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FXAK68 PAFC 161404
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
600 AM AKDT WED OCT 16 2013
.ANALYSIS AND UPPER LEVELS...THE RIDGE OF HIGH PRESSURE CENTERED OVER
THE EASTERN GULF OF AK REMAINS QUITE PERSISTENT AND CONTINUES TO
DIRECT MUCH OF THE WEATHER THROUGH OUR AREA. A 120 KT JET IS MOVING
OVER TOP OF IT WHILE A 160 KT JET IS DIVING OFF THE KAMCHATKA
PENINSULA INTO THE BASE OF A BROAD TROUGH THAT EXTENDS FROM THE
BERING SEA INTO THE NORTH PACIFIC. THIS BROAD TROUGH IS SERVING TO
BRING UP PLENTY OF SUBTROPICAL MOISTURE. THE NEXT PLUME OF MOISTURE
ON SATELLITE NEAR 51N 155W IS SHOWING PRECIPITABLE WATER VALUES ABOVE
200 PERCENT OF NORMAL. THIS DEEP TROUGH IS ALSO HELPING TO PULL
PLENTY OF WARM AIR INTO THE WESTERN PORTION OF THE RIDGE IN THE LOW
TO MID LEVELS.
MUCH OF THE SOUTHERN PORTION OF THE STATE REMAINS "PINCHED" BETWEEN
THE RIDGE AND THE TROUGH. THIS IS WHAT LED TO THE STRONG WINDS FROM
THE COPPER RIVER BASIN TO BRISTOL BAY ON TUESDAY. WINDS REMAIN GUSTY
IN MANY OF THESE AREAS AND WILL CONTINUE TO BE SO UNTIL THERE IS A
SHIFT IN THIS LONGWAVE PATTERN.
.MODEL DISCUSSION...MODELS REMAIN IN GOOD AGREEMENT REGARDING THE
OVERALL SYNOPTIC PATTERN. THE BROAD TROUGH IN THE WEST WILL CONTINUE
TO BE REINFORCED BY COLD UPPER LEVEL WAVES DIGGING SOUTHWARD. THE
RIDGE OVER THE EASTERN GULF IS PROGGED TO CHANGE VERY LITTLE THROUGH
MOST OF THURSDAY. ON FRIDAY...IT SHOULD MOVE SLOWLY TO THE SOUTH AND
EAST ALLOW THE TROUGH TO BUILD FURTHER EASTWARD IN THE GULF. BUT
THERE ARE SOME MINOR TIMING AND STRENGTH DIFFERENCES BETWEEN THE
MODELS ON HOW THEY HANDLE THE SHORTWAVES MOVING THROUGH THE TROUGH.
THESE WILL BE THE SENSIBLE WEATHER MAKERS FOR MUCH OF THE AREA
THROUGH THE END OF THE WEEK. THIS LEADS TO AVERAGE FORECAST
CONFIDENCE IN THE STRENGTH OF THE WINDS AND THE AMOUNT OF
PRECIPITATION MOST PLACES WILL SEE.
.SHORT TERM FORECAST......
SOUTH AND EAST OF THE AK RANGE...WHILE THE SOUTH TO SOUTHEAST WINDS
WILL SUBSIDE SOME FROM TUESDAY...THEY WILL REMAIN QUITE GUSTY THROUGH
THE DAY TODAY. SHOWERS WILL CONTINUE ACROSS MUCH OF THE AREA AS THE
AIRMASS REMAINS VERY MOIST. THE HEAVIEST PRECIP AMOUNTS WILL ONCE
AGAIN FALL ON FAVORED UPSLOPE LOCATIONS. AS THE NEXT PIECE OF ENERGY
EJECTS NORTHWARD ON THURSDAY...WINDS WILL ONCE AGAIN INCREASE. MAX
SPEEDS SHOULD BE VERY SIMILAR TO TUESDAY. SOME DOWNSLOPING COMPONENT
WILL LIKELY KEEP THE ANCHORAGE BOWL FROM SEEING HEAVY AMOUNTS OF
RAIN...BUT IT WILL NO DOUBT BE ANOTHER WET DAY.
FOR SOUTHWEST AK...SYSTEMS WILL CONTINUE TO PUSH THROUGH THE AREA ALL
WEEK. THERE WILL BE RELATIVE LULLS IN THE ACTION...BUT OVERALL...THE
PATTERN WILL REMAIN WET AND WINDY. THE STRONGEST WINDS WILL BE
THROUGH FAVORED GAPS FROM THE SOUTHEAST ALONG THE ALEUTIAN AND ALASKA
RANGES.
IN THE ALEUTIANS...A WEAK SYSTEM WILL MOVE QUICKLY FROM ADAK THIS
MORNING TO THE SOUTH OF DUTCH HARBOR BY EARLY THURSDAY. IT WILL BRING
A BRIEF BOUT OF GUSTY WINDS AND INCREASED CHANCES FOR PRECIP. THE
BIGGER STORY WILL BE THE TYPHOON REMNANTS THAT MOVE TOWARD SHEMYA
THIS EVENING. THIS SYSTEM WILL BRING STORM FORCE WINDS AND SOME OF
THE HIGHEST SEAS SEEN THUS FAR THIS SEASON. WAVES WILL BE ON THE
ORDER OF 40 TO 50 FT ON THE PACIFIC SIDE OF THE ALEUTIANS. THIS
SYSTEM WILL SLOWLY WEAKEN AS IT TRACKS ALONG THE CHAIN TOWARDS THE
MAINLAND BY SATURDAY.
.LONG TERM FORECAST...THE STORM MENTIONED ABOVE WILL FINALLY PUSH THE
RIDGE OVER THE EASTERN GULF OUT OF OUR AREA ON SATURDAY. AS IT DOES
SO...IT WILL OPEN THE DOOR FOR EVEN MORE RAIN AND WIND ACROSS THE
STATE...ESPECIALLY FOR THE BRISTOL BAY AREA. SEVERAL MORE PIECES OF
ENERGY WILL THEN DROP INTO THE LONGWAVE TROUGH CENTERED FROM THE
BERING INTO THE NORTH PACIFIC THROUGH THE WEEKEND.
THE EC AND GFS ARE BOTH STILL HINTING AT A VERY DEEP CYCLONE (950MB)
TRACKING SOUTH OF THE ALEUTIANS BY THE MIDDLE OF NEXT WEEK. WE WILL
MONITOR THIS SITUATION TO SEE HOW SUBSEQUENT MODEL RUNS HANDLE IT.
.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FLOOD ADVISORY 121 125 (KENAI LAKE AND KENAI RIVER).
MARINE...STORM WARNING...178.
GALE WARNING...150 160 173 174 175 176 177 185 411 412 413
119 130 131 132 352.
FIRE WEATHER...NONE
MSO OCT 13