Prognostic Meteorological Discussion
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000
FXUS02 KWBC 071457
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1057 AM EDT TUE JUL 07 2015

VALID 12Z FRI JUL 10 2015 - 12Z TUE JUL 14 2015


...OVERVIEW AND GUIDANCE EVALUATION/PREFERENCES...

THE GUIDANCE REMAINS CONSISTENT WITH THE PERSISTENCE OF THE UPPER
LOW OVER THE SOUTHERN BERING SEA AND BUILDING THE DEEP LAYER
ANTICYCLONE WEST FROM THE SOUTHEAST ACROSS THE LOWER MS VALLEY AND
THEN THE SOUTHERN PLAINS.  NRN PAC ENERGY FEEDS INTO A TROUGH JUST
OFF THE WEST COAST.

ENERGY ASSOC WITH THE SHORT RANGE UPR LOW REACHING CA IS FORECAST
TO ROUND THE BUILDING ROCKIES/HIGH PLAINS RIDGE AND THEN HELP TO
RE AMPLIFY THE ERN TROUGH.  HOWEVER SOLNS HAVE NOT YET LOCKED ONTO
EXACTLY HOW SHEARED THE ENERGY WILL BECOME AS IT ROUNDS THE RIDGE
AND WHETHER THE WAVE WILL PERSIST OR DECAY MORE QUICKLY
DOWNSTREAM OVER THE NORTHERN PLAINS AND UPPER MS VALLEY AND
BEYOND.  THE 06Z GFS WAS MOST ASSERTIVE IN DEVELOPING A DOWNSTREAM
CLOSED LOW IN THE VICINITY OF LK ERIE 00Z TUE AND IN WESTERN PA
12Z TUE 14 JULY.  SINCE THIS FEATURE WAS NOT SHOWN IN THE 00Z GFS
RUN OR OTHER OPERATIONAL MODELS...CONFIDENCE IS LOW WHETHER THE
LOW WILL DEVELOP.

THERE IS GOOD CLUSTERING FOR THE DAYS 3-5 FORECASTS. THUS FOR DAYS
3-5 FRI 10 JULY -SUN 12 JULY A CONSENSUS BLEND AMONG THE 06Z
GFS/00Z ECMWF WITH LESSER WEIGHTING OF THE 06Z GEFS/00Z ECMWF
MEANS WAS USED.  GREATER SPREAD EMERGES AFTER SUN SO THE DAYS 6-7
MON 13 JUL -TUE 14 JUL FCST ADJUSTS TO HIGHER WEIGHTING OF THE
ENSEMBLE MEANS...WITH SUFFICIENTLY LOW WEIGHTING OF EITHER
OPERATIONAL RUN TO DOWNPLAY SMALLER SCALE FEATURES THAT HAVE LOWER
CONFIDENCE.  THERE IS GOOD AGREEMENT ON A WAVY FRONTAL SYSTEM
EXTENDING FROM THE MID MS VALLEY ACROSS THE OH VALLEY TO THE MID
ATLANTIC...BUT DETAIL DIFFERENCES AS TO WHERE CIRCULATION CENTERS
ARE ALONG THE FRONTAL ZONE.

THE EARLY NEXT WEEK PREFERENCE AWAY FROM OPERATIONAL SOLNS WAS
BASED ON TELECONNECTIONS FROM BOTH THE UPSTREAM BERING SEA CLOSED
LOW AND SOUTHERN PLAINS ANTICYCLONE...WHICH TELECONNECT TO A HIGH
AMPLITUDE WESTERN CANADA RIDGE AND PERSISTENT TROUGH NEAR THE WEST
COAST. THE 06Z GFS RUN AND 00Z ECMWF/ECMWF ENSEMBLE MEAN ARE
LITTLE FASTER MOVING THE 500 MB TROUGH ONSHORE IN THE PACIFIC
NORTHWEST AND THE SLOWER 06Z GEFS/00Z NAEFS MEANS ARE PREFERRED
SINCE THEY MATCH TELECONNECTIONS BETTER.

...SENSIBLE WEATHER HIGHLIGHTS...

ENERGY ASSOC WITH THE UPR SYSTEM INITIALLY EJECTING THROUGH THE
WEST SHOULD SUPPORT AN AREA OF ENHANCED RNFL IN THE PACIFIC
NORTHWEST AND NRN ROCKIES.  DOWNSTREAM THIS ENERGY ALONG WITH THE
AMPLIFYING ERN NOAM TROUGH ALOFT SHOULD GENERATE AREAS OF
CONVECTION AS LOW PRESSURE AND A FRONTAL SYSTEM PROGRESS ACROSS
THE MID MS VALLEY AND OHIO VALLEY/CENTRAL APPALACHIANS/MID
ATLANTIC.  ENHANCED RAINFALL EXTENDS NORTH INTO THE UPPER MS
VALLEY AND GREAT LAKES AS WELL AS NEAR THE FRONT FURTHER SOUTH.
EXPECT CONVECTION OVER AZ/NM/CO/SOUTHEAST UT AS MONSOONAL MOISTURE
ROTATES AROUND THE WESTERN PERIPHERY OF THE SOUTHERN PLAINS HIGH.

THE NORTHWEST SHOULD BE IN THE PROCESS OF COOLING DOWN AFTER ONE
MORE DAY OF HOT TEMPS DAY 3.  TEMPS STABILIZE WITHIN A FEW DEGS OF
NORMAL BY EARLY NEXT WEEK.   THE REMAINDER OF THE WEST WILL LIKELY
SEE BELOW NORMAL HIGHS...WITH MOST AREAS 3-4 DEGREES BELOW
AVERAGE.  THE SOUTHEAST SHOULD BE 4-8 DEGREES ABOVE NORMAL WITH A
SECONDARY CENTER OF ABOVE NORMAL TEMPERATURES DEVELOPING OVER THE
SOUTHERN TO SOUTH CENTRAL PLAINS UNDER THE ANTICYCLONE EARLY NEXT
WEEK.

PETERSEN

$$





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