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000
FXAK68 PAFC 021430 AAA
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ANCHORAGE AK
630 AM AKDT THU OCT 2 2014

UPDATED

.ANALYSIS AND UPPER LEVELS...
THE SHARP UPPER LEVEL RIDGE THAT WAS STRETCHED OVER THE SOUTHWEST
MAINLAND AND EASTERN BERING PREVIOUSLY IS NOW IN THE PROCESS OF
BEING PINCHED OFF BY AN ARCTIC TROUGH SLOWLY ESTABLISHING ITSELF
OVER MAINLAND ALASKA AND A CUT-OFF LOW CENTERED SOUTH OF THE
ALASKA PENINSULA. THIS WILL FORM A CLOSED UPPER HIGH OVER THE
BERING AND WORK TO CHANGE THE FLOW TO A MORE MERIDIONAL (NORTH TO
SOUTH) FLOW OVER THE MAINLAND. AT THE SURFACE...HIGH PRESSURE
OVER MUCH OF SOUTH CENTRAL HAS BEGUN TO ERODE AS LOWER PRESSURES
ASSOCIATED WITH THE LOW SOUTH OF THE AKPEN CONTINUE TO PUSH
NORTHEASTWARD. HIGHER CLOUD COVER AND GUSTY WINDS HAVE BEEN
BEGUN TO CREEP INTO PORTIONS OF SOUTHERN ALASKA AS THESE CHANGES
ARE GETTING UNDERWAY.

FURTHER WEST...RAIN AND GUSTY WINDS CONTINUE AS THE FRONT
ASSOCIATED WITH THE WEAKENING LOW EAST OF THE KAMCHATKA PENINSULA
MOVES THROUGH THE FAR WESTERN ALEUTIANS.


&&

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD SYNOPTIC AGREEMENT WITH THE OVERALL FEATURES
THROUGH MUCH OF THE SHORT-TERM (84 HOURS) FORECAST PACKAGE.
MODELS CONTINUE TO CONVERGE ON A COMMON SOLUTION FOR THE TRACK OF
THE STRENGTHENING LOW THAT WILL TRACK THROUGH THE GULF OVER THE
NEXT 48 HOURS. MODELS HAVE BEEN CONSISTENT IN TRACKING THE LOW
THROUGH THE GULF EARLY FRIDAY MORNING AND ENDING UP OVER THE NORTH
GULF COAST LATE FRIDAY EVENING. THE MODELS THEN SHOW THE UPPER
LEVEL ENERGY TRACKING NORTHEAST INTO THE YUKON AND SPLITTING THE
SURFACE LOW INTO TWO SEPARATE LOWS. ONE FOLLOWING THE UPPER LEVEL
LOW INTO THE YUKON AND THE OTHER TURNING WESTWARD TOWARD PRINCE
WILLIAM SOUND. THERE REMAIN SOME KEY DIFFERENCES IN THE MODELS IN
TERMS OF TEMPERATURES AND MOISTURE WHICH WILL BE IMPORTANT IN
DETERMINING PRECIPITATION TYPE IN THE COPPER RIVER BASIN AS WELL
AS HOW FAR WEST THE PRECIPITATION WILL MOVE. AS OF THE 00Z MODEL
RUNS...THE ECMWF AND GFS ARE THE PREFERRED SOLUTIONS...WITH THE
NAM BEING A SLIGHT OUTLIER REGARDING PLACEMENT AND TIMING OF
PRECIPITATION OVER SOUTHCENTRAL. THE ECMWF AND GFS KEEP THE
PRECIP MAINLY OVER THE COPPER RIVER BASIN AND NORTHERN GULF COAST
DURING THE DAY FRIDAY...THEN BEGIN TO SPILL OVER INTO THE WESTERN
PORTION OF SOUTHCENTRAL OVERNIGHT. THE NAM BRINGS THIS
PRECIPITATION WESTWARD INTO ANCHORAGE MUCH FASTER...WITH THE 6Z
NAM COMING IN EVEN FASTER WITH PRECIP REACHING ANCHORAGE AND THE
MAT-SU BY FRIDAY MORNING. THE NEXT CHALLENGE FOR THE MODELS IN
THE GULF OF ALASKA REGION WILL BE THIS WEEKEND AS ANOTHER LOW
DEVELOPS TO THE SOUTH OF THE ALASKA PENINSULA AND TAKES A SIMILAR
TRACK TO THE ONE MOVING INTO THE AREA OVER THE NEXT FEW DAYS.
MODELS ALL HAVE THIS HAPPENING BUT THE TIMING AND STRENGTH OF THIS
LOW VARY GREATLY.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
INCREASING CLOUDS AND WIND ARE EXPECTED TO MOVE INTO SOUTHCENTRAL
ALASKA FROM THE SOUTH AS A STRENGTHENING LOW SOUTH OF KODIAK
RAPIDLY DEEPENS AND BEGINS TO PUSH INTO THE GULF THIS AFTERNOON.
RAIN AND INCREASED GAP WINDS ARE EXPECTED ALONG THE NORTHERN GULF
COAST LATER TONIGHT...AND PERSIST THROUGH MUCH OF THE WEEKEND. A
MIXTURE OF RAIN AND SNOW IS EXPECTED TO START UP TONIGHT OVER THE
EASTERN COPPER RIVER BASIN AND SPREAD WESTWARD INTO TOMORROW
MORNING. THE RAIN AND SNOW MIX WILL LIKELY NUDGE INTO PORTIONS OF ANCHORAGE
AND THE MAT-SU VALLEY FRIDAY NIGHT...AS COLDER AIR ASSOCIATED WITH
THE COLD UPPER LEVEL TROUGH DESCENDS FURTHER INTO SOUTHCENTRAL.
HOWEVER...AS MENTIONED ABOVE...THERE IS STILL SIGNIFICANT MODEL
DISAGREEMENT ON HOW FAR WEST THE DEFORMATION ZONE WILL MOVE AND
THE TIMING OF THE COLDER AIR FILTERING DOWN FROM THE NORTH.

SOUTHWEST ALASKA...
SOUTHWEST ALASKA IS UNDER THE STRONG RIDGE AND WILL REMAIN MOSTLY
CLEAR FOR THE NEXT FEW DAYS...WITH THE EXCEPTION OF THE EASTERN
KUSKOKWIM VALLEY WHO WILL SEE SOME SNOWFALL SPILL ACROSS THE
ALASKA RANGE ON FRIDAY. GUSTY WINDS ASSOCIATED WITH THE LOW SOUTH
OF THE AKPEN AND HIGH PRESSURE OVER THE BERING SEA ARE EXPECTED TO
DEVELOP TODAY ALONG THE AKPEN AND COASTAL BRISTOL BAY ZONE. THERE
MAY BE A FEW CLOUDS ALONG THE ALASKA RANGE FRIDAY DUE TO AN UPPER
LEVEL TROUGH DESCENDING OVER SOUTH CENTRAL ALASKA AT THAT TIME.

BERING SEA/ALEUTIANS...
HIGH PRESSURE OVER THE CENTRAL BERING SEA WILL PERSIST INTO THE
WEEKEND. WINDS WILL REMAIN SOMEWHAT GUSTY OVER THE EASTERN HALF OF
THE ALEUTIAN CHAIN AS TIGHTENED GRADIENTS CONTINUE TO ENHANCE THE
GUSTY EASTERLY FLOW. THE FAR WESTERN ALEUTIANS WILL CONTINUE TO
SEE RAIN INTO TOMORROW MORNING...AS THE FRONTAL SYSTEM ASSOCIATED
WITH THE LOW NEAR KAMCHATKA CONTINUES TO LINGER OVER THE AREA AND
WEAKEN.

&&

.LONG TERM FORECAST (SUN OCT 5 - WED OCT 8)...

THE EXTENDED FORECAST BECOMES INCREASINGLY COMPLEX AND CHALLENGING
AS A COLD UPPER LOW FORMS ACROSS SOUTHERN ALASKA...AND A SERIES OF
NORTH PACIFIC LOWS MOVES INTO THE GULF. THE FIRST OF THESE WILL BE
TRACKING THROUGH THE COPPER BASIN AT THE BEGINNING OF THE
WEEKEND...WITH ANOTHER LOW MOVING IN SOMETIME SUNDAY AFTERNOON
THROUGH SUNDAY NIGHT. THE TRACK REMAINS HIGHLY UNCERTAIN...WITH
THE ECMWF TAKING A MORE EASTERLY TRACK...AND THE GFS AND CANADIAN
GDPS FAVORING A WESTWARD TRACK INTO THE COPPER BASIN. THE IMPACT
WOULD BE THE POTENTIAL FOR ACCUMULATING SNOW SPREADING TO THE
WESTERN COPPER BASIN IN THE LATTER SOLUTIONS...WITH LITTLE TO NONE
IN THE FORMER SOLUTION. ONE CERTAINTY IS THE COLDEST AIR OF THE
SEASON WILL BE ADVECTING INTO SOUTHERN ALASKA. HIGH PRESSURE WILL
BUILD WEST TO EAST...WITH OVERNIGHT LOWS PLUMMETING AS SKIES CLEAR
IN THE WAKE OF THE UPPER LOW. UNCERTAINTY GROWS BY MIDWEEK AS A
SERIES OF STRONG LOWS ASSOCIATED WITH A POWERFUL NORTH PACIFIC JET
STREAM SLOWLY ERODE THE BLOCKING PATTERN OVER THE BERING AND TRACK
EAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...STORM 132
         GALE 119 120 131 132 136 137 138 150 155.
FIRE WEATHER...NONE.

&&

$$

TP OCT 14





000
FXAK68 PAFC 021430 AAA
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ANCHORAGE AK
630 AM AKDT THU OCT 2 2014

UPDATED

.ANALYSIS AND UPPER LEVELS...
THE SHARP UPPER LEVEL RIDGE THAT WAS STRETCHED OVER THE SOUTHWEST
MAINLAND AND EASTERN BERING PREVIOUSLY IS NOW IN THE PROCESS OF
BEING PINCHED OFF BY AN ARCTIC TROUGH SLOWLY ESTABLISHING ITSELF
OVER MAINLAND ALASKA AND A CUT-OFF LOW CENTERED SOUTH OF THE
ALASKA PENINSULA. THIS WILL FORM A CLOSED UPPER HIGH OVER THE
BERING AND WORK TO CHANGE THE FLOW TO A MORE MERIDIONAL (NORTH TO
SOUTH) FLOW OVER THE MAINLAND. AT THE SURFACE...HIGH PRESSURE
OVER MUCH OF SOUTH CENTRAL HAS BEGUN TO ERODE AS LOWER PRESSURES
ASSOCIATED WITH THE LOW SOUTH OF THE AKPEN CONTINUE TO PUSH
NORTHEASTWARD. HIGHER CLOUD COVER AND GUSTY WINDS HAVE BEEN
BEGUN TO CREEP INTO PORTIONS OF SOUTHERN ALASKA AS THESE CHANGES
ARE GETTING UNDERWAY.

FURTHER WEST...RAIN AND GUSTY WINDS CONTINUE AS THE FRONT
ASSOCIATED WITH THE WEAKENING LOW EAST OF THE KAMCHATKA PENINSULA
MOVES THROUGH THE FAR WESTERN ALEUTIANS.


&&

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD SYNOPTIC AGREEMENT WITH THE OVERALL FEATURES
THROUGH MUCH OF THE SHORT-TERM (84 HOURS) FORECAST PACKAGE.
MODELS CONTINUE TO CONVERGE ON A COMMON SOLUTION FOR THE TRACK OF
THE STRENGTHENING LOW THAT WILL TRACK THROUGH THE GULF OVER THE
NEXT 48 HOURS. MODELS HAVE BEEN CONSISTENT IN TRACKING THE LOW
THROUGH THE GULF EARLY FRIDAY MORNING AND ENDING UP OVER THE NORTH
GULF COAST LATE FRIDAY EVENING. THE MODELS THEN SHOW THE UPPER
LEVEL ENERGY TRACKING NORTHEAST INTO THE YUKON AND SPLITTING THE
SURFACE LOW INTO TWO SEPARATE LOWS. ONE FOLLOWING THE UPPER LEVEL
LOW INTO THE YUKON AND THE OTHER TURNING WESTWARD TOWARD PRINCE
WILLIAM SOUND. THERE REMAIN SOME KEY DIFFERENCES IN THE MODELS IN
TERMS OF TEMPERATURES AND MOISTURE WHICH WILL BE IMPORTANT IN
DETERMINING PRECIPITATION TYPE IN THE COPPER RIVER BASIN AS WELL
AS HOW FAR WEST THE PRECIPITATION WILL MOVE. AS OF THE 00Z MODEL
RUNS...THE ECMWF AND GFS ARE THE PREFERRED SOLUTIONS...WITH THE
NAM BEING A SLIGHT OUTLIER REGARDING PLACEMENT AND TIMING OF
PRECIPITATION OVER SOUTHCENTRAL. THE ECMWF AND GFS KEEP THE
PRECIP MAINLY OVER THE COPPER RIVER BASIN AND NORTHERN GULF COAST
DURING THE DAY FRIDAY...THEN BEGIN TO SPILL OVER INTO THE WESTERN
PORTION OF SOUTHCENTRAL OVERNIGHT. THE NAM BRINGS THIS
PRECIPITATION WESTWARD INTO ANCHORAGE MUCH FASTER...WITH THE 6Z
NAM COMING IN EVEN FASTER WITH PRECIP REACHING ANCHORAGE AND THE
MAT-SU BY FRIDAY MORNING. THE NEXT CHALLENGE FOR THE MODELS IN
THE GULF OF ALASKA REGION WILL BE THIS WEEKEND AS ANOTHER LOW
DEVELOPS TO THE SOUTH OF THE ALASKA PENINSULA AND TAKES A SIMILAR
TRACK TO THE ONE MOVING INTO THE AREA OVER THE NEXT FEW DAYS.
MODELS ALL HAVE THIS HAPPENING BUT THE TIMING AND STRENGTH OF THIS
LOW VARY GREATLY.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
INCREASING CLOUDS AND WIND ARE EXPECTED TO MOVE INTO SOUTHCENTRAL
ALASKA FROM THE SOUTH AS A STRENGTHENING LOW SOUTH OF KODIAK
RAPIDLY DEEPENS AND BEGINS TO PUSH INTO THE GULF THIS AFTERNOON.
RAIN AND INCREASED GAP WINDS ARE EXPECTED ALONG THE NORTHERN GULF
COAST LATER TONIGHT...AND PERSIST THROUGH MUCH OF THE WEEKEND. A
MIXTURE OF RAIN AND SNOW IS EXPECTED TO START UP TONIGHT OVER THE
EASTERN COPPER RIVER BASIN AND SPREAD WESTWARD INTO TOMORROW
MORNING. THE RAIN AND SNOW MIX WILL LIKELY NUDGE INTO PORTIONS OF ANCHORAGE
AND THE MAT-SU VALLEY FRIDAY NIGHT...AS COLDER AIR ASSOCIATED WITH
THE COLD UPPER LEVEL TROUGH DESCENDS FURTHER INTO SOUTHCENTRAL.
HOWEVER...AS MENTIONED ABOVE...THERE IS STILL SIGNIFICANT MODEL
DISAGREEMENT ON HOW FAR WEST THE DEFORMATION ZONE WILL MOVE AND
THE TIMING OF THE COLDER AIR FILTERING DOWN FROM THE NORTH.

SOUTHWEST ALASKA...
SOUTHWEST ALASKA IS UNDER THE STRONG RIDGE AND WILL REMAIN MOSTLY
CLEAR FOR THE NEXT FEW DAYS...WITH THE EXCEPTION OF THE EASTERN
KUSKOKWIM VALLEY WHO WILL SEE SOME SNOWFALL SPILL ACROSS THE
ALASKA RANGE ON FRIDAY. GUSTY WINDS ASSOCIATED WITH THE LOW SOUTH
OF THE AKPEN AND HIGH PRESSURE OVER THE BERING SEA ARE EXPECTED TO
DEVELOP TODAY ALONG THE AKPEN AND COASTAL BRISTOL BAY ZONE. THERE
MAY BE A FEW CLOUDS ALONG THE ALASKA RANGE FRIDAY DUE TO AN UPPER
LEVEL TROUGH DESCENDING OVER SOUTH CENTRAL ALASKA AT THAT TIME.

BERING SEA/ALEUTIANS...
HIGH PRESSURE OVER THE CENTRAL BERING SEA WILL PERSIST INTO THE
WEEKEND. WINDS WILL REMAIN SOMEWHAT GUSTY OVER THE EASTERN HALF OF
THE ALEUTIAN CHAIN AS TIGHTENED GRADIENTS CONTINUE TO ENHANCE THE
GUSTY EASTERLY FLOW. THE FAR WESTERN ALEUTIANS WILL CONTINUE TO
SEE RAIN INTO TOMORROW MORNING...AS THE FRONTAL SYSTEM ASSOCIATED
WITH THE LOW NEAR KAMCHATKA CONTINUES TO LINGER OVER THE AREA AND
WEAKEN.

&&

.LONG TERM FORECAST (SUN OCT 5 - WED OCT 8)...

THE EXTENDED FORECAST BECOMES INCREASINGLY COMPLEX AND CHALLENGING
AS A COLD UPPER LOW FORMS ACROSS SOUTHERN ALASKA...AND A SERIES OF
NORTH PACIFIC LOWS MOVES INTO THE GULF. THE FIRST OF THESE WILL BE
TRACKING THROUGH THE COPPER BASIN AT THE BEGINNING OF THE
WEEKEND...WITH ANOTHER LOW MOVING IN SOMETIME SUNDAY AFTERNOON
THROUGH SUNDAY NIGHT. THE TRACK REMAINS HIGHLY UNCERTAIN...WITH
THE ECMWF TAKING A MORE EASTERLY TRACK...AND THE GFS AND CANADIAN
GDPS FAVORING A WESTWARD TRACK INTO THE COPPER BASIN. THE IMPACT
WOULD BE THE POTENTIAL FOR ACCUMULATING SNOW SPREADING TO THE
WESTERN COPPER BASIN IN THE LATTER SOLUTIONS...WITH LITTLE TO NONE
IN THE FORMER SOLUTION. ONE CERTAINTY IS THE COLDEST AIR OF THE
SEASON WILL BE ADVECTING INTO SOUTHERN ALASKA. HIGH PRESSURE WILL
BUILD WEST TO EAST...WITH OVERNIGHT LOWS PLUMMETING AS SKIES CLEAR
IN THE WAKE OF THE UPPER LOW. UNCERTAINTY GROWS BY MIDWEEK AS A
SERIES OF STRONG LOWS ASSOCIATED WITH A POWERFUL NORTH PACIFIC JET
STREAM SLOWLY ERODE THE BLOCKING PATTERN OVER THE BERING AND TRACK
EAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...STORM 132
         GALE 119 120 131 132 136 137 138 150 155.
FIRE WEATHER...NONE.

&&

$$

TP OCT 14




000
FXAK68 PAFC 021358
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
558 AM AKDT THU OCT 2 2014

.ANALYSIS AND UPPER LEVELS...
THE SHARP UPPER LEVEL RIDGE THAT WAS STRETCHED OVER THE SOUTHWEST
MAINLAND AND EASTERN BERING PREVIOUSLY IS NOW IN THE PROCESS OF
BEING PINCHED OFF BY AN ARCTIC TROUGH SLOWLY ESTABLISHING ITSELF
OVER MAINLAND ALASKA AND A CUT-OFF LOW CENTERED SOUTH OF THE
ALASKA PENINSULA. THIS WILL FORM A CLOSED UPPER HIGH OVER THE
BERING AND WORK TO CHANGE THE FLOW TO A MORE MERIDIONAL (NORTH TO
SOUTH) FLOW OVER THE MAINLAND. AT THE SURFACE...HIGH PRESSURE
OVER MUCH OF SOUTH CENTRAL HAS BEGUN TO ERODE AS LOWER PRESSURES
ASSOCIATED WITH THE LOW SOUTH OF THE AKPEN CONTINUE TO PUSH
NORTHEASTWARD. HIGHER CLOUD COVER AND GUSTY WINDS HAVE BEEN
BEGUN TO CREEP INTO PORTIONS OF SOUTHERN ALASKA AS THESE CHANGES
ARE GETTING UNDERWAY.

FURTHER WEST...RAIN AND GUSTY WINDS CONTINUE AS THE FRONT
ASSOCIATED WITH THE WEAKENING LOW EAST OF THE KAMCHATKA PENINSULA
MOVES THROUGH THE FAR WESTERN ALEUTIANS.


&&

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD SYNOPTIC AGREEMENT WITH THE OVERALL FEATURES
THROUGH MUCH OF THE SHORT-TERM (84 HOURS) FORECAST PACKAGE.
MODELS CONTINUE TO CONVERGE ON A COMMON SOLUTION FOR THE TRACK OF
THE STRENGTHENING LOW THAT WILL TRACK THROUGH THE GULF OVER THE
NEXT 48 HOURS. MODELS HAVE BEEN CONSISTENT IN TRACKING THE LOW
THROUGH THE GULF EARLY FRIDAY MORNING AND ENDING UP OVER THE NORTH
GULF COAST LATE FRIDAY EVENING. THE MODELS THEN SHOW THE UPPER
LEVEL ENERGY TRACKING NORTHEAST INTO THE YUKON AND SPLITTING THE
SURFACE LOW INTO TWO SEPARATE LOWS. ONE FOLLOWING THE UPPER LEVEL
LOW INTO THE YUKON AND THE OTHER TURNING WESTWARD TOWARD PRINCE
WILLIAM SOUND. THERE REMAIN SOME KEY DIFFERENCES IN THE MODELS IN
TERMS OF TEMPERATURES AND MOISTURE WHICH WILL BE IMPORTANT IN
DETERMINING PRECIPITATION TYPE IN THE COPPER RIVER BASIN AS WELL
AS HOW FAR WEST THE PRECIPITATION WILL MOVE. AS OF THE 00Z MODEL
RUNS...THE ECMWF AND GFS ARE THE PREFERRED SOLUTIONS...WITH THE
NAM BEING A SLIGHT OUTLIER REGARDING PLACEMENT AND TIMING OF
PRECIPITATION OVER SOUTHCENTRAL. THE ECMWF AND GFS KEEP THE
PRECIP MAINLY OVER THE COPPER RIVER BASIN AND NORTHERN GULF COAST
DURING THE DAY FRIDAY...THEN BEGIN TO SPILL OVER INTO THE WESTERN
PORTION OF SOUTHCENTRAL OVERNIGHT. THE NAM BRINGS THIS
PRECIPITATION WESTWARD INTO ANCHORAGE MUCH FASTER...WITH THE 6Z
NAM COMING IN EVEN FASTER WITH PRECIP REACHING ANCHORAGE AND THE
MAT-SU BY FRIDAY MORNING. THE NEXT CHALLENGE FOR THE MODELS IN
THE GULF OF ALASKA REGION WILL BE THIS WEEKEND AS ANOTHER LOW
DEVELOPS TO THE SOUTH OF THE ALASKA PENINSULA AND TAKES A SIMILAR
TRACK TO THE ONE MOVING INTO THE AREA OVER THE NEXT FEW DAYS.
MODELS ALL HAVE THIS HAPPENING BUT THE TIMING AND STRENGTH OF THIS
LOW VARY GREATLY.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
INCREASING CLOUDS AND WIND ARE EXPECTED TO MOVE INTO SOUTHCENTRAL
ALASKA FROM THE SOUTH AS A STRENGTHENING LOW SOUTH OF KODIAK
RAPIDLY DEEPENS AND BEGINS TO PUSH INTO THE GULF THIS AFTERNOON.
RAIN AND INCREASED GAP WINDS ARE EXPECTED ALONG THE NORTHERN GULF
COAST LATER TONIGHT...AND PERSIST THROUGH MUCH OF THE WEEKEND. A
MIXTURE OF RAIN AND SNOW IS EXPECTED TO START UP TONIGHT OVER THE
EASTERN COPPER RIVER BASIN AND SPREAD WESTWARD INTO TOMORROW
MORNING. THE RAIN AND SNOW MIX WILL LIKELY NUDGE INTO PORTIONS OF ANCHORAGE
AND THE MAT-SU VALLEY FRIDAY NIGHT...AS COLDER AIR ASSOCIATED WITH
THE COLD UPPER LEVEL TROUGH DESCENDS FURTHER INTO SOUTHCENTRAL.
HOWEVER...AS MENTIONED ABOVE...THERE IS STILL SIGNIFICANT MODEL
DISAGREEMENT ON HOW FAR WEST THE DEFORMATION ZONE WILL MOVE AND
THE TIMING OF THE COLDER AIR FILTERING DOWN FROM THE NORTH.

SOUTHWEST ALASKA...
SOUTHWEST ALASKA IS UNDER THE STRONG RIDGE AND WILL REMAIN MOSTLY
CLEAR FOR THE NEXT FEW DAYS...WITH THE EXCEPTION OF THE EASTERN
KUSKOKWIM VALLEY WHO WILL SEE SOME SNOWFALL SPILL ACROSS THE
ALASKA RANGE ON FRIDAY. GUSTY WINDS ASSOCIATED WITH THE LOW SOUTH
OF THE AKPEN AND HIGH PRESSURE OVER THE BERING SEA ARE EXPECTED TO
DEVELOP TODAY ALONG THE AKPEN AND COASTAL BRISTOL BAY ZONE. THERE
MAY BE A FEW CLOUDS ALONG THE ALASKA RANGE FRIDAY DUE TO AN UPPER
LEVEL TROUGH DESCENDING OVER SOUTH CENTRAL ALASKA AT THAT TIME.

BERING SEA/ALEUTIANS...
HIGH PRESSURE OVER THE CENTRAL BERING SEA WILL PERSIST INTO THE
WEEKEND. WINDS WILL REMAIN SOMEWHAT GUSTY OVER THE EASTERN HALF OF
THE ALEUTIAN CHAIN AS TIGHTENED GRADIENTS CONTINUE TO ENHANCE THE
GUSTY EASTERLY FLOW. THE FAR WESTERN ALEUTIANS WILL CONTINUE TO
SEE RAIN INTO TOMORROW MORNING...AS THE FRONTAL SYSTEM ASSOCIATED
WITH THE LOW NEAR KAMCHATKA CONTINUES TO LINGER OVER THE AREA AND
WEAKEN.

&&

.LONG TERM FORECAST (SUN OCT 5 - WED OCT 8)...

THE EXTENDED FORECAST BECOMES INCREASINGLY COMPLEX AND CHALLENGING
AS A COLD UPPER LOW FORMS ACROSS SOUTHERN ALASKA...AND A SERIES OF
NORTH PACIFIC LOWS MOVES INTO THE GULF. THE FIRST OF THESE WILL BE
TRACKING THROUGH THE COPPER BASIN AT THE BEGINNING OF THE
WEEKEND...WITH ANOTHER LOW MOVING IN SOMETIME SUNDAY AFTERNOON
THROUGH SUNDAY NIGHT. THE TRACK REMAINS HIGHLY UNCERTAIN...WITH
THE ECMWF TAKING A MORE EASTERLY TRACK...AND THE GFS AND CANADIAN
GDPS FAVORING A WESTWARD TRACK INTO THE COPPER BASIN. THE IMPACT
WOULD BE THE POTENTIAL FOR ACCUMULATING SNOW SPREADING TO THE
WESTERN COPPER BASIN IN THE LATTER SOLUTIONS...WITH LITTLE TO NONE
IN THE FORMER SOLUTION. ONE CERTAINTY IS THE COLDEST AIR OF THE
SEASON WILL BE ADVECTING INTO SOUTHERN ALASKA. HIGH PRESSURE WILL
BUILD WEST TO EAST...WITH OVERNIGHT LOWS PLUMMETING AS SKIES CLEAR
IN THE WAKE OF THE UPPER LOW. UNCERTAINTY GROWS BY MIDWEEK AS A
SERIES OF STRONG LOWS ASSOCIATED WITH A POWERFUL NORTH PACIFIC JET
STREAM SLOWLY ERODE THE BLOCKING PATTERN OVER THE BERING AND TRACK
EAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 119 120 131 132 136 138 150 155.
FIRE WEATHER...NONE.

&&

$$

TP OCT 14




000
FXAK68 PAFC 021358
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
558 AM AKDT THU OCT 2 2014

.ANALYSIS AND UPPER LEVELS...
THE SHARP UPPER LEVEL RIDGE THAT WAS STRETCHED OVER THE SOUTHWEST
MAINLAND AND EASTERN BERING PREVIOUSLY IS NOW IN THE PROCESS OF
BEING PINCHED OFF BY AN ARCTIC TROUGH SLOWLY ESTABLISHING ITSELF
OVER MAINLAND ALASKA AND A CUT-OFF LOW CENTERED SOUTH OF THE
ALASKA PENINSULA. THIS WILL FORM A CLOSED UPPER HIGH OVER THE
BERING AND WORK TO CHANGE THE FLOW TO A MORE MERIDIONAL (NORTH TO
SOUTH) FLOW OVER THE MAINLAND. AT THE SURFACE...HIGH PRESSURE
OVER MUCH OF SOUTH CENTRAL HAS BEGUN TO ERODE AS LOWER PRESSURES
ASSOCIATED WITH THE LOW SOUTH OF THE AKPEN CONTINUE TO PUSH
NORTHEASTWARD. HIGHER CLOUD COVER AND GUSTY WINDS HAVE BEEN
BEGUN TO CREEP INTO PORTIONS OF SOUTHERN ALASKA AS THESE CHANGES
ARE GETTING UNDERWAY.

FURTHER WEST...RAIN AND GUSTY WINDS CONTINUE AS THE FRONT
ASSOCIATED WITH THE WEAKENING LOW EAST OF THE KAMCHATKA PENINSULA
MOVES THROUGH THE FAR WESTERN ALEUTIANS.


&&

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD SYNOPTIC AGREEMENT WITH THE OVERALL FEATURES
THROUGH MUCH OF THE SHORT-TERM (84 HOURS) FORECAST PACKAGE.
MODELS CONTINUE TO CONVERGE ON A COMMON SOLUTION FOR THE TRACK OF
THE STRENGTHENING LOW THAT WILL TRACK THROUGH THE GULF OVER THE
NEXT 48 HOURS. MODELS HAVE BEEN CONSISTENT IN TRACKING THE LOW
THROUGH THE GULF EARLY FRIDAY MORNING AND ENDING UP OVER THE NORTH
GULF COAST LATE FRIDAY EVENING. THE MODELS THEN SHOW THE UPPER
LEVEL ENERGY TRACKING NORTHEAST INTO THE YUKON AND SPLITTING THE
SURFACE LOW INTO TWO SEPARATE LOWS. ONE FOLLOWING THE UPPER LEVEL
LOW INTO THE YUKON AND THE OTHER TURNING WESTWARD TOWARD PRINCE
WILLIAM SOUND. THERE REMAIN SOME KEY DIFFERENCES IN THE MODELS IN
TERMS OF TEMPERATURES AND MOISTURE WHICH WILL BE IMPORTANT IN
DETERMINING PRECIPITATION TYPE IN THE COPPER RIVER BASIN AS WELL
AS HOW FAR WEST THE PRECIPITATION WILL MOVE. AS OF THE 00Z MODEL
RUNS...THE ECMWF AND GFS ARE THE PREFERRED SOLUTIONS...WITH THE
NAM BEING A SLIGHT OUTLIER REGARDING PLACEMENT AND TIMING OF
PRECIPITATION OVER SOUTHCENTRAL. THE ECMWF AND GFS KEEP THE
PRECIP MAINLY OVER THE COPPER RIVER BASIN AND NORTHERN GULF COAST
DURING THE DAY FRIDAY...THEN BEGIN TO SPILL OVER INTO THE WESTERN
PORTION OF SOUTHCENTRAL OVERNIGHT. THE NAM BRINGS THIS
PRECIPITATION WESTWARD INTO ANCHORAGE MUCH FASTER...WITH THE 6Z
NAM COMING IN EVEN FASTER WITH PRECIP REACHING ANCHORAGE AND THE
MAT-SU BY FRIDAY MORNING. THE NEXT CHALLENGE FOR THE MODELS IN
THE GULF OF ALASKA REGION WILL BE THIS WEEKEND AS ANOTHER LOW
DEVELOPS TO THE SOUTH OF THE ALASKA PENINSULA AND TAKES A SIMILAR
TRACK TO THE ONE MOVING INTO THE AREA OVER THE NEXT FEW DAYS.
MODELS ALL HAVE THIS HAPPENING BUT THE TIMING AND STRENGTH OF THIS
LOW VARY GREATLY.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
INCREASING CLOUDS AND WIND ARE EXPECTED TO MOVE INTO SOUTHCENTRAL
ALASKA FROM THE SOUTH AS A STRENGTHENING LOW SOUTH OF KODIAK
RAPIDLY DEEPENS AND BEGINS TO PUSH INTO THE GULF THIS AFTERNOON.
RAIN AND INCREASED GAP WINDS ARE EXPECTED ALONG THE NORTHERN GULF
COAST LATER TONIGHT...AND PERSIST THROUGH MUCH OF THE WEEKEND. A
MIXTURE OF RAIN AND SNOW IS EXPECTED TO START UP TONIGHT OVER THE
EASTERN COPPER RIVER BASIN AND SPREAD WESTWARD INTO TOMORROW
MORNING. THE RAIN AND SNOW MIX WILL LIKELY NUDGE INTO PORTIONS OF ANCHORAGE
AND THE MAT-SU VALLEY FRIDAY NIGHT...AS COLDER AIR ASSOCIATED WITH
THE COLD UPPER LEVEL TROUGH DESCENDS FURTHER INTO SOUTHCENTRAL.
HOWEVER...AS MENTIONED ABOVE...THERE IS STILL SIGNIFICANT MODEL
DISAGREEMENT ON HOW FAR WEST THE DEFORMATION ZONE WILL MOVE AND
THE TIMING OF THE COLDER AIR FILTERING DOWN FROM THE NORTH.

SOUTHWEST ALASKA...
SOUTHWEST ALASKA IS UNDER THE STRONG RIDGE AND WILL REMAIN MOSTLY
CLEAR FOR THE NEXT FEW DAYS...WITH THE EXCEPTION OF THE EASTERN
KUSKOKWIM VALLEY WHO WILL SEE SOME SNOWFALL SPILL ACROSS THE
ALASKA RANGE ON FRIDAY. GUSTY WINDS ASSOCIATED WITH THE LOW SOUTH
OF THE AKPEN AND HIGH PRESSURE OVER THE BERING SEA ARE EXPECTED TO
DEVELOP TODAY ALONG THE AKPEN AND COASTAL BRISTOL BAY ZONE. THERE
MAY BE A FEW CLOUDS ALONG THE ALASKA RANGE FRIDAY DUE TO AN UPPER
LEVEL TROUGH DESCENDING OVER SOUTH CENTRAL ALASKA AT THAT TIME.

BERING SEA/ALEUTIANS...
HIGH PRESSURE OVER THE CENTRAL BERING SEA WILL PERSIST INTO THE
WEEKEND. WINDS WILL REMAIN SOMEWHAT GUSTY OVER THE EASTERN HALF OF
THE ALEUTIAN CHAIN AS TIGHTENED GRADIENTS CONTINUE TO ENHANCE THE
GUSTY EASTERLY FLOW. THE FAR WESTERN ALEUTIANS WILL CONTINUE TO
SEE RAIN INTO TOMORROW MORNING...AS THE FRONTAL SYSTEM ASSOCIATED
WITH THE LOW NEAR KAMCHATKA CONTINUES TO LINGER OVER THE AREA AND
WEAKEN.

&&

.LONG TERM FORECAST (SUN OCT 5 - WED OCT 8)...

THE EXTENDED FORECAST BECOMES INCREASINGLY COMPLEX AND CHALLENGING
AS A COLD UPPER LOW FORMS ACROSS SOUTHERN ALASKA...AND A SERIES OF
NORTH PACIFIC LOWS MOVES INTO THE GULF. THE FIRST OF THESE WILL BE
TRACKING THROUGH THE COPPER BASIN AT THE BEGINNING OF THE
WEEKEND...WITH ANOTHER LOW MOVING IN SOMETIME SUNDAY AFTERNOON
THROUGH SUNDAY NIGHT. THE TRACK REMAINS HIGHLY UNCERTAIN...WITH
THE ECMWF TAKING A MORE EASTERLY TRACK...AND THE GFS AND CANADIAN
GDPS FAVORING A WESTWARD TRACK INTO THE COPPER BASIN. THE IMPACT
WOULD BE THE POTENTIAL FOR ACCUMULATING SNOW SPREADING TO THE
WESTERN COPPER BASIN IN THE LATTER SOLUTIONS...WITH LITTLE TO NONE
IN THE FORMER SOLUTION. ONE CERTAINTY IS THE COLDEST AIR OF THE
SEASON WILL BE ADVECTING INTO SOUTHERN ALASKA. HIGH PRESSURE WILL
BUILD WEST TO EAST...WITH OVERNIGHT LOWS PLUMMETING AS SKIES CLEAR
IN THE WAKE OF THE UPPER LOW. UNCERTAINTY GROWS BY MIDWEEK AS A
SERIES OF STRONG LOWS ASSOCIATED WITH A POWERFUL NORTH PACIFIC JET
STREAM SLOWLY ERODE THE BLOCKING PATTERN OVER THE BERING AND TRACK
EAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 119 120 131 132 136 138 150 155.
FIRE WEATHER...NONE.

&&

$$

TP OCT 14





000
FXAK68 PAFC 012153
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
153 PM AKDT WED OCT 1 2014

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL PATTERN IS INTERESTING TODAY WITH A RIDGE OVERT HE
BERING SEA AND A LOW CENTERED IN THE ARCTIC WHICH EXTENDS INTO
WESTERN CANADA. THIS IS PRODUCING ZONAL WEST TO NORTHWESTERLY
FLOW ALOFT OVER THE MAINLAND PART OF THE STATE. A CUT-OFF LOW IS
CENTERED WELL SOUTH OF THE ALASKA PENINSULA WITH THE JET STREAM
RUNNING AROUND IT TO THE SOUTH AND EAST AND THEN CLIPPING THE
GULF OF ALASKA AS IT TRACKS OVER SOUTHEAST ALASKA.
THIS CUT-OFF LOW WITH JET SUPPORT IS THE REASON THE SURFACE LOW
NEAR IT WILL STRENGTHEN AND THEN TRACK INTO THE GULF OF ALASKA.
THE MAINLAND OF THE STATE REMAINS UNDER A STRONG RIDGE OF HIGH
PRESSURE AT THE SURFACE.

&&

.MODEL DISCUSSION...
MODELS ARE HONING IN ON A COMMON SOLUTION FOR THE TRACK OF THE LOW
THAT IS CURRENTLY SOUTH OF THE ALASKA PENINSULA WHICH WILL BE
STRENGTHENING AND MOVING INTO THE GULF OF ALASKA TOMORROW AND THEN
TO THE NORTH GULF COAST FRIDAY. THE GFS IS A LITTLE FASTER IN ITS
PROGRESSION THROUGH THURSDAY NIGHT THAN THE ECMWF, NAM AND GEM
WHICH ARE ALL THREE CLUSTERED CLOSE TOGETHER. BY FRIDAY NIGHT THEY
ARE ALL IN AGREEMENT IN PUSHING THE UPPER LEVEL ENERGY NORTHEAST
INTO THE YUKON AND SPLITTING THE SURFACE LOW INTO TWO SEPARATE
LOWS. ONE FOLLOWING THE UPPER LEVEL LOW INTO THE YUKON AND THE
OTHER ALONG THE NORTH GULF COAST. THE NORTH GULF COAST LOW WILL
BECOME THE MAIN ONE AS COLD AIR FROM THE INTERIOR OF THE STATE
FILTERS INTO IT.
THERE ARE SOME SUBTLE DIFFERENCES IN THE MODELS IN TERMS OF
TEMPERATURES AND MOISTURE WHICH WILL BE IMPORTANT IN DETERMINING
PRECIPITATION TYPE IN THE COPPER RIVER BASIN AS WELL AS HAS FAR
WEST THE PRECIPITATION WILL MOVE.
THE NEXT CHALLENGE FOR THE
MODELS IN THE GULF OF ALASKA REGION WILL BE THIS WEEKEND AS
ANOTHER LOW DEVELOPS TO THE SOUTH OF THE ALASKA PENINSULA AND
TAKES A SIMILAR TRACK AS THE ONE MOVING INTO THE AREA THE NEXT TWO
DAYS. MODELS ALL HAVE THIS HAPPENING BUT THE TIMING AND STRENGTH
OF THIS LOW VARY GREATLY. THE RIDGE OF HIGH PRESSURE OVER THE
BERING SEA WILL PERSIST LARGELY UNCHANGED INTO THE WEEKEND.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
SUNNY SKIES WILL START TO GIVE WAY TO A FRONT APPROACHING FROM
THE SOUTH. THIS WILL START TONIGHT IN KODIAK AND THEN TOMORROW
NIGHT ALONG THE NORTH GULF COAST. BY THURSDAY NIGHT THE SURFACE
LOW WILL BE MOVING TOWARD THE GULF COAST WITH A COLD UPPER LEVEL
TROUGH DESCENDING OVER SOUTHCENTRAL FROM THE NORTH. THE RESULT
WILL BE TO BRING PRECIPITATION ALONG THE NORTH GULF COAST AND INTO
THE COPPER RIVER BASIN. PRECIPITATION TYPE WILL BE RAIN ALONG THE
COAST BUT THE BIG QUESTION WILL BE HOW MUCH COLD AIR WILL BE ABLE
TO MAKE IT INTO THE COPPER RIVER BASIN AND AT WHAT ELEVATION THE
SNOW WILL TURN TO RAIN. AT THIS TIME IT LOOKS LIKELY THAT THOMPSON
PASS, CHICKALOON PASS, MACLAREN PASS AND ISABEL PASS WILL BE COLD
ENOUGH TO SEE ACCUMULATING SNOWFALL FRIDAY AND FRIDAY NIGHT. THE
QUESTION IS WHETHER THIS WILL MAKE IT ALL THE WAY DOWN TO THE
GLENNALLEN AREA AND THIS IS WHERE THE SUBTLE DIFFERENCES IN THE
MODELS COMES INTO PLAY. TEMPERATURES ARE CLOSE TO WHAT THEY SHOULD
BE FOR SNOW BUT EARLY SEASON SITUATIONS OFTEN FAVOR RAIN. IT IS
POSSIBLE THAT THERE IS COLD RAIN IN THE LOWER PARTS OF THE COPPER
RIVER BASIN AND THE PASSES WILL SEE SNOWFALL. THE COLD AIR WILL
BUILD IN BETTER THIS WEEKEND OVER SOUTHCENTRAL ALASKA. THEREFORE
IF A SECONDARY LOW MOVES OVER THE COPPER RIVER BASIN SATURDAY INTO
SUNDAY THERE IS A BETTER CHANCE OF SNOW OVER THE ENTIRE AREA.
THERE IS A CHANCE...A CHANCE...THAT THE MOISTURE FROM THE COPPER
RIVER WILL MOVE FAR ENOUGH WESTWARD BY SATURDAY, IN CONJUNCTION
WITH THE COLDER AIR, TO BRING SOME SNOW PRETTY FAR DOWN THE
MOUNTAINS AROUND ANCHORAGE AND THE MAT-SU VALLEY.

SOUTHWEST ALASKA...
SOUTHWEST ALASKA IS UNDER THE STRONG RIDGE AND WILL REMAIN MOSTLY
CLEAR FOR THE NEXT FEW DAYS. THERE MAY BE A FEW CLOUDS TRACKING
ALONG THE NORTHERN PART OF THE AREA OVERNIGHT FROM A SHORT WAVE
MOVING THROUGH THE ZONAL FLOW OVER THE NORTHERN PART OF THE STATE.
MORE CLOUDS MAY ALSO SNEAK INTO THE AREA NEAR THE ALASKA RANGE BY
FRIDAY DUE TO AN UPPER LEVEL TROUGH DESCENDING OVER SOUTH CENTRAL
ALASKA AT THAT TIME.

BERING SEA/ALEUTIANS...
HIGH PRESSURE OVER THE CENTRAL BERING SEA WILL PERSIST INTO THE
WEEKEND. THERE IS A FRONT THAT IS BRUSHING UP TO THE EASTERN
ALEUTIANS AND ALASKA PENINSULA TODAY WHICH IS BRINGING SOME GUSTY
WINDS AND A CHANCE OF RAIN TO THE AREA THROUGH TONIGHT. THIS WILL
MOVE OUT OF THE AREA AS THE LOW THAT IS SOUTH OF THE AREA MOVES
INTO THE GULF OF ALASKA TOMORROW. WINDS WILL REMAIN SOMEWHAT GUSTY
BUT NOT AS STRONG AS TODAY AND THEY WILL ALSO SHIFT FROM MORE OF
AN EAST TO NORTHWEST DIRECTION TO THE NORTHWEST.
THE FAR WESTERN ALEUTIANS ARE ON THE OTHER SIDE OF THE RIDGE AND
WILL BE IMPACTED BY A FRONT FROM A LOW NEAR KAMCHATKA THOUGH
TOMORROW. THIS WILL BRING IN SOME GUSTY SOUTHEAST WINDS AND A
CHANCE OF RAIN.

&&

.LONG TERM FORECAST (SUN OCT 5 - WED OCT 8)...

THE EXTENDED FORECAST BECOMES INCREASINGLY COMPLEX AND CHALLENGING
AS A COLD UPPER LOW FORMS ACROSS SOUTHERN ALASKA...AND A SERIES OF
NORTH PACIFIC LOWS MOVES INTO THE GULF. THE FIRST OF THESE WILL BE
TRACKING THROUGH THE COPPER BASIN AT THE BEGINNING OF THE
WEEKEND...WITH ANOTHER LOW MOVING IN SOMETIME SUNDAY AFTERNOON
THROUGH SUNDAY NIGHT. THE TRACK REMAINS HIGHLY UNCERTAIN...WITH
THE ECMWF TAKING A MORE EASTERLY TRACK...AND THE GFS AND CANADIAN
GDPS FAVORING A WESTWARD TRACK INTO THE COPPER BASIN. THE IMPACT
WOULD BE THE POTENTIAL FOR ACCUMULATING SNOW SPREADING TO THE
WESTERN COPPER BASIN IN THE LATTER SOLUTIONS...WITH LITTLE TO NONE
IN THE FORMER SOLUTION. ONE CERTAINTY IS THE COLDEST AIR OF THE
SEASON WILL BE ADVECTING INTO SOUTHERN ALASKA. HIGH PRESSURE WILL
BUILD WEST TO EAST...WITH OVERNIGHT LOWS PLUMMETING AS SKIES CLEAR
IN THE WAKE OF THE UPPER LOW. UNCERTAINTY GROWS BY MIDWEEK AS A
SERIES OF STRONG LOWS ASSOCIATED WITH A POWERFUL NORTH PACIFIC JET
STREAM SLOWLY ERODE THE BLOCKING PATTERN OVER THE BERING AND TRACK
EAST.

-AHSENMACHER

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 119 120 130 131 132 138 150 155 172 174.
FIRE WEATHER...NONE.

&&

$$

OCT 14




000
FXAK68 PAFC 012153
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
153 PM AKDT WED OCT 1 2014

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL PATTERN IS INTERESTING TODAY WITH A RIDGE OVERT HE
BERING SEA AND A LOW CENTERED IN THE ARCTIC WHICH EXTENDS INTO
WESTERN CANADA. THIS IS PRODUCING ZONAL WEST TO NORTHWESTERLY
FLOW ALOFT OVER THE MAINLAND PART OF THE STATE. A CUT-OFF LOW IS
CENTERED WELL SOUTH OF THE ALASKA PENINSULA WITH THE JET STREAM
RUNNING AROUND IT TO THE SOUTH AND EAST AND THEN CLIPPING THE
GULF OF ALASKA AS IT TRACKS OVER SOUTHEAST ALASKA.
THIS CUT-OFF LOW WITH JET SUPPORT IS THE REASON THE SURFACE LOW
NEAR IT WILL STRENGTHEN AND THEN TRACK INTO THE GULF OF ALASKA.
THE MAINLAND OF THE STATE REMAINS UNDER A STRONG RIDGE OF HIGH
PRESSURE AT THE SURFACE.

&&

.MODEL DISCUSSION...
MODELS ARE HONING IN ON A COMMON SOLUTION FOR THE TRACK OF THE LOW
THAT IS CURRENTLY SOUTH OF THE ALASKA PENINSULA WHICH WILL BE
STRENGTHENING AND MOVING INTO THE GULF OF ALASKA TOMORROW AND THEN
TO THE NORTH GULF COAST FRIDAY. THE GFS IS A LITTLE FASTER IN ITS
PROGRESSION THROUGH THURSDAY NIGHT THAN THE ECMWF, NAM AND GEM
WHICH ARE ALL THREE CLUSTERED CLOSE TOGETHER. BY FRIDAY NIGHT THEY
ARE ALL IN AGREEMENT IN PUSHING THE UPPER LEVEL ENERGY NORTHEAST
INTO THE YUKON AND SPLITTING THE SURFACE LOW INTO TWO SEPARATE
LOWS. ONE FOLLOWING THE UPPER LEVEL LOW INTO THE YUKON AND THE
OTHER ALONG THE NORTH GULF COAST. THE NORTH GULF COAST LOW WILL
BECOME THE MAIN ONE AS COLD AIR FROM THE INTERIOR OF THE STATE
FILTERS INTO IT.
THERE ARE SOME SUBTLE DIFFERENCES IN THE MODELS IN TERMS OF
TEMPERATURES AND MOISTURE WHICH WILL BE IMPORTANT IN DETERMINING
PRECIPITATION TYPE IN THE COPPER RIVER BASIN AS WELL AS HAS FAR
WEST THE PRECIPITATION WILL MOVE.
THE NEXT CHALLENGE FOR THE
MODELS IN THE GULF OF ALASKA REGION WILL BE THIS WEEKEND AS
ANOTHER LOW DEVELOPS TO THE SOUTH OF THE ALASKA PENINSULA AND
TAKES A SIMILAR TRACK AS THE ONE MOVING INTO THE AREA THE NEXT TWO
DAYS. MODELS ALL HAVE THIS HAPPENING BUT THE TIMING AND STRENGTH
OF THIS LOW VARY GREATLY. THE RIDGE OF HIGH PRESSURE OVER THE
BERING SEA WILL PERSIST LARGELY UNCHANGED INTO THE WEEKEND.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
SUNNY SKIES WILL START TO GIVE WAY TO A FRONT APPROACHING FROM
THE SOUTH. THIS WILL START TONIGHT IN KODIAK AND THEN TOMORROW
NIGHT ALONG THE NORTH GULF COAST. BY THURSDAY NIGHT THE SURFACE
LOW WILL BE MOVING TOWARD THE GULF COAST WITH A COLD UPPER LEVEL
TROUGH DESCENDING OVER SOUTHCENTRAL FROM THE NORTH. THE RESULT
WILL BE TO BRING PRECIPITATION ALONG THE NORTH GULF COAST AND INTO
THE COPPER RIVER BASIN. PRECIPITATION TYPE WILL BE RAIN ALONG THE
COAST BUT THE BIG QUESTION WILL BE HOW MUCH COLD AIR WILL BE ABLE
TO MAKE IT INTO THE COPPER RIVER BASIN AND AT WHAT ELEVATION THE
SNOW WILL TURN TO RAIN. AT THIS TIME IT LOOKS LIKELY THAT THOMPSON
PASS, CHICKALOON PASS, MACLAREN PASS AND ISABEL PASS WILL BE COLD
ENOUGH TO SEE ACCUMULATING SNOWFALL FRIDAY AND FRIDAY NIGHT. THE
QUESTION IS WHETHER THIS WILL MAKE IT ALL THE WAY DOWN TO THE
GLENNALLEN AREA AND THIS IS WHERE THE SUBTLE DIFFERENCES IN THE
MODELS COMES INTO PLAY. TEMPERATURES ARE CLOSE TO WHAT THEY SHOULD
BE FOR SNOW BUT EARLY SEASON SITUATIONS OFTEN FAVOR RAIN. IT IS
POSSIBLE THAT THERE IS COLD RAIN IN THE LOWER PARTS OF THE COPPER
RIVER BASIN AND THE PASSES WILL SEE SNOWFALL. THE COLD AIR WILL
BUILD IN BETTER THIS WEEKEND OVER SOUTHCENTRAL ALASKA. THEREFORE
IF A SECONDARY LOW MOVES OVER THE COPPER RIVER BASIN SATURDAY INTO
SUNDAY THERE IS A BETTER CHANCE OF SNOW OVER THE ENTIRE AREA.
THERE IS A CHANCE...A CHANCE...THAT THE MOISTURE FROM THE COPPER
RIVER WILL MOVE FAR ENOUGH WESTWARD BY SATURDAY, IN CONJUNCTION
WITH THE COLDER AIR, TO BRING SOME SNOW PRETTY FAR DOWN THE
MOUNTAINS AROUND ANCHORAGE AND THE MAT-SU VALLEY.

SOUTHWEST ALASKA...
SOUTHWEST ALASKA IS UNDER THE STRONG RIDGE AND WILL REMAIN MOSTLY
CLEAR FOR THE NEXT FEW DAYS. THERE MAY BE A FEW CLOUDS TRACKING
ALONG THE NORTHERN PART OF THE AREA OVERNIGHT FROM A SHORT WAVE
MOVING THROUGH THE ZONAL FLOW OVER THE NORTHERN PART OF THE STATE.
MORE CLOUDS MAY ALSO SNEAK INTO THE AREA NEAR THE ALASKA RANGE BY
FRIDAY DUE TO AN UPPER LEVEL TROUGH DESCENDING OVER SOUTH CENTRAL
ALASKA AT THAT TIME.

BERING SEA/ALEUTIANS...
HIGH PRESSURE OVER THE CENTRAL BERING SEA WILL PERSIST INTO THE
WEEKEND. THERE IS A FRONT THAT IS BRUSHING UP TO THE EASTERN
ALEUTIANS AND ALASKA PENINSULA TODAY WHICH IS BRINGING SOME GUSTY
WINDS AND A CHANCE OF RAIN TO THE AREA THROUGH TONIGHT. THIS WILL
MOVE OUT OF THE AREA AS THE LOW THAT IS SOUTH OF THE AREA MOVES
INTO THE GULF OF ALASKA TOMORROW. WINDS WILL REMAIN SOMEWHAT GUSTY
BUT NOT AS STRONG AS TODAY AND THEY WILL ALSO SHIFT FROM MORE OF
AN EAST TO NORTHWEST DIRECTION TO THE NORTHWEST.
THE FAR WESTERN ALEUTIANS ARE ON THE OTHER SIDE OF THE RIDGE AND
WILL BE IMPACTED BY A FRONT FROM A LOW NEAR KAMCHATKA THOUGH
TOMORROW. THIS WILL BRING IN SOME GUSTY SOUTHEAST WINDS AND A
CHANCE OF RAIN.

&&

.LONG TERM FORECAST (SUN OCT 5 - WED OCT 8)...

THE EXTENDED FORECAST BECOMES INCREASINGLY COMPLEX AND CHALLENGING
AS A COLD UPPER LOW FORMS ACROSS SOUTHERN ALASKA...AND A SERIES OF
NORTH PACIFIC LOWS MOVES INTO THE GULF. THE FIRST OF THESE WILL BE
TRACKING THROUGH THE COPPER BASIN AT THE BEGINNING OF THE
WEEKEND...WITH ANOTHER LOW MOVING IN SOMETIME SUNDAY AFTERNOON
THROUGH SUNDAY NIGHT. THE TRACK REMAINS HIGHLY UNCERTAIN...WITH
THE ECMWF TAKING A MORE EASTERLY TRACK...AND THE GFS AND CANADIAN
GDPS FAVORING A WESTWARD TRACK INTO THE COPPER BASIN. THE IMPACT
WOULD BE THE POTENTIAL FOR ACCUMULATING SNOW SPREADING TO THE
WESTERN COPPER BASIN IN THE LATTER SOLUTIONS...WITH LITTLE TO NONE
IN THE FORMER SOLUTION. ONE CERTAINTY IS THE COLDEST AIR OF THE
SEASON WILL BE ADVECTING INTO SOUTHERN ALASKA. HIGH PRESSURE WILL
BUILD WEST TO EAST...WITH OVERNIGHT LOWS PLUMMETING AS SKIES CLEAR
IN THE WAKE OF THE UPPER LOW. UNCERTAINTY GROWS BY MIDWEEK AS A
SERIES OF STRONG LOWS ASSOCIATED WITH A POWERFUL NORTH PACIFIC JET
STREAM SLOWLY ERODE THE BLOCKING PATTERN OVER THE BERING AND TRACK
EAST.

-AHSENMACHER

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 119 120 130 131 132 138 150 155 172 174.
FIRE WEATHER...NONE.

&&

$$

OCT 14





000
FXAK68 PAFC 011359
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
559 AM AKDT WED OCT 1 2014

.ANALYSIS AND UPPER LEVELS...

COOL AND DRY CONDITIONS ARE BEING OBSERVED OVER MUCH OF
SOUTHCENTRAL AND THE SOUTHWEST MAINLAND...AS HIGH PRESSURE
CONTINUES TO BUILD IN FROM THE WEST. GAP WINDS AROUND PRINCE
WILLIAM SOUND HAVE DIMINISHED OVERNIGHT IN RESPONSE TO A WEAKENING
SURFACE PRESSURE GRADIENT AS WELL AS DIMINISHING NORTHWEST WINDS
ALOFT.

OUT WEST...THE PRESSURE GRADIENT HAS BEGUN TO TIGHTEN ACROSS THE
SOUTHERN BERING AND ALEUTIANS AS A VERTICALLY STACKED LOW IN THE
NORTH PACIFIC CONTINUES TO DRIFT NORTHWARD AND ENCOUNTER ENTRENCHED
HIGH PRESSURE IN THE NORTHERN BERING. AS A RESULT...GUSTY
EASTERLY WINDS AND GAP WINDS ARE CURRENTLY BEING OBSERVED OVER
PARTS OF THE AKPEN AND EASTERN ALEUTIANS. FURTHER WEST...A SLOW
MOVING FRONT ASSOCIATED WITH A LOW TRACKING ALONG THE KAMCHATKA
PENINSULA IS CURRENTLY BRINGING GUSTY WINDS AND RAIN TO THE FAR WESTERN
ALEUTIANS.

&&

.MODEL DISCUSSION...

