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553
FXAK67 PAJK 220002
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
402 PM AKDT TUE OCT 21 2014

.SHORT TERM...A VIGOROUS LOW OVER THE SOUTHEAST GULF OF ALASKA HAS
SPREAD ITS FRONTAL BAND NORTH ACROSS THE REGION AND IS NOW IN THE
VICINITY OF ICY STRAIT, CONTINUING NORTHWARD. NUMEROUS CONVECTIVE
CELLS BEHIND THE FRONT ARE ROTATING NORTHWARD. THERE WAS
SUFFICIENT INSTABILITY TO SUPPORT PLENTY OF MARINE THUNDERSTORM
ACTIVITY. LIGHTNING STRIKES DETECTED OVER THE EASTERN PACIFIC, HAIDA
GWAII, HECATE STRAIT AND SOUTH TO VANCOUVER ISLAND. THINK THAT
THIS ACTIVITY WILL BE SPREADING NORTH AND OUT OVER THE EASTERN
HALF OF THE GULF TONIGHT. THUNDER SHOULD BE LIMITED TO COASTAL
AREAS.

THE LOW WILL BE MOVING WEST TO THE WEST CENTRAL GULF OF ALASKA BY
WEDNESDAY MORNING. HOWEVER BEFORE IT PULLS AWAY THE SECOND WRAP
WILL GRAZE THE SOUTHERN COAST. AM EXPECTING GUSTY WINDS WITH
STRONG WIND HEADLINES FOR A LARGE PORTION OF SOUTHERN PANHANDLE
THROUGH THE EVENING HOURS.

WILL BEGIN TO SEE SOME IMPROVEMENT IN THE WEATHER AND WINDS AS THE
LOW RETREATS WEST. SEAS IN THE COASTAL WATERS IN THE UPPER TEENS
AND THAT WILL PERSIST THROUGH TONIGHT AND SLOWLY RECEDE AS WELL.

.LONG TERM...MODEL DIVERGENCE EARLY ON AS A WAVE DEVELOPS ALONG
THE PRE-EXISTING FRONTAL BOUNDARY ASSOCIATED WITH THE LOW DISCUSSED
ABOVE. THESE TWO FEATURES WILL ROTATE AROUND EACH OTHER, WITH THE
PARENT FILLING AND THE CHILD DEEPENING WHILE APPROACHING THE
SOUTHEAST OUTER COAST WEDNESDAY NIGHT. THE SECOND LOW WILL THEN
REMAIN SOMEWHAT ANCHORED OVER THE SOUTHEASTERN GULF THROUGH FRIDAY
NIGHT WHILE WEAKENING BEFORE EXITING THE FORECAST AREA TO THE
SOUTHEAST. TROUGHING WILL REMAIN OVER THE EASTERN GULF WITH
MULTIPLE EMBEDDED MID LEVEL CIRCULATIONS. THE VARIOUS LOWS AND
TROUGHS WILL CONTINUE TO PRODUCE SCATTERED SHOWERS AND/OR A CHANCE
OF RAIN THROUGH MUCH OF THE UPCOMING WEEK.

ATTENTION THEN TURNS TO TROPICAL STORM ANA. MORNING MODEL GUIDANCE
WAS VERY DISAPPOINTING WITH GFS KEEPING THE REMNANTS WELL TO THE
SOUTH AND TRACKING THEM INTO WESTERN CONUS WHILE ECMWF WAS
TRACKING AN EXTREMELY DEEP SYSTEM RIGHT INTO THE EASTERN GULF
EARLY NEXT WEEK. BASED ON THE CURRENT LOCATION OF THE STORM JUST
WEST OF HAWAII, IT DID NOT SEEM LIKELY THAT IT COULD GET DRIVEN
FAR ENOUGH NORTH IN THE PREVAILING WESTERLIES TO ENTER THE GULF.
SIMILAR THINKING BY WPC. 12Z ECMWF THEN CAME IN MUCH BETTER
AGREEMENT WITH THE MORNING GFS AND WHILE THE GFS IS STILL
EXHIBITING SOME RUN TO RUN VARIABILITY, THE AFTERNOON RUN
SUBSTANTIALLY IN AGREEMENT WITH THE MORNING RUN.

USED AN ENSEMBLE APPROACH WEDNESDAY NIGHT THROUGH SATURDAY NIGHT
FOR PRESSURE AND WIND, THEN TRANSITIONED TO WPC. USED GFS, GEM,
AND ECMWF FOR POP/QPF WEDNESDAY NIGHT THROUGH FRIDAY NIGHT,
BLENDING IN PROGRESSIVELY MORE OF THE EXISTING GRIDS. NO CHANGES
TO TEMPERATURES. OVERALL FORECAST CONFIDENCE IS AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND THROUGH LATE TONIGHT FOR AKZ026.
         STRONG WIND UNTIL 1 AM AKDT WEDNESDAY FOR AKZ027-028.
         STRONG WIND UNTIL 7 PM AKDT THIS EVENING FOR AKZ025.
         STRONG WIND THROUGH WEDNESDAY MORNING FOR AKZ023.
MARINE...GALE WARNING FOR PKZ022-033-035-036-041>043-051.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-031-032-034-052.

&&

$$

BEZENEK/FRITSCH

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