Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1032 AM EST Tue Nov 12 2019
Valid 12Z Fri Nov 15 2019 - 12Z Tue Nov 19 2019
...Pattern Overview and Guidance/Predictability Assessment...
Upper ridging on either side of North America will favor a series
of troughs progressing across the CONUS.
For days 3-4, an upper trough crossing the southeast causes
low pressure to develop just off the Southeast coast and move
northeastward to off the Mid Atlantic coast by day 5 and off the
New England coast days 6-7. Models cluster in 2 camps, with the
GFS/GEFS Members/Canadian slightly faster in moving the low
northeast and the ECMWF/ECMWF mean/00z UKMET slower. A blended
solution is proposed to mitigate the timing differences.
A Western trough on Friday will progress across the northwest and
northern Rockies and then the northern Plains Sat and into the
upper Great Lakes/mid MS Valley Sun 17 Nov. The southern portion
of the trough amplifies over western Gulf states Sun night-Mon
with low pressure developing over the Gulf and continuing a slow
east movement on Tue, with a wave of low pressure along the front
traversing Florida.
The next wave crossing the northern Pacific toward the Pacific
northwest is poised to approach or move onshore Monday 18 Nov.
The last couple of runs of the ECMWF showed a closed low
developing within the wave (just off the northern Ca/Southern OR
coast 12z Tue 19 Nov), but most ECMWF and GEFS ensemble members
show an open wave persisting.
The operational progs blended the operational run with the
operational GFS and respective 00z ECMWF and 06z GEFS ensemble
means and show an open wave until more solutions show the closed
low developing.
...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, moderating early next week with the arrival
of the next upper trough.
The system in the southeast to mid Atlantic coastal waters should
keep the heaviest rains offshore but is close enough to produce
showers in coastal areas. The strong pressure gradient between the
low and mid 1030s high over New England leads to windy conditions
along the southeast to the mid Atlantic coasts. The precipitation
shield will move northward into New England early next week.
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.
Petersen/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