Small Craft Advisory 31, NWS Anchorage, AK

AREA FORECAST DISCUSSION SOUTHCENTRAL ALASKA
500 PM AST SUN JAN 9 2005

.DISCUSSION...
ANALYSIS - THE MONDO BLOCKING HIGH AFFECTING ALL OF SOUTHERN ALASKA
HAS TWO RIDGES THAT HAVE INCREASED IN AMPLITUDE: ONE WELL INTO
SIBERIA AND THE OTHER OVER NW CANADA. THE HIGH CENTER IS AROUND 50N
160W AT 12Z. THE JET IS INTERESTING BECAUSE A DEEP UPPER LOW IS NEAR
BANKS ISL. AT 250 MB 12Z THE CORE IS ALREADY 115 KT AS PER PAOT RAOB
WHICH IS UNDERDONE ON THE 12Z MODEL INITIALS. DRY CONDITIONS PREVAIL
FOR THE MAINLAND AREAS AND THE FOG IN ANCHORAGE IS GONE TANX TO SOME
LOW LEVEL WINDS JUST ABOVE THE BOUNDARY LAYER FOR EVER SO SLIGHT
MIXING...BUT FOG JUST CAME INTO KENAI. ANOTHER INTERESTING FEATURE IS
AN ARCTIC DRYLINE THAT HAS MOVED PAST CANTWELL INTO ZONE 145. WINDS
HAVE SHIFTED WHICH IS THE BEGINNING OF THE COLD ADVECTION. OUT WEST
THE OLD FRONT HAS MOVED TO AROUND 172W AS PER GOES IMAGERY. THE N
ADVANCE OF WARM AIR AHEAD OF THIS SYSTEM IS MEETING A 1056 SURFACE
HIGH CELL OVER N SIBERIA. A 990 MB LOW IS JUST OFF KAMCHATKA WITH A
SECONDARY AROUND 997 MB NEAR 45N 180 AT 17Z.

EASTERN FORECASTS - IT IS CERTAIN THAT TEMPERATURES ARE IN A COOLING
TREND FOR ALL MAINLAND AREAS AS THE COLD ADVECTION ADVANCES. THE
COOLING WILL BE AIDED BY A FASTER THE WESTERLY JET OVER ANCHORAGE
OVER THE NEXT TWO DAYS AND SUSPECT THAT THE SPEEDS ARE UNDERDONE DUE
TO THE INITIAL PROBLEM MENTIONED ABOVE. OUTFLOW GAP WINDS WILL BE A
PROBLEM OVER THE NEXT COUPLE OF DAYS AND FREEZING SPRAY WILL PROBABLY
NEED TO BE ADDED TO THE MARINE FORECASTS. DEVELOPMENT OF A MAJOR
UPPER LOW OFF KAMCHATKA BY MID WEEK IS SUPPOSED TO BREAK DOWN OUR
BLOCKING UPPER RIDGE ON EARLIER GFS-190 RUNS. METHINKS THAT THE NEW
12Z GFS RUN WHICH HOLDS ONTO THE RIDGE LONGER IS CORRECT.

WESTERN FORECASTS - THE REAL DEAL FOR MAINLAND AREAS IS OFFSHORE
FLOW. FOR THE WESTERN AND CENTRAL ALEUTIANS THE GFS-190 IS
FORECASTING SOME GALES ESPECIALLY WHEN THE OLD FRONT MOVES UP TOWARD
ST MATTHEW ISL THIS EVENING. THE SURFACE LOW WILL REMAIN COMPLEX IN
THE WESTERN BERING SEA BUT THE LOWS GET DEEPER IN THE MEDIUM RANGE
UNDER THE SUPPORT OF THE DEVELOPING MAJOR UPPER LOW MID WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...WIND ADVISORY 131 135 191. DENSE FOG ADV THIS MORNING 121.
MARINE...GALES 12B 13A 14. HVY FRZ SPRAY 8 14.
FIRE WEATHER...NONE.

JC JAN 05