Preliminary Forecasts
Issued by NWS

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FXUS02 KWNH 280700
PREEPD

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT THU APR 28 2016

VALID 12Z SUN MAY 01 2016 - 12Z THU MAY 05 2016

...GUIDANCE ASSESSMENT AND WEATHER HIGHLIGHTS/THREATS...

SRN STREAM MID-UPPER LEVEL TROUGH ENERGIES SHEAR OVER THE CENTRAL
THEN ERN US SUN-MON. CYCLOGENESIS AND FAVORABLE LEAD THETAE
ADVECTION ALONG/AHEAD OF A WAVY FRONT WILL FUEL A WIDESPREAD
RAINFALL EPISODE. MEANWHILE...GUIDANCE DIGS AMPLE NEW MID-UPPER
LEVEL TROUGH ENERGIES BACK DOWN INTO THE SWRN US/S-CENTRAL ROCKIES
TO PRODUCE COOLED PCPN WITH SOME ENHANCED SNOWS OVER FAVORED
ELEVATED TERRAIN. THIS ENERGY IS SLATED TO EJECT OUT ACROSS THE
SRN/SERN US TIER EARLY-MID NEXT WEEK THEN POSSIBLYT UP THE EAST
COAST TO REFOCUS PCPN/WAVES ALONG THE LEAD TRAILING FRONT. THIS IS
POSSIBLE AS NRN STREAM FLOW ALOFT MEANWHILE AMPLIFIES NEXT WEEK
OVERTOP WITH EXPECTED EVENTUAL DEVELOPMENT OF AN E-CENTRAL NOAM
TROUGH AS IMPULSES DIG TO THE LEE OF A BUILDING W-CENTRAL NOAM
RIDGE. MEANWHILE UPSTREAM...POTENT ERN PACIFIC SYSTEM APPROACH TO
THE WEST COAST IN RE-EMERGING SPLIT FLOW SHOULD PROVE GRADUAL
MID-LATE WEEK GIVEN OVERALL FLOW AMPLIFICATION BUT SHOULD
EVENTUALLY USHER IN WET FLOW.

OVERALL...THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED
FROM A COMPOSITE BLEND OF THE REASONABLY COMPATABLE 18 UTC
GFS...12 UTC ECMWF...AND 12 UTC NAEFS/ECMWF ENSEMBLE MEAN SUN-MON
BEFORE SWITCHING TO JUST THE MEANS THROUGH LATER IN THE WEEK.
APPLIED HEAVIER WEIGHTING IN THIS BLEND TO THE MORE AMPLIFIED
ECMWF ENSEMBLE MEAN THAT SEEMS TO BETTER FIT AMPLIFYING FLOW.

SCHICHTEL



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