Prognostic Meteorological Discussion
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FXUS02 KWBC 280557
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1256 AM EST WED JAN 28 2015

VALID 12Z SAT JAN 31 2015 - 12Z WED FEB 04 2015

...GUIDANCE/UNCERTAINTY EVALUATION AND PATTERN OVERVIEW...

THE WPC MEDIUM-RANGE PRODUCT SUITE IS PRIMARILY DERIVED FROM A
BLEND OF THE 12 UTC GFS/ECMWF AND GFS/ECMWF/NAEFS ENSEMBLE MEANS
ALONG WITH CONTINUITY. THESE GUIDANCE CHOICES OVERALL OFFER
FAVORABLE SOLUTION CLUSTERING...BUT FORECAST SPREAD AND RUN TO RUN
GUIDANCE VARIANCE SUGGEST ONLY AVERAGE TO BELOW NORMAL
PREDICTABILITY.

THE FAVORED WPC GUIDANCE COMPOSITE SHOWS THAT LARGE SCALE FLOW
WILL EVOLVE TOWARD A BROAD CONUS MEAN TROUGH DOWNSTREAM FROM A
RIDGE NEAR/JUST OFFSHORE THE WEST COAST. WITHIN THIS DEVELOPING
MEAN PATTERN THE MOST SIGNIFICANT FCST PROBLEM THIS PERIOD APPEARS
TO BE THE TIMING/DEPTH OF AMPLIFYING WRN CANADA FLOW AND DEGREE OF
INTERACTION WITH SRN STREAM FLOW INITIALLY CONTAINING AN UPPER LOW
OVER THE EXTREME SOUTHWEST. DETAILS OF THESE FEATURES AND
INTERACTIONS WILL AFFECT THE SFC EVOLUTION AND PCPN
TYPE/INTENSITY/COVERAGE FROM THE SWRN STATES THROUGH MUCH OF THE
CNTRL-ERN U.S. FROM LATE THIS WEEK INTO THE START OF NEXT WEEK.
MEANWHILE SOME ERN PAC ENERGY PUSHING THROUGH THE WEST COAST MEAN
RIDGE WILL SPREAD SOME MOISTURE/PCPN SEWD OVER THE NW QUARTER OF
THE NATION SUN-NEXT WED.

...SENSIBLE WEATHER HIGHLIGHTS...

THE EXIT OF A VIGOROUS SYSTEM OFF THE NORTHEAST SATURDAY WILL
BRING AN END TO A PERIOD OF WINTRY WEATHER AND STRONG WINDS. AN
UPPER LOW BY THIS WEEKEND OVER THE SWR US/MEXICO WILL SUPPORT
VARIOUS PCPN TYPES FROM THE FOUR CORNERS REGION INTO THE HIGH
PLAINS. THE PCPN SHIELD WILL CONTINUE ACROSS THE PLAINS THEN NEWD
TO THE ERN US AS NRN STREAM ENERGY GAINS INFLUENCE. GUIDANCE HAS
STILL NOT YET STABILIZED ON A PARTICULAR SOLUTION SO CONFIDENCE
REMAINS LOWER THAN DESIRED WITH EXACT PLACEMENT OF PCPN TYPES FOR
THIS SYSTEM...BUT FULLY EXPECT A SWATH OF ORGANIZED SNOWS ON THE
NRN PERIPHERY OF THE EXPANDING PCPN SHIELD WITH A MIX OF PCPN
TYPES OR CHANGEOVER ZONE JUST S. WPC WEATHER/PRECIPIATION TYPE
GRIDS/GRAPHICS OFFER OUR BEST ESTIMATE AT THIS TIME BASED FROM
LATEST GUIDANCE PREFERENCES. LOCATIONS WITHIN THE BROAD PCPN AREA
MAY SEE LOCALLY HEAVY AMOUNTS. PASSAGE OF THIS SYSTEM SHOULD
SUPPORT A PERIOD OF LAKE EFFECT SNOW. DRY CONDS ACROSS THE NW
QUARTER OF THE COUNTRY WILL TREND WETTER SUN-WED AS ERN PAC ENERGY
SLIPS THROUGH THE LONGER TERM MEAN RIDGE ALOFT...ESPECIALLY OVER
FAVORED TERRAIN...BUT AT LEAST THE LATEST SLEW OF MODELS HAVE
TRENDED BACK TOWARD A MUCH LESS DIGGY LOOK.

SCHICHTEL

$$




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