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000
FXAK67 PAJK 191319
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
519 AM AKDT SUN APR 19 2015

.SHORT TERM...LARGE UPPER TROUGH AND ASSOCIATED SURFACE LOW
PRESSURE WAS SITUATED OVER THE ERN BERING SEA AND ERN ALEUTIANS
EARLY THIS MORNING. FRONTAL BOUNDARY EXTENDED EWD FROM THE SURFACE
LOW ACROSS THE NRN GULF...AND THEN CURVED SWD ACROSS THE CNTRL
GULF. SRN FRONTAL SEGMENT WILL SLOWLY PROGRESS TOWARD THE COAST OF
SERN AK BY SUN NIGHT AS AN UPPER-LEVEL SHORTWAVE TROUGH SHIFTS E
ACROSS THE CNTRL GULF. IN ADDITION...MODEL GUIDANCE SHOWS A SUBTLE
UPPER IMPULSE MOVING N IN ADVANCE OF THE CNTRL GULF
SHORTWAVE...AND IS FORECAST TO AID IN THE DEVELOPMENT OF A MODEST
SURFACE WAVE/LOW PRESSURE CENTER SSW OF SITKA DURING SUN NIGHT.

GALE FORCE WINDS CURRENTLY OCCURRING ALONG THE FRONT THIS MORNING
WILL WEAKEN BY MIDDAY...BUT SMALL CRAFT WINDS WILL CONTINUE INTO
PART OF THE NIGHT OVER OUTSIDE MARINE ZONES 41 AND 42 IN RESPONSE
TO PREVIOUSLY MENTIONED WEAK SURFACE CYCLOGENESIS. OVER THE INSIDE
WATERS...SURFACE ISOBAR ORIENTATION IS GENERALLY PARALLEL TO N-S
CHANNELS. HOWEVER...BELIEVE SLY SPEEDS WILL BE ENHANCED SOMEWHAT
BY 30 KT 925 MB JET. THUS...MAINTAINED 20 KT WINDS FROM CLARENCE
STRAIT TO STEPHENS PASSAGE AND LYNN CANAL FOR MUCH OF THE SHORT
TERM PERIOD.

MEANWHILE...SATELLITE DERIVED PW GUIDANCE SHOWS VALUES NEAR 1 INCH
/CLOSE TO 3 STANDARD DEVIATIONS ABOVE CLIMATOLOGY/ SPREADING NWD
TOWARD THE CNTRL/SRN COAST OF SERN AK THIS MORNING. THIS MOISTURE
WILL SPREAD INLAND ACROSS THE SOUTHERN TWO THIRDS OF THE CWA BY
TONIGHT. IN ADDITION...A WARM PRE-FRONTAL BOUNDARY LAYER AIRMASS
WILL AID IN RAISING FREEZING LEVELS TO AROUND 3000 FT AMSL OVER
THE NRN PANHANDLE...AND 7000 FT AMSL OVER THE SRN PANHANDLE.
THE COMBINATION OF RELATIVELY RICH MOISTURE AND A DEEP WARM CLOUD
LAYER WILL SUPPORT THE POTENTIAL FOR ROBUST STRATIFORM RAINFALL.

THE FINAL INGREDIENT FOR HEAVY RAIN WILL BE A PLUME OF STRONG
700-500 MB UVV/S FORCED BY PREVIOUSLY MENTIONED UPPER
IMPULSE...WHICH WILL REACH THE SITKA AREA BY 03-06Z TONIGHT...AND
THEN THE GUSTAVUS TO JUNEAU AREA TOWARD 06-12Z. AS A
RESULT...RAINFALL RATES IN EXCESS OF 0.5 IN/HR WILL BE
POSSIBLE...YIELDING RAINFALL TOTALS FROM 1-2 INCHES BY 15Z MON.
FARTHER W...A DEEP LAYER OF COLD AIR WILL SPREAD ACROSS THE CNTRL
GULF AND AKZ017 TONIGHT. THIS WILL DESTABILIZE THE ATMOSPHERE AND
SUPPORT A TRANSITION TO A CONVECTIVE SHOWER REGIME.

INHERITED PRESSURE GRIDS WERE NUDGED TOWARD THE 00Z NAM AND
ECMWF...WHICH GAVE THE WEAK SURFACE LOW FORMING TONIGHT OVER THE
ERN GULF MORE DEFINITION. POP AND QPF GRIDS WERE UPDATED WITH A
BLEND OF THE ECMWF/GFS/NAM.

.LONG TERM...THE HEAVY RAIN OVER THE PANHANDLE SUNDAY NIGHT WILL
RELENT MONDAY FOR TWO REASONS. FIRST A SHORTWAVE CURRENTLY
ROUNDING THE BASE OF THE TROUGH AROUND 45 N 160 W WILL RIDE AHEAD
OF THE NORTHWARD MOVING WAVE OVER THE CENTRAL GULF, AND DIFFUSE
THE ENERGY EARLIER CONCENTRATED ACROSS THE NORTHEAST GULF TO AREAS
WELL TO THE SOUTH. IN ADDITION, THIS SHORTWAVE BYPASSING SOUTHEAST
ALASKA WILL SHUNT MUCH OF THE FEEDING MOISTURE EASTWARD RATHER
THAN NORTHWARD. FINALLY A WEAK BUT DRYING RIDGE IN THE LOW AND MID
LEVELS WILL HELP THIN THE DEEP MOISTURE SITUATED OVER THE
PANHANDLE FROM MONDAY NIGHT. THUS QPF AMOUNTS FOR MONDAY WILL
TOTAL LESS THAN A HALF INCH FOR ALL BUT MISTY FJORDS.

TO THE NORTHWEST IN YAKUTAT, ONSHORE FLOW COUPLED WITH COOLER
TEMPERATURES ALOFT WILL KEEP SHOWERS IN THE FORECAST. AS THE
FRONT SLOWLY MAKES PROGRESS THROUGH THE PANHANDLE, SOME
INSTABILITY MAY DEVELOP IN THE LOW LEVELS AS COOLER AIR SLIDES
EAST. HOWEVER, SINCE THE UPPER LEVELS WILL REMAIN RELATIVELY
WARM, AT 500 MB FOR EXAMPLE, WE KEPT THINGS STRATIFORM FOR MONDAY.
BY MONDAY NIGHT, THE TEMPERATURES AT 500 MB DROP ENOUGH TO SUGGEST
A MORE DEEPLY UNSTABLE AIR MASS AND STIR US TO WONDER ABOUT THE
POSSIBILITY OF CONVECTION THAT COULD SUPPORT LIGHTNING OVER THE
NORTHERN GULF. HELD OFF ON MENTIONING THUNDERSTORMS AT THIS TIME,
AS THE SUPPORTING CHARACTER OF THE SHORT-WAVE ITSELF DOES NOT
IMPRESS US WITH GRAVITAS. BUT EVEN WITHOUT THE SHORT-WAVE,
CONDITIONS COULD BE TOO RIPE AND THE PROXIMITY TO FORCED ASCENT
IN THE FORM OF THE ST. ELIAS MOUNTAINS MAY JUST PROVIDE THE
SPARK.

THE RIDGING EARLY IN THE WEEK THAT THAT MAY YIELD SOME SUNSHINE
STILL HAS THIS POTENTIAL. HOWEVER, THE ECMWF HAS NOW ADOPTED A
SLIGHTLY LESS FAVORABLE ORIENTATION FOR THIS RESULT. THE IDEA OF A
DIRTY RIDGE WHERE ONSHORE FLOW IN THE LOW TO MID LEVELS SPREADS
MOISTURE AND CLOUDINESS ONSHORE NEEDS TO BE PRESERVED. THE NEWEST RUN
OF THE ECMWF APPEARS TO BE LEANING MORE TOWARDS A WESTERLY
COMPONENT TO THESE WINDS, RATHER THAN THE SLIGHTLY MORE NORTHERLY
COMPONENT OF THE GFS AND NAM, AND EVEN THE GEM. IN ADDITION, THE
ECMWF ADVANCES THE RIDGE AXIS QUICKER TUESDAY EVENING. LARGELY
BROAD-BRUSHED THE NORTHERN PANHANDLE WITH MAINLY CLOUDY SKIES
TUESDAY. HOWEVER, THIS COULD BE A SUNNIER KIND OF MOSTLY CLOUDY.
SCATTERED SHOWERS WILL DIMINISH THROUGH LATE TUESDAY AS THE FLOW
BEGINS TO VEER OFFSHORE WITH A MAJOR SYSTEM REACHING THE CENTRAL
PANHANDLE BY WEDNESDAY.

WITH THE GFS AND ECWMF IN MODERATE AGREEMENT, WE RAISED WINDSPEEDS
TO GALE FORCE OVER 310 AND SOME OF THE OUTSIDE WATERS AHEAD OF THE
WEDNESDAY SYSTEM. AS THE LATITUDE OF THE SYSTEM WILL BE EQUAL TO
THAT OF DIXON ENTRANCE, PRECIPITATION OVER THE PANHANDLE WILL BE
LIMITED TO CHANCE POPS ACROSS THE COAST AND THE SOUTH. BUT AS THIS
SYSTEM EDGES NORTHWARD INTO THURSDAY, WHETHER A WHOLE LOW AS THE
ECMWF SUGGESTS OR A STRONG TRIPLE POINT FEATURE AS THE GFS HINTS
AT, WE HAVE NUDGED THE MOISTURE A LITTLE FARTHER NORTH SOONER
THAN PREVIOUS.

TEMPERATURES DURING THE NIGHTTIME AND SNOW LEVELS WILL FALL
BEHIND THE FRONT TO NEAR FREEZING/SEA LEVEL ACROSS THE FAR
NORTHERN ZONES INTO MID-WEEK. A SLOW BUT STEADY REBOUND WILL BEGIN
TO OCCUR WEDNESDAY NIGHT INTO THE WEEKEND WITH SOME WARM AIR
ADVECTION ASSOCIATED WITH THE MID-WEEK GULF SYSTEM.

USED NAM AND ECMWF FOR UPDATES MONDAY/MONDAY NIGHT. STRONGLY
NUDGED TO ECMWF AND GFS TO ADD STRENGTH TO THE WEDNESDAY SYSTEM.
EXTENDED FORECAST REMAINS WELL INTACT. COOLED TEMPERATURES A TAD
IN THE MID-RANGE WHILE WARMING THINGS A TAD TOWARD THE WEEKEND.
FORECAST CONFIDENCE DECENT.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ021-022-033>036-041-053.

&&

$$

GARNER/ADKINS

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU













000
FXAK67 PAJK 191319
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
519 AM AKDT SUN APR 19 2015

.SHORT TERM...LARGE UPPER TROUGH AND ASSOCIATED SURFACE LOW
PRESSURE WAS SITUATED OVER THE ERN BERING SEA AND ERN ALEUTIANS
EARLY THIS MORNING. FRONTAL BOUNDARY EXTENDED EWD FROM THE SURFACE
LOW ACROSS THE NRN GULF...AND THEN CURVED SWD ACROSS THE CNTRL
GULF. SRN FRONTAL SEGMENT WILL SLOWLY PROGRESS TOWARD THE COAST OF
SERN AK BY SUN NIGHT AS AN UPPER-LEVEL SHORTWAVE TROUGH SHIFTS E
ACROSS THE CNTRL GULF. IN ADDITION...MODEL GUIDANCE SHOWS A SUBTLE
UPPER IMPULSE MOVING N IN ADVANCE OF THE CNTRL GULF
SHORTWAVE...AND IS FORECAST TO AID IN THE DEVELOPMENT OF A MODEST
SURFACE WAVE/LOW PRESSURE CENTER SSW OF SITKA DURING SUN NIGHT.

GALE FORCE WINDS CURRENTLY OCCURRING ALONG THE FRONT THIS MORNING
WILL WEAKEN BY MIDDAY...BUT SMALL CRAFT WINDS WILL CONTINUE INTO
PART OF THE NIGHT OVER OUTSIDE MARINE ZONES 41 AND 42 IN RESPONSE
TO PREVIOUSLY MENTIONED WEAK SURFACE CYCLOGENESIS. OVER THE INSIDE
WATERS...SURFACE ISOBAR ORIENTATION IS GENERALLY PARALLEL TO N-S
CHANNELS. HOWEVER...BELIEVE SLY SPEEDS WILL BE ENHANCED SOMEWHAT
BY 30 KT 925 MB JET. THUS...MAINTAINED 20 KT WINDS FROM CLARENCE
STRAIT TO STEPHENS PASSAGE AND LYNN CANAL FOR MUCH OF THE SHORT
TERM PERIOD.

MEANWHILE...SATELLITE DERIVED PW GUIDANCE SHOWS VALUES NEAR 1 INCH
/CLOSE TO 3 STANDARD DEVIATIONS ABOVE CLIMATOLOGY/ SPREADING NWD
TOWARD THE CNTRL/SRN COAST OF SERN AK THIS MORNING. THIS MOISTURE
WILL SPREAD INLAND ACROSS THE SOUTHERN TWO THIRDS OF THE CWA BY
TONIGHT. IN ADDITION...A WARM PRE-FRONTAL BOUNDARY LAYER AIRMASS
WILL AID IN RAISING FREEZING LEVELS TO AROUND 3000 FT AMSL OVER
THE NRN PANHANDLE...AND 7000 FT AMSL OVER THE SRN PANHANDLE.
THE COMBINATION OF RELATIVELY RICH MOISTURE AND A DEEP WARM CLOUD
LAYER WILL SUPPORT THE POTENTIAL FOR ROBUST STRATIFORM RAINFALL.

THE FINAL INGREDIENT FOR HEAVY RAIN WILL BE A PLUME OF STRONG
700-500 MB UVV/S FORCED BY PREVIOUSLY MENTIONED UPPER
IMPULSE...WHICH WILL REACH THE SITKA AREA BY 03-06Z TONIGHT...AND
THEN THE GUSTAVUS TO JUNEAU AREA TOWARD 06-12Z. AS A
RESULT...RAINFALL RATES IN EXCESS OF 0.5 IN/HR WILL BE
POSSIBLE...YIELDING RAINFALL TOTALS FROM 1-2 INCHES BY 15Z MON.
FARTHER W...A DEEP LAYER OF COLD AIR WILL SPREAD ACROSS THE CNTRL
GULF AND AKZ017 TONIGHT. THIS WILL DESTABILIZE THE ATMOSPHERE AND
SUPPORT A TRANSITION TO A CONVECTIVE SHOWER REGIME.

INHERITED PRESSURE GRIDS WERE NUDGED TOWARD THE 00Z NAM AND
ECMWF...WHICH GAVE THE WEAK SURFACE LOW FORMING TONIGHT OVER THE
ERN GULF MORE DEFINITION. POP AND QPF GRIDS WERE UPDATED WITH A
BLEND OF THE ECMWF/GFS/NAM.

.LONG TERM...THE HEAVY RAIN OVER THE PANHANDLE SUNDAY NIGHT WILL
RELENT MONDAY FOR TWO REASONS. FIRST A SHORTWAVE CURRENTLY
ROUNDING THE BASE OF THE TROUGH AROUND 45 N 160 W WILL RIDE AHEAD
OF THE NORTHWARD MOVING WAVE OVER THE CENTRAL GULF, AND DIFFUSE
THE ENERGY EARLIER CONCENTRATED ACROSS THE NORTHEAST GULF TO AREAS
WELL TO THE SOUTH. IN ADDITION, THIS SHORTWAVE BYPASSING SOUTHEAST
ALASKA WILL SHUNT MUCH OF THE FEEDING MOISTURE EASTWARD RATHER
THAN NORTHWARD. FINALLY A WEAK BUT DRYING RIDGE IN THE LOW AND MID
LEVELS WILL HELP THIN THE DEEP MOISTURE SITUATED OVER THE
PANHANDLE FROM MONDAY NIGHT. THUS QPF AMOUNTS FOR MONDAY WILL
TOTAL LESS THAN A HALF INCH FOR ALL BUT MISTY FJORDS.

TO THE NORTHWEST IN YAKUTAT, ONSHORE FLOW COUPLED WITH COOLER
TEMPERATURES ALOFT WILL KEEP SHOWERS IN THE FORECAST. AS THE
FRONT SLOWLY MAKES PROGRESS THROUGH THE PANHANDLE, SOME
INSTABILITY MAY DEVELOP IN THE LOW LEVELS AS COOLER AIR SLIDES
EAST. HOWEVER, SINCE THE UPPER LEVELS WILL REMAIN RELATIVELY
WARM, AT 500 MB FOR EXAMPLE, WE KEPT THINGS STRATIFORM FOR MONDAY.
BY MONDAY NIGHT, THE TEMPERATURES AT 500 MB DROP ENOUGH TO SUGGEST
A MORE DEEPLY UNSTABLE AIR MASS AND STIR US TO WONDER ABOUT THE
POSSIBILITY OF CONVECTION THAT COULD SUPPORT LIGHTNING OVER THE
NORTHERN GULF. HELD OFF ON MENTIONING THUNDERSTORMS AT THIS TIME,
AS THE SUPPORTING CHARACTER OF THE SHORT-WAVE ITSELF DOES NOT
IMPRESS US WITH GRAVITAS. BUT EVEN WITHOUT THE SHORT-WAVE,
CONDITIONS COULD BE TOO RIPE AND THE PROXIMITY TO FORCED ASCENT
IN THE FORM OF THE ST. ELIAS MOUNTAINS MAY JUST PROVIDE THE
SPARK.

THE RIDGING EARLY IN THE WEEK THAT THAT MAY YIELD SOME SUNSHINE
STILL HAS THIS POTENTIAL. HOWEVER, THE ECMWF HAS NOW ADOPTED A
SLIGHTLY LESS FAVORABLE ORIENTATION FOR THIS RESULT. THE IDEA OF A
DIRTY RIDGE WHERE ONSHORE FLOW IN THE LOW TO MID LEVELS SPREADS
MOISTURE AND CLOUDINESS ONSHORE NEEDS TO BE PRESERVED. THE NEWEST RUN
OF THE ECMWF APPEARS TO BE LEANING MORE TOWARDS A WESTERLY
COMPONENT TO THESE WINDS, RATHER THAN THE SLIGHTLY MORE NORTHERLY
COMPONENT OF THE GFS AND NAM, AND EVEN THE GEM. IN ADDITION, THE
ECMWF ADVANCES THE RIDGE AXIS QUICKER TUESDAY EVENING. LARGELY
BROAD-BRUSHED THE NORTHERN PANHANDLE WITH MAINLY CLOUDY SKIES
TUESDAY. HOWEVER, THIS COULD BE A SUNNIER KIND OF MOSTLY CLOUDY.
SCATTERED SHOWERS WILL DIMINISH THROUGH LATE TUESDAY AS THE FLOW
BEGINS TO VEER OFFSHORE WITH A MAJOR SYSTEM REACHING THE CENTRAL
PANHANDLE BY WEDNESDAY.

WITH THE GFS AND ECWMF IN MODERATE AGREEMENT, WE RAISED WINDSPEEDS
TO GALE FORCE OVER 310 AND SOME OF THE OUTSIDE WATERS AHEAD OF THE
WEDNESDAY SYSTEM. AS THE LATITUDE OF THE SYSTEM WILL BE EQUAL TO
THAT OF DIXON ENTRANCE, PRECIPITATION OVER THE PANHANDLE WILL BE
LIMITED TO CHANCE POPS ACROSS THE COAST AND THE SOUTH. BUT AS THIS
SYSTEM EDGES NORTHWARD INTO THURSDAY, WHETHER A WHOLE LOW AS THE
ECMWF SUGGESTS OR A STRONG TRIPLE POINT FEATURE AS THE GFS HINTS
AT, WE HAVE NUDGED THE MOISTURE A LITTLE FARTHER NORTH SOONER
THAN PREVIOUS.

TEMPERATURES DURING THE NIGHTTIME AND SNOW LEVELS WILL FALL
BEHIND THE FRONT TO NEAR FREEZING/SEA LEVEL ACROSS THE FAR
NORTHERN ZONES INTO MID-WEEK. A SLOW BUT STEADY REBOUND WILL BEGIN
TO OCCUR WEDNESDAY NIGHT INTO THE WEEKEND WITH SOME WARM AIR
ADVECTION ASSOCIATED WITH THE MID-WEEK GULF SYSTEM.

USED NAM AND ECMWF FOR UPDATES MONDAY/MONDAY NIGHT. STRONGLY
NUDGED TO ECMWF AND GFS TO ADD STRENGTH TO THE WEDNESDAY SYSTEM.
EXTENDED FORECAST REMAINS WELL INTACT. COOLED TEMPERATURES A TAD
IN THE MID-RANGE WHILE WARMING THINGS A TAD TOWARD THE WEEKEND.
FORECAST CONFIDENCE DECENT.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ021-022-033>036-041-053.

&&

$$

GARNER/ADKINS

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU












000
FXAK67 PAJK 191319
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
519 AM AKDT SUN APR 19 2015

.SHORT TERM...LARGE UPPER TROUGH AND ASSOCIATED SURFACE LOW
PRESSURE WAS SITUATED OVER THE ERN BERING SEA AND ERN ALEUTIANS
EARLY THIS MORNING. FRONTAL BOUNDARY EXTENDED EWD FROM THE SURFACE
LOW ACROSS THE NRN GULF...AND THEN CURVED SWD ACROSS THE CNTRL
GULF. SRN FRONTAL SEGMENT WILL SLOWLY PROGRESS TOWARD THE COAST OF
SERN AK BY SUN NIGHT AS AN UPPER-LEVEL SHORTWAVE TROUGH SHIFTS E
ACROSS THE CNTRL GULF. IN ADDITION...MODEL GUIDANCE SHOWS A SUBTLE
UPPER IMPULSE MOVING N IN ADVANCE OF THE CNTRL GULF
SHORTWAVE...AND IS FORECAST TO AID IN THE DEVELOPMENT OF A MODEST
SURFACE WAVE/LOW PRESSURE CENTER SSW OF SITKA DURING SUN NIGHT.

GALE FORCE WINDS CURRENTLY OCCURRING ALONG THE FRONT THIS MORNING
WILL WEAKEN BY MIDDAY...BUT SMALL CRAFT WINDS WILL CONTINUE INTO
PART OF THE NIGHT OVER OUTSIDE MARINE ZONES 41 AND 42 IN RESPONSE
TO PREVIOUSLY MENTIONED WEAK SURFACE CYCLOGENESIS. OVER THE INSIDE
WATERS...SURFACE ISOBAR ORIENTATION IS GENERALLY PARALLEL TO N-S
CHANNELS. HOWEVER...BELIEVE SLY SPEEDS WILL BE ENHANCED SOMEWHAT
BY 30 KT 925 MB JET. THUS...MAINTAINED 20 KT WINDS FROM CLARENCE
STRAIT TO STEPHENS PASSAGE AND LYNN CANAL FOR MUCH OF THE SHORT
TERM PERIOD.

MEANWHILE...SATELLITE DERIVED PW GUIDANCE SHOWS VALUES NEAR 1 INCH
/CLOSE TO 3 STANDARD DEVIATIONS ABOVE CLIMATOLOGY/ SPREADING NWD
TOWARD THE CNTRL/SRN COAST OF SERN AK THIS MORNING. THIS MOISTURE
WILL SPREAD INLAND ACROSS THE SOUTHERN TWO THIRDS OF THE CWA BY
TONIGHT. IN ADDITION...A WARM PRE-FRONTAL BOUNDARY LAYER AIRMASS
WILL AID IN RAISING FREEZING LEVELS TO AROUND 3000 FT AMSL OVER
THE NRN PANHANDLE...AND 7000 FT AMSL OVER THE SRN PANHANDLE.
THE COMBINATION OF RELATIVELY RICH MOISTURE AND A DEEP WARM CLOUD
LAYER WILL SUPPORT THE POTENTIAL FOR ROBUST STRATIFORM RAINFALL.

THE FINAL INGREDIENT FOR HEAVY RAIN WILL BE A PLUME OF STRONG
700-500 MB UVV/S FORCED BY PREVIOUSLY MENTIONED UPPER
IMPULSE...WHICH WILL REACH THE SITKA AREA BY 03-06Z TONIGHT...AND
THEN THE GUSTAVUS TO JUNEAU AREA TOWARD 06-12Z. AS A
RESULT...RAINFALL RATES IN EXCESS OF 0.5 IN/HR WILL BE
POSSIBLE...YIELDING RAINFALL TOTALS FROM 1-2 INCHES BY 15Z MON.
FARTHER W...A DEEP LAYER OF COLD AIR WILL SPREAD ACROSS THE CNTRL
GULF AND AKZ017 TONIGHT. THIS WILL DESTABILIZE THE ATMOSPHERE AND
SUPPORT A TRANSITION TO A CONVECTIVE SHOWER REGIME.

INHERITED PRESSURE GRIDS WERE NUDGED TOWARD THE 00Z NAM AND
ECMWF...WHICH GAVE THE WEAK SURFACE LOW FORMING TONIGHT OVER THE
ERN GULF MORE DEFINITION. POP AND QPF GRIDS WERE UPDATED WITH A
BLEND OF THE ECMWF/GFS/NAM.

.LONG TERM...THE HEAVY RAIN OVER THE PANHANDLE SUNDAY NIGHT WILL
RELENT MONDAY FOR TWO REASONS. FIRST A SHORTWAVE CURRENTLY
ROUNDING THE BASE OF THE TROUGH AROUND 45 N 160 W WILL RIDE AHEAD
OF THE NORTHWARD MOVING WAVE OVER THE CENTRAL GULF, AND DIFFUSE
THE ENERGY EARLIER CONCENTRATED ACROSS THE NORTHEAST GULF TO AREAS
WELL TO THE SOUTH. IN ADDITION, THIS SHORTWAVE BYPASSING SOUTHEAST
ALASKA WILL SHUNT MUCH OF THE FEEDING MOISTURE EASTWARD RATHER
THAN NORTHWARD. FINALLY A WEAK BUT DRYING RIDGE IN THE LOW AND MID
LEVELS WILL HELP THIN THE DEEP MOISTURE SITUATED OVER THE
PANHANDLE FROM MONDAY NIGHT. THUS QPF AMOUNTS FOR MONDAY WILL
TOTAL LESS THAN A HALF INCH FOR ALL BUT MISTY FJORDS.

TO THE NORTHWEST IN YAKUTAT, ONSHORE FLOW COUPLED WITH COOLER
TEMPERATURES ALOFT WILL KEEP SHOWERS IN THE FORECAST. AS THE
FRONT SLOWLY MAKES PROGRESS THROUGH THE PANHANDLE, SOME
INSTABILITY MAY DEVELOP IN THE LOW LEVELS AS COOLER AIR SLIDES
EAST. HOWEVER, SINCE THE UPPER LEVELS WILL REMAIN RELATIVELY
WARM, AT 500 MB FOR EXAMPLE, WE KEPT THINGS STRATIFORM FOR MONDAY.
BY MONDAY NIGHT, THE TEMPERATURES AT 500 MB DROP ENOUGH TO SUGGEST
A MORE DEEPLY UNSTABLE AIR MASS AND STIR US TO WONDER ABOUT THE
POSSIBILITY OF CONVECTION THAT COULD SUPPORT LIGHTNING OVER THE
NORTHERN GULF. HELD OFF ON MENTIONING THUNDERSTORMS AT THIS TIME,
AS THE SUPPORTING CHARACTER OF THE SHORT-WAVE ITSELF DOES NOT
IMPRESS US WITH GRAVITAS. BUT EVEN WITHOUT THE SHORT-WAVE,
CONDITIONS COULD BE TOO RIPE AND THE PROXIMITY TO FORCED ASCENT
IN THE FORM OF THE ST. ELIAS MOUNTAINS MAY JUST PROVIDE THE
SPARK.

THE RIDGING EARLY IN THE WEEK THAT THAT MAY YIELD SOME SUNSHINE
STILL HAS THIS POTENTIAL. HOWEVER, THE ECMWF HAS NOW ADOPTED A
SLIGHTLY LESS FAVORABLE ORIENTATION FOR THIS RESULT. THE IDEA OF A
DIRTY RIDGE WHERE ONSHORE FLOW IN THE LOW TO MID LEVELS SPREADS
MOISTURE AND CLOUDINESS ONSHORE NEEDS TO BE PRESERVED. THE NEWEST RUN
OF THE ECMWF APPEARS TO BE LEANING MORE TOWARDS A WESTERLY
COMPONENT TO THESE WINDS, RATHER THAN THE SLIGHTLY MORE NORTHERLY
COMPONENT OF THE GFS AND NAM, AND EVEN THE GEM. IN ADDITION, THE
ECMWF ADVANCES THE RIDGE AXIS QUICKER TUESDAY EVENING. LARGELY
BROAD-BRUSHED THE NORTHERN PANHANDLE WITH MAINLY CLOUDY SKIES
TUESDAY. HOWEVER, THIS COULD BE A SUNNIER KIND OF MOSTLY CLOUDY.
SCATTERED SHOWERS WILL DIMINISH THROUGH LATE TUESDAY AS THE FLOW
BEGINS TO VEER OFFSHORE WITH A MAJOR SYSTEM REACHING THE CENTRAL
PANHANDLE BY WEDNESDAY.

WITH THE GFS AND ECWMF IN MODERATE AGREEMENT, WE RAISED WINDSPEEDS
TO GALE FORCE OVER 310 AND SOME OF THE OUTSIDE WATERS AHEAD OF THE
WEDNESDAY SYSTEM. AS THE LATITUDE OF THE SYSTEM WILL BE EQUAL TO
THAT OF DIXON ENTRANCE, PRECIPITATION OVER THE PANHANDLE WILL BE
LIMITED TO CHANCE POPS ACROSS THE COAST AND THE SOUTH. BUT AS THIS
SYSTEM EDGES NORTHWARD INTO THURSDAY, WHETHER A WHOLE LOW AS THE
ECMWF SUGGESTS OR A STRONG TRIPLE POINT FEATURE AS THE GFS HINTS
AT, WE HAVE NUDGED THE MOISTURE A LITTLE FARTHER NORTH SOONER
THAN PREVIOUS.

TEMPERATURES DURING THE NIGHTTIME AND SNOW LEVELS WILL FALL
BEHIND THE FRONT TO NEAR FREEZING/SEA LEVEL ACROSS THE FAR
NORTHERN ZONES INTO MID-WEEK. A SLOW BUT STEADY REBOUND WILL BEGIN
TO OCCUR WEDNESDAY NIGHT INTO THE WEEKEND WITH SOME WARM AIR
ADVECTION ASSOCIATED WITH THE MID-WEEK GULF SYSTEM.

USED NAM AND ECMWF FOR UPDATES MONDAY/MONDAY NIGHT. STRONGLY
NUDGED TO ECMWF AND GFS TO ADD STRENGTH TO THE WEDNESDAY SYSTEM.
EXTENDED FORECAST REMAINS WELL INTACT. COOLED TEMPERATURES A TAD
IN THE MID-RANGE WHILE WARMING THINGS A TAD TOWARD THE WEEKEND.
FORECAST CONFIDENCE DECENT.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ021-022-033>036-041-053.

&&

$$

GARNER/ADKINS

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU












000
FXAK67 PAJK 191319
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
519 AM AKDT SUN APR 19 2015

.SHORT TERM...LARGE UPPER TROUGH AND ASSOCIATED SURFACE LOW
PRESSURE WAS SITUATED OVER THE ERN BERING SEA AND ERN ALEUTIANS
EARLY THIS MORNING. FRONTAL BOUNDARY EXTENDED EWD FROM THE SURFACE
LOW ACROSS THE NRN GULF...AND THEN CURVED SWD ACROSS THE CNTRL
GULF. SRN FRONTAL SEGMENT WILL SLOWLY PROGRESS TOWARD THE COAST OF
SERN AK BY SUN NIGHT AS AN UPPER-LEVEL SHORTWAVE TROUGH SHIFTS E
ACROSS THE CNTRL GULF. IN ADDITION...MODEL GUIDANCE SHOWS A SUBTLE
UPPER IMPULSE MOVING N IN ADVANCE OF THE CNTRL GULF
SHORTWAVE...AND IS FORECAST TO AID IN THE DEVELOPMENT OF A MODEST
SURFACE WAVE/LOW PRESSURE CENTER SSW OF SITKA DURING SUN NIGHT.

GALE FORCE WINDS CURRENTLY OCCURRING ALONG THE FRONT THIS MORNING
WILL WEAKEN BY MIDDAY...BUT SMALL CRAFT WINDS WILL CONTINUE INTO
PART OF THE NIGHT OVER OUTSIDE MARINE ZONES 41 AND 42 IN RESPONSE
TO PREVIOUSLY MENTIONED WEAK SURFACE CYCLOGENESIS. OVER THE INSIDE
WATERS...SURFACE ISOBAR ORIENTATION IS GENERALLY PARALLEL TO N-S
CHANNELS. HOWEVER...BELIEVE SLY SPEEDS WILL BE ENHANCED SOMEWHAT
BY 30 KT 925 MB JET. THUS...MAINTAINED 20 KT WINDS FROM CLARENCE
STRAIT TO STEPHENS PASSAGE AND LYNN CANAL FOR MUCH OF THE SHORT
TERM PERIOD.

MEANWHILE...SATELLITE DERIVED PW GUIDANCE SHOWS VALUES NEAR 1 INCH
/CLOSE TO 3 STANDARD DEVIATIONS ABOVE CLIMATOLOGY/ SPREADING NWD
TOWARD THE CNTRL/SRN COAST OF SERN AK THIS MORNING. THIS MOISTURE
WILL SPREAD INLAND ACROSS THE SOUTHERN TWO THIRDS OF THE CWA BY
TONIGHT. IN ADDITION...A WARM PRE-FRONTAL BOUNDARY LAYER AIRMASS
WILL AID IN RAISING FREEZING LEVELS TO AROUND 3000 FT AMSL OVER
THE NRN PANHANDLE...AND 7000 FT AMSL OVER THE SRN PANHANDLE.
THE COMBINATION OF RELATIVELY RICH MOISTURE AND A DEEP WARM CLOUD
LAYER WILL SUPPORT THE POTENTIAL FOR ROBUST STRATIFORM RAINFALL.

THE FINAL INGREDIENT FOR HEAVY RAIN WILL BE A PLUME OF STRONG
700-500 MB UVV/S FORCED BY PREVIOUSLY MENTIONED UPPER
IMPULSE...WHICH WILL REACH THE SITKA AREA BY 03-06Z TONIGHT...AND
THEN THE GUSTAVUS TO JUNEAU AREA TOWARD 06-12Z. AS A
RESULT...RAINFALL RATES IN EXCESS OF 0.5 IN/HR WILL BE
POSSIBLE...YIELDING RAINFALL TOTALS FROM 1-2 INCHES BY 15Z MON.
FARTHER W...A DEEP LAYER OF COLD AIR WILL SPREAD ACROSS THE CNTRL
GULF AND AKZ017 TONIGHT. THIS WILL DESTABILIZE THE ATMOSPHERE AND
SUPPORT A TRANSITION TO A CONVECTIVE SHOWER REGIME.

INHERITED PRESSURE GRIDS WERE NUDGED TOWARD THE 00Z NAM AND
ECMWF...WHICH GAVE THE WEAK SURFACE LOW FORMING TONIGHT OVER THE
ERN GULF MORE DEFINITION. POP AND QPF GRIDS WERE UPDATED WITH A
BLEND OF THE ECMWF/GFS/NAM.

.LONG TERM...THE HEAVY RAIN OVER THE PANHANDLE SUNDAY NIGHT WILL
RELENT MONDAY FOR TWO REASONS. FIRST A SHORTWAVE CURRENTLY
ROUNDING THE BASE OF THE TROUGH AROUND 45 N 160 W WILL RIDE AHEAD
OF THE NORTHWARD MOVING WAVE OVER THE CENTRAL GULF, AND DIFFUSE
THE ENERGY EARLIER CONCENTRATED ACROSS THE NORTHEAST GULF TO AREAS
WELL TO THE SOUTH. IN ADDITION, THIS SHORTWAVE BYPASSING SOUTHEAST
ALASKA WILL SHUNT MUCH OF THE FEEDING MOISTURE EASTWARD RATHER
THAN NORTHWARD. FINALLY A WEAK BUT DRYING RIDGE IN THE LOW AND MID
LEVELS WILL HELP THIN THE DEEP MOISTURE SITUATED OVER THE
PANHANDLE FROM MONDAY NIGHT. THUS QPF AMOUNTS FOR MONDAY WILL
TOTAL LESS THAN A HALF INCH FOR ALL BUT MISTY FJORDS.

TO THE NORTHWEST IN YAKUTAT, ONSHORE FLOW COUPLED WITH COOLER
TEMPERATURES ALOFT WILL KEEP SHOWERS IN THE FORECAST. AS THE
FRONT SLOWLY MAKES PROGRESS THROUGH THE PANHANDLE, SOME
INSTABILITY MAY DEVELOP IN THE LOW LEVELS AS COOLER AIR SLIDES
EAST. HOWEVER, SINCE THE UPPER LEVELS WILL REMAIN RELATIVELY
WARM, AT 500 MB FOR EXAMPLE, WE KEPT THINGS STRATIFORM FOR MONDAY.
BY MONDAY NIGHT, THE TEMPERATURES AT 500 MB DROP ENOUGH TO SUGGEST
A MORE DEEPLY UNSTABLE AIR MASS AND STIR US TO WONDER ABOUT THE
POSSIBILITY OF CONVECTION THAT COULD SUPPORT LIGHTNING OVER THE
NORTHERN GULF. HELD OFF ON MENTIONING THUNDERSTORMS AT THIS TIME,
AS THE SUPPORTING CHARACTER OF THE SHORT-WAVE ITSELF DOES NOT
IMPRESS US WITH GRAVITAS. BUT EVEN WITHOUT THE SHORT-WAVE,
CONDITIONS COULD BE TOO RIPE AND THE PROXIMITY TO FORCED ASCENT
IN THE FORM OF THE ST. ELIAS MOUNTAINS MAY JUST PROVIDE THE
SPARK.

THE RIDGING EARLY IN THE WEEK THAT THAT MAY YIELD SOME SUNSHINE
STILL HAS THIS POTENTIAL. HOWEVER, THE ECMWF HAS NOW ADOPTED A
SLIGHTLY LESS FAVORABLE ORIENTATION FOR THIS RESULT. THE IDEA OF A
DIRTY RIDGE WHERE ONSHORE FLOW IN THE LOW TO MID LEVELS SPREADS
MOISTURE AND CLOUDINESS ONSHORE NEEDS TO BE PRESERVED. THE NEWEST RUN
OF THE ECMWF APPEARS TO BE LEANING MORE TOWARDS A WESTERLY
COMPONENT TO THESE WINDS, RATHER THAN THE SLIGHTLY MORE NORTHERLY
COMPONENT OF THE GFS AND NAM, AND EVEN THE GEM. IN ADDITION, THE
ECMWF ADVANCES THE RIDGE AXIS QUICKER TUESDAY EVENING. LARGELY
BROAD-BRUSHED THE NORTHERN PANHANDLE WITH MAINLY CLOUDY SKIES
TUESDAY. HOWEVER, THIS COULD BE A SUNNIER KIND OF MOSTLY CLOUDY.
SCATTERED SHOWERS WILL DIMINISH THROUGH LATE TUESDAY AS THE FLOW
BEGINS TO VEER OFFSHORE WITH A MAJOR SYSTEM REACHING THE CENTRAL
PANHANDLE BY WEDNESDAY.

WITH THE GFS AND ECWMF IN MODERATE AGREEMENT, WE RAISED WINDSPEEDS
TO GALE FORCE OVER 310 AND SOME OF THE OUTSIDE WATERS AHEAD OF THE
WEDNESDAY SYSTEM. AS THE LATITUDE OF THE SYSTEM WILL BE EQUAL TO
THAT OF DIXON ENTRANCE, PRECIPITATION OVER THE PANHANDLE WILL BE
LIMITED TO CHANCE POPS ACROSS THE COAST AND THE SOUTH. BUT AS THIS
SYSTEM EDGES NORTHWARD INTO THURSDAY, WHETHER A WHOLE LOW AS THE
ECMWF SUGGESTS OR A STRONG TRIPLE POINT FEATURE AS THE GFS HINTS
AT, WE HAVE NUDGED THE MOISTURE A LITTLE FARTHER NORTH SOONER
THAN PREVIOUS.

TEMPERATURES DURING THE NIGHTTIME AND SNOW LEVELS WILL FALL
BEHIND THE FRONT TO NEAR FREEZING/SEA LEVEL ACROSS THE FAR
NORTHERN ZONES INTO MID-WEEK. A SLOW BUT STEADY REBOUND WILL BEGIN
TO OCCUR WEDNESDAY NIGHT INTO THE WEEKEND WITH SOME WARM AIR
ADVECTION ASSOCIATED WITH THE MID-WEEK GULF SYSTEM.

USED NAM AND ECMWF FOR UPDATES MONDAY/MONDAY NIGHT. STRONGLY
NUDGED TO ECMWF AND GFS TO ADD STRENGTH TO THE WEDNESDAY SYSTEM.
EXTENDED FORECAST REMAINS WELL INTACT. COOLED TEMPERATURES A TAD
IN THE MID-RANGE WHILE WARMING THINGS A TAD TOWARD THE WEEKEND.
FORECAST CONFIDENCE DECENT.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ021-022-033>036-041-053.

&&

$$

GARNER/ADKINS

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU













000
FXAK67 PAJK 182343
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
343 PM AKDT SAT APR 18 2015

.SHORT TERM...CURRENT SATELLITE IMAGERY SHOWS DEEP CLOUDS MOVING
OVER THE PANHANDLE AS FRONT CONTINUES ITS SLOW PUSH
EASTWARD...PRIMARY DYNAMICS ARE TO THE WEST OF THE AREA MOVING
NORTHEAST. THIS IS CONSISTENT WITH MODEL-ANTICIPATED WINDS NOT
INCREASING SIGNIFICANTLY OVER MOST LAND AREAS WITH THIS SYSTEM.
HOWEVER PLUME OF MOISTURE FROM THE SOUTH IS DEEP AND EXTENDED AND AS
EXPECTED YAKUTAT AREA HAS BEEN THE FOCUS OF RAINFALL SO FAR IN THE
PROGRESSION OF THE SLOW-MOVING GALE-FORCE FRONT. MODEL UPDATES
HAVE 1.5 TO 2 INCHES OF RAINFALL THERE BY 03Z MON AND THIS IS
CONSISTENT WITH PREVIOUS RUNS. OTHER AREAS AT SEA LEVEL IN THE
CENTRAL/NORTHERN PANHANDLE EXPECT 0.75 TO 1 INCH MOSTLY TOMORROW
AS THE PRIMARY FRONTAL IMPACT OCCURS AFTER MOSTLY LIGHT RAINS
TODAY AND TONIGHT. MEANWHILE...WINDS ARE GALE-FORCE AS PREDICTED
OVER THE NORTHWESTERN OFFSHORE MARINE ZONES ENHANCED BY BARRIER
JET PROCESSES...AND GALES SHOULD REACH INTO ZONES 43 AND 42
TONIGHT. SLOW- MOVING NATURE OF FRONT WILL ALLOW STRONG OFFSHORE
WINDS TO PERSIST THROUGH TOMORROW MORNING...SLOWLY WEAKENING
AFTER THAT. SCA-LEVEL WINDS ANTICIPATED FOR THE EXPOSED INNER
CHANNELS AS WELL AS THOSE FAVORED FOR NORTH- SOUTH ISOBAR
ORIENTATION INTO TOMORROW AFTERNOON. LOCAL NORTHERN LYNN AND
SKAGWAY VICINITY WINDS HAVE PERSISTED GUSTING TO 40 KTS AT THE
FORMER THIS AFTERNOON. ANTICIPATE THAT THESE WILL SLOWLY DECREASE AFTER
00Z AS GRADIENT DOES THE SAME.

SHOULD BE NO PRECIP TYPE ISSUES OUTSIDE OF THE UPPER KLONDIKE
HIGHWAY REGION TONIGHT AS TEMPERATURES SHOULD BE A BIT WARMER
TONIGHT. BORDER TEMPERATURES AT THE KLONDIKE REMAIN JUST BELOW
FREEZING THIS AFTERNOON AND AN INCH OR TWO IS EXPECTED TONIGHT UP
HIGH. ONLY UPDATES TO THE INHERITED PRESSURE/WIND GRIDS WERE
TWEAKS IN THE WINDS AS PRESSURE FIELD WAS IN GOOD SHAPE.
THERMODYNAMIC FIELDS UPDATED WITH AN EC/NAM/INHERITED COMBO WITH
NO MAJOR CHANGES. TEMPS UPDATED PER MOS AND AGAIN THE CHANGES WERE
MINOR. WENT WITH STRATIFORM PRECIP REGION-WIDE PER CURRENT VIS
SATELLITE AND RADAR IMAGERY.

.LONG TERM...MODEL AGREEMENT ALOFT ON THE SYNOPTIC SCALE IS GOOD.
BOTH ECMWF AND GFS ARE PAINTING THE SAME OVERALL PICTURES WITH
DIFFERENCES IN THE DETAILS. A DEEP UPPER LOW IS SITUATED OVER THE
EASTERN BERING SEA AND AN UPPER RIDGE EXTENDS SOUTH FROM THE
BEAUFORT SEA OVER WESTERN CANADA, THEN OUT TO SEA OVER VANCOUVER
ISLAND AT THE START OF THE LONG RANGE FORECAST SUNDAY AFTERNOON.
THE RIDGE SHIFTS TO THE EAST AS AN UPPER TROUGH PUSHES EAST ACROSS
THE GULF.

BY TUESDAY MORNING, THE BERING SEA UPPER LOW WILL MOVE
NORTH TO NEAR THE BERING STRAIT AND A NEW UPPER LOW WILL DEVELOP
IN THE BASE OF THE TROUGH OVER THE ALEUTIANS. THIS NEW FEATURE
WILL DIG ESE TO NEAR HAIDA GWAII BY THURSDAY MORNING, BUT THEN
RETROGRADE BACK TO THE WEST AND BECOME ABSORBED BY A STRONGER
UPPER LOW THAT WILL DIG EVEN FURTHER TO THE SOUTHEAST THROUGH THE
MIDDLE OF NEXT WEEK.

AT THE SURFACE, THE NEW ALEUTIAN UPPER LOW WILL PHASE WITH A
DEVELOPING SURFACE LOW THAT WILL ENTER THE WESTERN GULF TUESDAY
NIGHT OR WEDNESDAY MORNING. THIS IS WHERE MODEL DIFFERENCES REALLY
BEGIN TO BE NOTICEABLE WRT WEATHER OVER THE EASTERN GULF AND
SOUTHEAST ALASKA. ALL MODELS DEEPEN THE SURFACE FEATURE RAPIDLY
ONCE IT PHASES WITH THE UPPER LOW. GFS TRACKS IT NORTH TO NEAR
KODIAK, OCCLUDES IT SOONER, AND THEN DEVELOPS A TRIPLE POINT LOW
OVER THE SOUTHWESTERN GULF BY WEDNESDAY MORNING. BETTER AGREEMENT
EXISTS BETWEEN ECMWF AND GEM, NEITHER OF WHICH TRACK THE SURFACE
LOW ANY FARTHER NORTH THAN 54N. BOTH GEM AND ECMWF THEN OCCLUDE
THE SYSTEM AND TRACK IT OFF TO THE SOUTHEAST. SOME RESIDUAL ENERGY
IN ECMWF THEN MOVES NORTHWEST ALONG THE OUTER COAST COAST ON
FRIDAY WHILE GFS MAINTAINS A SIGNIFICANT SURFACE CIRCULATION OVER
THE EASTERN GULF THROUGH FRIDAY NIGHT.

OPTED TO USE WPC FOR UPDATES TO PRESSURE AND WIND BEGINNING
WEDNESDAY MORNING WITH NO CHANGES SUNDAY NIGHT THROUGH TUESDAY
NIGHT. DID UPDATE POP AND QPF THROUGH SUNDAY NIGHT USING A BLEND
OF GEM AND GFS WHICH MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS
FORECAST. UPDATES TO TEMPERATURES LIMITED TO OVERNIGHT LOWS MONDAY
NIGHT THROUGH THURSDAY NIGHT TO BETTER REFLECT COLDER LOW LEVEL
AIR ADVECTING IN BEHIND A FRONTAL FEATURE CURRENTLY LOCATED OVER
THE WESTERN GULF. OVERALL FORECAST CONFIDENCE IS AVERAGE.


&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-021-022-033>036-041-053.

&&

$$

WESLEY/FRITSCH

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU










000
FXAK67 PAJK 182343
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
343 PM AKDT SAT APR 18 2015

.SHORT TERM...CURRENT SATELLITE IMAGERY SHOWS DEEP CLOUDS MOVING
OVER THE PANHANDLE AS FRONT CONTINUES ITS SLOW PUSH
EASTWARD...PRIMARY DYNAMICS ARE TO THE WEST OF THE AREA MOVING
NORTHEAST. THIS IS CONSISTENT WITH MODEL-ANTICIPATED WINDS NOT
INCREASING SIGNIFICANTLY OVER MOST LAND AREAS WITH THIS SYSTEM.
HOWEVER PLUME OF MOISTURE FROM THE SOUTH IS DEEP AND EXTENDED AND AS
EXPECTED YAKUTAT AREA HAS BEEN THE FOCUS OF RAINFALL SO FAR IN THE
PROGRESSION OF THE SLOW-MOVING GALE-FORCE FRONT. MODEL UPDATES
HAVE 1.5 TO 2 INCHES OF RAINFALL THERE BY 03Z MON AND THIS IS
CONSISTENT WITH PREVIOUS RUNS. OTHER AREAS AT SEA LEVEL IN THE
CENTRAL/NORTHERN PANHANDLE EXPECT 0.75 TO 1 INCH MOSTLY TOMORROW
AS THE PRIMARY FRONTAL IMPACT OCCURS AFTER MOSTLY LIGHT RAINS
TODAY AND TONIGHT. MEANWHILE...WINDS ARE GALE-FORCE AS PREDICTED
OVER THE NORTHWESTERN OFFSHORE MARINE ZONES ENHANCED BY BARRIER
JET PROCESSES...AND GALES SHOULD REACH INTO ZONES 43 AND 42
TONIGHT. SLOW- MOVING NATURE OF FRONT WILL ALLOW STRONG OFFSHORE
WINDS TO PERSIST THROUGH TOMORROW MORNING...SLOWLY WEAKENING
AFTER THAT. SCA-LEVEL WINDS ANTICIPATED FOR THE EXPOSED INNER
CHANNELS AS WELL AS THOSE FAVORED FOR NORTH- SOUTH ISOBAR
ORIENTATION INTO TOMORROW AFTERNOON. LOCAL NORTHERN LYNN AND
SKAGWAY VICINITY WINDS HAVE PERSISTED GUSTING TO 40 KTS AT THE
FORMER THIS AFTERNOON. ANTICIPATE THAT THESE WILL SLOWLY DECREASE AFTER
00Z AS GRADIENT DOES THE SAME.

SHOULD BE NO PRECIP TYPE ISSUES OUTSIDE OF THE UPPER KLONDIKE
HIGHWAY REGION TONIGHT AS TEMPERATURES SHOULD BE A BIT WARMER
TONIGHT. BORDER TEMPERATURES AT THE KLONDIKE REMAIN JUST BELOW
FREEZING THIS AFTERNOON AND AN INCH OR TWO IS EXPECTED TONIGHT UP
HIGH. ONLY UPDATES TO THE INHERITED PRESSURE/WIND GRIDS WERE
TWEAKS IN THE WINDS AS PRESSURE FIELD WAS IN GOOD SHAPE.
THERMODYNAMIC FIELDS UPDATED WITH AN EC/NAM/INHERITED COMBO WITH
NO MAJOR CHANGES. TEMPS UPDATED PER MOS AND AGAIN THE CHANGES WERE
MINOR. WENT WITH STRATIFORM PRECIP REGION-WIDE PER CURRENT VIS
SATELLITE AND RADAR IMAGERY.

.LONG TERM...MODEL AGREEMENT ALOFT ON THE SYNOPTIC SCALE IS GOOD.
BOTH ECMWF AND GFS ARE PAINTING THE SAME OVERALL PICTURES WITH
DIFFERENCES IN THE DETAILS. A DEEP UPPER LOW IS SITUATED OVER THE
EASTERN BERING SEA AND AN UPPER RIDGE EXTENDS SOUTH FROM THE
BEAUFORT SEA OVER WESTERN CANADA, THEN OUT TO SEA OVER VANCOUVER
ISLAND AT THE START OF THE LONG RANGE FORECAST SUNDAY AFTERNOON.
THE RIDGE SHIFTS TO THE EAST AS AN UPPER TROUGH PUSHES EAST ACROSS
THE GULF.

BY TUESDAY MORNING, THE BERING SEA UPPER LOW WILL MOVE
NORTH TO NEAR THE BERING STRAIT AND A NEW UPPER LOW WILL DEVELOP
IN THE BASE OF THE TROUGH OVER THE ALEUTIANS. THIS NEW FEATURE
WILL DIG ESE TO NEAR HAIDA GWAII BY THURSDAY MORNING, BUT THEN
RETROGRADE BACK TO THE WEST AND BECOME ABSORBED BY A STRONGER
UPPER LOW THAT WILL DIG EVEN FURTHER TO THE SOUTHEAST THROUGH THE
MIDDLE OF NEXT WEEK.

AT THE SURFACE, THE NEW ALEUTIAN UPPER LOW WILL PHASE WITH A
DEVELOPING SURFACE LOW THAT WILL ENTER THE WESTERN GULF TUESDAY
NIGHT OR WEDNESDAY MORNING. THIS IS WHERE MODEL DIFFERENCES REALLY
BEGIN TO BE NOTICEABLE WRT WEATHER OVER THE EASTERN GULF AND
SOUTHEAST ALASKA. ALL MODELS DEEPEN THE SURFACE FEATURE RAPIDLY
ONCE IT PHASES WITH THE UPPER LOW. GFS TRACKS IT NORTH TO NEAR
KODIAK, OCCLUDES IT SOONER, AND THEN DEVELOPS A TRIPLE POINT LOW
OVER THE SOUTHWESTERN GULF BY WEDNESDAY MORNING. BETTER AGREEMENT
EXISTS BETWEEN ECMWF AND GEM, NEITHER OF WHICH TRACK THE SURFACE
LOW ANY FARTHER NORTH THAN 54N. BOTH GEM AND ECMWF THEN OCCLUDE
THE SYSTEM AND TRACK IT OFF TO THE SOUTHEAST. SOME RESIDUAL ENERGY
IN ECMWF THEN MOVES NORTHWEST ALONG THE OUTER COAST COAST ON
FRIDAY WHILE GFS MAINTAINS A SIGNIFICANT SURFACE CIRCULATION OVER
THE EASTERN GULF THROUGH FRIDAY NIGHT.

OPTED TO USE WPC FOR UPDATES TO PRESSURE AND WIND BEGINNING
WEDNESDAY MORNING WITH NO CHANGES SUNDAY NIGHT THROUGH TUESDAY
NIGHT. DID UPDATE POP AND QPF THROUGH SUNDAY NIGHT USING A BLEND
OF GEM AND GFS WHICH MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS
FORECAST. UPDATES TO TEMPERATURES LIMITED TO OVERNIGHT LOWS MONDAY
NIGHT THROUGH THURSDAY NIGHT TO BETTER REFLECT COLDER LOW LEVEL
AIR ADVECTING IN BEHIND A FRONTAL FEATURE CURRENTLY LOCATED OVER
THE WESTERN GULF. OVERALL FORECAST CONFIDENCE IS AVERAGE.


&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-021-022-033>036-041-053.

&&

$$

WESLEY/FRITSCH

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU









000
FXAK67 PAJK 181331
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
531 AM AKDT SAT APR 18 2015

.SHORT TERM...GALE FORCE FRONT MOVING ACROSS THE GULF WILL BE THE
MAIN FEATURE IN THE SHORT TERM PERIOD. THIS FRONT WILL BE SLOW TO
ADVANCE EASTWARD UNTIL A SECONDARY WAVES ACTS TO PUSH IT OVER THE
PANHANDLE TONIGHT. STRONGEST WINDS WITH THIS SYSTEM WILL OCCUR
OVER THE NORTHERN GULF. CURRENTLY THE CAPE SUCKLING BUOY 46082 IS
SUSTAINED AT 41 KT WITH GUSTS TO 48 KT AND 18 FT SEAS. EXPECT
THESE BARRIER JET WINDS TO GRADUALLY WEAKEN THROUGH TONIGHT. SOME
SMALL CRAFT WINDS CAN BE EXPECTED IN THE EAST-WEST ORIENTED INNER
CHANNELS BUT STRONGEST WINDS WILL STAY OUT OVER THE GULF. WINDS
OVER LAND WILL GENERALLY BE OUT OF THE SOUTHEAST IN THE 10 TO 20
MPH RANGE BUT WILL SEE SOME HIGHER GUSTS ALONG THE OUTER COAST.
HEAVIEST PRECIPITATION WILL FALL OVER THE NORTHERN GULF COAST
INCLUDING YAKUTAT WITH UP TO 2 INCHES OF RAINFALL BY LATE TONIGHT.
PRECIPITATION RATES HAVE RESULTED IN SOME SNOW MIXING IN WITH THE
RAIN AT THE YAKUTAT AIRPORT THIS MORNING BUT EXPECTING WARM AIR
ADVECTION ASSOCIATED WITH THE FRONT WILL CHANGE THIS OVER TO ALL
RAIN LATER THIS MORNING. THINKING RAINFALL WILL BE LIGHT OVER A
MAJORITY OF THE PANHANDLE EXCLUDING THE NORTHERN COAST UNTIL THE
SECONDARY WAVE PUSHES THE FRONT INTO THE PANHANDLE TONIGHT AT
WHICH TIME RAINFALL RATES WILL PICK UP OVER THE NORTHERN AND
CENTRAL PANHANDLE.

USED THE 00Z NAM AND HI RES ARW AND NMM FOR UPDATES TO THE
PREVIOUS FORECAST. MAIN CHANGE TO THE FORECAST WERE TO MAKE
PRECIPITATION LIGHT ACROSS A MAJORITY OF THE PANHANDLE TODAY.
OTHERWISE, CHANGES WERE MINIMAL AND MAINLY LIMITED TO LOCAL EFFECT
EDITS. FORECASTER CONFIDENCE IS ABOVE AVERAGE.

.LONG TERM...GALE FORCE FRONT INITIALLY LOCATED NEAR THE ERN/NERN
GULF COAST ON SUN WILL GRADUALLY WEAKEN AS IT IS SHUNTED EWD
ACROSS THE PANHANDLE THROUGH MON NIGHT IN RESPONSE TO AN EWD
PROGRESSING UPPER TROUGH. BEFORE FRONTAL PASSAGE TAKES
PLACE...MODERATE TO LOCALLY HEAVY RAINFALL IS FORECAST TO OCCUR
OVER SERN AK DUE TO A PERSISTENT INFLUX OF RELATIVELY RICH
MOISTURE CHARACTERIZED BY PW VALUES RANGING FROM 0.5-0.8 INCH.
AFTER FRONTAL PASSAGE ON TUE...A DEEP LAYER OF COLD AIR /AOB -6 C
AT 850 MB...AOB -30 C AT 500 MB/ WILL SPREAD EWD INTO THE
REGION...AIDING IN A TRANSITION TO SHOWERS. BY MIDWEEK
/WED/...GFS...ECMWF...AND GEM SHOW AN UPPER LOW ENTERING THE SWRN
GULF AND ADJACENT NERN PAC. HOWEVER...POOR AGREEMENT EXISTS WITH
ITS LOCATION...AND SOLUTIONS FURTHER DIVERGE DURING THU...WITH THE
GFS EJECTING THE LOW NE INTO THE NERN GULF...WHILE THE GEM AND
ECMWF DIG IT SEWD. THIS MARKS THE BEGINNING OF A RAPID REDUCTION
IN FORECAST CONFIDENCE. AS A RESULT...LITTLE DETAIL IS DEPICTED IN
POP AND QPF GRIDS THROUGH THE REMAINDER OF THE LONG TERM.

INHERITED PRESSURE GRIDS WERE UPDATED WITH THE ECMWF AND GEM
THROUGH 00Z TUE. POP AND QPF WERE UPDATED WITH THE ECMWF AND
GFS...THOUGH CHANGES WERE GENERALLY MINOR. AS PREVIOUSLY
MENTIONED...POP AND QPF VALUES WERE SMOOTHED OUT AND LOWERED IN
MAGNITUDE DURING THE SECOND HALF OF THE LONG TERM PERIOD.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ021-022-031-033>036-041-053.

&&

$$

TPS/GARNER

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU








000
FXAK67 PAJK 181331
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
531 AM AKDT SAT APR 18 2015

.SHORT TERM...GALE FORCE FRONT MOVING ACROSS THE GULF WILL BE THE
MAIN FEATURE IN THE SHORT TERM PERIOD. THIS FRONT WILL BE SLOW TO
ADVANCE EASTWARD UNTIL A SECONDARY WAVES ACTS TO PUSH IT OVER THE
PANHANDLE TONIGHT. STRONGEST WINDS WITH THIS SYSTEM WILL OCCUR
OVER THE NORTHERN GULF. CURRENTLY THE CAPE SUCKLING BUOY 46082 IS
SUSTAINED AT 41 KT WITH GUSTS TO 48 KT AND 18 FT SEAS. EXPECT
THESE BARRIER JET WINDS TO GRADUALLY WEAKEN THROUGH TONIGHT. SOME
SMALL CRAFT WINDS CAN BE EXPECTED IN THE EAST-WEST ORIENTED INNER
CHANNELS BUT STRONGEST WINDS WILL STAY OUT OVER THE GULF. WINDS
OVER LAND WILL GENERALLY BE OUT OF THE SOUTHEAST IN THE 10 TO 20
MPH RANGE BUT WILL SEE SOME HIGHER GUSTS ALONG THE OUTER COAST.
HEAVIEST PRECIPITATION WILL FALL OVER THE NORTHERN GULF COAST
INCLUDING YAKUTAT WITH UP TO 2 INCHES OF RAINFALL BY LATE TONIGHT.
PRECIPITATION RATES HAVE RESULTED IN SOME SNOW MIXING IN WITH THE
RAIN AT THE YAKUTAT AIRPORT THIS MORNING BUT EXPECTING WARM AIR
ADVECTION ASSOCIATED WITH THE FRONT WILL CHANGE THIS OVER TO ALL
RAIN LATER THIS MORNING. THINKING RAINFALL WILL BE LIGHT OVER A
MAJORITY OF THE PANHANDLE EXCLUDING THE NORTHERN COAST UNTIL THE
SECONDARY WAVE PUSHES THE FRONT INTO THE PANHANDLE TONIGHT AT
WHICH TIME RAINFALL RATES WILL PICK UP OVER THE NORTHERN AND
CENTRAL PANHANDLE.

USED THE 00Z NAM AND HI RES ARW AND NMM FOR UPDATES TO THE
PREVIOUS FORECAST. MAIN CHANGE TO THE FORECAST WERE TO MAKE
PRECIPITATION LIGHT ACROSS A MAJORITY OF THE PANHANDLE TODAY.
OTHERWISE, CHANGES WERE MINIMAL AND MAINLY LIMITED TO LOCAL EFFECT
EDITS. FORECASTER CONFIDENCE IS ABOVE AVERAGE.

.LONG TERM...GALE FORCE FRONT INITIALLY LOCATED NEAR THE ERN/NERN
GULF COAST ON SUN WILL GRADUALLY WEAKEN AS IT IS SHUNTED EWD
ACROSS THE PANHANDLE THROUGH MON NIGHT IN RESPONSE TO AN EWD
PROGRESSING UPPER TROUGH. BEFORE FRONTAL PASSAGE TAKES
PLACE...MODERATE TO LOCALLY HEAVY RAINFALL IS FORECAST TO OCCUR
OVER SERN AK DUE TO A PERSISTENT INFLUX OF RELATIVELY RICH
MOISTURE CHARACTERIZED BY PW VALUES RANGING FROM 0.5-0.8 INCH.
AFTER FRONTAL PASSAGE ON TUE...A DEEP LAYER OF COLD AIR /AOB -6 C
AT 850 MB...AOB -30 C AT 500 MB/ WILL SPREAD EWD INTO THE
REGION...AIDING IN A TRANSITION TO SHOWERS. BY MIDWEEK
/WED/...GFS...ECMWF...AND GEM SHOW AN UPPER LOW ENTERING THE SWRN
GULF AND ADJACENT NERN PAC. HOWEVER...POOR AGREEMENT EXISTS WITH
ITS LOCATION...AND SOLUTIONS FURTHER DIVERGE DURING THU...WITH THE
GFS EJECTING THE LOW NE INTO THE NERN GULF...WHILE THE GEM AND
ECMWF DIG IT SEWD. THIS MARKS THE BEGINNING OF A RAPID REDUCTION
IN FORECAST CONFIDENCE. AS A RESULT...LITTLE DETAIL IS DEPICTED IN
POP AND QPF GRIDS THROUGH THE REMAINDER OF THE LONG TERM.

INHERITED PRESSURE GRIDS WERE UPDATED WITH THE ECMWF AND GEM
THROUGH 00Z TUE. POP AND QPF WERE UPDATED WITH THE ECMWF AND
GFS...THOUGH CHANGES WERE GENERALLY MINOR. AS PREVIOUSLY
MENTIONED...POP AND QPF VALUES WERE SMOOTHED OUT AND LOWERED IN
MAGNITUDE DURING THE SECOND HALF OF THE LONG TERM PERIOD.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ021-022-031-033>036-041-053.

&&

$$

TPS/GARNER

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU







000
FXAK67 PAJK 172329
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
329 PM AKDT FRI APR 17 2015

.SHORT TERM...SHOWERS CONTINUE TO BE THE RULE OF THE DAY ACROSS
THE PANHANDLE THOUGH NOT FOR MUCH LONGER. LOCAL UPPER AIR
SOUNDINGS SHOW AROUND 100 TO 200 J/KG OF CAPE BUT UPPER LEVEL
TEMPS ARE STARTING TO WARM UP BRING MORE STABILITY TO THE AREA.
THE WEAK TROUGH THAT BROUGHT THE STRONGER SHOWERS TO THE AREA THIS
MORNING IS STARTING TO MOVE INTO CANADA. BEHIND IT SHOWERS ARE
BECOMING FEWER AND FARTHER BETWEEN AS A SURFACE RIDGE BUILDS
ACROSS THE SE GULF AND DIFFLUENT FLOW ALOFT BEGINS TO DEVELOP.
CLOUDS ARE STARTING TO BREAK UP AS WELL WITH AREAS OF SUN
DEVELOPING. STILL THERE ARE ONE OR TWO STRONGER SHOWERS AROUND.
YAKUTAT HAD A SHOWER MOVE THROUGH AROUND 1130 AM THAT DROPPED A
QUARTER INCH OF SMALL HAIL AND ICE PELLETS ON THE AIRPORT.

THIS EVENING IS LOOKING MOSTLY DRY WITH SOME MOSTLY TO PARTLY
CLOUDY SKIES AS SHOWERS CONTINUE TO SHOW A DIMINISHING TREND. SOME
SCATTERED TO ISOLATED SHOWERS COULD STILL LINGER, ESPECIALLY NEAR
THE HIGHER TERRAIN. THESE SHOWERS SHOULD REMAIN LIGHT FOR THE
MOST PART AS WHAT UPPER SUPPORT THEY HAD HAS MOVED INTO CANADA
BY THIS POINT. WINDS TOO WILL BE ON THE DECREASING TREND. THE
GUSTY SOUTHERLY WINDS IN LYNN CANAL AND SKAGWAY WILL DIMINISH THIS
EVENING AS THE BUILDING RIDGE GET FAR ENOUGH NORTH THAT PRESSURE
GRADIENTS TURN MORE PARALLEL TO LYNN CANAL THEN PERPENDICULAR.

LATER TONIGHT AND INTO TOMORROW, FOCUS SHIFTS TO THE GALE FORCE
FRONT THAT IS ADVANCING ACROSS THE GULF. MOST OF THE GULF WILL
EXPERIENCE GALE FORCE WINDS WITH THE HIGHEST WINDS NEAR CAPE
SUCKLING DUE TO BARRIER JET EFFECTS. THESE WINDS WILL SPREAD INTO
THE NORTHERN PANHANDLE TOMORROW AS THE FRONT DRIFTS TO THE EAST.
NOT EXPECTING TO NEED STRONG WIND HEADLINES FOR THE NORTHERN OUTER
COAST AS BARRIER INFLUENCES KEEP MOST OF THE STRONG WIND OFFSHORE.
AS FOR RAIN, IT LOOKS TO COME IN TWO MAIN BURSTS. HOW FAR EAST
EACH BURST GETS WILL LIKELY DEPEND ON HOW STRONG THE RIDGE OVER
BRITISH COLUMBIA IS THAT IS SUPPRESSING THE EASTWARD MOVEMENT OF
THE FRONT AS A WHOLE. THE FIRST PULSE WILL BE LATE TONIGHT AS AN
INITIAL WARM FRONT CROSSES THE PANHANDLE. MOST AREAS EXCEPT FOR THE
EXTREME SOUTHERN PANHANDLE WILL LIKELY SEE RAIN OUT OF THIS
FEATURE WITH LIGHTER RAINFALL AMOUNTS THE FARTHER EAST AND SOUTH
YOU ARE. 850 MB TEMPS AHEAD OF THE FRONT ARE STILL AROUND -7 TO -6
C OVER THE EXTREME NORTHERN PANHANDLE SO RAIN MAY MIX WITH SNOW
AROUND YAKUTAT LATE TONIGHT BEFORE THE HEAVIER RAIN AND STRONGER
WARM AIR ADVECTION MAKES IT INTO THE AREA. PULSE NUMBER TWO IS A
TRAILING WAVE ON THE COLD FRONT THAT WILL PUSH THE FRONTAL RAIN
BANDS INTO THE PANHANDLE ON SAT. RIGHT NOW MOST OF THE RAIN
APPEARS TO BE ON A LINE FROM TAKU INLET DOWN TO FIVE FINGERS TO
JUST WEST OF KLAWOCK AND WESTWARD. EAST OF THAT LINE RAIN CHANCES
DROP TO CHANCE OR LESS FOR SAT AS THE BRITISH COLUMBIA RIDGE
BLOCKS ANY MORE EASTWARD MOVEMENT. HEAVIEST RAINFALL WILL MOSTLY
BE OVER THE YAKUTAT AREA AS THE MAIN MOISTURE PLUME IS AIMED IN
THAT DIRECTION AND EFFECTS FROM TERRAIN WILL JUST WRING EVEN MORE
RAIN OUT OF THE CLOUDS.

WINDS WILL ALSO BE INCREASING ACROSS THE NORTHERN PANHANDLE AS
WELL AS THE FRONT GETS CLOSER. MOST AREAS SHOULD HAVE SOME GUSTY
WINDS BUT I DO NOT THINK STRONG WIND HEADLINES WILL BE NEEDED AS
850 MB WINDS ONLY REACH 35 TO 40 KT AND THE PARENT LOW IS WELL
WEST OF THE AREA. STILL LYNN CANAL, SOUTHERN CHATHAM STRAIT AND
CROSS SOUND WILL LIKELY SEE 25 TO 30 KT SMALL CRAFT WINDS
DEVELOPING TOMORROW.

SHORT RANGE MODELS WERE IN GOOD AGREEMENT WITH ONLY VERY MINOR
DIFFERENCES THAT DID NOT AFFECT THE OVERALL FORECAST. MAIN CHANGES
WERE SMALL LOCAL EFFECT CHANGES. OF NOTE IS THAT THE MODELS ARE
ONCE AGAIN UNDERESTIMATING THE SOUTHERLY PRESSURE GRADIENT THAT
DEVELOPED AROUND LYNN CANAL. MOST WERE 1 TO 2 MB TOO WEAK AND AS
SUCH TOO WEAK WITH WINDS. MAIN CHANGE FROM THIS WAS INCREASING WINDS
IN LYNN CANAL TO SMALL CRAFT FOR EARLY THIS EVENING AND TOMORROW
AFTERNOON.

.LONG TERM...MODELS CONSISTENT WITH PREVIOUS RUNS IN PRODUCING 2.5
TO 4 INCHES OF RAIN IN THE YAKUTAT AREA IN A 3-DAY PERIOD
BEGINNING LATE TONIGHT. 2-3 INCHES IS ALSO PREDICTED DURING THIS
TIME PERIOD IN JUNEAU AND AROUND SITKA WITH LESSER AMOUNTS IN
OTHER SEA LEVEL LOCATIONS AND OFFSHORE. THIS IS IN RESPONSE TO
WELL-ADVERTISED FRONT WHICH WILL PUSH INTO THE PANHANDLE TOMORROW.
THE SITUK RIVER IS STILL SHOWING LESS THAN 67 FEET...FLOOD IS AT
71.5...COORDINATED THINKING WITH RFC ON CONF CALL TODAY AND AGREE
WITH THEM TO MONITOR AND THAT BANKFULL IS IMPROBABLE AT THIS
POINT. THOUGH FREEZING LEVELS WILL RISE IN THAT AREA WILL STRUGGLE
EARLY IN THE SYSTEM TO GET ABOVE 3000 FEET AND WILL FALL ONCE THE
SLOW FRONT MOVES THROUGH. THIS WILL RESTRICT CONTRIBUTION OF
SNOWMELT TO RUNOFF.

INHERITED PRESSURE/WIND GRIDS WERE GOOD FOR
TOMORROW NIGHT AND SUNDAY BASED ON NEW MODEL DATA WITH JUST SOME
UPWARD TWEAKS IN THE CHANNELS WITH ORIENTATION PERPENDICULAR TO
ISOBARS. OFFSHORE GALES WILL BE COMMON THROUGH ABOUT SUNDAY
MORNING WITH THE FRONT WHILE SCA WINDS WILL PREVAIL IN CROSS AND
FAVORED SOUTHERN CHANNELS INTO SUNDAY ALSO. ONLY THREAT FOR
WEEKEND MIXED STRATIFORM PRECIP SHOULD BE UP THE ROADS AND AMOUNTS
OF WET SNOW SHOULD BE LIGHT AND CONFINED MOSTLY TO LATE NIGHT
PERIODS. I HAVE AN INCH OR SO AT WHITE PASS ON SATURDAY AND SUNDAY
NIGHTS. SLOW-MOVING FRONTAL PRECIP SHOULD DIMINISH MONDAY
AFTERNOON AND A SHOWERY PERIOD SHOULD BEGIN WITH LESS UPPER
FORCING BUT MORE SOLAR EFFECTS. WITH WEAKENING PRESSURE GRADIENTS
THE CONSENSUS ON MODEL MSLP FIELDS DETERIORATES BY MONDAY. WENT
WITH AN EC/NAM COMBO ALONG WITH INHERITED GRIDS THROUGH MONDAY BUT
WITHOUT A LOT OF CONFIDENCE FOR THE LATTER PERIOD. THEN USED
MOSTLY EC/INHERITED ON THE WAY TO WPC GUIDANCE FOR THE EXTENDED
PERIOD. THE PREVIOUSLY DRYING TREND BY MIDWEEK IS CERTAINLY IN
DANGER AT THIS POINT AS MODELS DELAY THE RIDGING ALOFT...ALONG WITH
PERSISTING -25 TO -35C TEMPS AT 500 THROUGH WEDNESDAY. THUS ANY
SURFACE WARMING WILL CERTAINLY LEAD TO SHOWERS. THIS IS REFLECTED
IN THE ZONE FORECASTS FROM TUE ONWARDS. NEW EC DETERMINISTIC RUN
NOW DELAYS UPPER RIDGING UNTIL THE END OF THE WEEK...A HIGH-
AMPLITUDE UPPER PATTERN IS LIKELY WHICH MODELS HAVE TYPICALLY MORE
PROBLEMS WITH...AND COULD BECOME SLOW-MOVING. AGREEMENT BETWEEN
THE DETERMINISTIC EC/GFS AT MID-LEVELS IS REASONABLE THROUGH
THURSDAY WITH BOTH ADVERTISING DEVELOPMENT OF A RIDGE OVER THE
WESTERN GULF AT THAT POINT. EC CHANGES VERY LITTLE BY FRI WHILE THE
GFS SHOWS A STRANGE ELONGATED NW-SE LOW OVER THE EASTERN GULF BY
FRI.

CAN SUMMARIZE THE EXTENDED WITH A STATEMENT OF LITTLE
CONFIDENCE...PROBABLY IS BETTER STATISTICALLY TO TRUST AN ENSEMBLE
APPROACH WHICH IS WHAT WPC CHOSE. A SIGNIFICANT DRYING/WARMING
PATTERN OVER THE PANHANDLE IS STILL IN THE CARDS...JUST LIKELY DELAYED
UNTIL LATE NEXT WEEK. FINALLY DECIDED TO INCREASE SKY COVER FOR
THE WED-THU PERIOD AS AFTERNOON SHOWER DEVELOPMENT IS LIKELY AS
LONG AS CYCLONIC COOL FLOW ALOFT PERSISTS...WITHOUT FRONTAL
FORCING, SURFACE HEATING WILL LIKELY BE A FACTOR. THIS MAY BE
EXTENDING CLOUDY CONDITIONS FOR TOO LONG BUT UPCOMING MODEL RUNS
WILL TELL. TRYING TO AVOID THE "PARTLY CLOUDY, CHANCE SHOWERS"
RUBBER STAMP.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-022-033-041-053.

&&

$$

EAL/WESLEY

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU












000
FXAK67 PAJK 172329
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
329 PM AKDT FRI APR 17 2015

.SHORT TERM...SHOWERS CONTINUE TO BE THE RULE OF THE DAY ACROSS
THE PANHANDLE THOUGH NOT FOR MUCH LONGER. LOCAL UPPER AIR
SOUNDINGS SHOW AROUND 100 TO 200 J/KG OF CAPE BUT UPPER LEVEL
TEMPS ARE STARTING TO WARM UP BRING MORE STABILITY TO THE AREA.
THE WEAK TROUGH THAT BROUGHT THE STRONGER SHOWERS TO THE AREA THIS
MORNING IS STARTING TO MOVE INTO CANADA. BEHIND IT SHOWERS ARE
BECOMING FEWER AND FARTHER BETWEEN AS A SURFACE RIDGE BUILDS
ACROSS THE SE GULF AND DIFFLUENT FLOW ALOFT BEGINS TO DEVELOP.
CLOUDS ARE STARTING TO BREAK UP AS WELL WITH AREAS OF SUN
DEVELOPING. STILL THERE ARE ONE OR TWO STRONGER SHOWERS AROUND.
YAKUTAT HAD A SHOWER MOVE THROUGH AROUND 1130 AM THAT DROPPED A
QUARTER INCH OF SMALL HAIL AND ICE PELLETS ON THE AIRPORT.

THIS EVENING IS LOOKING MOSTLY DRY WITH SOME MOSTLY TO PARTLY
CLOUDY SKIES AS SHOWERS CONTINUE TO SHOW A DIMINISHING TREND. SOME
SCATTERED TO ISOLATED SHOWERS COULD STILL LINGER, ESPECIALLY NEAR
THE HIGHER TERRAIN. THESE SHOWERS SHOULD REMAIN LIGHT FOR THE
MOST PART AS WHAT UPPER SUPPORT THEY HAD HAS MOVED INTO CANADA
BY THIS POINT. WINDS TOO WILL BE ON THE DECREASING TREND. THE
GUSTY SOUTHERLY WINDS IN LYNN CANAL AND SKAGWAY WILL DIMINISH THIS
EVENING AS THE BUILDING RIDGE GET FAR ENOUGH NORTH THAT PRESSURE
GRADIENTS TURN MORE PARALLEL TO LYNN CANAL THEN PERPENDICULAR.

LATER TONIGHT AND INTO TOMORROW, FOCUS SHIFTS TO THE GALE FORCE
FRONT THAT IS ADVANCING ACROSS THE GULF. MOST OF THE GULF WILL
EXPERIENCE GALE FORCE WINDS WITH THE HIGHEST WINDS NEAR CAPE
SUCKLING DUE TO BARRIER JET EFFECTS. THESE WINDS WILL SPREAD INTO
THE NORTHERN PANHANDLE TOMORROW AS THE FRONT DRIFTS TO THE EAST.
NOT EXPECTING TO NEED STRONG WIND HEADLINES FOR THE NORTHERN OUTER
COAST AS BARRIER INFLUENCES KEEP MOST OF THE STRONG WIND OFFSHORE.
AS FOR RAIN, IT LOOKS TO COME IN TWO MAIN BURSTS. HOW FAR EAST
EACH BURST GETS WILL LIKELY DEPEND ON HOW STRONG THE RIDGE OVER
BRITISH COLUMBIA IS THAT IS SUPPRESSING THE EASTWARD MOVEMENT OF
THE FRONT AS A WHOLE. THE FIRST PULSE WILL BE LATE TONIGHT AS AN
INITIAL WARM FRONT CROSSES THE PANHANDLE. MOST AREAS EXCEPT FOR THE
EXTREME SOUTHERN PANHANDLE WILL LIKELY SEE RAIN OUT OF THIS
FEATURE WITH LIGHTER RAINFALL AMOUNTS THE FARTHER EAST AND SOUTH
YOU ARE. 850 MB TEMPS AHEAD OF THE FRONT ARE STILL AROUND -7 TO -6
C OVER THE EXTREME NORTHERN PANHANDLE SO RAIN MAY MIX WITH SNOW
AROUND YAKUTAT LATE TONIGHT BEFORE THE HEAVIER RAIN AND STRONGER
WARM AIR ADVECTION MAKES IT INTO THE AREA. PULSE NUMBER TWO IS A
TRAILING WAVE ON THE COLD FRONT THAT WILL PUSH THE FRONTAL RAIN
BANDS INTO THE PANHANDLE ON SAT. RIGHT NOW MOST OF THE RAIN
APPEARS TO BE ON A LINE FROM TAKU INLET DOWN TO FIVE FINGERS TO
JUST WEST OF KLAWOCK AND WESTWARD. EAST OF THAT LINE RAIN CHANCES
DROP TO CHANCE OR LESS FOR SAT AS THE BRITISH COLUMBIA RIDGE
BLOCKS ANY MORE EASTWARD MOVEMENT. HEAVIEST RAINFALL WILL MOSTLY
BE OVER THE YAKUTAT AREA AS THE MAIN MOISTURE PLUME IS AIMED IN
THAT DIRECTION AND EFFECTS FROM TERRAIN WILL JUST WRING EVEN MORE
RAIN OUT OF THE CLOUDS.

WINDS WILL ALSO BE INCREASING ACROSS THE NORTHERN PANHANDLE AS
WELL AS THE FRONT GETS CLOSER. MOST AREAS SHOULD HAVE SOME GUSTY
WINDS BUT I DO NOT THINK STRONG WIND HEADLINES WILL BE NEEDED AS
850 MB WINDS ONLY REACH 35 TO 40 KT AND THE PARENT LOW IS WELL
WEST OF THE AREA. STILL LYNN CANAL, SOUTHERN CHATHAM STRAIT AND
CROSS SOUND WILL LIKELY SEE 25 TO 30 KT SMALL CRAFT WINDS
DEVELOPING TOMORROW.

SHORT RANGE MODELS WERE IN GOOD AGREEMENT WITH ONLY VERY MINOR
DIFFERENCES THAT DID NOT AFFECT THE OVERALL FORECAST. MAIN CHANGES
WERE SMALL LOCAL EFFECT CHANGES. OF NOTE IS THAT THE MODELS ARE
ONCE AGAIN UNDERESTIMATING THE SOUTHERLY PRESSURE GRADIENT THAT
DEVELOPED AROUND LYNN CANAL. MOST WERE 1 TO 2 MB TOO WEAK AND AS
SUCH TOO WEAK WITH WINDS. MAIN CHANGE FROM THIS WAS INCREASING WINDS
IN LYNN CANAL TO SMALL CRAFT FOR EARLY THIS EVENING AND TOMORROW
AFTERNOON.

.LONG TERM...MODELS CONSISTENT WITH PREVIOUS RUNS IN PRODUCING 2.5
TO 4 INCHES OF RAIN IN THE YAKUTAT AREA IN A 3-DAY PERIOD
BEGINNING LATE TONIGHT. 2-3 INCHES IS ALSO PREDICTED DURING THIS
TIME PERIOD IN JUNEAU AND AROUND SITKA WITH LESSER AMOUNTS IN
OTHER SEA LEVEL LOCATIONS AND OFFSHORE. THIS IS IN RESPONSE TO
WELL-ADVERTISED FRONT WHICH WILL PUSH INTO THE PANHANDLE TOMORROW.
THE SITUK RIVER IS STILL SHOWING LESS THAN 67 FEET...FLOOD IS AT
71.5...COORDINATED THINKING WITH RFC ON CONF CALL TODAY AND AGREE
WITH THEM TO MONITOR AND THAT BANKFULL IS IMPROBABLE AT THIS
POINT. THOUGH FREEZING LEVELS WILL RISE IN THAT AREA WILL STRUGGLE
EARLY IN THE SYSTEM TO GET ABOVE 3000 FEET AND WILL FALL ONCE THE
SLOW FRONT MOVES THROUGH. THIS WILL RESTRICT CONTRIBUTION OF
SNOWMELT TO RUNOFF.

INHERITED PRESSURE/WIND GRIDS WERE GOOD FOR
TOMORROW NIGHT AND SUNDAY BASED ON NEW MODEL DATA WITH JUST SOME
UPWARD TWEAKS IN THE CHANNELS WITH ORIENTATION PERPENDICULAR TO
ISOBARS. OFFSHORE GALES WILL BE COMMON THROUGH ABOUT SUNDAY
MORNING WITH THE FRONT WHILE SCA WINDS WILL PREVAIL IN CROSS AND
FAVORED SOUTHERN CHANNELS INTO SUNDAY ALSO. ONLY THREAT FOR
WEEKEND MIXED STRATIFORM PRECIP SHOULD BE UP THE ROADS AND AMOUNTS
OF WET SNOW SHOULD BE LIGHT AND CONFINED MOSTLY TO LATE NIGHT
PERIODS. I HAVE AN INCH OR SO AT WHITE PASS ON SATURDAY AND SUNDAY
NIGHTS. SLOW-MOVING FRONTAL PRECIP SHOULD DIMINISH MONDAY
AFTERNOON AND A SHOWERY PERIOD SHOULD BEGIN WITH LESS UPPER
FORCING BUT MORE SOLAR EFFECTS. WITH WEAKENING PRESSURE GRADIENTS
THE CONSENSUS ON MODEL MSLP FIELDS DETERIORATES BY MONDAY. WENT
WITH AN EC/NAM COMBO ALONG WITH INHERITED GRIDS THROUGH MONDAY BUT
WITHOUT A LOT OF CONFIDENCE FOR THE LATTER PERIOD. THEN USED
MOSTLY EC/INHERITED ON THE WAY TO WPC GUIDANCE FOR THE EXTENDED
PERIOD. THE PREVIOUSLY DRYING TREND BY MIDWEEK IS CERTAINLY IN
DANGER AT THIS POINT AS MODELS DELAY THE RIDGING ALOFT...ALONG WITH
PERSISTING -25 TO -35C TEMPS AT 500 THROUGH WEDNESDAY. THUS ANY
SURFACE WARMING WILL CERTAINLY LEAD TO SHOWERS. THIS IS REFLECTED
IN THE ZONE FORECASTS FROM TUE ONWARDS. NEW EC DETERMINISTIC RUN
NOW DELAYS UPPER RIDGING UNTIL THE END OF THE WEEK...A HIGH-
AMPLITUDE UPPER PATTERN IS LIKELY WHICH MODELS HAVE TYPICALLY MORE
PROBLEMS WITH...AND COULD BECOME SLOW-MOVING. AGREEMENT BETWEEN
THE DETERMINISTIC EC/GFS AT MID-LEVELS IS REASONABLE THROUGH
THURSDAY WITH BOTH ADVERTISING DEVELOPMENT OF A RIDGE OVER THE
WESTERN GULF AT THAT POINT. EC CHANGES VERY LITTLE BY FRI WHILE THE
GFS SHOWS A STRANGE ELONGATED NW-SE LOW OVER THE EASTERN GULF BY
FRI.

CAN SUMMARIZE THE EXTENDED WITH A STATEMENT OF LITTLE
CONFIDENCE...PROBABLY IS BETTER STATISTICALLY TO TRUST AN ENSEMBLE
APPROACH WHICH IS WHAT WPC CHOSE. A SIGNIFICANT DRYING/WARMING
PATTERN OVER THE PANHANDLE IS STILL IN THE CARDS...JUST LIKELY DELAYED
UNTIL LATE NEXT WEEK. FINALLY DECIDED TO INCREASE SKY COVER FOR
THE WED-THU PERIOD AS AFTERNOON SHOWER DEVELOPMENT IS LIKELY AS
LONG AS CYCLONIC COOL FLOW ALOFT PERSISTS...WITHOUT FRONTAL
FORCING, SURFACE HEATING WILL LIKELY BE A FACTOR. THIS MAY BE
EXTENDING CLOUDY CONDITIONS FOR TOO LONG BUT UPCOMING MODEL RUNS
WILL TELL. TRYING TO AVOID THE "PARTLY CLOUDY, CHANCE SHOWERS"
RUBBER STAMP.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-022-033-041-053.

&&

$$

EAL/WESLEY

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU













000
FXAK67 PAJK 172329
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
329 PM AKDT FRI APR 17 2015

.SHORT TERM...SHOWERS CONTINUE TO BE THE RULE OF THE DAY ACROSS
THE PANHANDLE THOUGH NOT FOR MUCH LONGER. LOCAL UPPER AIR
SOUNDINGS SHOW AROUND 100 TO 200 J/KG OF CAPE BUT UPPER LEVEL
TEMPS ARE STARTING TO WARM UP BRING MORE STABILITY TO THE AREA.
THE WEAK TROUGH THAT BROUGHT THE STRONGER SHOWERS TO THE AREA THIS
MORNING IS STARTING TO MOVE INTO CANADA. BEHIND IT SHOWERS ARE
BECOMING FEWER AND FARTHER BETWEEN AS A SURFACE RIDGE BUILDS
ACROSS THE SE GULF AND DIFFLUENT FLOW ALOFT BEGINS TO DEVELOP.
CLOUDS ARE STARTING TO BREAK UP AS WELL WITH AREAS OF SUN
DEVELOPING. STILL THERE ARE ONE OR TWO STRONGER SHOWERS AROUND.
YAKUTAT HAD A SHOWER MOVE THROUGH AROUND 1130 AM THAT DROPPED A
QUARTER INCH OF SMALL HAIL AND ICE PELLETS ON THE AIRPORT.

THIS EVENING IS LOOKING MOSTLY DRY WITH SOME MOSTLY TO PARTLY
CLOUDY SKIES AS SHOWERS CONTINUE TO SHOW A DIMINISHING TREND. SOME
SCATTERED TO ISOLATED SHOWERS COULD STILL LINGER, ESPECIALLY NEAR
THE HIGHER TERRAIN. THESE SHOWERS SHOULD REMAIN LIGHT FOR THE
MOST PART AS WHAT UPPER SUPPORT THEY HAD HAS MOVED INTO CANADA
BY THIS POINT. WINDS TOO WILL BE ON THE DECREASING TREND. THE
GUSTY SOUTHERLY WINDS IN LYNN CANAL AND SKAGWAY WILL DIMINISH THIS
EVENING AS THE BUILDING RIDGE GET FAR ENOUGH NORTH THAT PRESSURE
GRADIENTS TURN MORE PARALLEL TO LYNN CANAL THEN PERPENDICULAR.

LATER TONIGHT AND INTO TOMORROW, FOCUS SHIFTS TO THE GALE FORCE
FRONT THAT IS ADVANCING ACROSS THE GULF. MOST OF THE GULF WILL
EXPERIENCE GALE FORCE WINDS WITH THE HIGHEST WINDS NEAR CAPE
SUCKLING DUE TO BARRIER JET EFFECTS. THESE WINDS WILL SPREAD INTO
THE NORTHERN PANHANDLE TOMORROW AS THE FRONT DRIFTS TO THE EAST.
NOT EXPECTING TO NEED STRONG WIND HEADLINES FOR THE NORTHERN OUTER
COAST AS BARRIER INFLUENCES KEEP MOST OF THE STRONG WIND OFFSHORE.
AS FOR RAIN, IT LOOKS TO COME IN TWO MAIN BURSTS. HOW FAR EAST
EACH BURST GETS WILL LIKELY DEPEND ON HOW STRONG THE RIDGE OVER
BRITISH COLUMBIA IS THAT IS SUPPRESSING THE EASTWARD MOVEMENT OF
THE FRONT AS A WHOLE. THE FIRST PULSE WILL BE LATE TONIGHT AS AN
INITIAL WARM FRONT CROSSES THE PANHANDLE. MOST AREAS EXCEPT FOR THE
EXTREME SOUTHERN PANHANDLE WILL LIKELY SEE RAIN OUT OF THIS
FEATURE WITH LIGHTER RAINFALL AMOUNTS THE FARTHER EAST AND SOUTH
YOU ARE. 850 MB TEMPS AHEAD OF THE FRONT ARE STILL AROUND -7 TO -6
C OVER THE EXTREME NORTHERN PANHANDLE SO RAIN MAY MIX WITH SNOW
AROUND YAKUTAT LATE TONIGHT BEFORE THE HEAVIER RAIN AND STRONGER
WARM AIR ADVECTION MAKES IT INTO THE AREA. PULSE NUMBER TWO IS A
TRAILING WAVE ON THE COLD FRONT THAT WILL PUSH THE FRONTAL RAIN
BANDS INTO THE PANHANDLE ON SAT. RIGHT NOW MOST OF THE RAIN
APPEARS TO BE ON A LINE FROM TAKU INLET DOWN TO FIVE FINGERS TO
JUST WEST OF KLAWOCK AND WESTWARD. EAST OF THAT LINE RAIN CHANCES
DROP TO CHANCE OR LESS FOR SAT AS THE BRITISH COLUMBIA RIDGE
BLOCKS ANY MORE EASTWARD MOVEMENT. HEAVIEST RAINFALL WILL MOSTLY
BE OVER THE YAKUTAT AREA AS THE MAIN MOISTURE PLUME IS AIMED IN
THAT DIRECTION AND EFFECTS FROM TERRAIN WILL JUST WRING EVEN MORE
RAIN OUT OF THE CLOUDS.

WINDS WILL ALSO BE INCREASING ACROSS THE NORTHERN PANHANDLE AS
WELL AS THE FRONT GETS CLOSER. MOST AREAS SHOULD HAVE SOME GUSTY
WINDS BUT I DO NOT THINK STRONG WIND HEADLINES WILL BE NEEDED AS
850 MB WINDS ONLY REACH 35 TO 40 KT AND THE PARENT LOW IS WELL
WEST OF THE AREA. STILL LYNN CANAL, SOUTHERN CHATHAM STRAIT AND
CROSS SOUND WILL LIKELY SEE 25 TO 30 KT SMALL CRAFT WINDS
DEVELOPING TOMORROW.

SHORT RANGE MODELS WERE IN GOOD AGREEMENT WITH ONLY VERY MINOR
DIFFERENCES THAT DID NOT AFFECT THE OVERALL FORECAST. MAIN CHANGES
WERE SMALL LOCAL EFFECT CHANGES. OF NOTE IS THAT THE MODELS ARE
ONCE AGAIN UNDERESTIMATING THE SOUTHERLY PRESSURE GRADIENT THAT
DEVELOPED AROUND LYNN CANAL. MOST WERE 1 TO 2 MB TOO WEAK AND AS
SUCH TOO WEAK WITH WINDS. MAIN CHANGE FROM THIS WAS INCREASING WINDS
IN LYNN CANAL TO SMALL CRAFT FOR EARLY THIS EVENING AND TOMORROW
AFTERNOON.

.LONG TERM...MODELS CONSISTENT WITH PREVIOUS RUNS IN PRODUCING 2.5
TO 4 INCHES OF RAIN IN THE YAKUTAT AREA IN A 3-DAY PERIOD
BEGINNING LATE TONIGHT. 2-3 INCHES IS ALSO PREDICTED DURING THIS
TIME PERIOD IN JUNEAU AND AROUND SITKA WITH LESSER AMOUNTS IN
OTHER SEA LEVEL LOCATIONS AND OFFSHORE. THIS IS IN RESPONSE TO
WELL-ADVERTISED FRONT WHICH WILL PUSH INTO THE PANHANDLE TOMORROW.
THE SITUK RIVER IS STILL SHOWING LESS THAN 67 FEET...FLOOD IS AT
71.5...COORDINATED THINKING WITH RFC ON CONF CALL TODAY AND AGREE
WITH THEM TO MONITOR AND THAT BANKFULL IS IMPROBABLE AT THIS
POINT. THOUGH FREEZING LEVELS WILL RISE IN THAT AREA WILL STRUGGLE
EARLY IN THE SYSTEM TO GET ABOVE 3000 FEET AND WILL FALL ONCE THE
SLOW FRONT MOVES THROUGH. THIS WILL RESTRICT CONTRIBUTION OF
SNOWMELT TO RUNOFF.

INHERITED PRESSURE/WIND GRIDS WERE GOOD FOR
TOMORROW NIGHT AND SUNDAY BASED ON NEW MODEL DATA WITH JUST SOME
UPWARD TWEAKS IN THE CHANNELS WITH ORIENTATION PERPENDICULAR TO
ISOBARS. OFFSHORE GALES WILL BE COMMON THROUGH ABOUT SUNDAY
MORNING WITH THE FRONT WHILE SCA WINDS WILL PREVAIL IN CROSS AND
FAVORED SOUTHERN CHANNELS INTO SUNDAY ALSO. ONLY THREAT FOR
WEEKEND MIXED STRATIFORM PRECIP SHOULD BE UP THE ROADS AND AMOUNTS
OF WET SNOW SHOULD BE LIGHT AND CONFINED MOSTLY TO LATE NIGHT
PERIODS. I HAVE AN INCH OR SO AT WHITE PASS ON SATURDAY AND SUNDAY
NIGHTS. SLOW-MOVING FRONTAL PRECIP SHOULD DIMINISH MONDAY
AFTERNOON AND A SHOWERY PERIOD SHOULD BEGIN WITH LESS UPPER
FORCING BUT MORE SOLAR EFFECTS. WITH WEAKENING PRESSURE GRADIENTS
THE CONSENSUS ON MODEL MSLP FIELDS DETERIORATES BY MONDAY. WENT
WITH AN EC/NAM COMBO ALONG WITH INHERITED GRIDS THROUGH MONDAY BUT
WITHOUT A LOT OF CONFIDENCE FOR THE LATTER PERIOD. THEN USED
MOSTLY EC/INHERITED ON THE WAY TO WPC GUIDANCE FOR THE EXTENDED
PERIOD. THE PREVIOUSLY DRYING TREND BY MIDWEEK IS CERTAINLY IN
DANGER AT THIS POINT AS MODELS DELAY THE RIDGING ALOFT...ALONG WITH
PERSISTING -25 TO -35C TEMPS AT 500 THROUGH WEDNESDAY. THUS ANY
SURFACE WARMING WILL CERTAINLY LEAD TO SHOWERS. THIS IS REFLECTED
IN THE ZONE FORECASTS FROM TUE ONWARDS. NEW EC DETERMINISTIC RUN
NOW DELAYS UPPER RIDGING UNTIL THE END OF THE WEEK...A HIGH-
AMPLITUDE UPPER PATTERN IS LIKELY WHICH MODELS HAVE TYPICALLY MORE
PROBLEMS WITH...AND COULD BECOME SLOW-MOVING. AGREEMENT BETWEEN
THE DETERMINISTIC EC/GFS AT MID-LEVELS IS REASONABLE THROUGH
THURSDAY WITH BOTH ADVERTISING DEVELOPMENT OF A RIDGE OVER THE
WESTERN GULF AT THAT POINT. EC CHANGES VERY LITTLE BY FRI WHILE THE
GFS SHOWS A STRANGE ELONGATED NW-SE LOW OVER THE EASTERN GULF BY
FRI.

CAN SUMMARIZE THE EXTENDED WITH A STATEMENT OF LITTLE
CONFIDENCE...PROBABLY IS BETTER STATISTICALLY TO TRUST AN ENSEMBLE
APPROACH WHICH IS WHAT WPC CHOSE. A SIGNIFICANT DRYING/WARMING
PATTERN OVER THE PANHANDLE IS STILL IN THE CARDS...JUST LIKELY DELAYED
UNTIL LATE NEXT WEEK. FINALLY DECIDED TO INCREASE SKY COVER FOR
THE WED-THU PERIOD AS AFTERNOON SHOWER DEVELOPMENT IS LIKELY AS
LONG AS CYCLONIC COOL FLOW ALOFT PERSISTS...WITHOUT FRONTAL
FORCING, SURFACE HEATING WILL LIKELY BE A FACTOR. THIS MAY BE
EXTENDING CLOUDY CONDITIONS FOR TOO LONG BUT UPCOMING MODEL RUNS
WILL TELL. TRYING TO AVOID THE "PARTLY CLOUDY, CHANCE SHOWERS"
RUBBER STAMP.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ042-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-022-033-041-053.

&&

$$

EAL/WESLEY

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU













000
FXAK67 PAJK 171250
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
450 AM AKDT FRI APR 17 2015

.SHORT TERM...MAIN FEATURE OVER THE NEXT 24 HOURS WILL BE A FRONT
MOVING ACROSS THE GULF, REACHING THE EASTERN GULF LATE TONIGHT.
BEFORE THIS CONTINUED ONSHORE FLOW WILL MEAN MORE OF THE SAME WITH
SHOWERS OVER SOUTHEAST ALASKA.

FOR TODAY, SHOWERS WILL BE ON THE DIMINISHING TREND AS RIDGING
BUILDS INTO THE PANHANDLE FROM THE SOUTH WITH MOST AREAS
EXPERIENCING A MOSTLY DRY PERIOD THIS AFTERNOON AND EVENING. ALSO
AM EXPECTING SOME BREAKS IN THE CLOUD COVER DURING THIS TIME
PERIOD AS WELL. THIS WILL BE SHORT LIVED HOWEVER AS EXPECT
STRATIFORM RAIN TO INCREASE LATE TONIGHT IN ASSOCIATION WITH THE
FRONT. THE FRONT WILL BRING GALE FORCE WINDS TO THE NORTHERN GULF
AND SOME STRONGER WINDS TO THE EAST-WEST ORIENTED INNER CHANNELS.
THE NORTH-SOUTH CHANNELS WILL EXPERIENCE LESS WIND AS THE PRESSURE
GRADIENT WILL BE PARALLEL TO THOSE CHANNELS. SNOW WILL MAINLY BE
CONFINED TO THE HIGHER ELEVATIONS AS THE BOUNDARY LAYER REMAINS A
LITTLE TOO WARM FOR MUCH, IF ANY AT SEA LEVEL.

USED THE 00Z NAM AND HI RES NMM AND ARW FOR UPDATES TO THE FORECAST
THROUGH THE FIRST 24 HOURS. MAIN CHANGES TO THE FORECAST WERE
SLIGHTLY FASTER MOVEMENT OF FRONT AND RAIN INTO THE PANHANDLE
TONIGHT AND WEAKENED SOME WINDS IN THE NORTH-SOUTH INNER CHANNELS
TONIGHT WITH PARALLEL FLOW PATTERN. FORECASTER CONFIDENCE IS ABOVE
AVERAGE.

.LONG TERM...DEEP-LAYER CYCLONE WILL REMAIN ANCHORED OVER THE
ALEUTIANS AND BERING SEA MIDDAY SAT THROUGH THE MIDDLE OF NEXT
WEEK. AS A SHORTWAVE EMBEDDED WITHIN THE BROADER SCALE LOW ROTATES
NWD INTO INTERIOR PORTIONS OF SWRN AK SAT INTO SUN...MULTIPLE
FRONTAL SEGMENTS WILL ADVANCE ENE ACROSS THE GULF. THE FIRST...IN
THE FORM OF A WARM FRONTAL-LIKE STRUCTURE...WILL ENTER THE NRN
GULF SAT AND AID IN A GALE FORCE ELY BARRIER JET THAT IS FORECAST
TO PERSIST THROUGH SUN MORNING. THE SECOND FRONT...THIS TIME
OCCLUDED...WILL THEN SWEEP ENE ACROSS THE GULF SUN...AND REACH
THE PANHANDLE SUN NIGHT INTO MON.

A MILD BOUNDARY LAYER AIRMASS...CHARACTERIZED BY FREEZING LEVELS
RISING TO AROUND 2 KM AMSL...WILL SPREAD NWD INTO SERN AK AHEAD
OF THE OCCLUDED FRONT. THIS AIRMASS COMBINED WITH PW VALUES
RANGING FROM 0.5-0.8 INCH WILL PROMOTE WARM RAIN PROCESSES
SUPPORTIVE OF LOCALLY HEAVY RAINFALL...PRIMARILY OVER YAKUTAT
WHERE LOW-LEVEL CONVERGENCE AND ASCENT WILL BE STRONGEST. MODERATE
RAINFALL RATES WILL ALSO BECOME INCREASINGLY PROBABLE OVER THE
CNTRL/SRN PANHANDLE AS THE WARM/MOIST AIRMASS SPREADS E SUN
AFTERNOON AND NIGHT.

A COOLER/DRIER BOUNDARY LAYER AIRMASS WILL THEN SPREAD INTO THE
REGION BEHIND THE OCCLUDED FRONT ON MON...AND SUBSEQUENTLY LOWER
PRECIPITATION INTENSITY/COVERAGE THROUGH THE REMAINDER OF THE LONG
TERM. MODEL GUIDANCE IS IN GENERAL AGREEMENT WITH THE LARGE-SCALE
EVOLUTION DURING TUE...SHOWING A SHORTWAVE TROUGH PASSING ACROSS
THE AREA...BUT DO DIFFER SLIGHTLY ON THE TIMING AND AMPLITUDE OF
THIS FEATURE. BASIC AGREEMENT ALSO EXISTS WITH THE DEVELOPMENT OF
AN UPPER RIDGE OVER THE GULF DURING THU-FRI. HOWEVER...THE GFS
QUICKLY BREAKS THE RIDGE DOWN AND ALLOWS A FRONT TO ADVANCE E
TOWARD THE GULF COAST...WHILE THE ECMWF IS MORE FIRM WITH RIDGE
MAINTENANCE. ENSEMBLE SPREAD BECOMES VERY LARGE DURING THIS LATE
TIME PERIOD...THUS HAVE LITTLE CONFIDENCE IN EITHER OF THE
DETERMINISTIC SOLUTIONS.

NO CHANGE WAS MADE TO INHERITED PRESSURE GRIDS. GFS AND ECMWF WERE
USED TO UPDATE POP AND QPF...MAINLY THROUGH 00Z TUE...WITH LITTLE
CHANGE MADE THEREAFTER AS FORECAST CONFIDENCE DECREASES DUE TO
INCREASING MODEL SPREAD.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ022-033-041-042-053.

&&

$$

TPS/GARNER

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU








000
FXAK67 PAJK 171250
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
450 AM AKDT FRI APR 17 2015

.SHORT TERM...MAIN FEATURE OVER THE NEXT 24 HOURS WILL BE A FRONT
MOVING ACROSS THE GULF, REACHING THE EASTERN GULF LATE TONIGHT.
BEFORE THIS CONTINUED ONSHORE FLOW WILL MEAN MORE OF THE SAME WITH
SHOWERS OVER SOUTHEAST ALASKA.

FOR TODAY, SHOWERS WILL BE ON THE DIMINISHING TREND AS RIDGING
BUILDS INTO THE PANHANDLE FROM THE SOUTH WITH MOST AREAS
EXPERIENCING A MOSTLY DRY PERIOD THIS AFTERNOON AND EVENING. ALSO
AM EXPECTING SOME BREAKS IN THE CLOUD COVER DURING THIS TIME
PERIOD AS WELL. THIS WILL BE SHORT LIVED HOWEVER AS EXPECT
STRATIFORM RAIN TO INCREASE LATE TONIGHT IN ASSOCIATION WITH THE
FRONT. THE FRONT WILL BRING GALE FORCE WINDS TO THE NORTHERN GULF
AND SOME STRONGER WINDS TO THE EAST-WEST ORIENTED INNER CHANNELS.
THE NORTH-SOUTH CHANNELS WILL EXPERIENCE LESS WIND AS THE PRESSURE
GRADIENT WILL BE PARALLEL TO THOSE CHANNELS. SNOW WILL MAINLY BE
CONFINED TO THE HIGHER ELEVATIONS AS THE BOUNDARY LAYER REMAINS A
LITTLE TOO WARM FOR MUCH, IF ANY AT SEA LEVEL.

USED THE 00Z NAM AND HI RES NMM AND ARW FOR UPDATES TO THE FORECAST
THROUGH THE FIRST 24 HOURS. MAIN CHANGES TO THE FORECAST WERE
SLIGHTLY FASTER MOVEMENT OF FRONT AND RAIN INTO THE PANHANDLE
TONIGHT AND WEAKENED SOME WINDS IN THE NORTH-SOUTH INNER CHANNELS
TONIGHT WITH PARALLEL FLOW PATTERN. FORECASTER CONFIDENCE IS ABOVE
AVERAGE.

.LONG TERM...DEEP-LAYER CYCLONE WILL REMAIN ANCHORED OVER THE
ALEUTIANS AND BERING SEA MIDDAY SAT THROUGH THE MIDDLE OF NEXT
WEEK. AS A SHORTWAVE EMBEDDED WITHIN THE BROADER SCALE LOW ROTATES
NWD INTO INTERIOR PORTIONS OF SWRN AK SAT INTO SUN...MULTIPLE
FRONTAL SEGMENTS WILL ADVANCE ENE ACROSS THE GULF. THE FIRST...IN
THE FORM OF A WARM FRONTAL-LIKE STRUCTURE...WILL ENTER THE NRN
GULF SAT AND AID IN A GALE FORCE ELY BARRIER JET THAT IS FORECAST
TO PERSIST THROUGH SUN MORNING. THE SECOND FRONT...THIS TIME
OCCLUDED...WILL THEN SWEEP ENE ACROSS THE GULF SUN...AND REACH
THE PANHANDLE SUN NIGHT INTO MON.

A MILD BOUNDARY LAYER AIRMASS...CHARACTERIZED BY FREEZING LEVELS
RISING TO AROUND 2 KM AMSL...WILL SPREAD NWD INTO SERN AK AHEAD
OF THE OCCLUDED FRONT. THIS AIRMASS COMBINED WITH PW VALUES
RANGING FROM 0.5-0.8 INCH WILL PROMOTE WARM RAIN PROCESSES
SUPPORTIVE OF LOCALLY HEAVY RAINFALL...PRIMARILY OVER YAKUTAT
WHERE LOW-LEVEL CONVERGENCE AND ASCENT WILL BE STRONGEST. MODERATE
RAINFALL RATES WILL ALSO BECOME INCREASINGLY PROBABLE OVER THE
CNTRL/SRN PANHANDLE AS THE WARM/MOIST AIRMASS SPREADS E SUN
AFTERNOON AND NIGHT.

A COOLER/DRIER BOUNDARY LAYER AIRMASS WILL THEN SPREAD INTO THE
REGION BEHIND THE OCCLUDED FRONT ON MON...AND SUBSEQUENTLY LOWER
PRECIPITATION INTENSITY/COVERAGE THROUGH THE REMAINDER OF THE LONG
TERM. MODEL GUIDANCE IS IN GENERAL AGREEMENT WITH THE LARGE-SCALE
EVOLUTION DURING TUE...SHOWING A SHORTWAVE TROUGH PASSING ACROSS
THE AREA...BUT DO DIFFER SLIGHTLY ON THE TIMING AND AMPLITUDE OF
THIS FEATURE. BASIC AGREEMENT ALSO EXISTS WITH THE DEVELOPMENT OF
AN UPPER RIDGE OVER THE GULF DURING THU-FRI. HOWEVER...THE GFS
QUICKLY BREAKS THE RIDGE DOWN AND ALLOWS A FRONT TO ADVANCE E
TOWARD THE GULF COAST...WHILE THE ECMWF IS MORE FIRM WITH RIDGE
MAINTENANCE. ENSEMBLE SPREAD BECOMES VERY LARGE DURING THIS LATE
TIME PERIOD...THUS HAVE LITTLE CONFIDENCE IN EITHER OF THE
DETERMINISTIC SOLUTIONS.

NO CHANGE WAS MADE TO INHERITED PRESSURE GRIDS. GFS AND ECMWF WERE
USED TO UPDATE POP AND QPF...MAINLY THROUGH 00Z TUE...WITH LITTLE
CHANGE MADE THEREAFTER AS FORECAST CONFIDENCE DECREASES DUE TO
INCREASING MODEL SPREAD.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ022-033-041-042-053.

&&

$$

TPS/GARNER

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU







000
FXAK67 PAJK 171250
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
450 AM AKDT FRI APR 17 2015

.SHORT TERM...MAIN FEATURE OVER THE NEXT 24 HOURS WILL BE A FRONT
MOVING ACROSS THE GULF, REACHING THE EASTERN GULF LATE TONIGHT.
BEFORE THIS CONTINUED ONSHORE FLOW WILL MEAN MORE OF THE SAME WITH
SHOWERS OVER SOUTHEAST ALASKA.

FOR TODAY, SHOWERS WILL BE ON THE DIMINISHING TREND AS RIDGING
BUILDS INTO THE PANHANDLE FROM THE SOUTH WITH MOST AREAS
EXPERIENCING A MOSTLY DRY PERIOD THIS AFTERNOON AND EVENING. ALSO
AM EXPECTING SOME BREAKS IN THE CLOUD COVER DURING THIS TIME
PERIOD AS WELL. THIS WILL BE SHORT LIVED HOWEVER AS EXPECT
STRATIFORM RAIN TO INCREASE LATE TONIGHT IN ASSOCIATION WITH THE
FRONT. THE FRONT WILL BRING GALE FORCE WINDS TO THE NORTHERN GULF
AND SOME STRONGER WINDS TO THE EAST-WEST ORIENTED INNER CHANNELS.
THE NORTH-SOUTH CHANNELS WILL EXPERIENCE LESS WIND AS THE PRESSURE
GRADIENT WILL BE PARALLEL TO THOSE CHANNELS. SNOW WILL MAINLY BE
CONFINED TO THE HIGHER ELEVATIONS AS THE BOUNDARY LAYER REMAINS A
LITTLE TOO WARM FOR MUCH, IF ANY AT SEA LEVEL.

USED THE 00Z NAM AND HI RES NMM AND ARW FOR UPDATES TO THE FORECAST
THROUGH THE FIRST 24 HOURS. MAIN CHANGES TO THE FORECAST WERE
SLIGHTLY FASTER MOVEMENT OF FRONT AND RAIN INTO THE PANHANDLE
TONIGHT AND WEAKENED SOME WINDS IN THE NORTH-SOUTH INNER CHANNELS
TONIGHT WITH PARALLEL FLOW PATTERN. FORECASTER CONFIDENCE IS ABOVE
AVERAGE.

.LONG TERM...DEEP-LAYER CYCLONE WILL REMAIN ANCHORED OVER THE
ALEUTIANS AND BERING SEA MIDDAY SAT THROUGH THE MIDDLE OF NEXT
WEEK. AS A SHORTWAVE EMBEDDED WITHIN THE BROADER SCALE LOW ROTATES
NWD INTO INTERIOR PORTIONS OF SWRN AK SAT INTO SUN...MULTIPLE
FRONTAL SEGMENTS WILL ADVANCE ENE ACROSS THE GULF. THE FIRST...IN
THE FORM OF A WARM FRONTAL-LIKE STRUCTURE...WILL ENTER THE NRN
GULF SAT AND AID IN A GALE FORCE ELY BARRIER JET THAT IS FORECAST
TO PERSIST THROUGH SUN MORNING. THE SECOND FRONT...THIS TIME
OCCLUDED...WILL THEN SWEEP ENE ACROSS THE GULF SUN...AND REACH
THE PANHANDLE SUN NIGHT INTO MON.

A MILD BOUNDARY LAYER AIRMASS...CHARACTERIZED BY FREEZING LEVELS
RISING TO AROUND 2 KM AMSL...WILL SPREAD NWD INTO SERN AK AHEAD
OF THE OCCLUDED FRONT. THIS AIRMASS COMBINED WITH PW VALUES
RANGING FROM 0.5-0.8 INCH WILL PROMOTE WARM RAIN PROCESSES
SUPPORTIVE OF LOCALLY HEAVY RAINFALL...PRIMARILY OVER YAKUTAT
WHERE LOW-LEVEL CONVERGENCE AND ASCENT WILL BE STRONGEST. MODERATE
RAINFALL RATES WILL ALSO BECOME INCREASINGLY PROBABLE OVER THE
CNTRL/SRN PANHANDLE AS THE WARM/MOIST AIRMASS SPREADS E SUN
AFTERNOON AND NIGHT.

A COOLER/DRIER BOUNDARY LAYER AIRMASS WILL THEN SPREAD INTO THE
REGION BEHIND THE OCCLUDED FRONT ON MON...AND SUBSEQUENTLY LOWER
PRECIPITATION INTENSITY/COVERAGE THROUGH THE REMAINDER OF THE LONG
TERM. MODEL GUIDANCE IS IN GENERAL AGREEMENT WITH THE LARGE-SCALE
EVOLUTION DURING TUE...SHOWING A SHORTWAVE TROUGH PASSING ACROSS
THE AREA...BUT DO DIFFER SLIGHTLY ON THE TIMING AND AMPLITUDE OF
THIS FEATURE. BASIC AGREEMENT ALSO EXISTS WITH THE DEVELOPMENT OF
AN UPPER RIDGE OVER THE GULF DURING THU-FRI. HOWEVER...THE GFS
QUICKLY BREAKS THE RIDGE DOWN AND ALLOWS A FRONT TO ADVANCE E
TOWARD THE GULF COAST...WHILE THE ECMWF IS MORE FIRM WITH RIDGE
MAINTENANCE. ENSEMBLE SPREAD BECOMES VERY LARGE DURING THIS LATE
TIME PERIOD...THUS HAVE LITTLE CONFIDENCE IN EITHER OF THE
DETERMINISTIC SOLUTIONS.

NO CHANGE WAS MADE TO INHERITED PRESSURE GRIDS. GFS AND ECMWF WERE
USED TO UPDATE POP AND QPF...MAINLY THROUGH 00Z TUE...WITH LITTLE
CHANGE MADE THEREAFTER AS FORECAST CONFIDENCE DECREASES DUE TO
INCREASING MODEL SPREAD.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ022-033-041-042-053.

&&

$$

TPS/GARNER

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU








000
FXAK67 PAJK 162331 AAB
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JUNEAU AK
331 PM AKDT THU APR 16 2015

.SHORT TERM...SW FLOW WITH SHOWERS CONTINUES ACROSS THE PANHANDLE
TODAY AS A LOW NEAR COOK INLET REMAINS MOSTLY STATIONARY. A FEW
DISTURBANCES HAVE BEEN EMBEDDED IN THE SW FLOW AND HAVE ENHANCED
THE SHOWERS AT TIMES. ONE SUCH DISTURBANCE WENT THROUGH THE
SOUTHERN PANHANDLE LAST NIGHT PRODUCING A FEW FLASHES OF LIGHTNING
FROM THE HEAVIER SHOWERS.

THESE SHOWERS WILL CONTINUE TONIGHT AS THE SURFACE PATTERN SHOWS
NO SIGNS OF DRASTICALLY CHANGING OVERNIGHT. TWO FEATURES EMBEDDED
IN THE FLOW WILL HAVE TO BE WATCHED HOWEVER. THE FIRST IS A
DEVELOPING WEAK LOW IN THE NE PACIFIC AROUND 50N 136W THAT
CURRENTLY IS SHOWING A NICE BAROCLINIC LEAF ON SATELLITE IMAGES.
CURRENT THINKING HAS THAT FEATURE SLIDE OVER THE SOUTHERN TIP OF
HAIDA GWAII THIS EVENING. MOST OF ITS RAIN SHOULD STAY SOUTH OF
THE PANHANDLE THOUGH ITS VERY NORTHERN RAIN BANDS COULD STILL
BRUSH THE SOUTHERN PARTS OF ZONES 28 AND 29 OVERNIGHT. IT WILL
CERTAINLY BRING MORE HIGH LEVEL CLOUD COVER TO THE SOUTHERN
PANHANDLE TONIGHT SO OVERNIGHT LOWS WILL BE JUST A BIT WARMER THEN
THEY COULD BE.

FEATURE TWO IS A UPPER LEVEL TROUGH AND VORTICITY MAX CURRENTLY
AROUND 150W. THAT WILL ROTATE THROUGH LATE TONIGHT AND EARLY FRI
ENHANCING THE SHOWERS JUST A BIT MORE. A SMALL SHOT OF COOLER AIR
ALOFT WILL ALSO ACCOMPANY IT. THE QUESTION IS WILL THIS BE ENOUGH
TO SPARK OFF MORE THUNDERSTORMS OVER THE SOUTHERN OUTER COAST
TONIGHT. CONVECTIVE INDEXES FROM THE NAM SHOW A POCKET OF 100 TO
300 J/KG OF CAPE OVER THE SOUTHERN OUTER COAST AROUND 9Z TONIGHT
BUT LIFTED INDEX NUMBER ARE NOT AS LOW AS LAST NIGHT. DECIDED TO
GO FOR IT AND PUT SLIGHT CHANCE OF THUNDER FOR THE SOUTHERN OUTER
COAST TONIGHT.

THE OTHER CONCERN WITH THE COOLER AIR ASSOCIATED WITH THIS TROUGH
IS THAT THE ATMOSPHERE COULD GET COOL ENOUGH FOR SNOW TO MIX IN
WITH THE RAIN IN THE EXTREME NORTHERN LOCATIONS AND MAYBE IN HYDER
LATE TONIGHT AND EARLY TOMORROW (850 MB TEMPS REACH -6 C AND 1000
TO 850 MB THICKNESS JUST BELOW 1290). ANY ACCUMULATIONS SHOULD BE AN
INCH OR LESS AS S TO SE FLOW AT THE SURFACE WILL KEEP MOST OF
THESE PLACES ABOVE FREEZING. ANY PLACES THAT DO START TO MIX WITH
SNOW OVERNIGHT WILL CHANGE BACK TO RAIN TOMORROW AS TEMPERATURES
BOTH AT THE SURFACE AND ALOFT RISE AGAIN.

INTO FRI SHOWERS WILL START TO DECREASE IN FREQUENCY GOING FROM
FREQUENT TO SCATTERED BY THE AFTERNOON AS A RIDGE BUILDS OVER THE
PANHANDLE AND DIFLUENT FLOW ALOFT BEGINS TO DEVELOP. CLOUD COVER
WILL ALSO SHOW MORE BREAKS AS WELL. FOCUS THEN SHIFTS TO THE FRONT
THAT IS APPROACHING FROM THE WEST AS IT STARTS TO INCREASE RAIN AND
WIND ACROSS THE CENTRAL GULF TOMORROW AFTERNOON.

AS FOR WIND, STRONG WINDS ARE BLOWING IN LYNN CANAL TODAY AS A 4
MB PRESSURE GRADIENT EXISTS BETWEEN JUNEAU AND SKAGWAY. WINDS
GUSTS UP TO 40 MPH AT SKAGWAY AND 50 KT AT ELDRED ROCK HAVE BEEN
OBSERVED SO FAR TODAY. THESE WINDS SHOULD START TO SLACKEN OFF
THIS EVENING AS THE TROUGH IN CANADA WEAKENS AND THE RIDGE OVER
THE SOUTHERN PANHANDLE GETS SLIGHTLY FLATTENED BY THE WEAK LOW
COMING FROM THE NE PACIFIC. WINDS ACROSS THE PANHANDLE SHOULD STAY
MOSTLY BELOW 20 KT INTO FRI. THE GULF IS ANOTHER MATTER AS SW
WINDS TONIGHT WILL SWITCH AROUND TO SE FRI. THEY WILL THEN
INCREASE IN THE CENTRAL GULF TO A 35 KT GALE IN ADVANCE OF THE
NEXT FRONT.

SHORT RANGE MODELS WERE IN GOOD AGREEMENT FOR THE NEXT 24 HOURS.
SOME SMALL DIFFERENCES NOTED HERE AND THERE BUT NOTHING THAT
WOULD CHANGE THE FORECAST IN A SIGNIFICANT WAY. ALTHOUGH MOST
MODELS DID UNDERESTIMATE THE LYNN CANAL PRESSURE GRADIENT TODAY.
FAVORED THE NAM OVERALL AS IT SEEMED TO HAVE THE BEST
REPRESENTATION OF FEATURES OVERALL.

.LONG TERM...PRIMARY UPDATE TO PRESSURE AND WIND FIELDS REQUIRED
FOR FRI NIGHT THROUGH SUNDAY AS NEW MODELS HAVE THE EASTERN EDGE
OF THE NEW FRONT COMING IN A BIT FASTER AND GRADIENTS BEGIN TO
TIGHTEN A BIT EARLIER. FRONT GETS TO THE PANHANDLE BY ABOUT 12Z
SAT. WENT WITH AN ENSEMBLE NAM/EC/GFS ON THESE UPDATES AS ALL
BRING THE FRONT IN A BIT FASTER. SHOULD BE NO PRECIP TYPE ISSUES
TOMORROW NIGHT ASIDE FROM LIGHT SNOW SHOWERS FOR THE UPPER ROAD
PORTIONS ON THE NORTH END. FRONT IS SLOW-MOVING AND WILL LEAD TO
AN EXTENDED RAINY CONDITIONS AND PROBLEM WINDS FOR EXPOSED AREAS
OF MAINLY THE FAVORED INNER CHANNELS FOR AN EAST-WEST GRADIENT AND
THE MORE OPEN SOUTHERNMOST CHANNELS AND COASTAL AREAS. WINDS
INITIALLY REACH GALE OFFSHORE BY 03Z SAT...THESE SPREAD QUICKLY
EASTWARD THROUGH THE MARINE ZONES AND ARE ENHANCED BY THE BARRIER
JET WEST OF YAKUTAT. ASSOCIATED GALES COULD PERSIST WELL INTO
SUNDAY OVER THE MARINE AREAS. POTENTIAL FOR MODERATE TO HEAVY RAIN
THROUGH EARLY MONDAY IN THE YAKUTAT REGION AS 2-4" DEFINES THE
MODEL ENVELOPE THROUGH ABOUT 96 HOURS OF SIMULATION. COORDINATED
WITH RFC...SITUK RIVER NEAR YAKUTAT IS AT A RELATIVELY LOW LEVEL
NOW...4.5 FEET BELOW FLOOD STAGE. THUS FEEL AT THIS POINT THAT
THERE IS CURRENTLY LOW FLOOD THREAT ALTHOUGH A STATEMENT REGARDING
HEAVY RAIN MAY BE WARRANTED TOMORROW OR TOMORROW NIGHT. FEEL THAT
WOULD BE A BIT PREMATURE AT THIS POINT. WENT WITH A SHOWERY
SCENARIO THROUGH 09Z SAT FOR THE PANHANDLE...THEN STRATIFORM RAIN
THROUGH MONDAY WITH THE SLOW MOVING FRONT...THEN SHOWERY AGAIN AS
THE FRONT DEPARTS AND RIDGING TAKES OVER AFTER THAT.

MODELS IN GOOD AGREEMENT THROUGH THE WEEKEND BUT THE LOW-LEVEL
DETAILS BEGIN TO SCATTER SIGNIFICANTLY LATE ON MONDAY AND EVEN AT
THE SYNOPTIC MID LEVELS BY TUE. ON TUE THE GFS HAS A STRANGE-
LOOKING MULTIPLE TROUGH CONFIGURATION OVER THE GULF WHILE THE EC
MAINTAINS A DEEP BERING LOW. BOTH MODELS GENERALLY AGREE ON UPPER
RIDGING IN THE MIDWEEK PERIOD BUT THE EC IS STRONGER ON THAT
FEATURE. THE GEM SOLUTION FAVORS WEAKER/EARLIER RIDGING ON TUE
WITH A NEW FRONT MOVING THROUGH THE GULF BY LATE WED. WPC
GUIDANCE...BASED ON AN EC/NAEFS ENSEMBLE...AGREES WITH THE DRYING/
RIDGING SCENARIO STARTING LATE TUES/WED AND WENT WITH THIS
GUIDANCE FOR DAYS 5-8.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 7 PM AKDT THIS EVENING FOR AKZ018.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ022-041>043-051-053.

&&

$$

EAL/WESLEY

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU












000
FXAK67 PAJK 162331 AAB
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JUNEAU AK
331 PM AKDT THU APR 16 2015

.SHORT TERM...SW FLOW WITH SHOWERS CONTINUES ACROSS THE PANHANDLE
TODAY AS A LOW NEAR COOK INLET REMAINS MOSTLY STATIONARY. A FEW
DISTURBANCES HAVE BEEN EMBEDDED IN THE SW FLOW AND HAVE ENHANCED
THE SHOWERS AT TIMES. ONE SUCH DISTURBANCE WENT THROUGH THE
SOUTHERN PANHANDLE LAST NIGHT PRODUCING A FEW FLASHES OF LIGHTNING
FROM THE HEAVIER SHOWERS.

THESE SHOWERS WILL CONTINUE TONIGHT AS THE SURFACE PATTERN SHOWS
NO SIGNS OF DRASTICALLY CHANGING OVERNIGHT. TWO FEATURES EMBEDDED
IN THE FLOW WILL HAVE TO BE WATCHED HOWEVER. THE FIRST IS A
DEVELOPING WEAK LOW IN THE NE PACIFIC AROUND 50N 136W THAT
CURRENTLY IS SHOWING A NICE BAROCLINIC LEAF ON SATELLITE IMAGES.
CURRENT THINKING HAS THAT FEATURE SLIDE OVER THE SOUTHERN TIP OF
HAIDA GWAII THIS EVENING. MOST OF ITS RAIN SHOULD STAY SOUTH OF
THE PANHANDLE THOUGH ITS VERY NORTHERN RAIN BANDS COULD STILL
BRUSH THE SOUTHERN PARTS OF ZONES 28 AND 29 OVERNIGHT. IT WILL
CERTAINLY BRING MORE HIGH LEVEL CLOUD COVER TO THE SOUTHERN
PANHANDLE TONIGHT SO OVERNIGHT LOWS WILL BE JUST A BIT WARMER THEN
THEY COULD BE.

FEATURE TWO IS A UPPER LEVEL TROUGH AND VORTICITY MAX CURRENTLY
AROUND 150W. THAT WILL ROTATE THROUGH LATE TONIGHT AND EARLY FRI
ENHANCING THE SHOWERS JUST A BIT MORE. A SMALL SHOT OF COOLER AIR
ALOFT WILL ALSO ACCOMPANY IT. THE QUESTION IS WILL THIS BE ENOUGH
TO SPARK OFF MORE THUNDERSTORMS OVER THE SOUTHERN OUTER COAST
TONIGHT. CONVECTIVE INDEXES FROM THE NAM SHOW A POCKET OF 100 TO
300 J/KG OF CAPE OVER THE SOUTHERN OUTER COAST AROUND 9Z TONIGHT
BUT LIFTED INDEX NUMBER ARE NOT AS LOW AS LAST NIGHT. DECIDED TO
GO FOR IT AND PUT SLIGHT CHANCE OF THUNDER FOR THE SOUTHERN OUTER
COAST TONIGHT.

THE OTHER CONCERN WITH THE COOLER AIR ASSOCIATED WITH THIS TROUGH
IS THAT THE ATMOSPHERE COULD GET COOL ENOUGH FOR SNOW TO MIX IN
WITH THE RAIN IN THE EXTREME NORTHERN LOCATIONS AND MAYBE IN HYDER
LATE TONIGHT AND EARLY TOMORROW (850 MB TEMPS REACH -6 C AND 1000
TO 850 MB THICKNESS JUST BELOW 1290). ANY ACCUMULATIONS SHOULD BE AN
INCH OR LESS AS S TO SE FLOW AT THE SURFACE WILL KEEP MOST OF
THESE PLACES ABOVE FREEZING. ANY PLACES THAT DO START TO MIX WITH
SNOW OVERNIGHT WILL CHANGE BACK TO RAIN TOMORROW AS TEMPERATURES
BOTH AT THE SURFACE AND ALOFT RISE AGAIN.

INTO FRI SHOWERS WILL START TO DECREASE IN FREQUENCY GOING FROM
FREQUENT TO SCATTERED BY THE AFTERNOON AS A RIDGE BUILDS OVER THE
PANHANDLE AND DIFLUENT FLOW ALOFT BEGINS TO DEVELOP. CLOUD COVER
WILL ALSO SHOW MORE BREAKS AS WELL. FOCUS THEN SHIFTS TO THE FRONT
THAT IS APPROACHING FROM THE WEST AS IT STARTS TO INCREASE RAIN AND
WIND ACROSS THE CENTRAL GULF TOMORROW AFTERNOON.

AS FOR WIND, STRONG WINDS ARE BLOWING IN LYNN CANAL TODAY AS A 4
MB PRESSURE GRADIENT EXISTS BETWEEN JUNEAU AND SKAGWAY. WINDS
GUSTS UP TO 40 MPH AT SKAGWAY AND 50 KT AT ELDRED ROCK HAVE BEEN
OBSERVED SO FAR TODAY. THESE WINDS SHOULD START TO SLACKEN OFF
THIS EVENING AS THE TROUGH IN CANADA WEAKENS AND THE RIDGE OVER
THE SOUTHERN PANHANDLE GETS SLIGHTLY FLATTENED BY THE WEAK LOW
COMING FROM THE NE PACIFIC. WINDS ACROSS THE PANHANDLE SHOULD STAY
MOSTLY BELOW 20 KT INTO FRI. THE GULF IS ANOTHER MATTER AS SW
WINDS TONIGHT WILL SWITCH AROUND TO SE FRI. THEY WILL THEN
INCREASE IN THE CENTRAL GULF TO A 35 KT GALE IN ADVANCE OF THE
NEXT FRONT.

SHORT RANGE MODELS WERE IN GOOD AGREEMENT FOR THE NEXT 24 HOURS.
SOME SMALL DIFFERENCES NOTED HERE AND THERE BUT NOTHING THAT
WOULD CHANGE THE FORECAST IN A SIGNIFICANT WAY. ALTHOUGH MOST
MODELS DID UNDERESTIMATE THE LYNN CANAL PRESSURE GRADIENT TODAY.
FAVORED THE NAM OVERALL AS IT SEEMED TO HAVE THE BEST
REPRESENTATION OF FEATURES OVERALL.

.LONG TERM...PRIMARY UPDATE TO PRESSURE AND WIND FIELDS REQUIRED
FOR FRI NIGHT THROUGH SUNDAY AS NEW MODELS HAVE THE EASTERN EDGE
OF THE NEW FRONT COMING IN A BIT FASTER AND GRADIENTS BEGIN TO
TIGHTEN A BIT EARLIER. FRONT GETS TO THE PANHANDLE BY ABOUT 12Z
SAT. WENT WITH AN ENSEMBLE NAM/EC/GFS ON THESE UPDATES AS ALL
BRING THE FRONT IN A BIT FASTER. SHOULD BE NO PRECIP TYPE ISSUES
TOMORROW NIGHT ASIDE FROM LIGHT SNOW SHOWERS FOR THE UPPER ROAD
PORTIONS ON THE NORTH END. FRONT IS SLOW-MOVING AND WILL LEAD TO
AN EXTENDED RAINY CONDITIONS AND PROBLEM WINDS FOR EXPOSED AREAS
OF MAINLY THE FAVORED INNER CHANNELS FOR AN EAST-WEST GRADIENT AND
THE MORE OPEN SOUTHERNMOST CHANNELS AND COASTAL AREAS. WINDS
INITIALLY REACH GALE OFFSHORE BY 03Z SAT...THESE SPREAD QUICKLY
EASTWARD THROUGH THE MARINE ZONES AND ARE ENHANCED BY THE BARRIER
JET WEST OF YAKUTAT. ASSOCIATED GALES COULD PERSIST WELL INTO
SUNDAY OVER THE MARINE AREAS. POTENTIAL FOR MODERATE TO HEAVY RAIN
THROUGH EARLY MONDAY IN THE YAKUTAT REGION AS 2-4" DEFINES THE
MODEL ENVELOPE THROUGH ABOUT 96 HOURS OF SIMULATION. COORDINATED
WITH RFC...SITUK RIVER NEAR YAKUTAT IS AT A RELATIVELY LOW LEVEL
NOW...4.5 FEET BELOW FLOOD STAGE. THUS FEEL AT THIS POINT THAT
THERE IS CURRENTLY LOW FLOOD THREAT ALTHOUGH A STATEMENT REGARDING
HEAVY RAIN MAY BE WARRANTED TOMORROW OR TOMORROW NIGHT. FEEL THAT
WOULD BE A BIT PREMATURE AT THIS POINT. WENT WITH A SHOWERY
SCENARIO THROUGH 09Z SAT FOR THE PANHANDLE...THEN STRATIFORM RAIN
THROUGH MONDAY WITH THE SLOW MOVING FRONT...THEN SHOWERY AGAIN AS
THE FRONT DEPARTS AND RIDGING TAKES OVER AFTER THAT.

MODELS IN GOOD AGREEMENT THROUGH THE WEEKEND BUT THE LOW-LEVEL
DETAILS BEGIN TO SCATTER SIGNIFICANTLY LATE ON MONDAY AND EVEN AT
THE SYNOPTIC MID LEVELS BY TUE. ON TUE THE GFS HAS A STRANGE-
LOOKING MULTIPLE TROUGH CONFIGURATION OVER THE GULF WHILE THE EC
MAINTAINS A DEEP BERING LOW. BOTH MODELS GENERALLY AGREE ON UPPER
RIDGING IN THE MIDWEEK PERIOD BUT THE EC IS STRONGER ON THAT
FEATURE. THE GEM SOLUTION FAVORS WEAKER/EARLIER RIDGING ON TUE
WITH A NEW FRONT MOVING THROUGH THE GULF BY LATE WED. WPC
GUIDANCE...BASED ON AN EC/NAEFS ENSEMBLE...AGREES WITH THE DRYING/
RIDGING SCENARIO STARTING LATE TUES/WED AND WENT WITH THIS
GUIDANCE FOR DAYS 5-8.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 7 PM AKDT THIS EVENING FOR AKZ018.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ022-041>043-051-053.

