Prognostic Meteorological Discussion
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000
FXUS02 KWBC 231600
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1200 PM EDT TUE SEP 23 2014

VALID 12Z FRI SEP 26 2014 - 12Z TUE SEP 30 2014

WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS ALONG
WITH ASSOCIATED 2.5 KM RESOLUTION SENSIBLE WEATHER GRIDS HAVE BEEN
PRIMARILY DERIVED FROM A BLEND OF THE 00 UTC ECMWF/ECMWF ENSEMBLE
MEAN AND THE 06 UTC GFS/GFS ENSEMBLE MEAN DAYS 3-5 FRI THROUGH THE
UPCOMING WEEKEND. LEANED JUST ON THESE ENSEMBLE MEANS BY MON/TUE
IN A PERIOD OF INCREASING DAYS 6/7 FORECAST SPREAD.

OVERALL...THE 06 UTC GFS/GEFS MEAN OVERALL TRENDED MORE IN LINE
WITH 00 UTC ECMWF/ECMWF ENSEMBLE MEAN VERSUS THE 00 UTC GFS/GEFS
MEAN. IN ALL THESE 3-7 DAY GUIDANCE BLENDS...WEIGHTED THE OVERALL
MORE AMPLIFIED AND LESS PROGRESSIVE ECMWF/ECMWF ENSEMBLE MEAN MORE
THAN THE GFS/GFS ENSEMBLE MEAN AS THAT SEEMS THE NATURE OF THE
FLOW AND CONSIDERING LEAD-IN WATER VAPOR LOOPS.  HOWEVER...THIS IS
A VERY COMPLEX AND STREAM DEPENDENT FLOW PATTERN RIPE WITH
UNCERTAINTY ESPECIALLY AT SMALL/MID SPATIAL SCALES AND WITH
SENSIBLE WEATHER FOCUS.

THIS PATTERN IS HIGHLIGHTED BY LEADING AND MEANDERING/LINGERING
WEAKNESSES ALOFT CENTERED OFF/NEAR THE EAST COAST...AND ALL
THROUGH THE CENTRAL US WHERE DEEP GULF MOISTURE COULD FAVOR HEAVY
RAINS CENTERED OVER THE LOWER MS VALLEY/GULF COAST STATES.
UPSTREAM...A DEEP MID-UPPER LEVEL TROUGH/LOWS MOVING OVER THE WRN
US THIS WEEK THEN EJECTS INTO THE N-CENTRAL US BY EARLY NEXT WEEK.
THIS LATTER SYSTEM HAS LESS FORECAST SPREAD AND BETTER
PREDICTABILITY THAN THE LESS DEFINED LEAD SYSTEMS AND SHOULD
SPEARHEAD LEAD SURFACE LOW/FRONTAL DEVELOPMENT AND WIDESPREAD
PCPN/CONVECTION FOCUS FOLLOWED BY COOLING TEMPS IN ITS WAKE.

SCHICHTEL

$$




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