Freeze Warning 1, NWS Anchorage, AK

729 
WWAK71 PAFC 091240
NPWAER

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE ANCHORAGE AK
440 AM AKDT SUN SEP 9 2012

AKZ101-111-091800-
/X.CON.PAFC.FZ.W.0001.000000T0000Z-120909T1800Z/
ANCHORAGE-MATANUSKA VALLEY-
INCLUDING THE CITIES OF...ANCHORAGE...EAGLE RIVER...INDIAN...
EKLUTNA...PALMER...WASILLA...SUTTON...CHICKALOON
440 AM AKDT SUN SEP 9 2012

...FREEZE WARNING REMAINS IN EFFECT UNTIL 10 AM AKDT THIS MORNING
FOR ANCHORAGE AND THE MATANUSKA VALLEY...

* LOCATION...MOST OF THE ANCHORAGE AREA EXCEPT NEAR THE INLET.
  THE MATANUSKA VALLEY WEST OF PALMER.

* TEMPERATURES...RANGING FROM 26 TO 32 DEGREES.

* TIMING...TEMPERATURES WILL CONTINUE TO SLOWLY FALL EARLY THIS
  MORNING AND BOTTOM OUT AROUND 8 AM THIS MORNING. TEMPERATURES
  WILL QUICKLY RISE ABOVE FREEZING BY LATE MORNING.

* IMPACTS...OUTDOOR VEGETATION SENSITIVE TO FREEZING TEMPERATURES
  SHOULD BE MOVED INDOORS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FREEZE WARNING MEANS SUB-FREEZING TEMPERATURES ARE IMMINENT OR
HIGHLY LIKELY. THESE CONDITIONS WILL KILL CROPS AND OTHER
SENSITIVE VEGETATION.

&&

$$

555 
WWAK71 PAFC 091816
NPWAER

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE ANCHORAGE AK
1015 AM AKDT SUN SEP 9 2012

AKZ101-111-091915-
/X.EXP.PAFC.FZ.W.0001.000000T0000Z-120909T1800Z/
ANCHORAGE-MATANUSKA VALLEY-
INCLUDING THE CITIES OF...ANCHORAGE...EAGLE RIVER...INDIAN...
EKLUTNA...PALMER...WASILLA...SUTTON...CHICKALOON
1015 AM AKDT SUN SEP 9 2012

...FREEZE WARNING HAS EXPIRED FOR ANCHORAGE AND THE MATANUSKA
VALLEY...

TEMPERATURES HAVE RISEN ABOVE FREEZING THIS MORNING. MINIMUM TEMPERATURES
LAST NIGHT RANGED FROM 27 TO 35. TEMPERATURES REACHED FREEZING
AROUND MIDNIGHT LAST NIGHT AND REMAINED BELOW FREEZING TIL 9AM.

$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT SAT SEP 8 2012

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL TROUGH IS OVER THE MAINLAND WITH A CLOSED LOW OVER
NUNIVAT AND IN THE GULF OF ALASKA. THE JET CORE IS AROUND 130KT
ROUNDING INTO THE BASE OF THE TROUGH OVER THE GULF. THIS WILL HELP TO
SWING THE TROUGH EAST. HIGH PRESSURE IS PRESENT OVER THE EASTERN
BERING WITH A SHORT WAVE RIDGE IN THE UPPER LEVELS. A SECOND SHORT
WAVE TROUGH MOVING OUT OF THE KAMCHATKA REGION THIS AFTERNOON WITH AN
ACCOMPANYING 130KT JET CORE AS WELL. A SURFACE LOW IS IN THE BASE OF
EACH TROUGH WITH SHOWERS. SOME MORE INTENSE SHOWERS OVER THE GULF OF
ALASKA AND OVER EASTERN RUSSIA.

