Prognostic Meteorological Discussion
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000
FXUS02 KWBC 170700
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EST FRI NOV 17 2017

VALID 12Z MON NOV 20 2017 - 12Z FRI NOV 24 2017

...PATTERN OVERVIEW AND GUIDANCE/UNCERTAINTY PREFERENCES......

RECENT GFS/ECMWF/CMC RUNS CLUSTER FAIRLY WELL AND PROGRESS A
DYNAMIC MID-UPPER LEVEL TROUGH/HEIGHT FALLS FROM THE UPPER MIDWEST
THROUGH THE GREAT LAKES/NERN US TUE-WED WITHIN NRN STREAM FLOW.
HOWEVER...THE RECENT UKMET RUNS OFFER A MORE DIGGY/AMPLIFIED
SOLUTION THAT HAS SOME POTENTIAL GIVEN UPSTREAM RIDGE
AMPLIFICATION. GEFS/ECMWF ENSEMBLE MEANS ARE IN BETWEEN AND
HEAVILY WEIGHTED IN THE WPC FORECAST GIVEN UNCERTAINTY. THIS
SUPPORTS A DEEPENED CLIPPER LOW TRACK AND SWATH OF PCPN ALONG THE
US/CANADIAN BORDER ALONG WITH A REINFORCING COOLING SURGE AND A
PERIOD OF LAKE EFFECT SNOWS IN THE WAKE OF SYSTEM PASSAGE.

THE EXTENT OF DIGGING OF EMBEDDED SRN STREAM IMPULSES UNDERNEATH
TO THE LEE OF A BUILDING WARMING WRN US MID-UPPER LEVEL RIDGE
EARLY NEXT WEEK AND MID-LATER NEXT WEEK POTENTIAL SRN STREAM
TROUGH/LOW SEPARATION OVER THE GULF COAST CAN FURTHER COMPLICATED
BY POTENTIAL FOR NRN STREAM INTERACTION WITH SOME SOLUTIONS.
FORECAST SPREAD AND UNCERTAINTY REMAINS ABOVE NORMAL ALONG WITH
MODEL RUN TO RUN VARIANCE. PREFER ECMWF ENSEMBLES THAT SHOW MORE
MODEST FLOW SEPARATION AND WEATHER FOCUS THAN THE ECMWF...BUT MUCH
MORE THAN THE GFS/GEFS. THAT SEEMS REASONABLE GIVEN OVERALL FLOW
AMPLIFICATION UPSTREAM AND RECENT OVERALL MODEL TRENDS.

MEANWHILE...CONTINUED INLAND FLOW OF ERN PACIFIC IMPULSES FROM AN
AMPLIFIED OFFSHORE MID-UPPER LEVEL MEAN TROUGH WILL PROLONG A WET
PATTERN INCLUDING ELEVATION SNOWS OVER THE NWRN US THROUGH NEXT
MIDWEEK. FORECAST SPREAD AND UNCERTAINTY GROWS RAPIDLY INTO
THANKSGIVING AROUND WHEN THE POTENTIAL EXISTS FOR SOME BULK OF
THIS TROUGH ENERGY TO WORK TO THE COAST ALONG WITH LEAD MOISTURE
PLUME TAP THAT COULD FUEL ENHANCED PCPN.

SCHICHTEL

$$





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