas northward and
northeastward as a front approaches the area from the northwest.
Some wintry precipitation may be supported on the northern fringe.
Should the system tap enough Gulf moisture, some heavy rainfall
will be possible along the northwestern Gulf coast into the
ArkLaTex.
Fracasso
Additional 3-7 Day Hazards information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, 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/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml