Preliminary Forecasts
Issued by NWS

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FXUS02 KWNH 290516
PREEPD

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
115 AM EDT TUE JUL 29 2014

VALID 12Z FRI AUG 01 2014 - 12Z TUE AUG 05 2014

...OVERVIEW...

THE BLOCKY AND HIGHLY AMPLIFIED PATTERN SHOULD BE SHOWING SIGNS OF
WEAKENING BY NEXT WEEK... BUT WILL STILL MAINTAIN THE LONGWAVE
RIDGE/TROUGH ACROSS THE CONUS. UPPER RIDGING SHOULD FLANK THE MEAN
TROUGH POSITION BETWEEN 80-90W... THE UPSTREAM RIDGE OVER
ALBERTA/SASKATCHEWAN AND THE DOWNSTREAM RIDGE OVER THE NW ATLANTIC
WHICH SHIFTS INTO THE LOWER LATITUDES NORTH OF PUERTO RICO AND THE
BAHAMAS.

...GUIDANCE PREFERENCES...

THE MODELS/ENSEMBLES ARE STILL IN GOOD AGREEMENT THROUGHOUT THE
PERIOD... BUT HAVE SHOWN A BIT MORE VARIETY IN THEIR DETAILS THAN
EARLIER RUNS. A BLEND OF THE 18Z GFS/GEFS MEAN AND 12Z ECMWF/ECENS
MEAN SUFFICED THROUGH ABOUT SUN/D5 BEFORE THEIR GOOD CLUSTERING
FELL APART. AT ISSUE WILL BE HOW TO HANDLE ENERGY MEANDERING
NORTHWARD IN THE WEST DURING THE SHORT RANGE THAT SHOULD BE IN THE
VICINITY OF IDAHO BY DAY 3 - FRI 1 AUG. THE 12Z ECMWF APPEARS TO
BE MUCH TOO STRONG WITH THIS AS IT CONTINUES NORTHWARD THEN
EASTWARD... WHICH MAY HELP KICK OUT THE EASTERN TROUGH A BIT
QUICKER THAN WHAT THE ENSEMBLES SUGGEST. THE 18Z GFS MAY HAVE A
BETTER HANDLE ON THIS VORT MAX... BUT GIVEN ITS SMALL SCALE AND
MANY DIFFERENT FORECASTS OVER THE PAST SEVERAL RUNS... WILL HAVE
TO WAIT SEVERAL MORE MODEL CYCLES TO GAIN MORE CONFIDENCE IN ITS
FUTURE COURSE. FOR EARLY NEXT WEEK... A BLEND OF THE GEFS AND
ECENS MEANS WAS DEEMED THE PATH OF LEAST RESISTANCE.

...SENSIBLE WEATHER HIGHLIGHTS...

PRECIPITATION SHOULD BE FAVORED ALONG THE NEARLY STATIONARY
FRONTAL BOUNDARY FROM THE FOUR CORNERS REGION... WHERE MONSOONAL
MOISTURE SHOULD PEAK MID-PERIOD... ALONG THE GULF COAST AND OVER
THE EASTERN THIRD OF THE CONUS. GFS/ECMWF ENSEMBLES VARY ON THEIR
PRECIP AXES THROUGH THE WEEKEND... EITHER ALONG AND WEST OF THE
APPALACHIANS OR ALONG THE COAST... RESPECTIVELY. BY EARLY NEXT
WEEK... MUCH OF THE COUNTRY OUTSIDE OF INTERIOR TEXAS AND THE WEST
COAST WILL SEE AT LEAST A CHANCE OF PRECIPITATION. THE
SOUTHEASTERN STATES SHOULD HAVE THE MOST FAVORABLE SYNOPTIC
INGREDIENTS BUT THE INTERIOR WEST WILL ALSO STAY ACTIVE. DEPENDING
ON HOW THE ENERGY IN IDAHO ON DAY 3 PROGRESSES... THE NORTHERN
PLAINS COULD SEE LITTLE PRECIP /ECMWF/ OR MUCH MORE SUBSTANTIAL
PRECIP /GFS/. ENSEMBLES FALL IN BETWEEN.


FRACASSO

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