000
FXAK67 PAJK 052226
AFDAJK
SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
126 PM AKST MON JAN 5 2009
.SHORT TERM...985 MB LOW IN THE NORTHEAST GULF WILL REMAIN QUASI
STATIONARY THROUGH TONIGHT THEN START TO DIG SE ON TUESDAY. A
TROUGH/ARCTIC COLD FRONT EXTENDS SE OF THE LOW AND ACROSS NORTH
CENTRAL PANHANDLE IS FORECAST TO SLOWLY PUSH SOUTH AND WEST TO
COASTAL WATERS BY TUESDAY AFTERNOON. A 1020 MB ARCTIC HIGH WILL
BUILD INTO THE SOUTHERN YUKON TONIGHT.
BANDS OF SNOW SHOWERS CONTINUE TO ROTATE INTO NORTHERN PANHANDLE
TODAY WHILE OPEN CELLED SHOWERS ARE MOVING INTO SOUTHERN
PANHANDLE. SOME OF THESE SHOWERS ARE PRODUCING MODERATE SNOW OF
AROUND 1 INCH PER HOUR BUT AREA USUALLY SHORT LIVED. EXPECT AT
LEAST ONE MORE VORT LOBE TO ROTATE ACROSS CENTRAL PANHANDLE
TONIGHT AS 50H LOW PUSHES NORTHEAST AND OVER NORTHERN SOUTHEAST
ALASKA. SNOWFALL AMOUNTS WILL BE HIGHLY VARIABLE AND OPTED TO
KEEP A GENERIC WINTER WEATHER ADVISORY FOR 3 TO 5 INCHES IN A
12 HOUR PERIOD FOR MUCH OF COASTAL AND CENTRAL PANHANDLE THROUGH
TONIGHT.
IN THE FAR NORTH THE NORTH WINDS HAVE TEMPORARILY SUBSIDED WITH
WINDS GUSTING LESS THAN ADVISORY AT THIS TIME...HOWEVER...DO
EXPECT NORTHERLY GRADIENTS TO REBUILD THROUGH THIS EVENING WITH
STRONG GALES RETURNING TO THE NORTHERN INNER CHANNELS TONIGHT.
WINDS IN HAINES AND SKAGWAY SHOULD ALSO INCREASE WITH GUSTS
50 MPH EXPECTED OVERNIGHT. WITH TEMPERATURES IN THE LOW SINGLE
DIGITS CURRENTLY HAVE WIND CHILLS AROUND 15 BELOW ZERO BUT THIS
SHOULD LOWER AS TEMPERATURES FALL TONIGHT. WIND CHILL FOR WHITE
PASS IS CLOSER TO 35 BELOW ZERO. ALSO STILL EXPECT ARES OF
BLOWING SNOW AND HAVE OPTED TO PACKAGE THIS AS A WINTER WEATHER
ADVISORY AS WELL THROUGH TUESDAY MORNING.
IN THE COASTAL AND OFFSHORE WATERS HAVE SEEN WESTERLY GALES
DIMINISH THROUGH THE MORNING AND SHOULD BE AT SMCR LEVELS THROUGH
TONIGHT. THE NORTHERN GULF SHOULD SEE WINDS GO TO THE NE TONIGHT
WITH STRONGER GUSTS OUT OF INTERIOR PASSES DEVELOPING. SEAS CAME
UP TO 20 FEET IN THE OFFSHORE WATERS DUE TO A SW SWELL BUT NOW
ARE STARTING TO SUBSIDE WHILE COASTAL BUOYS HAVE AROUND 14 FT
WHICH SHOULD START TO EASE LATER TONIGHT. ALSO NOTE TEMPERATURES
NOW IN THE 20S WITH DEW POINT AS LOW AS THE SINGLE DIGITS ACROSS
THE WESTERN GULF AND TEMPERATURES NOW BELOW FREEZING FOR EASTERN
GULF SO WILL INCLUDE SOME FREEZING SPRAY IN PKZ043-051 TONIGHT.
.LONG TERM... WEATHER WILL REMAIN COLD THROUGH THE FIRST HALF OF
THE LONG TERM PERIOD BEHIND THE CURRENT SNOW. HIGH PRESSURE
BUILDING IN THE YUKON WILL CONTINUE TO PRODUCE HIGH PRESSURE
GRADIENTS ALONG THE COAST RANGES REINFORCING THE ARCTIC AIR THAT
IS ALREADY IN PLACE. IN THE UPPER ATMOSPHERE...A LONG WAVE TROUGH
IS FIXED OVER THE AREA AT THE BEGINNING OF THE PERIOD AND WILL BE
PUSHED OFF TO THE EAST AS A RIDGE BUILDS IN AHEAD OF THE NEXT
SYSTEM ON THURSDAY.
MAJOR FORECASTING CONCERN FOR THE LONG TERM IS THE SYSTEM MOVING
INTO THE AREA FOR FRIDAY. CURRENTLY IT LOOKS LIKE THE PRECIP WILL
START TO FALL LATE THURSDAY AS THE MOIST ONSHORE FLOW AHEAD OF
THE SYSTEM STARTS OVERRUNNING THE ARCTIC AIR AT THE SURFACE AND
CONTINUE THROUGH THE WEEKEND. EXPECT PRECIP TO REMAIN FROZEN OVER
MOST OF THE PANHANDLE TO START OUT BUT SOUTHERLY WINDS WILL
POSSIBLY WARM TEMPS UP ENOUGH TO HAVE THE SNOW START MIXING WITH
RAIN AS FAR NORTH AS JUNEAU SATURDAY AFTERNOON.
AFTER SATURDAY THE MODELS DIFFER BY A LARGE MARGIN BUT SEEM TO
POINT TO A WARMING TREND INTO EARLY NEXT WEEK. GRIDS WERE
UPDATED WITH A BLEND OF INHERITED/GFS/EC BLEND WITH A NOD MORE
TOWARD THE EC OUT THROUGH 12Z SATURDAY. USED A BLEND OF THE HPC
GUIDANCE AFTER THAT POINT AS IT PROVIDED A GOOD MIDDLE GROUND
SOLUTION TO THE DIFFERENCES SEEN FARTHER OUT. FORECAST CONFIDENCE
IS FAIR TO GOOD THROUGH SATURDAY THEN POOR FARTHER OUT.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 AM AKST
TUESDAY FOR AKZ023-024-026.
WINTER WEATHER ADVISORY UNTIL 3 AM AKST TUESDAY FOR AKZ021-025.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT AKST TONIGHT FOR AKZ020-
022.
WINTER WEATHER ADVISORY UNTIL 6 AM AKST TUESDAY FOR AKZ018-019.
WINTER WEATHER ADVISORY UNTIL 9 PM AKST THIS EVENING FOR AKZ017.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ011>013.
STORM WARNING FOR PKZ012.
GALE WARNING FOR PKZ011-013-021-022-031-032-041-042.
SMALL CRAFT ADVISORY FOR PKZ033-034-036-043-051-052.
&&
$$
MM/EAL
