Preliminary Forecasts
Issued by NWS

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FXUS02 KWNH 290509
PREEPD

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
109 AM EDT SUN MAR 29 2015

VALID 12Z WED APR 01 2015 - 12Z SUN APR 05 2015

...OVERVIEW AND GUIDANCE PREFERENCES...

THE LOWER AMPLITUDE QUASI-ZONAL FLOW IS EXPECTED TO MANIFEST
ITSELF IN THE FIRST WEEK OF APRIL... MARKED BY CHANGEABLE
TEMPERATURES AND SCATTERED PRECIPITATION OUTSIDE THE SOUTHWESTERN
STATES. THE ENSEMBLE SYSTEMS REMAIN AT ODDS WITH THE ECMWF MEMBERS
GENERALLY SLOWER AND MORE AMPLIFIED THAN THE GEFS MEMBERS. THE
CANADIAN MEMBERS LIE ACROSS BOTH CAMPS... THUS TUGGING THE BLENDED
NAEFS MEAN TOWARD THE ECMWF ENSEMBLE MEAN. ECMWF-LED CAMP HAS
SHOWN MORE STABILITY IN RECENT RUNS EARLY IN THE FORECAST THAN THE
GEFS CAMP... AND WEIGHTED THE FORECAST WITH THE ECMWF/ECENS MEAN
WED-FRI. BY NEXT WEEKEND... A BLEND BETWEEN THE ECENS AND NAEFS
MEAN OFFERS BETTER CONTINUITY IN LIGHT OF THE MULTI-CYCLE
SHUFFLINGS... WHICH FAVORS TROUGHING DIGGING TOWARD THE WEST COAST
AND INTO THE EASTERN STATES YET AGAIN AFTER A COUPLE DAY BREAK.
ECMWF IS PROBABLY TOO DEVELOPED WITH LOW PRESSURE IN THE NORTHEAST
ON SATURDAY WITH BASICALLY NO OTHER DETERMINISTIC SUPPORT.
HOWEVER... MANY ENSEMBLE MEMBERS FAVOR LOW PRESSURE IN THIS AREA
-- ALBEIT WEAKER THAN THE ECMWF -- RATHER THAN FARTHER SOUTH.


...SENSIBLE WEATHER HIGHLIGHTS...

MILD TEMPERATURES AHEAD OF THE MAIN SYSTEM MOVING THOUGH SOUTHERN
CANADA WED-FRI WILL BE REPLACED BY COOLER THAN AVERAGE READINGS
FROM WEST TO EAST. SOME RECORD HIGH MINIMUM TEMPERATURES MAY BE
CHALLENGED IN THE WARM SECTOR. PRECIPITATION IS FORECAST TO SPREAD
FROM THE CENTRAL PLAINS TO THE OHIO VALLEY AS WELL AS IN THE
SOUTH/SOUTHEAST. SECONDARY SFC WAVE DEVELOPMENT SHOULD MOVE
NORTHEASTWARD WITH MORE PRECIPITATION INTO THE OHIO VALLEY AND THE
NORTHEAST/MID-ATLANTIC... DEPENDING ON ITS TRACK. TEMPERATURES
WILL COOL AGAIN IN THE EAST POST-FROPA.


FRACASSO

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