Preliminary Forecasts
Issued by NWS

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FXUS02 KWNH 250511
PREEPD

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
110 AM EDT MON SEP 25 2017

VALID 12Z THU SEP 28 2017 - 12Z MON OCT 02 2017

A PROGRESSIVE PATTERN WILL RETURN TO THE CONUS THIS WEEKEND AS THE
BLOCKINESS IN THE SHORT TERM UNRAVELS. THE ENSEMBLES HAVE BEEN
FAIRLY CONSISTENT ON TELEGRAPHING THE BREAKDOWN OF THE PATTERN BUT
THE UPSTREAM FLOW OUT OF THE PACIFIC THIS WEEKEND REMAINS SHROUDED
IN UNCERTAINTY. A COLD FRONT WILL PUSH OFF THE EAST COAST ON
THURSDAY AND HELP PUSH HURRICANE MARIA OUT TO SEA AS A SECONDARY
FRONT USHERS IN MUCH COOLER AIR TO THE CENTRAL/EASTERN STATES. THE
WEST WILL SEE A PACIFIC FRONT CRUISE THROUGH THE NORTHWEST CORNER
OF THE CONUS AS HEIGHTS LOWER AND THE RIDGE MOVES EASTWARD. THIS
WILL BRING AN INCREASED CHANCE OF RAIN TO THE CENTRAL PLAINS LATER
THIS WEEKEND INTO MONDAY. THE COLD FRONT WILL STALL ACROSS FLORIDA
BY THE END OF THE WEEKEND WHICH WILL MAINTAIN THE CHANCE FOR
WIDESPREAD SHOWERS THERE. 12Z GFS/ECMWF OFFERED A REASONABLE
STARTING POINT BUT SWITCHED TO THE 18Z RUNS OF EACH DUE TO THE
BETTER CLUSTERING (ESP IN THE GREAT LAKES WITH THE SECONDARY
FRONT) WITH THE 12Z ECMWF/ECENS MEAN. BY NEXT SUN/MON, ENSEMBLES
HAVE SHOWN LITTLE CONSISTENCY OUT OF THE NORTHEASTERN PACIFIC
WHICH MAY BE COMPRISED OF LOW-AMPLITUDE AND LOW-PREDICTABILITY
SHORT WAVES.


FRACASSO


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