Prognostic Meteorological Discussion
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FXAK02 KWNH 031931
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
331 PM EDT TUE MAY 03 2016

VALID 12Z SAT MAY 07 2016 - 12Z WED MAY 11 2016

...GUIDANCE/UNCERTAINTY ASSESSMENT...

THE WPC ALASKAN MEDIUM RANGE PRODUCT SUITE HAS BEEN PRIMARILY
DERIVED FROM A COMPOSITE BLEND OF GENERALLY COMPATABLE GUIDANCE
FROM THE 12 UTC GFS AND 00 UTC ECMWF AND 00 UTC GEFS/NAEFS/ECMWF
ENSEMBLE MEANS DAYS 4-6 SAT-MON. THE LATEST 12 UTC ECMWF SEEMS
ALSO PRETTY MUCH IN LINE. PREFER TO FOCUS WPC BLEND WEIGHTING MORE
IN FAVOR OF THE ENSEMBLE MEANS DAYS 7/8 AMID GROWING FORECAST
SPREAD. HOWEVER...FORECAST SPREAD HAS IMPROVED COMPARED TO THE
PAST FEW DAYS. AN EXCEPTION IS THE 06 UTC GFS THAT SHIFTS LATER
PERIOD LOW DEVELOPENTS MORE EASTWARD OVER THE SRN BERING SEA AND
WITH A LEAD NE PACIFIC LOW MORE NORTHWARD TO THE SRN GULF OF AK.
THIS IS CONSIDERED A LESS LIKELY OUTLIER SOLUTION AS FLOW NATURE
SEEMS TO TREND INCREASINGLY BLOCKY HIGH LATITUDES WITH TIME
OVERALL.

...FORECAST HIGHLIGHTS/THREATS...

LEADING MID-UPPER LEVEL TROUGH ENERGY PASSAGE FROM THE GULF OF AK
INLAND OVER THE SERN PANHANDLE AND ASSOCIATED SURFACE LOW/FRONT
DEVELOPMENT WILL LIFT MOISTURE TO FUEL TERRAIN AN ENHANCED HEAVY
PCPN SWATH THIS WEEKEND. WHILE ADDITIONAL TROUGH ENERGIES ARE
SLATED TO SUBSEQUENTLY WORK FROM THE SRN BERING SEA AND NRN
PACIFIC TO EFFECT THE ALEUTIANS/SW AK THEN THE GULF OF AK THIS
WEEKEND AND EARLY-MID NEXT WEEK WITH SOME INFLUENCE/PCPN...THE
MAIN STORM FOCUS SHOULD SHIFT UPSTREAM WITH SLOW APPROACH OF A
DEEP ALEUTIANS/SRN BERING SEA LOW THAT WOULD SPREAD PCPN ACROSS
THE REGION THEN INTO SW/WRN AK IN ABOUT A WEEK.

A SERIES OF WEAKER SHORTWAVE TROUGHS WILL MEANWHILE TRACK OVER
NWRN/N-CENTRAL ALASKA TO ENHANCE LOCAL GRADIENTS AND OFFER SOME
MODEST PCPN POTENTIAL MAINLY THIS WEEKEND PRIOR TO SIGNIFICANT
RIDGE BUILDING EXPECTED UP OVER THE INTERIOR NEXT WEEK IN ADVANCE
OF THE MAIN BERING SEA LOW.

SCHICHTEL

$$





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