Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1217 PM EDT Thu Jul 09 2020
Valid 12Z Sun Jul 12 2020 - 12Z Thu Jul 16 2020
Significant shorter range model differences remain with an Eastern
Seaboard coastal low whose potential development is being
monitored by NHC. Recent GFS and to a lesser extent GEFS runs have
been the most progressive with this low into the Northeast this
weekend. Recent UKMET runs have been the most developed. While
plausible, the WPC product suite was primarily derived instead
from a blend of the 00 UTC ECMWF an ECENS/NAEFS ensemble means,
which offers good continuity for this coastal low and also seems
to provide a good forecast starting point and continuity for the
rest of the contiguous U.S. days 3-7.
...Weather Pattern/Hazard Highlights...
Wrapping heavy rains and winds will linger over northern New
England Sunday as dependent on the development and track of a
current coastal Carolina low being monitored by NHC. An amplified
upper trough and wavy/reinforcing cold front settles over the
eastern U.S. Sunday/Monday in the wake of this low. This rainfall
focusing system may be kicked out Tuesday and usher in hot
summertime conditions. The kicker amplified upper trough will work
into an unsettled Northwestern U.S. and western Canada by Sunday.
This system/height falls will progress steadily downstream over
southern Canada and the U.S. northern tier Monday-next Thursday.
This will force a moderating leading front over the region and
pooling moisture/instability may fuel some strong to severe
thunderstorms. Heavy rain potential may focus near the Upper
Midwest. Uncertain upper troughing may work back into the
Northwest U.S. and western Canada in a week. Meanwhile, triple
digits maximum temperatures to approach or exceed heat records are
likely from portions of CA and the Southwest/southern Great Basin
to the south-central Plains.
Additional 3-7 Day Hazards information can be found on the WPC
medium range hazards chart at:
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at: