Gale Warning 177, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
1203 PM AKDT SUN JUL 20 2008

.SHORT TERM... MAJOR UPR LOW CENTER NEAR 55N 145W AT 12Z IS
MOVING EASTWARD AS PER GOES SATELLITE LOOP. THIS SUPPORTS A
DEVELOPING SFC LOW THAT WILL MAKE LANDFALL NEAR CAPE DECISION
THIS AFTERNOON. HIGH LEVEL JET PERSISTS ALONG 50N WHICH BECOMES
SW OVR SOUTHERN PANHANDLE. PANT 12Z RAOB HAD 105 KT AROUND
250 HPA. FRONT AROUND SFC LOW OCCLUDED WITH LOTS OF MOISTURE OVR
BARANOF ISL AS OF 18Z. COLD FRONT FROM QUEEN CHARLOTTES THEN
ACROSS 48N OR SO 18Z. SOME  TRAPPED LOW LEVEL MOISTURE IN INNER
CHANNELS EARLY THIS MORNING.

 ALL OPERATIONAL MODELS REVIEWED PRETTY CLOSE ON SFC LOW LANDFALL
THIS AFTERNOON BUT NCEP 20/12Z RUNS INDICATE UPR LOW CENTER OVR
CENTRAL PANHANDLE TONIGHT. THIS ONE HAD COLD AIR BACK IN WESTERN
GULF FOR SOME ENHANCEMENT OF SHOWERS TONITE. TRICKY FORECAST FOR
HOW MUCH RAIN OR SHOWERS FOR NORTHERN SECTIONS. WILL PROBABLY
FOLLOW PREVIOUS SHIFT ON THAT. EXPECT SOME WIND WITH SFC LOW FOR
SOUTHERN SECTIONS INTO TONIGHT. ALSO SOME SMALL CRAFT WIND LYNN
CANAL MON AFTERNOON FOR A THERMAL LOW IN THE YUKON. WILL USE
AK-GFS-40 FOR THIS PACKAGE.

.LONG TERM...NO CHANGES TO OVERALL PATTERN THAT HAS BEEN IN PLACE
AND DISCUSSED OVER THE PAST SEVERAL DAYS...A LONG WAVE TROUGH
CENTERED OVER THE GULF THAT IS INTERRUPTED BRIEFLY BY THE PASSAGE
OF A WEAK UPPER RIDGE LATE IN THE WEEK. ALTHOUGH SOME SIGNIFICANT
RUN-TO-RUN DIFFERENCES CONTINUE TO TAKE PLACE IN BOTH GFS AND
ECMWF...A MAJORITY OF THOSE DIFFERENCES TAKE PLACE WELL AWAY FROM
THE PANHANDLE. HOWEVER...GFS CONTINUES TO DEPICT THE SURFACE RIDGE
AXIS OFFSHORE OVER THE GULF AND THEREFORE HAVE A PREFERENCE FOR
ECMWF AND UKMET WHICH KEEP THE AXIS OVER THE COAST.

OTHERWISE PRETTY GOOD AGREEMENT BETWEEN GFS AND ECMWF AT THE
BEGINNING OF THE LONG RANGE FORECAST PERIOD WITH A SURFACE HIGH
RIDGING NORTH AND WEST OVER THE PANHANDLE AND A BROAD AREA OF WEAK
LOW PRESSURE ALONG THE EXTREME NORTHERN GULF THAT EXTENDS INTO THE
INTERIOR. AM STILL EXPECTING TUESDAY AND TUESDAY NIGHT TO BE
FAIRLY DRY FOR THE SOUTHERN HALF OF THE PANHANDLE...WITH DRY
CONDITIONS POSSIBLE LASTING THROUGH WEDNESDAY AS WELL FOR THE
EXTREME SOUTHERN PANHANDLE.

BY MONDAY NIGHT GFS...UKMET...AND ECMWF ARE PICKING UP ON A LOW
NEAR THE DATELINE AND OVER THE ALEUTIANS. GFS DIGS THIS LOW SOUTH
AND BRINGS IT ASHORE LATE IN THE WEEK OVER VANCOUVER ISLAND. BOTH
UKMET AND ECMWF KEEP THIS SYSTEM AT OR NORTH OF 50N AS IT ROUNDS
THE BASE OF THE UPPER TROUGH AND TRACKS INTO THE NORTHEAST GULF.
BELIEVE THIS SOLUTION TO BE BETTER BUT DO NOT THINK IT WILL BE AS
DEEP OR AS FAR EAST AS ECMWF IS DEPICTING. AM EXPECTING A LOT OF
PRECIP OUT OF THIS LOW OVER MUCH OF THE PANHANDLE ON THURSDAY
SINCE IT WILL HAVE TAPPED A TROPICAL MOISTURE SOURCE BEFORE
ARRIVING IN THE NORTHEAST PACIFIC.

ANOTHER LOW OVER BRISTOL BAY LATE IN THE WEEK WILL TRACK EAST
ACROSS THE NORTHERN GULF AND APPROACH THE CENTRAL OUTER COAST LATE
IN THE WEEKEND. IT LOOKS LIKE THIS SYSTEM WILL MAKE A MID-LEVEL
MOISTURE CONNECTION TO A SYSTEM FARTHER UPSTREAM SO IT HAS THE
POTENTIAL FOR A LOT OF PRECIP AS WELL.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ036-041-042.

&&

JCC/FRITSCH