Prognostic Meteorological Discussion
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FXUS02 KWBC 280615
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
214 AM EDT THU JUL 28 2016

VALID 12Z SUN JUL 31 2016 - 12Z THU AUG 04 2016

...OVERVIEW AND GUIDANCE EVALUATION/UNCERTAINTY ASSESSMENT...

THE AREA EXTENDING FROM THE BERING SEA/ALASKA THROUGH NERN PAC AND
NRN CONUS/SRN CANADA REMAINS A ZONE OF RELATIVELY HIGHER FCST
UNCERTAINTY... BUT AS A WHOLE THE MODELS AND ENSEMBLE MEANS FROM
THE 12Z-18Z CYCLES CONTINUE A GRADUAL IMPROVEMENT IN DEFINING THE
INDIVIDUAL FEATURES.  CURRENT EXPECTATION IS FOR THE CORE OF A
LEADING TROUGH TO PROGRESS FROM WRN CANADA TOWARD HUDSON BAY WITH
A LEADING COLD FRONT PUSHING INTO THE NRN PLAINS.  A TRAILING
BUNDLE OF NERN PAC ENERGY IS NOW SCHEDULED TO REACH THE PAC NW
AROUND MON-TUE.  AS THIS FEATURE CONTINUES EWD IT MAY SUPPORT A
WAVE ALONG THE TRAILING PART OF THE NRN PLAINS FRONT.  ENSEMBLE
MEANS HINT AT TIMING MORE SIMILAR TO AN AVG OF 18Z/12Z GFS RUNS
AND 00Z/27 ECMWF RATHER THAN THE FASTER 12Z/27 ECMWF AFTER EARLY
TUE.  THEN BEHIND THIS SHRTWV A CLOSED LOW IS FCST TO TRACK TO OR
SLIGHTLY OFFSHORE THE BC COAST.  MODELS/MEANS ARE MORE SIMILAR
WITH THIS CLOSED LOW THAN IN PREVIOUS DAYS.  A BLEND INCLUDING THE
MOST COMMON ASPECTS THE 12Z ECMWF/12Z-18Z GFS AND 18Z GEFS/12Z
ECMWF MEANS REFLECTS THE MOST LIKELY SCENARIO FOR THIS STREAM OF
FLOW AT THIS TIME... THOUGH GUIDANCE HISTORY AND TYPICAL FCST
ERRORS SUGGEST FURTHER ADJUSTMENTS ARE LIKELY.

THERE ARE STILL LINGERING QUESTIONS OVER THE EXACT EVOLUTION OF
THE UPR TROUGH CROSSING THE NORTHEAST DURING THE FIRST HALF OF THE
PERIOD AND ASSOC SFC REFLECTION.  AT THE MOMENT THE 12Z AND NEW
00Z UKMET/CMC REPRESENT LESS LIKELY SOLNS THAT ARE STRONGER/NWD AT
THE SFC DUE TO DEEPER UPR SUPPORT.  AMONG REMAINING GUIDANCE AN
AVG BTWN THE 12Z ECMWF/ECMWF MEAN AND SOMEWHAT MORE SUPPRESSED
GFS/GEFS MEAN RUNS PROVIDES A REASONABLE ACCOUNT FOR ONGOING
DETAIL UNCERTAINTY.

THE BEST DEFINED RIDGING ALOFT SHOULD EXTEND ACROSS THE FOUR
CORNERS AND S-CNTRL PLAINS.  CURRENT CONSENSUS SHOWS A SLIGHTLY
STRONGER TREND WITH THE WRN PART OF THE OVERALL RIDGE COMPARED TO
24 HRS AGO.

DAYS 3-4 SUN-MON START WITH AN OPERATIONAL BLEND OF HALF 12Z ECMWF
AND THE REMAINDER 12Z/18Z GFS TO PROVIDE GREATER DEFINITION THAN
THE OTHERWISE SIMILAR ENSEMBLE MEANS.  THEREAFTER THE FCST USES A
MORE EVEN WEIGHTING AMONG MODELS AND THEIR MEANS AS CONFIDENCE IN
ANY PARTICULAR SOLN DECREASES BUT NOT TO AS GREAT AN EXTENT AS IN
PREVIOUS DAYS.


...SENSIBLE WEATHER HIGHLIGHTS...

THE WAVY FRONT EXTENDING FROM THE MID ATLC BACK INTO THE PLAINS
WILL CONTINUE TO SERVE AS A FOCUS FOR LOCALLY ENHANCED RNFL.  THE
STEADIEST SIGNAL FOR HIGHEST TOTALS DURING THE 5-DAY PERIOD IS
NEAR THE SRN MID ATLC COAST BUT POCKETS OF HVY RNFL ARE PSBL OVER
OTHER AREAS FROM THE MS VLY TO EAST COAST.  EXPECT THE NRN TIER TO
SEE ONE OR MORE EPISODES OF CONVECTION WITH THE LEADING FRONT
PUSHING ACROSS THE PLAINS AND ANY TRAILING WAVES SFC/ALOFT.  SOME
OF THIS CONVECTION MAY BE STRONG TO SEVERE.  MONITOR SPC OUTLOOKS
AS IMPORTANT DETAILS COME INTO CLEARER FOCUS.  MONSOONAL
CONVECTION IS LIKELY TO BE ACTIVE OVER PARTS OF THE
SOUTHWEST/GREAT BASIN/SRN-CNTRL ROCKIES WITH SOME SHWRS/TSTMS
PRODUCING LOCALLY HVY RNFL.

WARM FLOW AHEAD OF THE ADVANCING NRN PLAINS FRONT WILL SPREAD A
FAIRLY BROAD AREA OF PLUS 5-10F OR SO ANOMALIES FOR TEMPS FROM THE
PLAINS INTO THE MID-UPR MS VLY AND EVENTUALLY INTO PARTS OF THE
EAST... WHILE NWRN U.S./NRN PLAINS LOCATIONS BEHIND THE FRONT
SHOULD TREND TO OR MODESTLY BELOW NORMAL.  THE SRN 2/3 OF THE
INTERIOR WEST AND PORTIONS OF THE SOUTHEAST SHOULD REMAIN SOMEWHAT
ABOVE NORMAL FOR MOST OF THE PERIOD.  IF THERE ARE ANY DAILY
RECORDS TO BE SET THEY WOULD MOST LIKELY BE FOR WARM LOWS OVER THE
SOUTHEAST/FLORIDA.

RAUSCH

$$




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