000
FXAK68 PAFC 180010
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKDT MON JUN 17 2013
.ANALYSIS AND UPPER LEVELS...A STRONG UPPER LEVEL HIGH IS CENTERED
OVER THE MIDDLE OF THE STATE AND BRINGING STRONG SUBSIDENCE AND SOME
RECORD HIGH TEMPERATURES TO MOST OF MAINLAND ALASKA. JUST EAST OF THE
ALCAN BORDER IN THE YUKON TERRITORY THERE IS AN UPPER LEVEL LOW
DESCENDING SOUTHWARD THAT WILL RETROGRADE INTO THE GULF OF ALASKA
TOMORROW. THE COMPLEX LOW IN THE WESTERN BERING SEA IS ALSO WEAKENING
TODAY.
AT THE SURFACE THE HIGH IS CENTERED ALONG THE ARCTIC COAST AND BROOKS
RANGE BUT IT IS SO LARGE IT IS COVERING THE MAJORITY OF THE MAINLAND.
THERE IS ALSO AS WEAK TROUGH ACROSS THE NORTHERN GULF OF ALASKA WHICH
IS SERVING TO CREATE SOME STRONG OFFSHORE WINDS TODAY.
.MODEL DISCUSSION...MODELS ARE IN GOOD AGREEMENT FOR THE NEXT FEW
DAYS WITH THE BIGGEST ISSUE BEING WITH THE TRACK OF THE UPPER LEVEL
LOW CURRENTLY IN THE YUKON AS IT MOVES THROUGH THE GULF OF ALASKA.
THE GFS AND ECMWF ARE KEEPING A MORE NORTHERLY TRACK THAN THE NAM
WHICH MAY BRING A GREATER CHANCE OF SHOWERS OR THUNDERSTORMS ALONG
THE MOUNTAINS IN SOUTHWEST ALASKA TUESDAY AND WEDNESDAY.
THE MODELS ALL AGREE OF THE TROUGH THAT IS IN THE GULF WILL MOVE
INLAND INTO THE KUSKOKWIM VALLEY AND INLAND BRISTOL BAY REGIONS
TOMORROW AS A RIDGE MOVES IN ALONG THE NORTH GULF COAST.
.SHORT TERM FORECAST...TODAY SHOULD BE THE HOTTEST DAY OF THE STRETCH
FOR SOUTH CENTRAL ALASKA AS THE UPPER RIDGE OVER THE MAINLAND AND THE
WEAK TROUGH IN THE NORTHERN GULF COMBINE TO BRING IN GUSTY WINDS AND
DRY AND HOT AIR TO THE REGION. THE NORTH GULF COAST IS SEEING MANY
READING INTO THE 80S TODAY WITH SEWARD ALREADY BREAKING ITS ALL TIME
MONTHLY HIGH. AS THE TROUGH MOVES INLAND AND THE RIDGE BUILDS IN IT
WILL BRING SOUTHERLY WINDS AND A TYPICAL SEA BREEZE TOMORROW...WITH
MUCH LOWER MAXIMUM TEMPERATURES.
OTHER INLAND PARTS OF SOUTH CENTRAL ALASKA SUCH AS THE COPPER RIVER
BASIN AND SUSITNA VALLEY WILL BE WARM BUT NOT AS WARM AS TODAY AS THE
NORTHERLY WINDS DIMINISH AND THE GRADIENT BEGINS TO TURN MORE
SOUTHEAST BY LATE IN THE AFTERNOON.
SOUTHWEST ALASKA WILL CONTINUE TO SEE SUNNY SKIES...WITH THE
EXCEPTION OF AROUND THE ALASKA AND ALEUTIAN RANGE DURING THE
AFTERNOON AND EVENING. OVER ALASKA/ALEUTIAN RANGE THERE IS VERY
UNSTABLE AIR WHICH COULD LEAD TO AFTERNOON CONVECTION. THERE IS SO
LITTLE AVAILABLE MOISTURE IN THE LOWER ATMOSPHERE THAT IT WILL BE
HARD TO GET AND PRECIPITATION GOING. WHAT IS MORE LIKELY ARE SOME
ISOLATED DRY THUNDERSTORMS WHICH PRODUCE LIGHTNING BUT THE RAIN
EVAPORATES IN THE DRY LOWER ATMOSPHERE BEFORE REACHING THE GROUND.
IT SEEMS TO BE AN ALL OR NOTHING SCENARIO WHERE THERE WILL EITHER BE
NO CONVECTIVE DEVELOPMENT OR THERE WILL BE DRY THUNDERSTORMS. THERE
DOES NOT SEEM TO BE A MIDDLE GROUND OF JUST SOME SCATTERED SHOWERS
LIKE THERE OFTEN IS. EACH DAY AS WE HEAD THROUGH THE MIDDLE OF THE
WEEK BRINGS A BETTER CHANCE FOR CONVECTION THAT THE DAY BEFORE.
.LONG TERM FORECAST...THE BLOCKING RIDGE WILL SLOWLY BREAK DOWN
DURING THE SECOND HALF OF THE WEEK. HOWEVER TEMPERATURES WILL
CONTINUE ABOVE NORMAL THROUGH THE END OF THE WEEK FOR SOUTHERN
ALASKA. A CLOSED LOW WILL MOVE INTO THE WESTERN ALEUTIANS THURSDAY.
MODELS VARY IN STRENGTH AND TRACK OF THIS LOW...HOWEVER IT LOOKS TO
TRACK EASTWARD WITH THE CENTER OF THE SYSTEM JUST SOUTH OF THE
EASTERN ALEUTIANS ON SATURDAY.
.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...RED FLAG WARNING 111 141 145 152 161.
JUN 13
