Debris Flows and Heavy Rain in Alaska, November 18 to 25, 2005

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST THU NOV 17 2005

.SYNOPSIS...
.SHORT RANGE...THE LATEST SATELLITE IMAGERY IS INDICATING THAT
THE FRONT HAS LIFTED THROUGH THE PANHANDLE THIS MORNING. HAVE
CANCELLED WIND ADVISORIES ACROSS THE OUTER COAST AND WILL
CANCEL THE REST BY NOON EXCEPT FOR PAGY AND PAHN. HAVE
EXTENDED THE ADVISORY FOR PAGY THROUGH TONIGHT...WITH THE LOW IN
THE SOUTHERN YUKON THE GRADIENT WILL REMAIN STRONG. THE RAIN WILL
CONTINUE TO CHANGE TO SHOWERS THROUGH THE EARLY AFTERNOON HOURS
ACROSS THE FORECAST AREA. THE LARGE RAIN AMOUNTS WILL GO DOWN
WITH THE SHOWERS THROUGH TODAY. THERE IS A SHORTWAVE MOVING
ACROSS THE GULF OF ALASKA THIS MORNING THAT WILL ENHANCE THE
SHOWERS OVER THE NORTHERN AREAS THIS EVENING BUT BY TONIGHT WILL
HAVE MOVED INTO CANADA.

A SURFACE AND UPPER RIDGE WILL BUILD OVER SOUTHEAST ALASKA AS THE
LONGWAVE TROF EXTENDING ACROSS WESTERN ALASKA AND ALEUTIANS
DRIFTS TO THE EAST. THIS WILL GIVE A SHORT BREAK IN THE STRONGER
SHOWERS AND WINDS TONIGHT. THIS WILL NOT LAST LONG AS THE NEXT
STRONG LOW MOVES OUT OF THE NORTH PACIFIC AND INTO THE WESTERN
GULF BY FRIDAY AFTERNOON. WILL GO WITH THE ETA20 POSITION OF THE
LOW BUT WITH A LOWER DEPTH AS WITH COLD AIR DROPPING DOWN
ACROSS THE BERING THINK THE CYCLOGENISIS WILL BE STRONGER.

THE ASSOCIATED WEATHER FRONT WILL LIFT NORTHEAST ACROSS THE GULF
THURSDAY NIGHT TO BE OVER THE EASTERN GULF BY THE MORNING. THE
WINDS WILL INCREASE TO GALES OVER THE OUTER COAST THROUGH THE
EARLY MORNING HOURS FRIDAY BUT DIMINISH BY THE AFTERNOON. AS THE
FRONT MOVES ONSHORE FRIDAY THE WINDS WILL INCREASE TO MAX SMALL
CRAFTS FOR THE INNER CHANNELS. AS FOR WINDS OVER LAND...WILL
ISSUE WIND ADIVSORIES FOR THE OUTER COAST AND CENTRAL INNER
CHANNEL FOR FRIDAY AND AS THE FRONT DRIFTS SOUTH ZONE 27 BY THE
AFTERNOON.

THE FRONT WILL MOVE ONSHORE BY DAY BREAK BUT IT WILL BE VERY SLOW
AS IT SLIDES SOUTH THROUGH THE PANHANDLE. THIS WEATHER SYSTEM HAS
THE POTENTIAL TO DROP 3 TO 4 INCHES OF RAIN FROM FRIDAY MORNING
THROUGH THE EARLY EVENING. THERE HAS BEEN CONSIDERABLE RISES TO
SMALL STREAMS THIS MORNING WITH THE PAST RAIN...SOME STREAMS ARE
AT BANKFULL THIS MORNING BUT SHOULD DOWN THROUGH TODAY AND
TONIGHT WITH LESS INTENSE RAIN WITH THE FRONT GONE THROUGH.

THE STREAMS ARE PRIMED AND FREEZING LEVELS WILL BE RISING TO 5500
FEET THROUGH FRIDAY AFTERNOON AND WITH THE AMOUNT OF RAIN
POSSIBLE THERE WILL BE ANOTHER CONSIDERABLE RISE TO SMALL STREAMS
ACROSS THE CENTRAL PANHANDLE. WILL ISSUE A HYDROLOGIC STATEMENT
THIS AFTERNOON AS STREAMS WILL GET TO BANKFULL AND COULD SPILL
OVER THEIR BANKS BY FRIDAY AFTERNOON. FOR MORE INFORMATION ABOUT
THIS EVENT PLEASE LOOK FOR THIS STATEMENT.

.LONG RANGE...NOT MUCH CHANGE EXPECTED IN THE LONGWAVE PATTERN
FROM THIS WEEKEND THROUGH NEXT WEEK. THE MEAN POSITION OF A
LONGWAVE TROUGH/LOW WILL EXTEND OVER CENTRAL TO WESTERN ALASKA
SOUTHWARD INTO THE PACIFIC BETWEEN 150W AND 175W THROUGH MID NEXT
WEEK. THIS WILL BRING A FAIRLY STRONG SOUTH TO SOUTHWEST JET UP
INTO THE GULF OF ALASKA AND BRING A SERIES OF DEEP LOW PRESSURE
SYSTEMS NORTH INTO THE WESTERN GULF OF ALASKA THROUGH NEXT WEEK.
THE BIGGEST FORECAST CHALLENGE THROUGH THE WEEK WILL BE THE
TIMING AND DEPTH OF THESE LOWS AND WHEN PERIODS OF FRONTAL
RAIN...WINDY CONDITIONS...AND WELL ABOVE NORMAL TEMPERATURES WILL
EFFECT SOUTHEAST ALASKA.

THE DEEP LOW MOVING NORTH OVER THE WESTERN GULF WILL WEAKEN TO
AROUND 970 MB FRI NIGHT AS IT MOVES INLAND OVER SOUTHCENTRAL
ALASKA. GALE FORCE WINDS AROUND 45 KT WILL CONTINUE OVER THE
OUTSIDE WATERS THROUGH FRI EVENING WITH GALE FORCE WINDS OVER A
GOOD PORTION OF THE INNER CHANNELS. WIND ADVISORIES GUSTS WILL
ALSO CONTINUE OVER SOUTHEAST ALASKA THROUGH FRI EVENING. THE
PRESSURE GRADIENT WEAKENS OVERNIGHT FRI WITH WINDS DIMINISHING TO
SMALL CRAFT OVER THE OUTSIDE WATERS AND LYNN CANAL...WINDS WILL
DIMINISH TO MINIMAL SMALL CRAFT OR LESS ELSEWHERE.

THE OCCLUDED FRONT ASSOCIATED WITH THIS LOW WILL BE SLOW TO MOVE
ACROSS THE PANHANDLE WHICH MAY POSE SOME HYDRO PROBLEMS. WARM
SUBTROPICAL AIR FEEDING INTO THIS SYSTEM WILL HELP BRING HIGH
RAINFALL AMOUNTS FRI NIGHT THROUGH SAT MORNING OVER THE NORTH
CENTRAL PANHANDLE AS THE FRONT SLOWLY MOVES THROUGH. QPF AMOUNTS
COULD RUN AROUND 1.5 INCHES EVERY SIX HOURS IN SOME LOCATIONS
WHILE THE FREEZING LEVEL RISES TO 4000 FEET OR HIGHER AT
TIMES...THEREFORE A HYDRO STATEMENT FOR SMALL STREAMS AT THIS
TIME WILL BE NEED OVER THE NORTHCENTRAL INNER CHANNELS THROUGH
SAT MORNING.

THE OCCLUDED FRONT FINALLY PASSES EAST SAT AFTERNOON WITH A
COLDER AIRMASS AND ONSHORE WEST TO SOUTHWEST FLOW BEHIND
RESULTING IN SHOWERS IN ALL AREAS THAT MAY MIX OR CHANGE TO SNOW
SHOWERS OVER THE NORTHERN INNER CHANNELS LATE SAT NIGHT AND EARLY
SUN MORNING. THE NEXT DEEP LOW AROUND 960 MB MOVES NORTH INTO THE
FAR WESTERN GULF AND JUST WEST OF KODIAK ISLAND SUN NIGHT THROUGH
MON. THIS DEEPER SYSTEM HAS THE POTENTIAL OF BRINGING GALES AND
STORM FORCE WINDS TO THE OUTSIDE WATERS SUN NIGHT AND MON MORNING
WITH WIND WARNING GUSTS ALONG THE COASTAL PUBLIC ZONES. GALES AND
WIND ADVISORY GUSTS WILL DEVELOP OVER THE INNER CHANNELS ON MON.
THE OCCLUDED FRONT WILL SPREAD RAIN OVER THE FORECAST AREA SUN
NIGHT THROUGH MON. A GOOD SUBTROPICAL FEED WITH THIS SYSTEM WILL
BRING HEAVY RAIN ALONG THE NORTHERN GULF COAST AND NORTHWEST
PANHANDLE ON MON.

SHOWERS BEHIND THIS SYSTEM MON NIGHT WILL DIMINISH ON TUE AS HIGH
PRESSURE BUILDS TO THE EAST. THE NEXT LOW MOVES NORTH INTO THE
WESTERN GULF DURING THE WED THROUGH THU TIME FRAME. CONFIDENCE IS
LOW ON THE TIMING AND TRACK OF THIS SYSTEM. SOME OF THE LONG
RANGE MODELS AMPLIFY THE PATTERN DURING THIS TIME WITH AN
AMPLIFIED RIDGE OVER WESTERN CANADA. THIS KEEPS THE NEXT SYSTEM
FURTHER WEST AND BRINGS A DRY PERIOD TO SOUTHEAST ALASKA LATE TUE
AND WED. AT THIS POINT WILL NOT MAKE ANY MAJOR CHANGES TO THE
EXTENDED PERIOD BUT WILL BRING INCREASING WINDS OVER THE OUTSIDE
WATERS AND TREND MORE TOWARD CLIMO INTO THU.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WIND ADVISORY...AKZ18 THROUGH EARLY FRIDAY MORNING
         WIND ADVISORY...AKZ20-26 FRIDAY
         WIND ADVISORY...AKZ27 FRIDAY AFTERNOON

MARINE...SCA...ALL MARINE AREAS EXCEPT SOUTHERN INNER CHANNELS.
         GALES...OUTER COAST FRIDAY MORNING.

ABJ/TAR