Preliminary Forecasts
Issued by NWS

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FXUS02 KWNH 010449
PREEPD

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1249 AM EDT WED APR 01 2015

VALID 12Z SAT APR 04 2015 - 12Z WED APR 08 2015

...OVERVIEW...

UPPER PATTERN NEXT WEEK WILL TREND TOWARD MORE RIDGING IN THE
EASTERN CONUS AS TROUGHING PUSHES THROUGH THE WEST. EXITING SYSTEM
IN THE EAST WILL USHER IN COOLER AIR YET AGAIN TO THE NORTHEAST
THIS WEEKEND AS A NORTHERN STREAM STATIONARY BOUNDARY SETTLES OVER
THE REGION. ALONG THIS FRONT WILL BE THE GREATEST UNCERTAINTY IN
SFC TEMPERATURES. BACK TO THE WEST... INCOMING TROUGHING WILL
SUPPORT A SFC COLD FRONT THAT WILL MARCH THROUGH THE ROCKIES AND
ONTO THE PLAINS NEXT WEEK.


...GUIDANCE PREFERENCES AND SENSIBLE WEATHER HIGHLIGHTS...

ENSEMBLES HAVE BEEN THE SAVING GRACE IN THIS FORECAST...
PARTICULARLY OUT WEST... WHERE THE ECMWF AND GFS SEEM TO HAVE
EXHIBITED THEIR BIASES -- ECMWF TOO SLOW AND GFS TOO QUICK. THE
COMPROMISE BETWEEN THE ENSEMBLE SYSTEMS HAS SERVED WELL AND THIS
CONTINUES TO BE THE PREFERRED BEST TRACK. 12Z GFS/ECMWF TIED IN
NICELY WITH THE 12Z NAEFS/ECENS MEANS THROUGH THE PERIOD AND THAT
BLEND WAS CARRIED THROUGH TO NEXT WED. 12Z ECMWF LIED ON THE
QUICKER SIDE WITH THE FLOW PATTERN BY THE END OF THE PERIOD AND
THE 18Z GFS TRENDED BACK TO A MUCH SLOWER WESTERN UPPER LOW --
WHICH DOES NOT FIT THE TREND IN THE GUIDANCE OVER THE PAST 36 HRS
-- BUT WITH CONTINUED HIGH SPREAD UPSTREAM NEITHER CANNOT TOTALLY
BE RULED OUT. TEMPERATURE EXTREMES MAY BE LIMITED DURING THE
PERIOD... WITH MAINE BEING HIGHLIGHTED AS A POTENTIAL COLD SPOT ON
MONDAY. RECORD LOW MINS AND MAXES MAY BE CHALLENGED AND HAVE BEEN
CONSISTENTLY SHOWING UP IN THE FORECAST GUIDANCE. OTHERWISE...
RETURN FLOW OUT OF THE GULF WILL INCREASE THE RAIN THREAT FOR THE
OH/TN/MS VALLEYS TUE-WED WHILE IN THE PAC NW ONLY MODEST RAINS ARE
EXPECTED.


FRACASSO

$$




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