MODELS REMAIN GOOD OVERALL AGREEMENT ON THE EVOLUTION OF THE
BASIC FEATURES THROUGHOUT THE SHORT TERM (84 HOUR) FORECAST
PERIOD. AS THE VERTICALLY STACKED LOW SOUTH OF THE ALEUTIANS
SLOWLY MOVES TOWARD THE GULF FOR THE LATTER HALF OF THE WEEK...A
STRONG SHORTWAVE AND ASSOCIATED REINFORCING SHOT OF COLD AIR WILL
DROP DOWN THE FRONT OF THE LARGE RIDGE OVER THE BERING SEA. AS
THESE TWO FEATURES COLLIDE IN THE NORTHERN GULF...THE MODELS ARE
STRUGGLING WITH THE TIMING...STRENGTH...AND PLACEMENT OF A SERIES
OF TRIPLE-POINT LOWS EXPECTED TO FORM ALONG THE OLD FRONTAL
BOUNDARY. THE OVERNIGHT RUNS TRENDED TOWARD A STRONGER LOW
CENTER IN THE GULF BY THURSDAY AFTERNOON...BUT WITH THE ONGOING
UNCERTAINTY AMONG THE MODELS...THE MORNING FORECAST WILL SHOW A
MORE CAUTIOUS TREND TOWARD A DEEPER LOW. THE 00Z GFS BECAME THE OUTLIER
REGARDING THIS FEATURE...AS IT WAS BOTH THE WEAKER AND SLOWER
SOLUTION WITH THE TRIPLE POINT LOW TRACKING THROUGH THE GULF
THURSDAY AFTERNOON THROUGH FRIDAY AFTERNOON. THUS...THE EASTERN
DOMAIN FAVORED A BLEND TOWARD THE ECMWF SOLUTION. HOWEVER...THE
GFS REMAINED THE PREFERRED SOLUTION OVER THE WESTERN DOMAIN WITH
BETTER RUN TO RUN CONSISTENCY REGARDING THE VERTICALLY STACKED
SYSTEMS SOUTH OF THE ALEUTIANS AND ALSO EAST OF THE KAMCHATKA
PENINSULA.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
COOL AND DRY CONDITIONS WITH DIMINISHING WINDS ARE EXPECTED TO
CONTINUE ACROSS MUCH OF SOUTHCENTRAL ALASKA THROUGH THURSDAY
MORNING. STRONG EASTERLY WINDS AND INCREASED CLOUD COVER IN
ADVANCE OF THE APPROACHING LOW WILL START PUSHING TOWARD THE
SOUTHERN GULF DURING THE DAY THURSDAY. GALES WILL CONTINUE TO
SPREAD NORTH WITH THE TRIPLE POINT ON THURSDAY NIGHT AND LOCAL GAP
FLOWS WILL REDEVELOP ACROSS THE SOUTHERN MAINLAND WITH INCREASING
PRESSURE AND TEMPERATURE GRADIENTS. PRECIPITATION SHOULD BEGIN TO
ENCROACH ON THE NORTHERN GULF COAST THURSDAY NIGHT...AND SPREAD
INLAND AS EARLY AS FRIDAY MORNING OVER THE EASTERN COPPER RIVER
BASIN. THE WESTWARD EXTENT AND CHARACTER OF THE PRECIPITATION
INLAND ON FRIDAY IS STILL UNCERTAIN GIVEN THE CURRENT MODEL DIFFERENCES.
HOWEVER...IT SEEMS THAT THE NORTHERN GULF COAST WILL MAINLY
EXPERIENCE RAIN AND THE COPPER RIVER BASIN COULD SEE A MIX OF BOTH
RAIN AND SNOW FRIDAY.

SOUTHWEST ALASKA...COOL AND DRY CONDITIONS ARE EXPECTED TO
CONTINUE OVER THE AREA THROUGH EARLY THURSDAY MORNING WITH
RIDGING OVER MUCH OF THE SOUTHWEST MAINLAND AND LOW PRESSURE
ENTERING THE GULF. GUSTY WINDS ALONG THE ALASKA PENINSULA AND
EASTERN ALEUTIANS WILL PERSIST AND EVEN STRENGTHEN THROUGH
THURSDAY...AS THE LOW SOUTH THE ALEUTIAN CHAIN TRACKS NORTHEAST
AND TIGHTENS THE PRESSURE GRADIENT UP OVER THE AREA.

BERING SEA/ALEUTIANS...RAIN AND WIND WILL CONTINUE BRUSH THE
EASTERN ALEUTIAN ISLANDS AS THE LOW CONTINUES TO SLOWLY TRACK
EASTWARD. OTHERWISE HIGH PRESSURE WILL DOMINATE OVER MUCH OF THE
CENTRAL AND EASTERN BERING SEA....CONTINUING THE SPLIT-FLOW
BLOCKING PATTERN AND PROVIDING VERY QUIET CONDITIONS FOR MOST OF
THE REGION. A VERTICALLY STACKED LOW EAST OF KAMCHATKA AND
ASSOCIATED FRONT WILL BRING WET AND WINDY CONDITIONS TO THE
WESTERN MOST ALEUTIANS THROUGH FRIDAY MORNING.

&&

.LONG TERM FORECAST (SAT OCT 4 - TUE OCT 7)...

BEGINNING THE EXTENDED PERIOD SATURDAY...A HIGHLY AMPLIFIED
PATTERN WILL CONTINUE ACROSS THE REGION...WITH A BLOCKING RIDGE
EXTENDING FROM THE BERING NORTHWARD INTO SIBERIA...AND A LONGWAVE
TROUGH OVER THE STATE OF ALASKA. EVENTUALLY THE TROUGH WILL
DEVELOP INTO A CLOSED VORTEX ALOFT OVER SOUTHERN ALASKA AND WILL
REMAIN IN PLACE THROUGH TUESDAY. WHILE THERE WILL NOT BE A
SUBTROPICAL CONNECTION...WEAK DISTURBANCES ROTATING AROUND THE
PERIPHERY OF THE LOW WILL SUPPORT RAIN AND SNOW CHANCES ACROSS
PORTIONS OF SOUTHERN ALASKA MAINLY EAST OF THE ALASKA AND ALEUTIAN
RANGES. THE BEST CHANCES FOR RAIN...THEN SNOW...WILL BE ACROSS THE
COPPER BASIN. ARCTIC AIR WILL CONTINUE TO FILTER INTO SOUTHERN
ALASKA THROUGH THE WEEKEND...WITH GRADUALLY COOLING TEMPERATURES.
RIGHT NOW...THE COLDEST TEMPERATURES WILL LIKELY DEVELOP ON MONDAY
AND TUESDAY AS THE UPPER VORTEX SLOWLY TRANSLATES EAST AND COLDER
AIR AND CLEARER SKIES FORM ACROSS THE STATE.


&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 132 150 155 172 174
FIRE WEATHER...NONE.

&&

$$

TP SEP 14




000
FXAK68 PAFC 011359
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
559 AM AKDT WED OCT 1 2014

.ANALYSIS AND UPPER LEVELS...

COOL AND DRY CONDITIONS ARE BEING OBSERVED OVER MUCH OF
SOUTHCENTRAL AND THE SOUTHWEST MAINLAND...AS HIGH PRESSURE
CONTINUES TO BUILD IN FROM THE WEST. GAP WINDS AROUND PRINCE
WILLIAM SOUND HAVE DIMINISHED OVERNIGHT IN RESPONSE TO A WEAKENING
SURFACE PRESSURE GRADIENT AS WELL AS DIMINISHING NORTHWEST WINDS
ALOFT.

OUT WEST...THE PRESSURE GRADIENT HAS BEGUN TO TIGHTEN ACROSS THE
SOUTHERN BERING AND ALEUTIANS AS A VERTICALLY STACKED LOW IN THE
NORTH PACIFIC CONTINUES TO DRIFT NORTHWARD AND ENCOUNTER ENTRENCHED
HIGH PRESSURE IN THE NORTHERN BERING. AS A RESULT...GUSTY
EASTERLY WINDS AND GAP WINDS ARE CURRENTLY BEING OBSERVED OVER
PARTS OF THE AKPEN AND EASTERN ALEUTIANS. FURTHER WEST...A SLOW
MOVING FRONT ASSOCIATED WITH A LOW TRACKING ALONG THE KAMCHATKA
PENINSULA IS CURRENTLY BRINGING GUSTY WINDS AND RAIN TO THE FAR WESTERN
ALEUTIANS.

&&

.MODEL DISCUSSION...

MODELS REMAIN GOOD OVERALL AGREEMENT ON THE EVOLUTION OF THE
BASIC FEATURES THROUGHOUT THE SHORT TERM (84 HOUR) FORECAST
PERIOD. AS THE VERTICALLY STACKED LOW SOUTH OF THE ALEUTIANS
SLOWLY MOVES TOWARD THE GULF FOR THE LATTER HALF OF THE WEEK...A
STRONG SHORTWAVE AND ASSOCIATED REINFORCING SHOT OF COLD AIR WILL
DROP DOWN THE FRONT OF THE LARGE RIDGE OVER THE BERING SEA. AS
THESE TWO FEATURES COLLIDE IN THE NORTHERN GULF...THE MODELS ARE
STRUGGLING WITH THE TIMING...STRENGTH...AND PLACEMENT OF A SERIES
OF TRIPLE-POINT LOWS EXPECTED TO FORM ALONG THE OLD FRONTAL
BOUNDARY. THE OVERNIGHT RUNS TRENDED TOWARD A STRONGER LOW
CENTER IN THE GULF BY THURSDAY AFTERNOON...BUT WITH THE ONGOING
UNCERTAINTY AMONG THE MODELS...THE MORNING FORECAST WILL SHOW A
MORE CAUTIOUS TREND TOWARD A DEEPER LOW. THE 00Z GFS BECAME THE OUTLIER
REGARDING THIS FEATURE...AS IT WAS BOTH THE WEAKER AND SLOWER
SOLUTION WITH THE TRIPLE POINT LOW TRACKING THROUGH THE GULF
THURSDAY AFTERNOON THROUGH FRIDAY AFTERNOON. THUS...THE EASTERN
DOMAIN FAVORED A BLEND TOWARD THE ECMWF SOLUTION. HOWEVER...THE
GFS REMAINED THE PREFERRED SOLUTION OVER THE WESTERN DOMAIN WITH
BETTER RUN TO RUN CONSISTENCY REGARDING THE VERTICALLY STACKED
SYSTEMS SOUTH OF THE ALEUTIANS AND ALSO EAST OF THE KAMCHATKA
PENINSULA.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
COOL AND DRY CONDITIONS WITH DIMINISHING WINDS ARE EXPECTED TO
CONTINUE ACROSS MUCH OF SOUTHCENTRAL ALASKA THROUGH THURSDAY
MORNING. STRONG EASTERLY WINDS AND INCREASED CLOUD COVER IN
ADVANCE OF THE APPROACHING LOW WILL START PUSHING TOWARD THE
SOUTHERN GULF DURING THE DAY THURSDAY. GALES WILL CONTINUE TO
SPREAD NORTH WITH THE TRIPLE POINT ON THURSDAY NIGHT AND LOCAL GAP
FLOWS WILL REDEVELOP ACROSS THE SOUTHERN MAINLAND WITH INCREASING
PRESSURE AND TEMPERATURE GRADIENTS. PRECIPITATION SHOULD BEGIN TO
ENCROACH ON THE NORTHERN GULF COAST THURSDAY NIGHT...AND SPREAD
INLAND AS EARLY AS FRIDAY MORNING OVER THE EASTERN COPPER RIVER
BASIN. THE WESTWARD EXTENT AND CHARACTER OF THE PRECIPITATION
INLAND ON FRIDAY IS STILL UNCERTAIN GIVEN THE CURRENT MODEL DIFFERENCES.
HOWEVER...IT SEEMS THAT THE NORTHERN GULF COAST WILL MAINLY
EXPERIENCE RAIN AND THE COPPER RIVER BASIN COULD SEE A MIX OF BOTH
RAIN AND SNOW FRIDAY.

SOUTHWEST ALASKA...COOL AND DRY CONDITIONS ARE EXPECTED TO
CONTINUE OVER THE AREA THROUGH EARLY THURSDAY MORNING WITH
RIDGING OVER MUCH OF THE SOUTHWEST MAINLAND AND LOW PRESSURE
ENTERING THE GULF. GUSTY WINDS ALONG THE ALASKA PENINSULA AND
EASTERN ALEUTIANS WILL PERSIST AND EVEN STRENGTHEN THROUGH
THURSDAY...AS THE LOW SOUTH THE ALEUTIAN CHAIN TRACKS NORTHEAST
AND TIGHTENS THE PRESSURE GRADIENT UP OVER THE AREA.

BERING SEA/ALEUTIANS...RAIN AND WIND WILL CONTINUE BRUSH THE
EASTERN ALEUTIAN ISLANDS AS THE LOW CONTINUES TO SLOWLY TRACK
EASTWARD. OTHERWISE HIGH PRESSURE WILL DOMINATE OVER MUCH OF THE
CENTRAL AND EASTERN BERING SEA....CONTINUING THE SPLIT-FLOW
BLOCKING PATTERN AND PROVIDING VERY QUIET CONDITIONS FOR MOST OF
THE REGION. A VERTICALLY STACKED LOW EAST OF KAMCHATKA AND
ASSOCIATED FRONT WILL BRING WET AND WINDY CONDITIONS TO THE
WESTERN MOST ALEUTIANS THROUGH FRIDAY MORNING.

&&

.LONG TERM FORECAST (SAT OCT 4 - TUE OCT 7)...

BEGINNING THE EXTENDED PERIOD SATURDAY...A HIGHLY AMPLIFIED
PATTERN WILL CONTINUE ACROSS THE REGION...WITH A BLOCKING RIDGE
EXTENDING FROM THE BERING NORTHWARD INTO SIBERIA...AND A LONGWAVE
TROUGH OVER THE STATE OF ALASKA. EVENTUALLY THE TROUGH WILL
DEVELOP INTO A CLOSED VORTEX ALOFT OVER SOUTHERN ALASKA AND WILL
REMAIN IN PLACE THROUGH TUESDAY. WHILE THERE WILL NOT BE A
SUBTROPICAL CONNECTION...WEAK DISTURBANCES ROTATING AROUND THE
PERIPHERY OF THE LOW WILL SUPPORT RAIN AND SNOW CHANCES ACROSS
PORTIONS OF SOUTHERN ALASKA MAINLY EAST OF THE ALASKA AND ALEUTIAN
RANGES. THE BEST CHANCES FOR RAIN...THEN SNOW...WILL BE ACROSS THE
COPPER BASIN. ARCTIC AIR WILL CONTINUE TO FILTER INTO SOUTHERN
ALASKA THROUGH THE WEEKEND...WITH GRADUALLY COOLING TEMPERATURES.
RIGHT NOW...THE COLDEST TEMPERATURES WILL LIKELY DEVELOP ON MONDAY
AND TUESDAY AS THE UPPER VORTEX SLOWLY TRANSLATES EAST AND COLDER
AIR AND CLEARER SKIES FORM ACROSS THE STATE.


&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 132 150 155 172 174
FIRE WEATHER...NONE.

&&

$$

TP SEP 14





000
FXAK68 PAFC 302151
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
151 PM AKDT TUE SEP 30 2014

.ANALYSIS AND UPPER LEVELS...

SNOW SHOWERS ASSOCIATED WITH AN UPPER WAVE WERE EVIDENT ALONG THE
EASTERN ALASKA RANGE. LOW VFR CONDITIONS WITH STRATUS ASSOCIATED
WITH SUBSIDENCE WAS EVIDENT OVER THE KUSKOKWIM DELTA. THE
REMAINDER OF THE MAINLAND WAS UNDER FAIR SKIES WITH RELATIVELY
COOL AND DRY NORTHERLY FLOW. OUTFLOW WINDS ACROSS
SOUTHCENTRAL...ESPECIALLY THE GULF...PEAKED OVERNIGHT AND ARE ON
THE DECLINE. THE PINCH IN PRESSURE GRADIENT BETWEEN THE EASTERN
BERING RIDGE AND THE LOW COMPLEX OVER THE NORTH PACIFIC CONTINUED BRISK
EASTERLY WINDS ACROSS THE AK PEN...EAST ALEUTIANS/EASTERN BERING
SEA.

