Prognostic Meteorological Discussion
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FXUS02 KWBC 280353
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1153 PM EDT FRI MAR 27 2015

VALID 12Z TUE MAR 31 2015 - 12Z SAT APR 04 2015

...OVERVIEW AND GUIDANCE PREFERENCES...

THE TRANSITION TO ZONAL FLOW HAS WREAKED HAVOC WITH THE
ENSEMBLES... AS CAN BE THE CASE. LOW AMPLITUDE WAVES SHOULD
DOMINATE THE PERIOD AS THE PERSISTENT EASTERN TROUGHING MAY ABATE
FOR PERHAPS A COUPLE DAYS NEXT THU-FRI. IT IS DIFFICULT TO ANY
DETERMINISTIC MODEL OVER ANOTHER SINCE ALL FALL WITHIN THE
MULTI-CENTER ENSEMBLE SPREAD. NEVERTHELESS... THE ECMWF HAS BEEN
MORE CONSISTENT WITH SOME -- NOT ALL -- FEATURES ACROSS THE CONUS
THAN THE GFS AND HAS MORE SUPPORT FROM THE CMC/UKMET. NOTHING
SHOWS GOOD MULTI-DAY CONTINUITY AND THE TREND HAS BEEN BOTH SLOWER
AND QUICKER... DEPENDING ON THE SYSTEM OF INTEREST.

OPTED TO BLEND THE 12Z ECMWF/ECENS MEAN TUE-WED IN RESPONSE TO A
SFC WAVE MOVING ALONG 40N OFF THE EAST COAST THAT HAS BETTER
SUPPORT FOR SOMETHING MORE DEFINED /ECMWF/ THAN LESS DEFINED
/GFS/. FOR THU-SAT... TRENDED TOWARD A SPLIT BETWEEN THE 12Z NAEFS
AND ECENS MEANS AS THE RECENT GEFS MEANS WERE MUCH QUICKER TO
BRING IN THE NEXT SHORTWAVE INTO THE PAC NW ON SAT 4/4. BEST
OVERLAPPING ENSEMBLE SUPPORT AMONG ALL THREE ENSEMBLE SYSTEMS --
ECMWF/GEFS/CANADIAN -- LIES IN THE MODESTLY SLOWER CAMP. BUT...
THE CAVEAT REMAINS TIMING DIFFERENCES/INCONSISTENCIES AND WOULD
NOT BE SURPRISED IF THIS CHANGES IN SUCCESSIVE RUNS. COURSE OF
LEAST REGRET LIES AWAY FROM EXTREME SOLUTIONS IN QUASI-ZONAL FLOW.


...SENSIBLE WEATHER HIGHLIGHTS...

WARM TEMPERATURES WILL TRAVEL EASTWARD AHEAD OF THE MAIN SYSTEM
INITIALLY IN THE INTERIOR NW ON TUESDAY. TEMPS 10-20F ABOVE AVG
WILL BE COMMON AHEAD OF THE COLD FRONT AND ABOUT 5-15F BELOW AVG
IN ITS WAKE. PRECIPITATION WILL FOCUS NEAR THE FRONT AND EASTWARD
LEAD SYSTEM AS WELL AS IN THE SOUTH WHERE SOME MODELS/ENSEMBLES
SHOW SE TEXAS RECEIVING A COUPLE INCHES OF RAIN. ENSEMBLES ARE
EXPECTEDLY LESS BULLISH BUT THE POTENTIAL DOES EXIST FOR AT LEAST
MODEST RAIN. MORE WIDESPREAD AND PERHAPS HEAVIER PRECIP MAY EXPAND
THROUGH THE OHIO VALLEY AND INTO THE NORTHEAST/MID-ATLANTIC AHEAD
OF THE PROGRESSIVE SFC FRONT NEXT FRIDAY.


FRACASSO

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