THE LOW IN THE GULF TAKING A TURN TO THE EAST COMBINED WITH UPPER
LEVEL NORTH/NORTHWEST FLOW WILL SPELL STRONG NORTH/NORTHWEST GAP
FLOWS OVER SOUTHCENTRAL ALASKA TONIGHT INTO TOMORROW.

.MODEL DISCUSSION...
MODELS CONTINUE TO BE IN GOOD AGREEMENT IN THE SHORT TERM (3 DAYS).
THIS KEEPS THE STACKED LOW OVER THE WESTERN GULF SHIFTING TO THE
EASTERN GULF TOMORROW AND REMAINING IN THE PANHANDLE THROUGH SUNDAY.
HIGH PRESSURE IS SITUATED OVER THE EASTERN BERING AND WILL SWING OVER
THE MAINLAND SUNDAY AS A LOW CURRENTLY IN THE WESTERN BERING WILL
MOVE INTO THE CENTRAL BERING SUNDAY NIGHT. THE LOW WILL THEN MOVE
SLOWLY TO BRISTOL BAY BY TUESDAY AFTERNOON. EVERY MODEL HAS THIS LOW
HANDLED WELL AND IT ROTATES INTO SOUTHCENTRAL ALASKA WEDNESDAY. THE
BIG UNCERTAINTY IS THE NEXT LOW MOVING OUT OF THE WESTERN
BERING/EASTERN RUSSIA STARTING TUESDAY. ALL MODELS DIFFER ON TIMING
AND PHASING OVER THE PAST COUPLE DAYS. EVENTUALLY A LOW SETS UP IN
TEH EASTERN BERING THURSDAY/FRIDAY. THE ORIENTATION IS WHAT WILL SET
UP WHERE THE STRONG WINDS WILL BE ON THURSDAY INTO SATURDAY. THE
DEPTH SEEMS TO BE CONSISTENT AMONG THE NON-NCEP MODELS AROUND 990MB.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
LOW IN THE GULF OF ALASKA WRAPPING UP A BIT WITH GOOD JET AND COLD
AIR SUPPORT. COMBINED WITH NORTH/NORTHWEST FLOW ALOFT AND HIGH
PRESSURE BUILDING OVER WESTERN ALASKA...STRONG NORTH/NORTHWEST GAP
FLOWS TO DEVELOP THIS AFTERNOON AND EVENING. AN UPPER LEVEL
DISTURBANCE IN THE NORTHERLY FLOW WILL SPARK A FEW SHOWERS OVER THE
MOUNTAINS THIS EVENING BUT BE GONE BY MORNING.

WE HAD SOME AREAS GO INTO A FREEZE LAST NIGHT WITH TEMPS IN THE UPPER
20S IN EAST ANCHORAGE AND PARTS OF THE MAT VALLEY. THE DRY AIR AND
LACK OF CLOUDS TONIGHT OVER THE MAT-SU AND ANCHORAGE BOWL COULD MEAN
ANOTHER NIGHT OF COLD TEMPS TONIGHT. ONE FLY IN THE OINTMENT IS THE
NORTHERLY FLOW ALOFT AND NORTHWEST GAP FLOWS. THIS COULD PROVIDE
ENOUGH MIXING TO KEEP TEMPS ABOVE THE HARD FREEZE TONIGHT.

THE STRONG GAP FLOWS TO LAST THROUGH THE DAY TOMORROW BUT IT WILL BE
DRY. DRY AND NOT WINDS CONDITIONS WILL PERSIST THROUGH MONDAY FOR THE
MAINLAND. HOWEVER...THE FRONT MOVING ACROSS SOUTHWEST ALASKA WILL
REACH KODIAK BY MONDAY AFTERNOON. AS THE LOW AND FRONT ROTATE INTO
THE GULF TUESDAY...A BARRIER JET IS POSSIBLE IN THE NORTHERN GULF.
RAIN WILL SPREAD TO THE GULF COAST LOCATIONS AS WELL WITH SOME
SHOWERS SPREADING INLAND OVERNIGHT TUESDAY.