&&

.MODEL DISCUSSION...
ALOFT...MODELS HAVE SIMILAR PHASING OF THE TROUGH OVER THE
MAINLAND AND THE CUT-OFF LOW OVER THE NORTH PACIFIC. THIS SOLUTION
SEEMS REASONABLE AS COLD AIR SHOULD DIVE SOUTH ALONG THE FORWARD
SIDE OF AN AMPLIFYING UPPER RIDGE OVER THE EASTERN BERING SEA AND
SHARPEN THE MAINLAND TROUGH. THIS EFFECTIVELY PINCHES OFF THE
BERING SEA RIDGE ON THU AND CREATES A WEAKNESS IN THE HEIGHT
FIELDS WHICH ALLOWS THE NORTH PACIFIC CUT-OFF LOW TO PROGRESS
NORTH.

SURFACE FEATURES HOWEVER ARE MORE PROBLEMATIC WITH RESPECT TO
TIMING...INTENSITY...AND POSITION. OVERALL...THERE SHOULD BE A
FAIRLY STRONG TRIPLE POINT FEATURE SPAWNING OFF THE THE BAROCLINIC
ZONE ASSOCIATED WITH THE CUT-OFF OVER THE NORTH PACIFIC. ALL
MODELS SHOW A FAIRLY GOOD LEFT EXIT JET POSITION OVER THE DEVELOPING
TRIPLE POINT WHICH HEADS INTO THE NORTHERN GULF THU NIGHT/FRI
MORNING. THE 00Z NAM IS THE FASTEST IN MOVING THIS FEATURE NORTH
WITH THE GLOBAL MODELS SOMEWHAT SLOWER. THERE IS A GENERAL
CONSENSUS FOR A FAIRLY STRONG LOW OVER THE NORTHEASTERN GULF FRI.
FOR NOW WILL CONTINUE WITH OFFICIAL GRIDS WITH BLEND OF THE GEM
GLOBAL/GFS IN THE GULF KEEPING GALES WITH THIS FEATURE FOR NOW.
OUT WEST...MODELS HAVE SIMILAR HANDING OF FEATURES...SO IN GENERAL
WILL LEAN TOWARD THE GFS.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
COOL AND DRY CONDITIONS WITH DIMINISHING WINDS ARE EXPECTED
ACROSS SOUTHCENTRAL OVER THE NEXT COUPLE OF DAYS. STRONG EASTERLY
WINDS AND INCREASED CLOUD COVER IN ADVANCE OF APPROACHING TRIPLE
POINT WILL START PUSHING TOWARD THE SOUTHERN GULF ON THU. GALES
WILL CONTINUE TO SPREAD NORTH WITH THE TRIPLE POINT ON THU NIGHT
AND LOCAL GAP FLOWS WILL DEVELOP ACROSS THE SOUTHERN MAINLAND WITH
INCREASING PRESSURE AND TEMP GRADIENTS. MOISTURE SHOULD SPREAD
INTO THE SOUTHEASTERN COPPER RIVER BASIN AND GULF COAST THU NIGHT
THEN SPREAD WEST ON FRI.  THE WESTWARD EXTENT OF THE MOISTURE
PUSH AND CHARACTER OF PRECIPITATION INLAND ON FRI IS STILL
UNCERTAIN WITH CURRENT MODELS DIFFERENCES. HOWEVER AT THIS
TIME...IT APPEARS THAT THE COAST WILL BE MAINLY RAIN AND THE
COPPER RIVER BASIN LIKELY WILL HAVE SNOW OR A MIX.

SOUTHWEST ALASKA...WHAT LITTLE STRATUS MOVED IN OVER THE DELTA
THIS MORNING SHOULD MOVE SOUTH AS THE NORTHERLY OFFSHORE
STRENGTHEN. EXPECT RELATIVELY DRY AND COOL CONDITIONS TO LAST
OVER THE NEXT COUPLE OF DAYS WITH RIDGING OVER THE MAINLAND AND
LOW PRESSURE IN THE GULF. ALSO EXPECT WINDS CONDITIONS TO PERSIST
AND EVEN STRENGTHEN SOME OVER THE AK PEN THROUGH THU. WILL ALSO
SEE SOME LOCALLY BRISK WINDS OVER BRISTOL BAY.

BERING SEA/ALEUTIANS...RAIN AND WIND WILL CONTINUE TO JUST BARELY
BRUSH THE ALEUTIAN ISLANDS AS THE LOW CONTINUES TO SLOWLY TRACK
TO THE EAST. OTHERWISE HIGH PRESSURE WILL BUILD OVER THE CENTRAL
BERING SEA AND CONTINUE TO STRENGTHEN THROUGH MID
WEEK...CONTINUING THE SPLIT-FLOW BLOCKING PATTERN AND PROVIDING
VERY QUIET CONDITIONS FOR MOST OF THE REGION.

&&

.LONG TERM FORECAST (SAT OCT 4 - TUE OCT 7)...

BEGINNING THE EXTENDED PERIOD SATURDAY...A HIGHLY AMPLIFIED
PATTERN WILL CONTINUE ACROSS THE REGION...WITH A BLOCKING RIDGE
EXTENDING FROM THE BERING NORTHWARD INTO SIBERIA...AND A LONGWAVE
TROUGH OVER THE STATE OF ALASKA. EVENTUALLY THE TROUGH WILL
DEVELOP INTO A CLOSED VORTEX ALOFT OVER SOUTHERN ALASKA AND WILL
REMAIN IN PLACE THROUGH TUESDAY. WHILE THERE WILL NOT BE A
SUBTROPICAL CONNECTION...WEAK DISTURBANCES ROTATING AROUND THE
PERIPHERY OF THE LOW WILL SUPPORT RAIN AND SNOW CHANCES ACROSS
PORTIONS OF SOUTHERN ALASKA MAINLY EAST OF THE ALASKA AND ALEUTIAN
RANGES. THE BEST CHANCES FOR RAIN...THEN SNOW...WILL BE ACROSS THE
COPPER BASIN. ARCTIC AIR WILL CONTINUE TO FILTER INTO SOUTHERN
ALASKA THROUGH THE WEEKEND...WITH GRADUALLY COOLING TEMPERATURES.
RIGHT NOW...THE COLDEST TEMPERATURES WILL LIKELY DEVELOP ON MONDAY
AND TUESDAY AS THE UPPER VORTEX SLOWLY TRANSLATES EAST AND COLDER
AIR AND CLEARER SKIES FORM ACROSS THE STATE.

- AHSENMACHER

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...150 155 172 174.
FIRE WEATHER...NONE.

&&

$$

RMC/AHSENMACHER SEP 14





000
FXAK68 PAFC 301346 AAA
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ANCHORAGE AK
546 AM AKDT TUE SEP 30 2014

ANALYSIS AND UPPER LEVELS...WATER VAPOR SATELLITE IMAGERY THIS
MORNING INDICATED THE ARCTIC TROUGH IN SOUTHERN ALASKA HAS CLOSED
OFF INTO A WEAK UPPER LEVEL CIRCULATION...WITH ASSOCIATED SURFACE
CIRCULATION MOVING QUICKLY INTO THE NORTHERN PANHANDLE. AS
EXPECTED...STRONG GAP FLOW AROUND PRINCE WILLIAM SOUND PEAKED
EARLIER THIS MORNING...WITH OBSERVATIONS SHOWING A STEADY DECLINE
IN THOSE WINDS AS THE TROUGH PUSHES OFF FURTHER TO THE EAST.
MEANWHILE...HIGH PRESSURE CONTINUES TO SLOWLY BUILD INTO FROM THE
WEST.

FURTHER WEST...AN UPPER RIDGE PERSISTS OVER THE NORTHERN BERING
SEA...WITH A VERTICALLY STACKED LOW NEARLY STATIONARY WELL SOUTH
OF THE ALEUTIANS. LIGHT RAIN AND GUSTY WINDS ON THE FRINGES OF
THIS SYSTEM ARE BEING OBSERVED ACROSS THE EASTERN HALF OF THE
ALEUTIAN CHAIN.

&&

MODEL DISCUSSION...THE MODELS REMAIN IN GOOD SYNOPTIC AGREEMENT AT
BOTH THE SURFACE AND UPPER LEVELS THROUGHOUT MUCH OF THE SHORT-
TERM (84 HOUR) FORECAST PERIOD. HOWEVER...DIFFERENCES DO ARISE
EARLY THURSDAY MORNING SOUTH OF THE GULF WITH THE HANDLING OF THE
NEXT LOW COMPLEX. THE MODELS GENERALLY SHOW THE REMNANTS OF AN OLD
TROPICAL SYSTEM (KAMMURI) WITH AMPLE MOISTURE BECOMING ABSORBED BY
THE LOW CURRENTLY SOUTH OF THE CENTRAL ALEUTIANS. AS EXPECTED THE
MODELS CONTINUE TO STRUGGLE WITH THIS COMPLEX SYSTEM AS IT TRACKS
SLOWLY NORTHEASTWARD TOWARD THE SOUTHERN GULF. THE FORECAST
CHALLENGE WITH THIS SYSTEM WILL BE IF AND WHERE A TRIPLE POINT
CIRCULATION FORMS ON THURSDAY...AND HOW DEEP/STRONG IT WILL GET.
WITH THIS BEING AT THE END OF THE SHORT TERM AND HAVING SUCH MODEL
SPREAD AT THAT TIME FRAME...FORECAST CONFIDENCE REMAINS LOW
REGARDING THE KEY DETAILS OF THIS EVOLUTION. THE GEM GLOBAL WAS
THE PREFERRED SOLUTION OVERALL WITH THIS SYSTEM AND IS FAIRLY
CLOSE TO THE GFS ENSEMBLE MEAN AND WPC SOLUTIONS.

PRIOR TO 60 HOURS...THE NAM WAS MAINLY UTILIZED OVER THE EAST
DOMAIN TO CONTINUE CAPTURING THE ONGOING GAP WINDS. THE ECMWF
SOLUTION WAS PREFERRED OVER THE WESTERN DOMAIN FOR THE MORNING
PACKAGE FOR SUPERIOR RUN-TO-RUN CONSISTENCY.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...SUBSIDENCE BEHIND THE DEPARTING UPPER LEVEL
WAVE COUPLED WITH TIGHT PRESSURE GRADIENTS LED TO GUSTY
CONDITIONS AND STRONG GAP FLOW OVER PRINCE WILLIAM SOUND AND PARTS
OF SOUTHCENTRAL OVERNIGHT. WINDS HAVE NOW PEAKED AT MANY
LOCATIONS...AND WILL GRADUALLY DIMINISH THROUGHOUT THE DAY TODAY
AS THE UPPER LEVEL TROUGH CONTINUES TO MOVE AWAY. PRECIPITATION
ASSOCIATED WITH THIS FEATURE IS LIMITED TO THE FAR EASTERN COPPER
RIVER BASIN...AND EVEN THIS WILL RAPIDLY DIMINISH BY LATER THIS
MORNING AS COLDER AND DRIER AIR MOVES IN FROM THE WEST.

SOUTHWEST ALASKA...CONDITIONS WILL BE RELATIVELY DRY ACROSS
THE SOUTHWEST MAINLAND OVER THE NEXT COUPLE OF DAYS AS HIGH
PRESSURE REMAINS OVER THE AREA. AN ONSHORE COMPONENT OF THE WINDS
ACROSS THE KUSKOKWIM DELTA WILL KEEP THE POTENTIAL FOR A LITTLE
FOG AROUND THE AREA THROUGH THIS EVENING. HOWEVER...INCREASINGLY
OFFSHORE FLOW BY LATE THIS AFTERNOON WILL LIKELY HAMPER ANY FOG
FORMATION/ADVECTION OVER THE MAJORITY OF THE AREA OVER THE NEXT
DAY OR SO. MEANWHILE...BRISK (BUT MOSTLY DRY) EASTERLY FLOW
ASSOCIATED WITH A LOW COMPLEX OVER THE NORTH PACIFIC WILL CONTINUE
ACROSS THE AK PEN THROUGH WED.

BERING SEA/ALEUTIANS...RAIN AND WIND WILL CONTINUE TO JUST BARELY
BRUSH THE ALEUTIAN ISLANDS AS THE LOW CONTINUES TO SLOWLY TRACK
TO THE EAST. OTHERWISE HIGH PRESSURE WILL BUILD OVER THE CENTRAL
BERING SEA AND CONTINUE TO STRENGTHEN THROUGH MID
WEEK...CONTINUING THE SPLIT-FLOW BLOCKING PATTERN AND PROVIDING
VERY QUIET CONDITIONS FOR MOST OF THE REGION.

&&

.LONG TERM FORECAST (FRI OCT 3 - MON OCT 6)...

ON FRIDAY...A HIGHLY AMPLIFIED PATTERN WILL BE DEVELOPING ACROSS
THE REGION...WITH A BLOCKING RIDGE ACROSS THE CENTRAL BERING
EXTENDING INTO SIBERIA...AND A LARGE TROUGH ACROSS THE MAINLAND.
ARCTIC AIR WILL ACCOMPANY THE TROUGH...WITH STEADILY DROPPING
TEMPERATURES HEADING INTO THE WEEKEND. THE PATTERN WILL GENERALLY
BE DRY...BUT THERE IS THE THREAT FOR SNOW AND SNOW SHOWERS ACROSS
MOST OF SOUTHCENTRAL BY THE WEEKEND...ESPECIALLY ACROSS THE COPPER
BASIN. THERE REMAINS UNCERTAINTY WITH A LOW MOVING THROUGH THE
EASTERN GULF OF ALASKA...SO A CONSERVATIVE MIDDLE GROUND APPROACH
WAS TAKEN WITH THE PRECIPITATION FORECAST. BY MONDAY...UNCERTAINTY
IN THE PATTERN GROWS IN MAGNITUDE QUICKLY AS THE TRACK OF
NORTHWEST PACIFIC CYCLONES (POSSIBLY INCLUDING RECURVING REMNANTS
OF PACIFIC TROPICAL CYCLONES) MOVING INTO THE BERING BECOMES
HIGHLY ERRATIC...THUS RESULTING IN SYNOPTIC SCALE DISAGREEMENT
AMONG THE VARIOUS GLOBAL NUMERICAL MODELS. WITH THAT SAID...THE
COLDEST TEMPS OF THE FALL CAN BE EXPECTED BY THIS WEEKEND.


&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...119 127 128 150 155 172 174.
FIRE WEATHER...NONE.

&&

$$

TP SEP 14





000
FXAK68 PAFC 301346 AAA
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ANCHORAGE AK
546 AM AKDT TUE SEP 30 2014

ANALYSIS AND UPPER LEVELS...WATER VAPOR SATELLITE IMAGERY THIS
MORNING INDICATED THE ARCTIC TROUGH IN SOUTHERN ALASKA HAS CLOSED
OFF INTO A WEAK UPPER LEVEL CIRCULATION...WITH ASSOCIATED SURFACE
CIRCULATION MOVING QUICKLY INTO THE NORTHERN PANHANDLE. AS
EXPECTED...STRONG GAP FLOW AROUND PRINCE WILLIAM SOUND PEAKED
EARLIER THIS MORNING...WITH OBSERVATIONS SHOWING A STEADY DECLINE
IN THOSE WINDS AS THE TROUGH PUSHES OFF FURTHER TO THE EAST.
MEANWHILE...HIGH PRESSURE CONTINUES TO SLOWLY BUILD INTO FROM THE
WEST.

