Heavy Snow in Alaska, January 13, 2004

SOUTHEAST ALASKA FORECAST DISCUSSION
1045 AM AST MON JAN 12 2004

.SYNOPSIS...

.SHORT RANGE...MODELS DOING A FAIR JOB WHEN COMPARED TO SATELLITE
IMAGERY THIS MORNING A LOW DRIFTING NORTHWARD OVER THE EASTERN
HALF OF THE GULF OF ALASKA. A BAND OF CLOUDS AND MOISTURE WILL
MOVE NORTH OVER SOUTHEAST ALASKA TODAY. SPREADING RAIN NORTH OVER
NEARLY ALL THE PANHANDLE EXPECT THE NORTHERN PORTION OF THE
PANHANDLE WHERE SOME LIGHT SNOW COULD FALL LATE THIS AFTERNOON
AND EVENING. COLD DRY AIR SPILLING FORTH OVER THE NORTHERN GULF
WILL HELP TO DEEPEN THE LOW AS MOVES TO SOUTHWEST OF YAKUTAT
TUESDAY NIGHT.

THE COLD AIR WILL WILL SLOWLY MOVE SOUTHEAST ACROSS THE NORTHEAST
GULF WHICH SHOULD BE ENOUGH TO CHANGE ALL THE SHOWERS OVER THAT
AREA TO SNOW.  THE NORTHWEST CORNER OF THE PANHANDLE...SAY NORTH
OF CROSS SOUND AND PROBABLY NORTHERN OF BERNERS BAY WILL BE SNOW
OR MIXED. REST OF PANHANDLE WILL CONTINUE TO HAVE SOME LIGHT RAIN
OR SHOWERS FROM WEAK LOWS OR THE UPPER LEVEL TROUGH BEGINNING TO
LIFT THROUGH SOUTHEAST ALASKA.

.LONG RANGE...THE PRIMARY SYNOPTIC FEATURE THROUGH WED IS A
LOW ALOFT DEVELOPIONG OVER SOUTH CENTRAL ALASKA.  THIS LOW WILL
BE QUASISTATIONARY UNTIL WED NIGHT WHEN AVN AND ETA SOLUTIONS
BEGIN TO TRACK IT ZONALLY E. THIS TRACK IS ACCEPTED WITH MINOR
CONCERNS GIVEN IN THE NEXT PARAGRAPH. THE DEVELOPMENT OF THIS
LOW ALOFT WILL SUPPORT A STRONG SOUTFLOW OF ARCTIC AIR OVER THE
WESTERN AND CENTAL GULF OF ALASKA.  THE STRONG ARCTIC OUTFLOW
WILL RESULT IN AN OUTFLOW ARCTIC BOUNDARY OVER THE GULF OF
ALASKA. DIABATIC HEATING FROM THE SURFACE OF THE GULF
OF ALASKA WILL MODIFY THIS AIRMASS DUE TO THE HIGHLY UNSTABLE
BOUNDARY LAYER THAT WILL BE HUMIDIFYING THE ARCTIC AIR.
NUMEROUS WEAK LOWS SHOULD TRAVEL ALONG THE FRONTAL BOUNDAY
BETWEEN THE ARCTIC AND HIGHLY MODIFIED ARCTIC AIR...THE
BOUNDARY SHOULD EXTEND FROM ABOUT 100 NM OFFSHORE OF
YAKUTAT TO ONSHORE NEAR SITKA BY TUE MORNING.

EUROPEAN MODEL DOES NOT HAVE EASTWARD TRACK OF LOW AND HAS
RETROGRESSOIN THAT WAS CHARACTERISTIC OF PRIOR RUNS OF
SEVERAL OTHER MODELS. THE RETROGRESSION IS NOT ACCEPTED BUT
MONITORING OF MODELS FOR ANY RETURN OF THE RETROGESSION
WILL BE MADE.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...NONE.
MARINE...CURRENTLY SMCR PKZ012>052

JT BMB