SCATTERED SHOWERS WILL TAPER OFF ACROSS MOST OF SOUTHCENTRAL AK BY
SATURDAY MORNING AS THE SYSTEM MOVES INTO THE GULF AND THEN OFF TO
THE EAST...LEADING TO A PLEASANT WEEKEND WITH SUNNY SKIES ON SUNDAY
AS UPPER LEVEL RIDGING BUILDS IN FROM THE WEST. GIVEN EXPECTED
CLEARING LATER IN THE WEEKEND...WILL HAVE TO MONITOR THE POSSIBILITY
OF FREEZING TEMPERATURES ON SATURDAY NIGHT FOR EASTERN PORTIONS OF
THE ANCHORAGE BOWL IF WINDS SUBSIDE ENOUGH TO ALLOW FOR OPTIMAL
RADIATIONAL COOLING.

SOUTHWEST ALASKA...
NORTHWESTERLY JET WITH HIGH PRESSURE MOVING INTO THE AREA WILL MEAN A
DRIER PATTERN SETTING UP. HOWEVER...WESTERLY GAP WINDS WILL BE
PRESENT THROUGH TOMORROW MORNING. DRY TOMORROW AWAITING A FRONT FOR
LATE SUNDAY NIGHT TO ARRIVE. MODERATE JET SUPPORT FOR 25-35 KT WINDS
ALONG THE FRONT AS IT HITS THE COAST BY MONDAY MORNING. GOOD SE GAP
FLOWS ALONG THE AKPEN WITH THIS FLOW AS WELL. THE FRONT DISSIPATES AS
IT MOVES INLAND MONDAY DUE TO A LACK OF JET SUPPORT. HOWEVER...SOME
MODERATE RAIN AND WIND WILL REMAIN MAINLY ALONG THE COAST. THE LOW
WEAKENS IN THE EASTERN BERING AND MOVES TO BRISTOL BAY MONDAY
NIGHT/TUESDAY. THIS WILL SPREAD SHOWERS OVER MUCH OF THE AREA BUT
WINDS WILL TAPER OFF MOSTLY.

ALEUTIANS/BERING SEA...
LOW ROTATING OUT OF THE KAMCHATKA AREA THIS AFTERNOON WITH MODERATE
PRECIP AND WINDS OVER THE WESTERN BERING. THE LOW WRAPS UP BETTER ON
SUNDAY WITH GALE FORCE WINDS STARTING TO STRETCH TO THE EASTERN
BERING BY MONDAY. THE BACK SIDE OF THE LOW HAS SOME GOOD COLD AIR
ADVECTION AND JET SUPPORT FOR STRONGER GALES AS IT RIDES ACROSS THE
BERING THROUGH MONDAY. THE LOW SLOWLY DRIFTS INTO BRISTOL BAY TUESDAY
WITH SHOWERS DECREASING FROM THE WEST. HIGH PRESSURE MOVES INTO THE
WESTERN BERING FOR A BRIEF PERIOD. WIND WILL REMAIN STRONG ON THE
BACK SIDE OF THE LOW.

.LONG TERM FORECAST...
THE LOW IN BRISTOL BAY TO SWING INTO THE GULF TEESDAY NIGHT/WEDNESDAY
WITH CONTINUED SHOWERS OVER SOUTHWEST AND SOUTHCENTRAL ALASKA. THEN
WE START TO SEE THE EFFECTS OF THE LOW MOVING ACROSS THE BERING. THE
UNCERTAINTY WILL MEAN NO CERTAIN AREAS OF STRONG WINDS AND PRECIP.
WHAT WE DO KNOW IS A LOW WILL BE IN THE EASTERN BERING SOMETIME LATE
NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FREEZE WARNING ZONE 101 AND 111
MARINE...GALE 127 130 132 150 172 175 176 185
FIRE WEATHER...NONE

JN SEP 12