Prognostic Meteorological Discussion
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000
FXUS02 KWBC 131541
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1140 AM EDT SUN JUL 13 2014

VALID 12Z WED JUL 16 2014 - 12Z SUN JUL 20 2014

...HEAVY RAIN POSSIBLE NEAR THE TX/OK BORDER MID/LATE WEEK...

...OVERVIEW AND GUIDANCE PREFERENCES...

A MORE TYPICAL SUMMERTIME PATTERN SHOULD RESUME OVER THE CONUS
LATER IN THE WEEK AFTER THE DEEP TROUGH LIFTS OUT OF THE GREAT
LAKES/NORTHEAST MIDWEEK. THE MODELS/ENSEMBLES HAVE LARGELY BEEN IN
LINE FOR SEVERAL CYCLES IN THE EAST WHICH WILL CARRY THE SFC FRONT
SLOWLY OFFSHORE NEW ENGLAND AND THE MID-ATLANTIC BEFORE BEING
BLOCKED BY STRONG ATLANTIC RIDGING... WITH ABOUT A 6000M CLOSED
HIGH NEAR 36N/50W. OVER THE NE PAC AND INTO BRITISH COLUMBIA...
THE MODELS/ENSEMBLES HAVE SHOWN RATHER POOR CONTINUITY WITH THE
HANDLING OF SHORT WAVES CRUISING THROUGH THE GULF OF ALASKA
DOWNSTREAM OF A WEAKENING UPPER LOW NEAR THE CENTRAL ALEUTIANS.
WITH THE STRENGTHENING OF EASTERN PACIFIC RIDGING... ALBEIT
BRIEFLY... TROUGHING SHOULD BE ALLOWED TO SWING THROUGH THE PAC NW
BUT NOT AS DEEPLY AS SOME EARLIER GFS/GEFS FORECASTS... SINCE IT
IS JULY AFTER ALL AND QUITE DIFFICULT TO GET A SUBSTANTIAL TROUGH
INTO THE GREAT BASIN.

THE 06Z GFS/GEFS WERE FAST OUTLIERS WITH THE ENERGY IN THE GULF OF
ALASKA COMPARED TO THE ECMWF/ECENS MEAN AND EARLIER GFS/GEFS
RUNS... AND WERE DISCOUNTED. THE 00Z GFS/ECMWF/ECENS/NAEFS OFFERED
A RELATIVELY COHERENT CLUSTER AND A BLEND OF THEM WAS USED AS A
BASE FOR THE FORECAST... TRENDING TO JUST THE MEANS BY SUN/D7 WHEN
OTHER SHORTWAVES FORECAST BY THE DETERMINISTIC MODELS BECOME OUT
OF SYNC WITH THE AGREEABLE MEANS.


...SENSIBLE WEATHER HIGHLIGHTS...

BIG STORY CONTINUES TO BE THE ANOMALOUS COOLING IN THE CENTRAL
PLAINS AND TOWARD THE EAST... WITH 850 TEMP STND ANOMALIES IN THE
-3 TO -3.5 RANGE YIELDING SFC TEMPS ABOUT 20-30F COOLER THAN
AVERAGE. DAILY RECORD COOL HIGH TEMPS SHOULD BE CHALLENGED IN MANY
LOCATIONS. FLIP SIDE WILL BE THE HEAT IN THE PAC NW... WHICH WILL
FADE BY THE END OF THE WEEK ONCE TROUGHING ENTERS THE REGION.
TEMPS SHOULD MODIFY BY NEXT WEEKEND EAST OF THE ROCKIES BUT STILL
AVERAGE JUST BELOW CLIMO.

PRECIPITATION WILL BE TIED TO THE UNUSUALLY FAR SOUTH FRONTAL
PROGRESSION... NEARLY TO THE GULF COAST... THAT SHOULD GET HUNG UP
OVER TEXAS AND ALSO THE NC/SC/COASTS. NW FLOW ALOFT ALONG WITH
ADDITIONAL SHORTWAVE ENERGY PUSHING THROUGH THE REGION... ALONG
WITH WELL ABOVE CLIMO PW VALUES... SHOULD FOCUS PRECIP OVER MUCH
OF THE SAME AREA FOR THE END OF THE WEEK. DETERMINISTIC MODELS
HAVE BEEN SHOWING SEVERAL INCHES... UP TO TEN... IN JUST A 48-HR
PERIOD. THE ENSEMBLES HAVE BEEN INCREASING AS WELL... NOW UP TO
ABOUT 3.50/2.50 INCHES PER THE GEFS/ECENS MEANS... RESPECTIVELY
LATE WED TO LATE FRI. BY THE WEEKEND... HEIGHTS WILL RISE AND THE
SFC FRONT SHOULD DISSIPATE AND THE HEAVY PRECIP POTENTIAL SHOULD
MOVES EAST INTO THE LOWER MS AND TN VALLEYS... AND LIKELY WITH
LOWER AMOUNTS.


FRACASSO

$$




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