FURTHER WEST...AN UPPER RIDGE PERSISTS OVER THE NORTHERN BERING
SEA...WITH A VERTICALLY STACKED LOW NEARLY STATIONARY WELL SOUTH
OF THE ALEUTIANS. LIGHT RAIN AND GUSTY WINDS ON THE FRINGES OF
THIS SYSTEM ARE BEING OBSERVED ACROSS THE EASTERN HALF OF THE
ALEUTIAN CHAIN.

&&

MODEL DISCUSSION...THE MODELS REMAIN IN GOOD SYNOPTIC AGREEMENT AT
BOTH THE SURFACE AND UPPER LEVELS THROUGHOUT MUCH OF THE SHORT-
TERM (84 HOUR) FORECAST PERIOD. HOWEVER...DIFFERENCES DO ARISE
EARLY THURSDAY MORNING SOUTH OF THE GULF WITH THE HANDLING OF THE
NEXT LOW COMPLEX. THE MODELS GENERALLY SHOW THE REMNANTS OF AN OLD
TROPICAL SYSTEM (KAMMURI) WITH AMPLE MOISTURE BECOMING ABSORBED BY
THE LOW CURRENTLY SOUTH OF THE CENTRAL ALEUTIANS. AS EXPECTED THE
MODELS CONTINUE TO STRUGGLE WITH THIS COMPLEX SYSTEM AS IT TRACKS
SLOWLY NORTHEASTWARD TOWARD THE SOUTHERN GULF. THE FORECAST
CHALLENGE WITH THIS SYSTEM WILL BE IF AND WHERE A TRIPLE POINT
CIRCULATION FORMS ON THURSDAY...AND HOW DEEP/STRONG IT WILL GET.
WITH THIS BEING AT THE END OF THE SHORT TERM AND HAVING SUCH MODEL
SPREAD AT THAT TIME FRAME...FORECAST CONFIDENCE REMAINS LOW
REGARDING THE KEY DETAILS OF THIS EVOLUTION. THE GEM GLOBAL WAS
THE PREFERRED SOLUTION OVERALL WITH THIS SYSTEM AND IS FAIRLY
CLOSE TO THE GFS ENSEMBLE MEAN AND WPC SOLUTIONS.

PRIOR TO 60 HOURS...THE NAM WAS MAINLY UTILIZED OVER THE EAST
DOMAIN TO CONTINUE CAPTURING THE ONGOING GAP WINDS. THE ECMWF
SOLUTION WAS PREFERRED OVER THE WESTERN DOMAIN FOR THE MORNING
PACKAGE FOR SUPERIOR RUN-TO-RUN CONSISTENCY.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...SUBSIDENCE BEHIND THE DEPARTING UPPER LEVEL
WAVE COUPLED WITH TIGHT PRESSURE GRADIENTS LED TO GUSTY
CONDITIONS AND STRONG GAP FLOW OVER PRINCE WILLIAM SOUND AND PARTS
OF SOUTHCENTRAL OVERNIGHT. WINDS HAVE NOW PEAKED AT MANY
LOCATIONS...AND WILL GRADUALLY DIMINISH THROUGHOUT THE DAY TODAY
AS THE UPPER LEVEL TROUGH CONTINUES TO MOVE AWAY. PRECIPITATION
ASSOCIATED WITH THIS FEATURE IS LIMITED TO THE FAR EASTERN COPPER
RIVER BASIN...AND EVEN THIS WILL RAPIDLY DIMINISH BY LATER THIS
MORNING AS COLDER AND DRIER AIR MOVES IN FROM THE WEST.

SOUTHWEST ALASKA...CONDITIONS WILL BE RELATIVELY DRY ACROSS
THE SOUTHWEST MAINLAND OVER THE NEXT COUPLE OF DAYS AS HIGH
PRESSURE REMAINS OVER THE AREA. AN ONSHORE COMPONENT OF THE WINDS
ACROSS THE KUSKOKWIM DELTA WILL KEEP THE POTENTIAL FOR A LITTLE
FOG AROUND THE AREA THROUGH THIS EVENING. HOWEVER...INCREASINGLY
OFFSHORE FLOW BY LATE THIS AFTERNOON WILL LIKELY HAMPER ANY FOG
FORMATION/ADVECTION OVER THE MAJORITY OF THE AREA OVER THE NEXT
DAY OR SO. MEANWHILE...BRISK (BUT MOSTLY DRY) EASTERLY FLOW
ASSOCIATED WITH A LOW COMPLEX OVER THE NORTH PACIFIC WILL CONTINUE
ACROSS THE AK PEN THROUGH WED.

BERING SEA/ALEUTIANS...RAIN AND WIND WILL CONTINUE TO JUST BARELY
BRUSH THE ALEUTIAN ISLANDS AS THE LOW CONTINUES TO SLOWLY TRACK
TO THE EAST. OTHERWISE HIGH PRESSURE WILL BUILD OVER THE CENTRAL
BERING SEA AND CONTINUE TO STRENGTHEN THROUGH MID
WEEK...CONTINUING THE SPLIT-FLOW BLOCKING PATTERN AND PROVIDING
VERY QUIET CONDITIONS FOR MOST OF THE REGION.

&&

.LONG TERM FORECAST (FRI OCT 3 - MON OCT 6)...

ON FRIDAY...A HIGHLY AMPLIFIED PATTERN WILL BE DEVELOPING ACROSS
THE REGION...WITH A BLOCKING RIDGE ACROSS THE CENTRAL BERING
EXTENDING INTO SIBERIA...AND A LARGE TROUGH ACROSS THE MAINLAND.
ARCTIC AIR WILL ACCOMPANY THE TROUGH...WITH STEADILY DROPPING
TEMPERATURES HEADING INTO THE WEEKEND. THE PATTERN WILL GENERALLY
BE DRY...BUT THERE IS THE THREAT FOR SNOW AND SNOW SHOWERS ACROSS
MOST OF SOUTHCENTRAL BY THE WEEKEND...ESPECIALLY ACROSS THE COPPER
BASIN. THERE REMAINS UNCERTAINTY WITH A LOW MOVING THROUGH THE
EASTERN GULF OF ALASKA...SO A CONSERVATIVE MIDDLE GROUND APPROACH
WAS TAKEN WITH THE PRECIPITATION FORECAST. BY MONDAY...UNCERTAINTY
IN THE PATTERN GROWS IN MAGNITUDE QUICKLY AS THE TRACK OF
NORTHWEST PACIFIC CYCLONES (POSSIBLY INCLUDING RECURVING REMNANTS
OF PACIFIC TROPICAL CYCLONES) MOVING INTO THE BERING BECOMES
HIGHLY ERRATIC...THUS RESULTING IN SYNOPTIC SCALE DISAGREEMENT
AMONG THE VARIOUS GLOBAL NUMERICAL MODELS. WITH THAT SAID...THE
COLDEST TEMPS OF THE FALL CAN BE EXPECTED BY THIS WEEKEND.


&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...119 127 128 150 155 172 174.
FIRE WEATHER...NONE.

&&

$$

TP SEP 14




000
FXAK68 PAFC 301333
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
533 AM AKDT TUE SEP 30 2014

ANALYSIS AND UPPER LEVELS...WATER VAPOR SATELLITE IMAGERY THIS
MORNING INDICATED THE ARCTIC TROUGH IN SOUTHERN ALASKA HAS CLOSED
OFF INTO A WEAK UPPER LEVEL CIRCULATION...WITH ASSOCIATED SURFACE
CIRCULATION MOVING QUICKLY INTO THE NORTHERN PANHANDLE. AS
EXPECTED...STRONG GAP FLOW AROUND PRINCE WILLIAM SOUND PEAKED
EARLIER THIS MORNING...WITH OBSERVATIONS SHOWING A STEADY DECLINE
IN THOSE WINDS AS THE TROUGH PUSHES OFF FURTHER TO THE EAST.
MEANWHILE...HIGH PRESSURE CONTINUES TO SLOWLY BUILD INTO FROM THE
WEST.

FURTHER WEST...AN UPPER RIDGE PERSISTS OVER THE NORTHERN BERING
SEA...WITH A VERTICALLY STACKED LOW NEARLY STATIONARY WELL SOUTH
OF THE ALEUTIANS. LIGHT RAIN AND GUSTY WINDS ON THE FRINGES OF
THIS SYSTEM ARE BEING OBSERVED ACROSS THE EASTERN HALF OF THE
ALEUTIAN CHAIN.

&&

MODEL DISCUSSION...THE MODELS REMAIN IN GOOD SYNOPTIC AGREEMENT AT
BOTH THE SURFACE AND UPPER LEVELS THROUGHOUT MUCH OF THE SHORT-
TERM (84 HOUR) FORECAST PERIOD. HOWEVER...DIFFERENCES DO ARISE
EARLY THURSDAY MORNING SOUTH OF THE GULF WITH THE HANDLING OF THE
NEXT LOW COMPLEX. THE MODELS GENERALLY SHOW THE REMNANTS OF AN OLD
TROPICAL SYSTEM (KAMMURI) WITH AMPLE MOISTURE BECOMING ABSORBED BY
THE LOW CURRENTLY SOUTH OF THE CENTRAL ALEUTIANS. AS EXPECTED THE
MODELS CONTINUE TO STRUGGLE WITH THIS COMPLEX SYSTEM AS IT TRACKS
SLOWLY NORTHEASTWARD TOWARD THE SOUTHERN GULF. THE FORECAST
CHALLENGE WITH THIS SYSTEM WILL BE IF AND WHERE A TRIPLE POINT
CIRCULATION FORMS ON THURSDAY...AND HOW DEEP/STRONG IT WILL GET.
WITH THIS BEING AT THE END OF THE SHORT TERM AND HAVING SUCH MODEL
SPREAD AT THAT TIME FRAME...FORECAST CONFIDENCE REMAINS LOW
REGARDING THE KEY DETAILS OF THIS EVOLUTION. THE GEM GLOBAL WAS
THE PREFERRED SOLUTION OVERALL WITH THIS SYSTEM AND IS FAIRLY
CLOSE TO THE GFS ENSEMBLE MEAN AND WPC SOLUTIONS.

PRIOR TO 60 HOURS...THE NAM WAS MAINLY UTILIZED OVER THE EAST
DOMAIN TO CONTINUE CAPTURING THE ONGOING GAP WINDS. THE ECMWF
SOLUTION WAS PREFERRED OVER THE WESTERN DOMAIN FOR THE MORNING
PACKAGE FOR SUPERIOR RUN-TO-RUN CONSISTENCY.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...SUBSIDENCE BEHIND THE DEPARTING UPPER LEVEL
WAVE COUPLED WITH TIGHT PRESSURE GRADIENTS LED TO GUSTY
CONDITIONS AND STRONG GAP FLOW OVER PRINCE WILLIAM SOUND AND PARTS
OF SOUTHCENTRAL OVERNIGHT. WINDS HAVE NOW PEAKED AT MANY
LOCATIONS...AND WILL GRADUALLY DIMINISH THROUGHOUT THE DAY TODAY
AS THE UPPER LEVEL TROUGH CONTINUES TO MOVE AWAY. PRECIPITATION
ASSOCIATED WITH THIS FEATURE IS LIMITED TO THE FAR EASTERN COPPER
RIVER BASIN...AND EVEN THIS WILL RAPIDLY DIMINISH BY LATER THIS
MORNING AS COLDER AND DRIER AIR MOVES IN FROM THE WEST.

SOUTHWEST ALASKA...CONDITIONS WILL BE RELATIVELY DRY ACROSS
THE SOUTHWEST MAINLAND OVER THE NEXT COUPLE OF DAYS AS HIGH
PRESSURE REMAINS OVER THE AREA. AN ONSHORE COMPONENT OF THE WINDS
ACROSS THE KUSKOKWIM DELTA WILL KEEP THE POTENTIAL FOR A LITTLE
FOG AROUND THE AREA THROUGH THIS EVENING. HOWEVER...INCREASINGLY
OFFSHORE FLOW BY LATE THIS AFTERNOON WILL LIKELY HAMPER ANY FOG
FORMATION/ADVECTION OVER THE MAJORITY OF THE AREA OVER THE NEXT
DAY OR SO. MEANWHILE...BRISK (BUT MOSTLY DRY) EASTERLY FLOW
ASSOCIATED WITH A LOW COMPLEX OVER THE NORTH PACIFIC WILL CONTINUE
ACROSS THE AK PEN THROUGH WED.

BERING SEA/ALEUTIANS...RAIN AND WIND WILL CONTINUE TO JUST BARELY
BRUSH THE ALEUTIAN ISLANDS AS THE LOW CONTINUES TO SLOWLY TRACK
TO THE EAST. OTHERWISE HIGH PRESSURE WILL BUILD OVER THE CENTRAL
BERING SEA AND CONTINUE TO STRENGTHEN THROUGH MID
WEEK...CONTINUING THE SPLIT-FLOW BLOCKING PATTERN AND PROVIDING
VERY QUIET CONDITIONS FOR MOST OF THE REGION.

&&

.LONG TERM FORECAST (FRI OCT 3 - MON OCT 6)...

ON FRIDAY...A HIGHLY AMPLIFIED PATTERN WILL BE DEVELOPING ACROSS
THE REGION...WITH A BLOCKING RIDGE ACROSS THE CENTRAL BERING
EXTENDING INTO SIBERIA...AND A LARGE TROUGH ACROSS THE MAINLAND.
ARCTIC AIR WILL ACCOMPANY THE TROUGH...WITH STEADILY DROPPING
TEMPERATURES HEADING INTO THE WEEKEND. THE PATTERN WILL GENERALLY
BE DRY...BUT THERE IS THE THREAT FOR SNOW AND SNOW SHOWERS ACROSS
MOST OF SOUTHCENTRAL BY THE WEEKEND...ESPECIALLY ACROSS THE COPPER
BASIN. THERE REMAINS UNCERTAINTY WITH A LOW MOVING THROUGH THE
EASTERN GULF OF ALASKA...SO A CONSERVATIVE MIDDLE GROUND APPROACH
WAS TAKEN WITH THE PRECIPITATION FORECAST. BY MONDAY...UNCERTAINTY
IN THE PATTERN GROWS IN MAGNITUDE QUICKLY AS THE TRACK OF
NORTHWEST PACIFIC CYCLONES (POSSIBLY INCLUDING RECURVING REMNANTS
OF PACIFIC TROPICAL CYCLONES) MOVING INTO THE BERING BECOMES
HIGHLY ERRATIC...THUS RESULTING IN SYNOPTIC SCALE DISAGREEMENT
AMONG THE VARIOUS GLOBAL NUMERICAL MODELS. WITH THAT SAID...THE
COLDEST TEMPS OF THE FALL CAN BE EXPECTED BY THIS WEEKEND.


&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...119 127 150 155 172 174.
FIRE WEATHER...NONE.

