Preliminary Forecasts
Issued by NWS

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FXUS02 KWNH 230550
PREEPD

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
149 AM EDT WED APR 23 2014

VALID 12Z SAT APR 26 2014 - 12Z WED APR 30 2014

...PATTERN OVERVIEW AND SENSIBLE WEATHER HIGHLIGHTS...

GUIDANCE CONTINUES TO TREND SUPPORT FOR QUITE A SLOWING AND
AMPLIFIED/BLOCKY LATE APRIL PATTERN.  THIS PATTERN OFFERS SEVERAL
SIGNIFICANT WEATHER SYSTEM THREATS.

MAJOR COOLING/UNSETTLING MID-UPPER LEVEL WRN US TROUGHING
SAT...ESPECIALLY THE SOUTHWEST...EJECTS THROUGH THE ROCKIES INTO
THE PLAINS SUN INTO MON.  THIS PATTERN WOULD BE FAVORABLE FOR
COLORADO LOW DEVELOPMENT WITH AN ASSOCIATED SPRING N-CENTRAL
ROCKIES/HIGH PLAINS SNOW THREAT IN A COOLED AIRMASS WRAPPED BACK
FROM THE NRN HALF OF THE CENTRAL AND ERN US.  MEANWHILE...THERE
SHOULD BE SEVERE WEATHER POTENTIAL IN A WELL DEFINED WARM SECTOR
OVER THE S-CENTRAL US AS PER SPC.

THE CLOSED TROUGH/LOW SHOULD SUBSEQUENTLY BE FORCED GRADUALLY
EASTWARD ACROSS THE EAST-CENTRAL US NEXT MON-WED DAYS 5-7 IN A
DEVELOPING REX BLOCK SETUP AS WARMING RIDGES BUILD STRONGLY
UPSTREAM OVER THE WRN US AND OVERTOP OVER S-CENTRAL CANADA.  THIS
ALL OCCURS THEN AS A LEAD NERN US/CANADIAN MARITIME CLOSED LOW
LOSES INFLUENCE.  SLOW WRAPPED SYSTEM TRANSLATION AND INCREASINGLY
DEEP MOISTURE INFLUX FROM THE GULF OF MEXICO THEN WRN ATLANTIC
SHOULD FUEL A WIDESPREAD CONVECTIVE AND OVERRUNNING HEAVY RAINFALL
THREAT SPREADING SLOWLY ACROSS THE EAST-CENTRAL TO ERN US.

...GUIDANCE/UNCERTAINTY ASSESSMENT...

THE BULK OF GUIDANCE SOLUTIONS ARE NOW MUCH BETTER CLUSTERED IN
DEPICTION OF THIS PATTERN...BOLSTERING FORECAST CONFIDENCE TO
ABOVE NORMAL LEVELS.  ACCORDINGLY...THE MEDIUM RANGE GUIDANCE
SUITE HAS BEEN PRIMARILY DERIVED FROM A COMPOSITE BLEND OF THE 12
UTC GFS/ECMWF AND GFS/ECMWF/NAEFS ENSEMBLE MEANS ALONG WITH
WPC/NDFD CONTINUITY.

SCHICHTEL

$$





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