Preliminary Forecasts
Issued by NWS

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FXUS02 KWNH 020719
PREEPD

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
218 AM EST MON MAR 02 2015

VALID 12Z THU MAR 05 2015 - 12Z MON MAR 09 2015

...GUIDANCE ASSESSMENT AND PATTERN/SENSIBLE WEATHER HIGHLIGHTS...

THE WPC MEDIUM-RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE MODEL BLEND OF THE 18 UTC GFS AND 12 UTC
ECMWF/UKMET/CANADIAN INTO THU/FRI BEFORE TRANSITIONING TO A
COMPOSITE BLEND THE 18 UTC GEFS MEAN AND 12 UTC ECMWF/NAEFS
ENSEMBLE MEANS OUT TO DAY 7/NEXT MON IN A PERIOD WITH MARGINALLY
INCREASED FORECAST SPREAD. THIS PATTERN SEEMS TO OFFER AVERAGE OR
BETTER PREDICTABILITY.

THE LAST IN A RECENT SERIES OF STORMY WINTER WEATHER FEATURES IS
QUICKLY TRANSFERING INTO SHORT RANGE TIME SCALES AND WPC
PRODUCTS...BUT LINGERING FRONTAL WAVE FOCUS SHOULD PROLONG AMPLE
WINTER WEATHER POTENTIAL EXITING THE APPALACHIANS ACROSS THE
COOLING MID-ATLANTIC INTO THU ON THE LEADING EDGE OF A
POST-FRONTAL ARCTIC SURGE SPREAD FAR SOUTHWARD ACROSS THE FROSTY
NATION. ALSO EXPECT SOME MODEST LINGERING TRAILING FRONTAL
FOCUSING WARM SECTOR PCPN OVER THE GULF COAST/SE US.

A TRANSITION TO AN ENSEMBLE FORECAST APPROACH SHOULD WORK WELL
LATER ON AS THE PATTERN BECOMES MORE BENIGN/DRY FOR MUCH OF THE
NATION. THIS INCLUDES SOME MODEST PCPN POTENTIAL OVER THE NWRN
US/NRN ROCKIES WITH UNCERTAIN IMPULSE PASSAGES ALOFT IN A PATTERN
WITH LIMITED MOISTURE. ONE LARGER GUIDANCE DIFFERENCE IS EVIDENT
DOWNSTREAM THOUGH. THE 12 UTC ECMWF/ECMWF ENSEMBLES AND NOW
ESPECIALLY THE 00 UTC ECMWF DO REBOUND MOISTURE AND PCPN MORE
ROBUSTLY INLAND INTO THE CENTRAL GULF COAST STATES/SERN US THAN
THE REST OF GUIDANCE INTO DAY 7 NEXT MON. THE WPC COMPOSITE BLEND
ALLOWS POTENTIAL FOR MOISTURE REBOUND CONSISTENT WITH A LARGER
SCALE FLOW PATTERN WITH SOME ROOM FOR AMPLIFICATION ALOFT AND
SURFACE RESPONSE AND QPF PROGS WILL ALLOW FOR THIS.

SCHICHTEL

$$





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