Prognostic Meteorological Discussion
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000
FXUS02 KWBC 231556
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1054 AM EST MON JAN 23 2017

VALID 12Z THU JAN 26 2017 - 12Z MON JAN 30 2017

A QUIET PATTERN IS SEEN IN THE MEDIUM RANGE AS A CONTINENTAL POLAR
AIRMASS SLIDES INTO THE EASTERN THIRD OF THE COUNTRY WHILE COLD
HIGH PRESSURE REMAINS ANCHORED IN THE WESTERN U.S.  PRECIPITATION
WILL BE LIMITED TO LAKE EFFECT SNOW OVER THE GREAT LAKES. THE
NORTHERN EDGE OF THE RAIN SHIELD ASSOCIATED WITH A STALLED FRONT
SHOULD SKIRT THE GULF COAST DURING THE WEEKEND WHILE SCATTERED
SHOWERS MOVE ACROSS FLORIDA.  OVER THE PACIFIC NORTHWEST...A GOOD
CHANCE OF PRECIPITATION IS FORECAST THROUGH NEXT MONDAY BUT IT
SHOULD BE CONFINED TO COASTAL WASHINGTON INTO THE CASCADES AS
PACIFIC SYSTEMS ARE DIRECTED INTO NW CANADA.  A CLIPPER-TYPE
SYSTEM DROPPING FROM CENTRAL CANADA SHOULD ONLY ENHANCE THE
LAKE-EFFECT SNOW SLIGHTLY DURING THE WEEKEND WITH AN INCREASING
CHANCE OF UPSLOPE SNOW ALONG THE WESTERN SLOPES OF THE CENTRAL
APPALACHIANS ON SUNDAY.  ANOTHER CLIPPER IS FORECAST TO BRING A
BETTER CHANCE OF SNOW INTO THE NORTHERN PLAINS BY NEXT MONDAY.
TEMPERATURES WILL MOSTLY STAY NEAR/BELOW AVERAGE IN THE WEST AND
SOUTHEAST/MID-ATLANTIC WHILE THE NORTHERN PLAINS INTO THE GREAT
LAKES SHOULD STAY ABOVE AVERAGE THANKS TO ENOUGH PACIFIC AIRMASS
INFLUENCE FROM THE WEST.

MODELS AND ENSEMBLES SHOW EXCELLENT AGREEMENT WITH THE OVERALL
PATTERN THROUGH NEXT MONDAY.  THE MAIN DISCREPANCY WAS NOTED OVER
THE GREAT LAKES INTO THE NORTHEAST WHERE LOWER SEA-LEVEL PRESSURE
IS INDICATED BY THE ECMWF COMPARED WITH THE GFS OVER THE WEEKEND.
IN ADDITION...MODELS HAVE TRENDED TOWARD LOWER PRESSURE ALONG WITH
A DEEPER TROUGH ALOFT IN THOSE AREAS.  ON ANOTHER NOTE...THE 06Z
GFS INDICATED CYCLOGENESIS OVER NORTHERN CAROLINA NEXT MONDAY.
HOWEVER...THE 06Z GEFS DID NOT SUPPORT THIS DEVELOPMENT...NEITHER
DID THE 00Z EC MEAN.  THEREFORE...THE WPC PRESSURE FIELDS WERE
DERIVED USING A BLEND OF 75% 00Z ECMWF/00Z EC MEAN WITH 25% 06Z
GFS/GEFS WITH THE BLEND TRENDING TOWARD THEIR ENSEMBLE MEANS BY
DAY 7.

KONG/FRACASSO


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