Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1200 PM EDT Wed Oct 23 2019
Valid 12Z Sat Oct 26 2019 - 12Z Wed Oct 30 2019
...Overview and Guidance/Uncertainty Assessment...
The model spread is significant during the extended period. For
nearly a week, the GFS solution has been consistently progressive
with energy tracking across the CONUS. This continues to be the
case with this morning's cycle and the NAEFS and Ensemble means
are in this camp as well. The CMC and UKMET solutions are closer
to the ECWMF and the its ensemble means where it has a deeper and
slower progression of the low/trough exiting the Southwest into
the central U.S. Therefore a compromise of those 4 pieces of
guidance was utilized in this forecast issuance. The nearly +3
height anomaly over Alaska/Gulf suggests much cooler temperatures
from the Pacific Northwest to the Northern/Central Plains and the
aforementioned blend supports this.
...Weather Highlights/Threats...
A favored slower evolution over the Southern Plains/Lower MS
Valley allows for a longer and continued lead fetch of
deep/tropical moisture out of the Gulf of Mexico. Several inches
of rain are possible from the Gulf Coast states to the Ohio Valley
with the main supporting/ejecting system trending more
northeastward than earlier guidance. This occurs a weak wave of
low pressure slows the front through the mid-South. The boundary
should slowly push northeastward through the Ohio Valley this
weekend and weaken as it encounters ridging to its east and as a
stronger front to its west largely absorbs/overtakes it. In the
West, incoming cold front late this week into the weekend will be
mostly cut off from the moisture supply but will still manage to
spread moderate precipitation including mountain snows, especially
over the n-central Rockies as enhanced by upslope fetch. Rain/snow
potential may also spread northeastward next week across the
n-central U.S. with slow system progression and emergence into the
Plains.
Temperatures will trend much colder than average in the West
behind the lead cold front this weekend, with max temperatures
10-25 deg F below average Sunday into next Tuesday along/east of
the Divide from western Montana to eastern Colorado as the front
whooshes southward. Above average temperatures will be confined to
the Southeast to the south and east of the front. Florida will
continue to see high temperatures well into the 80s with some
record highs possible this weekend.
Campbell
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