&&

$$

TP SEP 14




000
FXAK68 PAFC 301333
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
533 AM AKDT TUE SEP 30 2014

ANALYSIS AND UPPER LEVELS...WATER VAPOR SATELLITE IMAGERY THIS
MORNING INDICATED THE ARCTIC TROUGH IN SOUTHERN ALASKA HAS CLOSED
OFF INTO A WEAK UPPER LEVEL CIRCULATION...WITH ASSOCIATED SURFACE
CIRCULATION MOVING QUICKLY INTO THE NORTHERN PANHANDLE. AS
EXPECTED...STRONG GAP FLOW AROUND PRINCE WILLIAM SOUND PEAKED
EARLIER THIS MORNING...WITH OBSERVATIONS SHOWING A STEADY DECLINE
IN THOSE WINDS AS THE TROUGH PUSHES OFF FURTHER TO THE EAST.
MEANWHILE...HIGH PRESSURE CONTINUES TO SLOWLY BUILD INTO FROM THE
WEST.

FURTHER WEST...AN UPPER RIDGE PERSISTS OVER THE NORTHERN BERING
SEA...WITH A VERTICALLY STACKED LOW NEARLY STATIONARY WELL SOUTH
OF THE ALEUTIANS. LIGHT RAIN AND GUSTY WINDS ON THE FRINGES OF
THIS SYSTEM ARE BEING OBSERVED ACROSS THE EASTERN HALF OF THE
ALEUTIAN CHAIN.

&&

MODEL DISCUSSION...THE MODELS REMAIN IN GOOD SYNOPTIC AGREEMENT AT
BOTH THE SURFACE AND UPPER LEVELS THROUGHOUT MUCH OF THE SHORT-
TERM (84 HOUR) FORECAST PERIOD. HOWEVER...DIFFERENCES DO ARISE
EARLY THURSDAY MORNING SOUTH OF THE GULF WITH THE HANDLING OF THE
NEXT LOW COMPLEX. THE MODELS GENERALLY SHOW THE REMNANTS OF AN OLD
TROPICAL SYSTEM (KAMMURI) WITH AMPLE MOISTURE BECOMING ABSORBED BY
THE LOW CURRENTLY SOUTH OF THE CENTRAL ALEUTIANS. AS EXPECTED THE
MODELS CONTINUE TO STRUGGLE WITH THIS COMPLEX SYSTEM AS IT TRACKS
SLOWLY NORTHEASTWARD TOWARD THE SOUTHERN GULF. THE FORECAST
CHALLENGE WITH THIS SYSTEM WILL BE IF AND WHERE A TRIPLE POINT
CIRCULATION FORMS ON THURSDAY...AND HOW DEEP/STRONG IT WILL GET.
WITH THIS BEING AT THE END OF THE SHORT TERM AND HAVING SUCH MODEL
SPREAD AT THAT TIME FRAME...FORECAST CONFIDENCE REMAINS LOW
REGARDING THE KEY DETAILS OF THIS EVOLUTION. THE GEM GLOBAL WAS
THE PREFERRED SOLUTION OVERALL WITH THIS SYSTEM AND IS FAIRLY
CLOSE TO THE GFS ENSEMBLE MEAN AND WPC SOLUTIONS.

PRIOR TO 60 HOURS...THE NAM WAS MAINLY UTILIZED OVER THE EAST
DOMAIN TO CONTINUE CAPTURING THE ONGOING GAP WINDS. THE ECMWF
SOLUTION WAS PREFERRED OVER THE WESTERN DOMAIN FOR THE MORNING
PACKAGE FOR SUPERIOR RUN-TO-RUN CONSISTENCY.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...SUBSIDENCE BEHIND THE DEPARTING UPPER LEVEL
WAVE COUPLED WITH TIGHT PRESSURE GRADIENTS LED TO GUSTY
CONDITIONS AND STRONG GAP FLOW OVER PRINCE WILLIAM SOUND AND PARTS
OF SOUTHCENTRAL OVERNIGHT. WINDS HAVE NOW PEAKED AT MANY
LOCATIONS...AND WILL GRADUALLY DIMINISH THROUGHOUT THE DAY TODAY
AS THE UPPER LEVEL TROUGH CONTINUES TO MOVE AWAY. PRECIPITATION
ASSOCIATED WITH THIS FEATURE IS LIMITED TO THE FAR EASTERN COPPER
RIVER BASIN...AND EVEN THIS WILL RAPIDLY DIMINISH BY LATER THIS
MORNING AS COLDER AND DRIER AIR MOVES IN FROM THE WEST.

SOUTHWEST ALASKA...CONDITIONS WILL BE RELATIVELY DRY ACROSS
THE SOUTHWEST MAINLAND OVER THE NEXT COUPLE OF DAYS AS HIGH
PRESSURE REMAINS OVER THE AREA. AN ONSHORE COMPONENT OF THE WINDS
ACROSS THE KUSKOKWIM DELTA WILL KEEP THE POTENTIAL FOR A LITTLE
FOG AROUND THE AREA THROUGH THIS EVENING. HOWEVER...INCREASINGLY
OFFSHORE FLOW BY LATE THIS AFTERNOON WILL LIKELY HAMPER ANY FOG
FORMATION/ADVECTION OVER THE MAJORITY OF THE AREA OVER THE NEXT
DAY OR SO. MEANWHILE...BRISK (BUT MOSTLY DRY) EASTERLY FLOW
ASSOCIATED WITH A LOW COMPLEX OVER THE NORTH PACIFIC WILL CONTINUE
ACROSS THE AK PEN THROUGH WED.

BERING SEA/ALEUTIANS...RAIN AND WIND WILL CONTINUE TO JUST BARELY
BRUSH THE ALEUTIAN ISLANDS AS THE LOW CONTINUES TO SLOWLY TRACK
TO THE EAST. OTHERWISE HIGH PRESSURE WILL BUILD OVER THE CENTRAL
BERING SEA AND CONTINUE TO STRENGTHEN THROUGH MID
WEEK...CONTINUING THE SPLIT-FLOW BLOCKING PATTERN AND PROVIDING
VERY QUIET CONDITIONS FOR MOST OF THE REGION.

&&

.LONG TERM FORECAST (FRI OCT 3 - MON OCT 6)...

ON FRIDAY...A HIGHLY AMPLIFIED PATTERN WILL BE DEVELOPING ACROSS
THE REGION...WITH A BLOCKING RIDGE ACROSS THE CENTRAL BERING
EXTENDING INTO SIBERIA...AND A LARGE TROUGH ACROSS THE MAINLAND.
ARCTIC AIR WILL ACCOMPANY THE TROUGH...WITH STEADILY DROPPING
TEMPERATURES HEADING INTO THE WEEKEND. THE PATTERN WILL GENERALLY
BE DRY...BUT THERE IS THE THREAT FOR SNOW AND SNOW SHOWERS ACROSS
MOST OF SOUTHCENTRAL BY THE WEEKEND...ESPECIALLY ACROSS THE COPPER
BASIN. THERE REMAINS UNCERTAINTY WITH A LOW MOVING THROUGH THE
EASTERN GULF OF ALASKA...SO A CONSERVATIVE MIDDLE GROUND APPROACH
WAS TAKEN WITH THE PRECIPITATION FORECAST. BY MONDAY...UNCERTAINTY
IN THE PATTERN GROWS IN MAGNITUDE QUICKLY AS THE TRACK OF
NORTHWEST PACIFIC CYCLONES (POSSIBLY INCLUDING RECURVING REMNANTS
OF PACIFIC TROPICAL CYCLONES) MOVING INTO THE BERING BECOMES
HIGHLY ERRATIC...THUS RESULTING IN SYNOPTIC SCALE DISAGREEMENT
AMONG THE VARIOUS GLOBAL NUMERICAL MODELS. WITH THAT SAID...THE
COLDEST TEMPS OF THE FALL CAN BE EXPECTED BY THIS WEEKEND.


&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...119 127 150 155 172 174.
FIRE WEATHER...NONE.

&&

$$

TP SEP 14





000
FXAK68 PAFC 292156
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
156 PM AKDT MON SEP 29 2014

ANALYSIS AND UPPER LEVELS...WATER VAPOR IMAGERY SHOWS A DIGGING
TROUGH MOVING EAST ACROSS THE CENTRAL MAINLAND. SHOWERS HAVE
STARTED TO DEVELOP EAST OF THE ALASKA RANGE IN RESPONSE TO STRONG
UPPER DYNAMICS ASSOCIATED WITH THIS FEATURE. BRISK GAP FLOWS WHERE
EVIDENT ACROSS MUCH OF SOUTHCENTRAL ESPECIALLY ALONG THE NORTH
GULF COAST AND EASTERN KENAI PENINSULA.

FURTHER WEST...AN UPPER RIDGE CONTINUED OVER THE NORTHERN BERING
SEA. A BROAD UPPER LEVEL LOW AND ITS ASSOCIATED SURFACE LOW WAS
EVIDENT SOUTH OF THE ALEUTIANS. THE SURFACE LOW AND ITS
ASSOCIATED FRONTAL TROUGH PRODUCED SOME LIGHT RAIN AS WELL AS
BRISK EASTERLY GALES ACROSS THE CENTRAL ALEUTIANS. WITH THE
EXCEPTION OF RAIN AND SNOW SHOWERS ALONG THE ALEUTIAN RANGE...MUCH
OF SW ALASKA WAS DRY.

&&

MODEL DISCUSSION...THE MODEL HANDING OF UPPER LEVEL AS WELL AS
SURFACE SYNOPTIC FEATURES ARE IN FAIRLY GOOD AGREEMENT THROUGH THE
SHORT TERM. DIFFERENCES HOWEVER DO ARISE THU SOUTH OF THE GULF
WITH THE HANDLING OF THE NEXT LOW COMPLEX. THE 00Z ECMWF RAPIDLY
DEVELOPED AN OLD TROPICAL SYSTEM AND MOVED SOUTH OF THE GULF ON
THU AFTERNOON. THE 12Z ECMWF HAS COME IN LINE WITH THE OTHER
GLOBAL MODELS WHICH DEPICT A BROADER/ELONGATED AND MUCH WEAKER
LOW PRESSURE TROUGH SOUTH OF THE GULF. THE NAM WILL BE INITIALLY
USED THROUGH WED IN THE EAST TO CAPTURE OUTFLOW CONDITIONS...THEN
WILL TRANSITION INTO THE GFS. OUT WEST...THE GFS WILL BE USED FOR
THE AFTERNOON PACKAGE.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...WINDS WILL BE THE MAIN WEATHER FEATURE OVER
THE NEXT 24 TO 36 HRS. WINDS WILL PICK UP ACROSS MUCH OF THE AREA
THROUGH THIS EVENING WITH THE ONSET OF SUPPORTING NW FLOW AND
SUBSIDENCE WITH THE PASSAGE OF THE UPPER TROUGH. VERY STRONG GAP
FLOWS WILL DEVELOP TONIGHT ACROSS MUCH OF THE NORTH GULF AND
EASTERN KENAI PEN AS PRESSURE AND TEMPS GRADIENTS INCREASE ACROSS
THE AREA. WINDS WILL BE AT A MAXIMUM DURING THE LATE TONIGHT AND
TUE MORNING THEN SLOWLY WEAKEN TUE AFTERNOON AS THE SURFACE AND
UPPER SUPPORT WANES.

STRONG DYNAMICS ACCOMPANYING THE TROUGH WILL PRODUCE RAIN AND
SNOW SHOWERS. HIGHER ELEVATIONS...ESPECIALLY OF THE NORTHERN AND
EASTERN COPPER RIVER BASIN WILL SEE SNOW WITH MEASURABLE
ACCUMULATIONS TONIGHT. PRECIPITATION WILL DECREASE ACROSS THE
AREA AS COLDER AND DRIER AIR SPREAD EAST BEHIND THE TROUGH.

SOUTHWEST ALASKA...CONDITIONS WILL BE RELATIVELY DRY ACROSS SW
ALASKA OVER THE NEXT COUPLE OF DAYS AS HIGH PRESSURE BUILDS OVER
THE AREA. FOG WILL BECOME A CONCERN FOR THE DELTA AND ADJACENT
COAST. THE NORTHERLY OFFSHORE FLOW WILL LIKELY HAMPER ANY FOG
DEVELOPMENT OVER BRISTOL BAY OVER THE NEXT DAY OR SO. BRISK
EASTERLY FLOW ASSOCIATED WITH A LOW COMPLEX OVER THE NORTH PACIFIC
WILL CONTINUE ACROSS THE AK PEN THROUGH WED.

BERING SEA/ALEUTIANS...RAIN AND WIND WILL HOLD ON ALONG THE
CENTRAL ALEUTIANS UNTIL THE LOW TO THE SOUTH FINALLY DROPS FURTHER
INTO THE PACIFIC LATER TONIGHT. OTHERWISE HIGH PRESSURE WILL BUILD
OVER THE CENTRAL BERING SEA AND CONTINUE TO STRENGTHEN THROUGH MID
WEEK...SETTING UP A BLOCKING PATTERN AND PROVIDING VERY QUIET
CONDITIONS FOR MOST OF THE REGION. THE ONE EXCEPTION WILL BE THE
WESTERN ALEUTIANS ON THE UPSTREAM SIDE OF THE RIDGE WHICH WILL SEE
IMPACTS FROM A SYSTEM PASSING TO THE WEST MID WEEK.

&&

.LONG TERM FORECAST (FRI OCT 3 - MON OCT 6)...

ON FRIDAY...A HIGHLY AMPLIFIED PATTERN WILL BE DEVELOPING ACROSS
THE REGION...WITH A BLOCKING RIDGE ACROSS THE CENTRAL BERING
EXTENDING INTO SIBERIA...AND A LARGE TROUGH ACROSS THE MAINLAND.
ARCTIC AIR WILL ACCOMPANY THE TROUGH...WITH STEADILY DROPPING
TEMPERATURES HEADING INTO THE WEEKEND. THE PATTERN WILL GENERALLY
BE DRY...BUT THERE IS THE THREAT FOR SNOW AND SNOW SHOWERS ACROSS
MOST OF SOUTHCENTRAL BY THE WEEKEND...ESPECIALLY ACROSS THE COPPER
BASIN. THERE CONTINUES TO REMAIN UNCERTAINTY WITH A LOW MOVING
THROUGH THE EASTERN GULF OF ALASKA...SO A CONSERVATIVE MIDDLE
GROUND APPROACH WAS TAKEN WITH THE PRECIPITATION FORECAST. BY
MONDAY...UNCERTAINTY IN THE PATTERN GROWS IN MAGNITUDE QUICKLY AS
THE TRACK OF NORTHWEST PACIFIC CYCLONES (POSSIBLY INCLUDING
RECURVING REMNANTS OF PACIFIC TROPICAL CYCLONES) MOVING INTO THE
BERING BECOMES HIGHLY ERRATIC...THUS RESULTING IN SYNOPTIC SCALE
DISAGREEMENT AMONG THE VARIOUS GLOBAL NUMERICAL MODELS. WITH THAT
SAID...THE COLDEST TEMPS OF THE FALL CAN BE EXPECTED BY THIS
WEEKEND.

- AHSENMACHER

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...119 120 121 126 127 129 130 131 172 174
176 351. FIRE WEATHER...NONE.

&&

$$

RMC/AHSENMACHER SEP 14




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