Prognostic Meteorological Discussion
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FXUS02 KWBC 280405
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1104 PM EST MON FEB 27 2017

VALID 12Z FRI MAR 03 2017 - 12Z TUE MAR 07 2017

...OVERVIEW...

THE PACIFIC NORTHWEST WILL BE UNDER THE GUN MOST OF THE MEDIUM
RANGE PERIOD AS A SERIES OF SYSTEMS PUSHES THROUGH THE REGION. THE
EASTERN HALF OF THE LOWER 48 WILL BE RELATIVELY QUIET UNTIL A
SYSTEM DEVELOPS LATE THIS WEEKEND OUT OF THE ROCKIES AND LIFTS
THROUGH THE GREAT LAKES INTO THE NORTHEAST EARLY NEXT WEEK.


...GUIDANCE PREFERENCES...

MODELS AND ENSEMBLES REMAIN IN GENERALLY GOOD AGREEMENT BUT HAVE
YET TO GET A HANDLE ON THE UPSTREAM PACIFIC FLOW. A DEEP UPPER LOW
SLOWLY DRIFTING THROUGH THE CANADIAN ARCHIPELAGO TELECONNECTS TO
TROUGHING IN THE WESTERN STATES EARLY IN THE PERIOD BEFORE THE
HIGH LATITUDE PATTERN RETROGRADES AND SENDS RIDGING THROUGH THE
ROCKIES IN THE WAKE OF THE DEVELOPING EASTERN SYSTEM. THE GEFS AND
ECMWF ENSEMBLES DIFFER ON HOW TO HANDLE THIS PATTERN PROGRESSION,
WITH THE ECMWF AND CANADIAN ENSEMBLES QUICKER WITH THE EASTERN
SYSTEM OWING TO FLATTER FLOW THROUGH THE WEST EARLY NEXT WEEK.
PREFER THE ECMWF ENSEMBLE ONLY SLIGHTLY MORE THAN THE GEFS SINCE
ITS CONSISTENCY HAS BEEN MORE STABLE THAN THE GEFS, WHICH HAS
SLOWED IN ITS 12/18Z RUNS COMPARED TO EARLIER RUNS (AND WAS THEN
FARTHER SOUTH WITH TROUGHING EARLY NEXT WEEK INTO N CA). POTENTIAL
EXISTS FOR A MODESTLY DEEP SURFACE LOW MOVING THROUGH THE ST.
LAWRENCE VALLEY EARLY NEXT WEEK BUT THAT DEPENDS ON THE PACIFIC
EVOLUTION (SEEMS LIKE RECENT PREDICTABILITY OF PACIFIC FEATURES
HAS ONLY BEEN ABOUT 3 DAYS LEAD TIME). GFS/GEFS WERE NOT INCLUDED
IN THE BLEND BUT CANNOT BE RULED OUT.


...WEATHER HIGHLIGHTS...

SEVERAL INCHES OF RAIN AND MOUNTAIN SNOW (SEVERAL FEET) ARE LIKELY
FOR PORTIONS OF WA/OR FRI-TUE (MAYBE INTO N CA). TEMPERATURES ARE
FORECAST TO GENERALLY BE NEAR TO BELOW AVERAGE IN THE NORTHWEST
QUARTER OF THE CONUS. THE EAST WILL SEE A WARMUP THROUGH THE
PERIOD AS HIGH PRESSURE MOVES OFFSHORE BY SUNDAY. THE PLAINS
SHOULD SEE WELL ABOVE AVERAGE TEMPERATURES (+15 TO +25F ANOMALIES)
THIS WEEKEND THOUGH PERHAPS SHORT OF RECORD HIGHS. PRECIPITATION
WILL BE ON THE INCREASE AS THE SYSTEM PROGRESSES EASTWARD NEXT
WEEK. FRONTAL BOUNDARY IN THE GULF WILL LIFT NORTHWARD TOWARD THE
TEXAS COAST AND HELP BRING IN SOME RAIN THIS WEEKEND INTO MONDAY.


FRACASSO


$$




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