Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
144 AM EST Mon Nov 11 2019
Valid 12Z Thu Nov 14 2019 - 12Z Mon Nov 18 2019
...Pattern Overview and Guidance/Predictability Assessment...
Amplified pattern with rebuilding western ridging and eastern
troughing is forecast to hold into next week. Multi-day
consistency and inter-ensemble system clustering has been subpar
which again leads to a majority ensemble mean weighting next week.
Trend has been for a bit more interaction in the Southeast between
a exiting/weakening upper low over Mexico and northern stream
troughing through the TN Valley Friday, leading to surface low
pressure organizing around Florida. How far this moves offshore vs
up the coast remains unclear but have trended a bit closer to the
coast yet still offshore Sat-Sun (enough to keep QPF over the I-95
corridor). In the West, differences between the ensembles were
reflected in the 12Z GFS vs ECMWF/Canadian-- the latter showed an
upper low perhaps splitting off well southwest of California and
remaining offshore as upper ridging builds atop the low rather
while the former moved it inland into the Baja. Ensembles were
split but slightly favored the ECMWF-led solution. Tempered this
via the 12Z/10 ECMWF ensemble mean. This also worked well in the
East/Southeast as the 12Z ECMWF was quite robust with offshore low
pressure vs its ensemble mean. Low confidence in this series of
events in the East.
...Weather Highlights/Threats...
Well below average temperatures will ease after Thursday. However,
highs will remain about 5-15 degrees below average along and east
of the Mississippi through next weekend. Along/west of the Rockies
(but including parts of the Front Range and central Plains),
temperatures will stay above average by about 5-15 degrees.
Interaction between the southern upper low and frontal boundary in
the Gulf could spread rain (possibly modest amounts) along the
I-10 corridor and across the Florida peninsula early in the
period. The surface low off the Southeast coast should keep the
heaviest rains offshore, though depending on coastal proximity,
heavy rains may clip the coastline. Next system into the Pacific
Northwest will provide focused rain/snow to coastal/mountain OR/WA
Thu-Fri with much less east of the Divide. Yet another system may
approach Washington late next Sunday into Monday.
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