Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
306 AM EDT Thu Oct 24 2019
Valid 12Z Sun Oct 27 2019 - 12Z Thu Oct 31 2019
...Overview and Guidance/Uncertainty Assessment...
Model spread remains significant during the extended period in an
active pattern. For the last week or so the GFS has been
consistently too progressive with energy tracking across the
CONUS. This seems to be the case with the latest GFS runs and
GEFS/NAEFS means are also in this camp to a lesser extent. Recent
UKMET and especially Canadian runs have been closer to the ECWMF
and the ECMWF ensemble mean and offer a deeper and slower
progression of the low/trough exiting to the eastern U.S. by early
next week and amplifying upstream upper troughing digging into the
West then w-central U.S. next week. Accordingly, the WPC medium
range product suite was primarily derived from a composite blend
of the best clustered soltuions from the ECMWF/Canadian and ECMWF
ensemble mean, with highest weighting applied to the ensemble mean
for max continuity amid uncertainty.
...Weather Highlights/Threats...
The resultant weather pattern may offer several significant
hazards. Lead system ejection over the eastern U.S. Sunday and a
wavy trailing front over the Southeast into early-mid next week
should act to focus precipitation. Rainfall may be enhanced with
potential entrainment of tropical moisture stemming from a
tropical distirbance that the NHC is monitoring over the Gulf of
Mexico.
Meanwhile upstream, the deep digging of a series of potent systems
favors an unsettled and cooled West then central U.S. next week
with advent of a series of post-frontal high pressure surges. Some
upwards of 15-30+ degree negative temperature anomalies may rival
record values and upper support/modest moisture sets the stage for
terrain enhanced snows over the West and especially the central
Rockies with potential likely spreading northeast over the central
Plains then Upper Midwest with gradual system progressions and
cooling. Lead heavier rains may also be re-develop along/ahead of
a reinforced low/frontal boundary with renewed return moisture
influx from the Gulf of Mexico over the east-central U.S.
mid-later next week.
Schichtel
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