&&

$$

EAL/WESLEY

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU











000
FXAK67 PAJK 162331 AAB
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JUNEAU AK
331 PM AKDT THU APR 16 2015

.SHORT TERM...SW FLOW WITH SHOWERS CONTINUES ACROSS THE PANHANDLE
TODAY AS A LOW NEAR COOK INLET REMAINS MOSTLY STATIONARY. A FEW
DISTURBANCES HAVE BEEN EMBEDDED IN THE SW FLOW AND HAVE ENHANCED
THE SHOWERS AT TIMES. ONE SUCH DISTURBANCE WENT THROUGH THE
SOUTHERN PANHANDLE LAST NIGHT PRODUCING A FEW FLASHES OF LIGHTNING
FROM THE HEAVIER SHOWERS.

THESE SHOWERS WILL CONTINUE TONIGHT AS THE SURFACE PATTERN SHOWS
NO SIGNS OF DRASTICALLY CHANGING OVERNIGHT. TWO FEATURES EMBEDDED
IN THE FLOW WILL HAVE TO BE WATCHED HOWEVER. THE FIRST IS A
DEVELOPING WEAK LOW IN THE NE PACIFIC AROUND 50N 136W THAT
CURRENTLY IS SHOWING A NICE BAROCLINIC LEAF ON SATELLITE IMAGES.
CURRENT THINKING HAS THAT FEATURE SLIDE OVER THE SOUTHERN TIP OF
HAIDA GWAII THIS EVENING. MOST OF ITS RAIN SHOULD STAY SOUTH OF
THE PANHANDLE THOUGH ITS VERY NORTHERN RAIN BANDS COULD STILL
BRUSH THE SOUTHERN PARTS OF ZONES 28 AND 29 OVERNIGHT. IT WILL
CERTAINLY BRING MORE HIGH LEVEL CLOUD COVER TO THE SOUTHERN
PANHANDLE TONIGHT SO OVERNIGHT LOWS WILL BE JUST A BIT WARMER THEN
THEY COULD BE.

FEATURE TWO IS A UPPER LEVEL TROUGH AND VORTICITY MAX CURRENTLY
AROUND 150W. THAT WILL ROTATE THROUGH LATE TONIGHT AND EARLY FRI
ENHANCING THE SHOWERS JUST A BIT MORE. A SMALL SHOT OF COOLER AIR
ALOFT WILL ALSO ACCOMPANY IT. THE QUESTION IS WILL THIS BE ENOUGH
TO SPARK OFF MORE THUNDERSTORMS OVER THE SOUTHERN OUTER COAST
TONIGHT. CONVECTIVE INDEXES FROM THE NAM SHOW A POCKET OF 100 TO
300 J/KG OF CAPE OVER THE SOUTHERN OUTER COAST AROUND 9Z TONIGHT
BUT LIFTED INDEX NUMBER ARE NOT AS LOW AS LAST NIGHT. DECIDED TO
GO FOR IT AND PUT SLIGHT CHANCE OF THUNDER FOR THE SOUTHERN OUTER
COAST TONIGHT.

THE OTHER CONCERN WITH THE COOLER AIR ASSOCIATED WITH THIS TROUGH
IS THAT THE ATMOSPHERE COULD GET COOL ENOUGH FOR SNOW TO MIX IN
WITH THE RAIN IN THE EXTREME NORTHERN LOCATIONS AND MAYBE IN HYDER
LATE TONIGHT AND EARLY TOMORROW (850 MB TEMPS REACH -6 C AND 1000
TO 850 MB THICKNESS JUST BELOW 1290). ANY ACCUMULATIONS SHOULD BE AN
INCH OR LESS AS S TO SE FLOW AT THE SURFACE WILL KEEP MOST OF
THESE PLACES ABOVE FREEZING. ANY PLACES THAT DO START TO MIX WITH
SNOW OVERNIGHT WILL CHANGE BACK TO RAIN TOMORROW AS TEMPERATURES
BOTH AT THE SURFACE AND ALOFT RISE AGAIN.

INTO FRI SHOWERS WILL START TO DECREASE IN FREQUENCY GOING FROM
FREQUENT TO SCATTERED BY THE AFTERNOON AS A RIDGE BUILDS OVER THE
PANHANDLE AND DIFLUENT FLOW ALOFT BEGINS TO DEVELOP. CLOUD COVER
WILL ALSO SHOW MORE BREAKS AS WELL. FOCUS THEN SHIFTS TO THE FRONT
THAT IS APPROACHING FROM THE WEST AS IT STARTS TO INCREASE RAIN AND
WIND ACROSS THE CENTRAL GULF TOMORROW AFTERNOON.

AS FOR WIND, STRONG WINDS ARE BLOWING IN LYNN CANAL TODAY AS A 4
MB PRESSURE GRADIENT EXISTS BETWEEN JUNEAU AND SKAGWAY. WINDS
GUSTS UP TO 40 MPH AT SKAGWAY AND 50 KT AT ELDRED ROCK HAVE BEEN
OBSERVED SO FAR TODAY. THESE WINDS SHOULD START TO SLACKEN OFF
THIS EVENING AS THE TROUGH IN CANADA WEAKENS AND THE RIDGE OVER
THE SOUTHERN PANHANDLE GETS SLIGHTLY FLATTENED BY THE WEAK LOW
COMING FROM THE NE PACIFIC. WINDS ACROSS THE PANHANDLE SHOULD STAY
MOSTLY BELOW 20 KT INTO FRI. THE GULF IS ANOTHER MATTER AS SW
WINDS TONIGHT WILL SWITCH AROUND TO SE FRI. THEY WILL THEN
INCREASE IN THE CENTRAL GULF TO A 35 KT GALE IN ADVANCE OF THE
NEXT FRONT.

SHORT RANGE MODELS WERE IN GOOD AGREEMENT FOR THE NEXT 24 HOURS.
SOME SMALL DIFFERENCES NOTED HERE AND THERE BUT NOTHING THAT
WOULD CHANGE THE FORECAST IN A SIGNIFICANT WAY. ALTHOUGH MOST
MODELS DID UNDERESTIMATE THE LYNN CANAL PRESSURE GRADIENT TODAY.
FAVORED THE NAM OVERALL AS IT SEEMED TO HAVE THE BEST
REPRESENTATION OF FEATURES OVERALL.

.LONG TERM...PRIMARY UPDATE TO PRESSURE AND WIND FIELDS REQUIRED
FOR FRI NIGHT THROUGH SUNDAY AS NEW MODELS HAVE THE EASTERN EDGE
OF THE NEW FRONT COMING IN A BIT FASTER AND GRADIENTS BEGIN TO
TIGHTEN A BIT EARLIER. FRONT GETS TO THE PANHANDLE BY ABOUT 12Z
SAT. WENT WITH AN ENSEMBLE NAM/EC/GFS ON THESE UPDATES AS ALL
BRING THE FRONT IN A BIT FASTER. SHOULD BE NO PRECIP TYPE ISSUES
TOMORROW NIGHT ASIDE FROM LIGHT SNOW SHOWERS FOR THE UPPER ROAD
PORTIONS ON THE NORTH END. FRONT IS SLOW-MOVING AND WILL LEAD TO
AN EXTENDED RAINY CONDITIONS AND PROBLEM WINDS FOR EXPOSED AREAS
OF MAINLY THE FAVORED INNER CHANNELS FOR AN EAST-WEST GRADIENT AND
THE MORE OPEN SOUTHERNMOST CHANNELS AND COASTAL AREAS. WINDS
INITIALLY REACH GALE OFFSHORE BY 03Z SAT...THESE SPREAD QUICKLY
EASTWARD THROUGH THE MARINE ZONES AND ARE ENHANCED BY THE BARRIER
JET WEST OF YAKUTAT. ASSOCIATED GALES COULD PERSIST WELL INTO
SUNDAY OVER THE MARINE AREAS. POTENTIAL FOR MODERATE TO HEAVY RAIN
THROUGH EARLY MONDAY IN THE YAKUTAT REGION AS 2-4" DEFINES THE
MODEL ENVELOPE THROUGH ABOUT 96 HOURS OF SIMULATION. COORDINATED
WITH RFC...SITUK RIVER NEAR YAKUTAT IS AT A RELATIVELY LOW LEVEL
NOW...4.5 FEET BELOW FLOOD STAGE. THUS FEEL AT THIS POINT THAT
THERE IS CURRENTLY LOW FLOOD THREAT ALTHOUGH A STATEMENT REGARDING
HEAVY RAIN MAY BE WARRANTED TOMORROW OR TOMORROW NIGHT. FEEL THAT
WOULD BE A BIT PREMATURE AT THIS POINT. WENT WITH A SHOWERY
SCENARIO THROUGH 09Z SAT FOR THE PANHANDLE...THEN STRATIFORM RAIN
THROUGH MONDAY WITH THE SLOW MOVING FRONT...THEN SHOWERY AGAIN AS
THE FRONT DEPARTS AND RIDGING TAKES OVER AFTER THAT.

MODELS IN GOOD AGREEMENT THROUGH THE WEEKEND BUT THE LOW-LEVEL
DETAILS BEGIN TO SCATTER SIGNIFICANTLY LATE ON MONDAY AND EVEN AT
THE SYNOPTIC MID LEVELS BY TUE. ON TUE THE GFS HAS A STRANGE-
LOOKING MULTIPLE TROUGH CONFIGURATION OVER THE GULF WHILE THE EC
MAINTAINS A DEEP BERING LOW. BOTH MODELS GENERALLY AGREE ON UPPER
RIDGING IN THE MIDWEEK PERIOD BUT THE EC IS STRONGER ON THAT
FEATURE. THE GEM SOLUTION FAVORS WEAKER/EARLIER RIDGING ON TUE
WITH A NEW FRONT MOVING THROUGH THE GULF BY LATE WED. WPC
GUIDANCE...BASED ON AN EC/NAEFS ENSEMBLE...AGREES WITH THE DRYING/
RIDGING SCENARIO STARTING LATE TUES/WED AND WENT WITH THIS
GUIDANCE FOR DAYS 5-8.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 7 PM AKDT THIS EVENING FOR AKZ018.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ022-041>043-051-053.

&&

$$

EAL/WESLEY

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU












000
FXAK67 PAJK 162331 AAB
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JUNEAU AK
331 PM AKDT THU APR 16 2015

.SHORT TERM...SW FLOW WITH SHOWERS CONTINUES ACROSS THE PANHANDLE
TODAY AS A LOW NEAR COOK INLET REMAINS MOSTLY STATIONARY. A FEW
DISTURBANCES HAVE BEEN EMBEDDED IN THE SW FLOW AND HAVE ENHANCED
THE SHOWERS AT TIMES. ONE SUCH DISTURBANCE WENT THROUGH THE
SOUTHERN PANHANDLE LAST NIGHT PRODUCING A FEW FLASHES OF LIGHTNING
FROM THE HEAVIER SHOWERS.

THESE SHOWERS WILL CONTINUE TONIGHT AS THE SURFACE PATTERN SHOWS
NO SIGNS OF DRASTICALLY CHANGING OVERNIGHT. TWO FEATURES EMBEDDED
IN THE FLOW WILL HAVE TO BE WATCHED HOWEVER. THE FIRST IS A
DEVELOPING WEAK LOW IN THE NE PACIFIC AROUND 50N 136W THAT
CURRENTLY IS SHOWING A NICE BAROCLINIC LEAF ON SATELLITE IMAGES.
CURRENT THINKING HAS THAT FEATURE SLIDE OVER THE SOUTHERN TIP OF
HAIDA GWAII THIS EVENING. MOST OF ITS RAIN SHOULD STAY SOUTH OF
THE PANHANDLE THOUGH ITS VERY NORTHERN RAIN BANDS COULD STILL
BRUSH THE SOUTHERN PARTS OF ZONES 28 AND 29 OVERNIGHT. IT WILL
CERTAINLY BRING MORE HIGH LEVEL CLOUD COVER TO THE SOUTHERN
PANHANDLE TONIGHT SO OVERNIGHT LOWS WILL BE JUST A BIT WARMER THEN
THEY COULD BE.

FEATURE TWO IS A UPPER LEVEL TROUGH AND VORTICITY MAX CURRENTLY
AROUND 150W. THAT WILL ROTATE THROUGH LATE TONIGHT AND EARLY FRI
ENHANCING THE SHOWERS JUST A BIT MORE. A SMALL SHOT OF COOLER AIR
ALOFT WILL ALSO ACCOMPANY IT. THE QUESTION IS WILL THIS BE ENOUGH
TO SPARK OFF MORE THUNDERSTORMS OVER THE SOUTHERN OUTER COAST
TONIGHT. CONVECTIVE INDEXES FROM THE NAM SHOW A POCKET OF 100 TO
300 J/KG OF CAPE OVER THE SOUTHERN OUTER COAST AROUND 9Z TONIGHT
BUT LIFTED INDEX NUMBER ARE NOT AS LOW AS LAST NIGHT. DECIDED TO
GO FOR IT AND PUT SLIGHT CHANCE OF THUNDER FOR THE SOUTHERN OUTER
COAST TONIGHT.

THE OTHER CONCERN WITH THE COOLER AIR ASSOCIATED WITH THIS TROUGH
IS THAT THE ATMOSPHERE COULD GET COOL ENOUGH FOR SNOW TO MIX IN
WITH THE RAIN IN THE EXTREME NORTHERN LOCATIONS AND MAYBE IN HYDER
LATE TONIGHT AND EARLY TOMORROW (850 MB TEMPS REACH -6 C AND 1000
TO 850 MB THICKNESS JUST BELOW 1290). ANY ACCUMULATIONS SHOULD BE AN
INCH OR LESS AS S TO SE FLOW AT THE SURFACE WILL KEEP MOST OF
THESE PLACES ABOVE FREEZING. ANY PLACES THAT DO START TO MIX WITH
SNOW OVERNIGHT WILL CHANGE BACK TO RAIN TOMORROW AS TEMPERATURES
BOTH AT THE SURFACE AND ALOFT RISE AGAIN.

INTO FRI SHOWERS WILL START TO DECREASE IN FREQUENCY GOING FROM
FREQUENT TO SCATTERED BY THE AFTERNOON AS A RIDGE BUILDS OVER THE
PANHANDLE AND DIFLUENT FLOW ALOFT BEGINS TO DEVELOP. CLOUD COVER
WILL ALSO SHOW MORE BREAKS AS WELL. FOCUS THEN SHIFTS TO THE FRONT
THAT IS APPROACHING FROM THE WEST AS IT STARTS TO INCREASE RAIN AND
WIND ACROSS THE CENTRAL GULF TOMORROW AFTERNOON.

AS FOR WIND, STRONG WINDS ARE BLOWING IN LYNN CANAL TODAY AS A 4
MB PRESSURE GRADIENT EXISTS BETWEEN JUNEAU AND SKAGWAY. WINDS
GUSTS UP TO 40 MPH AT SKAGWAY AND 50 KT AT ELDRED ROCK HAVE BEEN
OBSERVED SO FAR TODAY. THESE WINDS SHOULD START TO SLACKEN OFF
THIS EVENING AS THE TROUGH IN CANADA WEAKENS AND THE RIDGE OVER
THE SOUTHERN PANHANDLE GETS SLIGHTLY FLATTENED BY THE WEAK LOW
COMING FROM THE NE PACIFIC. WINDS ACROSS THE PANHANDLE SHOULD STAY
MOSTLY BELOW 20 KT INTO FRI. THE GULF IS ANOTHER MATTER AS SW
WINDS TONIGHT WILL SWITCH AROUND TO SE FRI. THEY WILL THEN
INCREASE IN THE CENTRAL GULF TO A 35 KT GALE IN ADVANCE OF THE
NEXT FRONT.

SHORT RANGE MODELS WERE IN GOOD AGREEMENT FOR THE NEXT 24 HOURS.
SOME SMALL DIFFERENCES NOTED HERE AND THERE BUT NOTHING THAT
WOULD CHANGE THE FORECAST IN A SIGNIFICANT WAY. ALTHOUGH MOST
MODELS DID UNDERESTIMATE THE LYNN CANAL PRESSURE GRADIENT TODAY.
FAVORED THE NAM OVERALL AS IT SEEMED TO HAVE THE BEST
REPRESENTATION OF FEATURES OVERALL.

.LONG TERM...PRIMARY UPDATE TO PRESSURE AND WIND FIELDS REQUIRED
FOR FRI NIGHT THROUGH SUNDAY AS NEW MODELS HAVE THE EASTERN EDGE
OF THE NEW FRONT COMING IN A BIT FASTER AND GRADIENTS BEGIN TO
TIGHTEN A BIT EARLIER. FRONT GETS TO THE PANHANDLE BY ABOUT 12Z
SAT. WENT WITH AN ENSEMBLE NAM/EC/GFS ON THESE UPDATES AS ALL
BRING THE FRONT IN A BIT FASTER. SHOULD BE NO PRECIP TYPE ISSUES
TOMORROW NIGHT ASIDE FROM LIGHT SNOW SHOWERS FOR THE UPPER ROAD
PORTIONS ON THE NORTH END. FRONT IS SLOW-MOVING AND WILL LEAD TO
AN EXTENDED RAINY CONDITIONS AND PROBLEM WINDS FOR EXPOSED AREAS
OF MAINLY THE FAVORED INNER CHANNELS FOR AN EAST-WEST GRADIENT AND
THE MORE OPEN SOUTHERNMOST CHANNELS AND COASTAL AREAS. WINDS
INITIALLY REACH GALE OFFSHORE BY 03Z SAT...THESE SPREAD QUICKLY
EASTWARD THROUGH THE MARINE ZONES AND ARE ENHANCED BY THE BARRIER
JET WEST OF YAKUTAT. ASSOCIATED GALES COULD PERSIST WELL INTO
SUNDAY OVER THE MARINE AREAS. POTENTIAL FOR MODERATE TO HEAVY RAIN
THROUGH EARLY MONDAY IN THE YAKUTAT REGION AS 2-4" DEFINES THE
MODEL ENVELOPE THROUGH ABOUT 96 HOURS OF SIMULATION. COORDINATED
WITH RFC...SITUK RIVER NEAR YAKUTAT IS AT A RELATIVELY LOW LEVEL
NOW...4.5 FEET BELOW FLOOD STAGE. THUS FEEL AT THIS POINT THAT
THERE IS CURRENTLY LOW FLOOD THREAT ALTHOUGH A STATEMENT REGARDING
HEAVY RAIN MAY BE WARRANTED TOMORROW OR TOMORROW NIGHT. FEEL THAT
WOULD BE A BIT PREMATURE AT THIS POINT. WENT WITH A SHOWERY
SCENARIO THROUGH 09Z SAT FOR THE PANHANDLE...THEN STRATIFORM RAIN
THROUGH MONDAY WITH THE SLOW MOVING FRONT...THEN SHOWERY AGAIN AS
THE FRONT DEPARTS AND RIDGING TAKES OVER AFTER THAT.

MODELS IN GOOD AGREEMENT THROUGH THE WEEKEND BUT THE LOW-LEVEL
DETAILS BEGIN TO SCATTER SIGNIFICANTLY LATE ON MONDAY AND EVEN AT
THE SYNOPTIC MID LEVELS BY TUE. ON TUE THE GFS HAS A STRANGE-
LOOKING MULTIPLE TROUGH CONFIGURATION OVER THE GULF WHILE THE EC
MAINTAINS A DEEP BERING LOW. BOTH MODELS GENERALLY AGREE ON UPPER
RIDGING IN THE MIDWEEK PERIOD BUT THE EC IS STRONGER ON THAT
FEATURE. THE GEM SOLUTION FAVORS WEAKER/EARLIER RIDGING ON TUE
WITH A NEW FRONT MOVING THROUGH THE GULF BY LATE WED. WPC
GUIDANCE...BASED ON AN EC/NAEFS ENSEMBLE...AGREES WITH THE DRYING/
RIDGING SCENARIO STARTING LATE TUES/WED AND WENT WITH THIS
GUIDANCE FOR DAYS 5-8.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 7 PM AKDT THIS EVENING FOR AKZ018.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ022-041>043-051-053.

&&

$$

EAL/WESLEY

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU











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