Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
146 AM EST Wed Nov 13 2019
Valid 12Z Sat Nov 16 2019 - 12Z Wed Nov 20 2019
...Pattern Overview and Guidance/Predictability Assessment...
Upper pattern will transition toward western troughing and eastern
quasi-zonal flow in about a week, after a two successive systems
lift northeastward along the East Coast. In the West, upper
ridging will weaken as it slides eastward atop a closed upper low
moving away from Baja California. This will pave the way for a
Pacific shortwave to dig through interior California as downstream
heights rise in response.
Off the Southeast coast, the models have come into better
agreement with mostly some timing differences as it looms
offshore. Model blend sufficed given recent shifts in the
ECMWF/GFS. 12Z UKMET/Canadian were close enough to the ensemble
range as well. Upstream system will act to kick the lead shortwave
along, but reinforce the surface boundary along the Gulf Stream.
This may develop another low and off the NC coast which should
move quicker out to sea as heights rebound. In the West, lead
front into Washington will weaken in favor of a stronger shortwave
on its heels. The ECMWF has been most aggressive with this feature
and dug it farther southwest than the other guidance. GFS has been
more in line with the ensembles but given how much upstream
ridging is forecast to build into the Gulf of Alaska, the ECMWF
solution cannot be ruled out completely. This would carry a cold
front through the Great Basin into the Four Corners region by next
Wednesday.
...Weather Highlights/Threats...
Below average temperatures in the East will slowly moderate back
toward more typical mid-November values by early next week. Much
of the West will have temperatures above normal by 5-15 degrees
through this weekend, cooling early next week with the arrival of
the next upper trough.
The system off the Southeast/mid-Atlantic coast should keep the
heaviest rains offshore but should be close enough to produce at
least showers along the I-95 corridor. Heavier rain is possible
right along the coast of North Carolina. The strong pressure
gradient between the low sfc high over New England will lead to
windy conditions along the coast. The precipitation shield will
move northward into New England early next week where temperatures
may be cold enough for some snow in higher elevations.
Several systems out of the Pacific will maintain a rather wet
period for at least coastal Washington/Oregon and the Cascades,
with less rain/snow along and just west of the Continental Divide.
With increased troughing toward the Southwest next week, some
light precipitation will be possible late Tue into Wed.
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