Prognostic Meteorological Discussion
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FXUS02 KWBC 030653
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
253 AM EDT WED JUN 03 2015

VALID 12Z SAT JUN 06 2015 - 12Z WED JUN 10 2015

...OVERVIEW...

LATEST GUIDANCE IS SHOWING FAIRLY RAPID WEAKENING/SHEARING OF THE
UPR LOW FCST TO BE OVER CA/NV EARLY IN THE PERIOD AS A SRN PLAINS
RIDGE ALOFT MAY TRY TO RETROGRADE TOWARD/INTO NRN MEXICO.  BTWN
THESE TWO FEATURES THERE IS STILL POTENTIAL FOR SOME ERN PAC
TROPICAL MSTR... PRIMARILY FROM HURCN BLANCA... TO FLOW INTO PARTS
OF THE WEST BUT WITH A FAIR DEGREE OF UNCERTAINTY AS TO SPECIFICS
AT THIS TIME.  MEANWHILE AGREEMENT REMAINS GOOD WITH THE GENERAL
IDEA OF AN AMPLIFYING ERN NOAM TROUGH ALBEIT WITH SIGNIFICANT
DETAIL DIFFS YET TO BE RESOLVED.


...GUIDANCE EVALUATION/PREFERENCES...

WITH OPERATIONAL MODELS DIFFERING FROM EACH OTHER AND THE ENSEMBLE
MEANS FOR SOME INDIVIDUAL SFC FEATURES AS EARLY AS DAY 3 SAT...
THE UPDATED FCST STARTS WITH A 70/30 BLEND OF THE 12Z ECMWF
MEAN/NAEFS MEAN THROUGH THE FCST PERIOD.  THIS SOLN PROVIDES
BETTER CONTINUITY THAN OTHER OPTIONS WHILE REFLECTING RECENT
TRENDS TOWARD MORE PROGRESSIVE NERN PAC INTO WRN CANADA FLOW BY
THE MIDDLE OF NEXT WEEK.

OVER THE WEST... TRENDS NOTED BESIDES THOSE FOR NRN STREAM FLOW
INCLUDE A SOMEWHAT EARLIER WEAKENING OF THE INITIAL UPR LOW AS
WELL AS GREATER WWD EXTENT AND/OR FASTER RETROGRESSION OF THE SRN
PLAINS/NRN MEXICO RIDGE.  BY MID-LATE PERIOD THERE IS CONSIDERABLE
SPREAD REGARDING THE ULTIMATE EVOLUTION/TRACK OF ONE OR MORE
PIECES OF ENERGY ORIGINALLY ASSOC WITH THE UPR LOW AND SURROUNDING
FLOW.  IN ADDITION THERE IS VERY WIDE TIMING SPREAD FOR EPAC HURCN
BLANCA WITH GFS RUNS TENDING TO BE ON THE FAST SIDE.  CONSULT NHC
PRODUCTS FOR LATEST INFO REGARDING BLANCA AND WEAKENING HURCN
ANDRES FARTHER TO THE W.

THE LIKELIHOOD THAT THE AMPLIFYING ERN NOAM TROUGH WILL CONSIST OF
MULTIPLE PIECES OF ENERGY COMPLICATES THE FCST OVER THE CNTRL-ERN
STATES.  THERE IS A DECENT SIGNAL TOWARD A SFC WAVE TRACKING FROM
THE PLAINS THROUGH THE UPR GRTLKS SAT-MON BEFORE MERGING WITH
TRAILING CANADIAN LOW PRES... BUT POOR AGREEMENT ON
STRENGTH/TIMING.  ECMWF/UKMET SOLNS MAY BE A LITTLE TOO STRONG
WITH THIS WAVE BASED ON EVOLUTION ALOFT SO THE MAJORITY-WEIGHTED
ECMWF MEAN SOLN PROVIDES A GOOD REFLECTION OF A MORE MODEST WAVE.
AFTER PASSAGE OF THIS WAVE THERE ARE STILL UNCERTAINTIES WITH
SHRTWV DETAILS THAT ARE BEST DOWNPLAYED VIA THE ENSEMBLE MEANS FOR
THE TIME BEING.


...SENSIBLE WEATHER HIGHLIGHTS...

THE INITIAL UPR LOW/SURROUNDING TROUGH OVER THE WEST SHOULD BRING
A BROAD AREA OF UNSETTLED WEATHER TO THE REGION.  TIMING ISSUES
WITH EPAC HURCN BLANCA AND LINGERING DETAIL DIFFS WITH FLOW ALOFT
TO ITS N KEEP CONFIDENCE LOWER THAN DESIRED REGARDING THE AMOUNT
AND PRECISE PATH OF TROPICAL MSTR THAT MAY BE DRAWN INTO THE SWRN
CONUS... MOST LIKELY OVER AZ/NM INTO THE CNTRL ROCKIES.  GIVEN
OPPOSING GFS/ECMWF TIMING AND INTERMEDIATE TIMING OF THE NHC TRACK
FROM THE 03Z ADVISORY A GFS/ECMWF COMPROMISE WOULD BE A REASONABLE
STARTING POINT FOR RESOLVING THE AMOUNT OF MSTR THAT MAY REACH
INTO THE CONUS.  CLOUDS/RNFL SHOULD KEEP HIGHS BELOW NORMAL OVER
THE SRN 2/3 OF THE WEST THOUGH WITH A NOTICEABLE WARMING TREND
NEXT WEEK ESPECIALLY OVER/NEAR CA.  THE NORTHWEST SHOULD BE QUITE
WARM AND MOSTLY DRY... WITH PLUS 10-20F OR SLIGHTLY GREATER
ANOMALIES FOR TEMPS ESPECIALLY SAT INTO MON.  CONTINUE TO SEE
POTENTIAL FOR SOME CALENDAR DAY RECORDS AND SOMEWHAT MORE LIKELY
FOR WARM LOWS VERSUS DAYTIME HIGHS.

ASIDE FROM THE SRN PLAINS THAT WILL BE UNDER A RIDGE ALOFT... MANY
PLACES FROM THE HIGH PLAINS TO EAST COAST SHOULD SEE ONE OR MORE
EPISODES OF RNFL DURING PERIOD WITH PARTICULAR FOCUS ALONG FRONTAL
BOUNDARIES AND IN ADVANCE OF SHRTWV IMPULSES EJECTING FROM THE
WEST.  ASIDE FROM A PSBL AREA OF CONVECTION TRACKING ACROSS THE
NRN TIER STATES... CURRENT SPREAD FOR SHRTWV DETAILS ALOFT IS
SUFFICIENTLY GREAT TO YIELD LOW CONFIDENCE IN PINPOINTING MOST
FAVORED AREAS FOR HEAVIEST RNFL AT THIS TIME.  CONSULT SPC
OUTLOOKS FOR FURTHER INFO REGARDING ANY SEVERE THREATS.  EXPECT
TEMPS TO BE WITHIN 10F OF NORMAL MOST DAYS THOUGH WITH MIN TEMPS
TENDING TO RUN MORE CONSISTENTLY ABOVE NORMAL OVER MOST AREAS E OF
THE ROCKIES.

RAUSCH

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