Prognostic Meteorological Discussion
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000
FXUS02 KWBC 251555
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1154 AM EDT FRI JUL 25 2014

VALID 12Z MON JUL 28 2014 - 12Z FRI AUG 01 2014


...PATTERN OF RARE AMPLITUDE FOR LATE JULY OVER THE UNITED
STATES...


THE GLOBAL NUMERICAL MODELS HAVE ALL LOCKED ONTO THE EXTREMELY
HIGH AMPLITUDE MERIDIONAL EVENT TAKING SHAPE ACROSS NORTH AMERICA
AT THE MEDIUM RANGE. AT THIS POINT, ONLY SMALLER SYNOPTIC-SCALE
DETAIL REMAIN TO BE SORTED. THE MOST SIGNIFICANT OF THE DETAIL
DIFFERENCES INVOLVES HOW MUCH SEPARATION BETWEEN THE POTENT
SHORTWAVE DIVING INTO THE UPPER MIDWEST AND THE BIG VORTEX OVER
EASTERN CANADA MANIFESTS. THE TREND OVER THE PAST DAY OR SO OF
DATA CYCLES IS FOR MORE SEPARATION--I.E., THE UPPER MIDWEST SYSTEM
MAINTAINS ITS INTEGRITY AS IT TRAVERSES THE BASE OF THE EASTERN
CANADIAN TROUGH. THE 00Z/25 ECMWF OFFERED A REASONABLE
REPRESENTATION OF THIS TREND, SO RELIED UPON IT AS A GUIDE FOR
FRONTS AND PRESSURES FOR MOST OF THIS FORECAST PERIOD. BOTH THE
00Z/25 GFS AND UKMET RESOLVED THE DISTINCT SURFACE LOW ALL THE WAY
TO THE EAST COAST, BUT THE ECMWF RELAYS THE ESSENCE OF THE SPLIT
THE BEST. THE GREATEST UPSHOT OF THE TREND IS THAT A FOCUSED
STRIPE OF RAINFALL WOULD AFFECT THE NORTHERN MID ATLANTIC AND
SOUTHERN NEW ENGLAND DAY 4, WITH AFTERNOON TEMPERATURES THROUGH
THE CLIMATOLOGICAL BASEMENT WHERE THE CLOUD COVER AND STEADIEST
RAINFALL OCCURS--MOST LIKELY OVER UPSTATE NEW YORK AND
NORTHEASTERN PENNSYLVANIA.

THE FACT THAT THE TROUGH SLOWLY DIGS ITS HEELS INTO THE EASTERN
UNITED STATES WITH TIME IMPLIES THAT THE POLAR FRONT SHOULD
CONTINUE TO OOZE SOUTH AND WESTWARD ACROSS TEXAS. BY DAY 7, MOST
OF THE LONE STAR STATE SHOULD BE NORTH OF THE FRONT, WITH ALL OF
NEW MEXICO ON THE COLD SIDE OF THE BOUNDARY AS WELL. OVERRUNNING
RAINFALL IN THESE AREAS WOULD DO THE SAME THING FOR DAYTIME HIGHS
THAT THE WAVE IN THE NORTHEAST WOULD DO EARLY IN THE FORECAST:
KEEP THEM AT RECORD LOW VALUES.

THE INTERIOR NORTHWEST LOOKS LOCKED UNDER THE RIDGE PORTION OF THE
BLOCKING PATTERN, WITH MORE SEARING HEAT IN STORE. WHATEVER
MONSOONAL MOISTURE IS ABLE TO BE TRANSPORTED FROM THE
SOUTHWEST--BEFORE EXTREME UNDERCUTTING LIMITS EVEN THAT--WOULD
FUEL HIGH-BASED CONVECTION AND KEEP THE THREAT OF NEW WILDLAND
FIRES HIGH.


CISCO

$$




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