High Wind in Alaska, March 12 to 13, 2003

SOUTHEAST ALASKA FORECAST DISCUSSION
1045 AM AST WED MAR 12 2003

.SYNOPSIS...
.SHORT RANGE...12Z AVN HAS SHIFTED THE UPPER TROF DROPPING INTO
THE GULF THURSDAY FURTHER WEST. THIS WOULD OPEN THE DOOR TO A
SURFACE LOW MOVING NORTH TO JUST EAST OF PAJN BY THURSDAY
EVENING. THIS WOULD BRING LOTS OF SNOW AS FAR N AS JUNEAU. 12Z
MESOETA KEEPS THE LOW FURTHER EAST...WOULD NOT BRING AS MUCH SNOW
AS FAR NORTH AND KEEPS MODERATE N-NE WINDS NORTH OF ANGOON.

MODELS AGREE PRETTY WELL THROUGH TONIGHT...BRINGING SNOW INTO THE
SOUTH TODAY WHICH IS ALREADY OCCURRING IN THE FAR SOUTHERN
PANHANDLE AND CHANGING IT TO RAIN THERE BY 06Z THIS EVENING. SNOW
WILL START AS FAR N AS PAPG-PAAP BY 9PM THIS EVENING AND WILL
CHANGE TO RAIN BY 15Z THRUSDAY MORNING AT PAAP-PAPG. SNOW WILL
BEGIN AT PASI-PAJN BY 3AM LATE TONIGHT.

LEANING TOWARD ISSUING SNOW ADVISORY FOR CENTRAL PANHANDLE
TONIGHT AND POSSIBLY FOR THE SOUTHERN PANHANDLE LATER TODAY AND
THIS EVENING. TEMPS WERE COMING UP QUICKLY AT PANT AND SN SHOULD
CHANGE TO RN SOON. WILL CONT WIND ADVISORIES FOR NORTHERN HALF OF
PANHANDLE TONIGHT.

.LONG RANGE...A DEEP UPPER LEVEL LOW AND SURFACE LOW FORM OVER
THE GULF THURSDAY AND WILL SLOWLY FILL AS IT PERSISTS INTO EARLY
NEXT WEEK. BY TUE THE LOW FILLS INTO AN UPPER LEVEL TROUGH THAT
EXTENDS ACROSS THE EASTERN GULF AND SLOWLY MOVES EASTWARD INTO
MIDWEEK.

BIG CHANGES ARE OCCURRING WITH THE SHORT RANGE MODELS FROM RUN TO
RUN IN HANDLING THE SYSTEM OVER THE NORTHEAST PACIFIC. EACH RUN
OVER THE PAST 12 HOURS IS MUCH FURTHER NORTH AND FASTER WITH THE
TRACK OF LOW. INSTEAD OF TRACKING THE LOW ACROSS DIXON ENTRANCE
BOTH THE 12Z ETA AND AVN MODELS TAKE THE LOW ACROSS FREDERICK
SOUND BY THU EVENING. COLD ARCTIC AIR IN PLACE WILL PROVIDE A
GOOD SET UP FOR STRONG OVERRUNNING PRECIPITATION WITH THE
POTENTIAL FOR HEAVY SNOW ACROSS THE CENTRAL PANHANDLE ON THU AND
A FAR NORTH AS ZONES 21 AND 24 IN THE NORTHERN PANHANDLE.

PREVIOUS FORECAST PACKAGE HAD ALREADY SPED UP PRECIPITATION AND
PUSHED IT NORTH. IF THE 18Z RUN IS STILL SHOWING THIS TREND WILL
HAVE TO PUSH THE ONSET OF PRECIPITATION UP BY ABOUT 12 HOURS AND
BRING HEAVY SNOW INTO ZONES 21 AND 24. SOUTHEAST FLOW DEVELOPS
OVER THE SOUTHERN THIRD WITH THE LOW TRACKING NORTH SO EXPECT
PRECIPITATION TO CHANGE TO RAIN BY THU MORNING WITH A CHANGE OVER
TO RAIN WORKING NORTH INTO ZONE 26 ON THU. THE TIGHT PRESSURE
GRADIENT OVER THE NORTHERN HALF OF THE PANHANDLE WILL WEAKEN
THROUGHOUT THE DAY SO EXPECT WINDS TO DROP BELOW WARNING AND
ADVISORY CRITERIA BY EVENING...BELOW STORM AND GALES IN THE
MARINE.

FROM FRIDAY INTO EARLY NEXT WEEK...LOW PRESSURE PERSISTS OVER THE
CENTRAL GULF WITH SHORT WAVE ENERGY ROTATING AROUND THE UPPER
LEVEL LOW. THIS WILL BRING THE POTENTIAL FOR LOW PRESSURE SYSTEMS
TO DEVELOP IN THE BAROCLINIC ZONE OVER THE NORTHEAST PACIFIC AND
MOVE NORTH INTO THE EASTERN GULF. THE TREND FOR A WETTER AND
MILDER PATTERN STILL LOOKS GOOD WITH PRECIPITATION TYPE TRICKY AT
TIMES OVER THE NORTHERN HALF OF PANHANDLE AS COLDER AIR MOVES IN
BEHIND THESE WAVES.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...SNOW ADVISORY ZN027..028..029
         HIGH WIND WARNING ZN024..025
         WIND ADVISORY ZN021..022..023..026.
MARINE...STORM 1A1..NORTHERN 1A3
         GALE 1A2..SOUTHERN 1A3..1B..2A
         HEAVY FREEZING SPRAY 1A1..1A2..NRN 1A3.

LN/TAR