172 FXAK68 PAFC 201338 AFDAFC SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ANCHORAGE AK 540 AM AKDT SAT JUL 20 2013 .ANALYSIS AND UPPER LEVELS... A STRONG VORTEX ALOFT IS SWINGING THROUGH CENTRAL AK AND MOVING SOUTHEAST. IR AND WATER VAPOR SATELLITE IMAGERY CAPTURES THIS DISTINCT CIRCULATION PUSHING PAST MCGRATH THIS MORNING. THERE ARE VARIOUS SHORTWAVES/VORTICITY MAX'S ROTATING AROUND THE VORTEX SUPPORTING SHOWERS THROUGH UPPER-COOK INLET. A 100 KT WEST TO EAST ORIENTED UPPER JET IS PUSHING OUT OF BRISTOL BAY INTO THE NORTHERN GULF AIDING THE FAST FLOW. BRISK OUTFLOW WINDS ARE NOTED ESPECIALLY FROM KODIAK ISLAND TO KAMISHAK BAY AS A SURFACE TROUGH IN THE NORTHERN GULF SQUEEZES THE PRESSURE GRADIENT. FURTHER WEST...RAIN FALLS ACROSS THE PRIBILOF ISLANDS WITH A FRONT DRAPED OVER THE CENTRAL TO EASTERN BERING THAT IS SHEARING OUT AND WEAKEING AS AN UPPER RIDGE BUILDS FROM THE SOUTH. THE RIDGE IS SUPPORTED BY AN UPPER-LVL HIGH CENTERED AROUND 450 MILES SOUTH OF SAND POINT WHICH IS DRIFTING WEST. THERE IS ALSO A NEARLY STATIONARY LOW COMPLEX CENTERED AROUND 400 MILES SOUTH OF SHEMYA. ALSO OF NOTE IS A VORTICITY MAX EJECTING OUT OF EASTERN SIBERIA TOWARDS NORTON SOUND. .MODEL DISCUSSION... IN THE EAST...MODELS SHOW THE VORTICITY MAX NEARING NORTON SOUND DROPPING THROUGH W AK TONIGHT AND SUN AND TRACKING TO THE WESTERN GULF EARLY MON. SOME PHASING OF SHORTWAVE ENERGY IS DEPICTED SE OF KODIAK ISLAND SUN NIGHT WITH AN UPPER-LOW FORMING AND MOVING TO AROUND 300 MILES SOUTH OF MIDDLETON ISLAND ON MON. THE VORTEX SWINGING THROUGH SOUTHCENTRAL MOVES TO NEAR SKAGWAY EARLY SUN MORNING THEN DRIFTS INTO NW BRITISH COLUMBIA ON MON BEFORE BECOMING ABSORBED BY THE OTHER DEEPENING LOW S OF MIDDLETON ISLAND. THIS CONSOLIDATED LOW THEN DRIFTS TOWARDS THE AK PANHANDLE INTO MID-WEEK. THE NAM SOLUTION IS AN OUTLIER IN THAT IT TENDS TO KEEP THE RESIDUAL LOBE IN BRITISH COLUMBIA THE DOMINANT ONE AS THE FEATURES INTERACT WITH EACH OTHER. REGARDLESS...THE NET EFFECT OF THIS CONSOLIDATED UPPER-LVL LOW DIGGING SE OF THE AOR IS TO ALLOW UPPER-RIDGING TO BUILD BACK INTO THE SOUTHERN MAINLAND BEHIND IT. FURTHER WEST...FRONTOLYSIS IS DEPICTED SIMILARLY WITH THE FRONT IN THE EASTERN BERING AS THE SUPPORTING UPPER JET MOVES EAST AND AWAY. THE NAM SEEMS AN OUTLIER IN BRINGING WETTING RAIN (0.10") ALL THE WAY TO NEAR AKHIOK SUN MORNING. THE MODEL CONSENSUS SHOWS AN EASTERN EXTENT OF PRECIP NEAR CHIGNIK AND PORT HEIDEN. WITH REGARDS TO THE LOW COMPLEX SOUTH OF SHEMYA...SATELLITE IMAGERY SUGGESTS THAT A CIRCULATION ALONG IT'S NORTHERN PERIPHERY MAY BE A TOUCH STRONGER AND WETTER THAN QPF FIELDS DEPICT...THOUGH THIS IS DIFFICULT TO INDEPENDENTLY CORROBORATE IN THIS DATA SPARSE AREA. IN GENERAL THE LOW COMPLEX SHOULD GET BUMPED WEST WITH TIME AS THE UPPER HIGH TO THE EAST NOSES TO THE NORTHWEST. .SHORT TERM FORECAST... SOUTHCENTRAL/GULF... OFF-SHORE FLOW ACROSS KODIAK ISLAND IS EXPECTED TO KEEP THINGS DRY AND WARM...ALBEIT A TOUCH WINDY. THE STRONGEST WINDS SHOULD BE TODAY AIDED BY THE JET SUPPORT ALOFT. A RESIDUAL TROUGH IN THE NORTHERN GULF WILL PERSIST AT LEAST UNTIL MON SO CONDITIONS WILL BE A LITTLE BREEZY UNTIL THAT FEATURE WEAKENS SUBSTANTIALLY. ACROSS THE SOUTHERN MAINLAND... THE MAIN FORECAST CHALLENGES SURROUND QPF. THE INDIVIDUAL WAVES MOVING THROUGH THE FLOW POSE A THREAT OF MODERATE RAIN SHOWERS...BUT THE FEATURES ARE TRANSITORY IN THE PROGRESSIVE FLOW SO THERE WILL BE SOME DRY BREAKS. THE FLOW ALOFT REMAINS CYCLONIC UNTIL LATE THIS AFTERNOON SO AREAS NORTH OF KENAI ARE FAIR GAME FOR PRECIP UNTIL THEN. SPEED DIFFLUENCE IS BECOMING MORE PRONOUNCED OVER THE COPPER RIVER BASIN AS THE JET PUSHES TO THE N GULF AND THIS SHOULD ALLOW THE PRECIPITATION SHIELD TO EXPAND AND BECOME STEADIER TODAY. STABILITY FIELDS ARE NOT IMPRESSIVE FOR THUNDERSTORMS...EVEN WITH A SMALL COLD POOL OF AIR ALOFT MOVING DOWN. OVERALL...DRY AIR LOOKS TO MOVE IN BEHIND THE VORTEX TONIGHT AND SUN...LEADING TO MORE SUNSHINE AND SEASONABLE TEMPERATURES. SOUTHWEST/AKPEN... AREAS OF FOG AND STRATUS LOOK TO GET TRAPPED UNDER INVERSIONS...MAINLY OVER COASTAL AREAS AS SURFACE RIDGING PREDOMINATES...THOUGH FLOW BECOMES A BIT MORE NORTH WITH TIME WHICH MAY ALLOW FOR LESS COVERAGE BY MON. SOME PASSING SPRINKLES OR SHOWERS ARE POSSIBLE WITH SOME OF THE ENERGY SWINGING DOWN FROM THE NORTHWEST...BUT FEW ORGANIZED AREAS OF PRECIPITATION APPEAR ON THE HORIZON. THE EXCEPTION IS THE AKPEN WHERE RESIDUAL MOISTURE FROM THE DYING FRONT MAY SQUEEZE OUT SOME LIGHT RAIN THIS AFTERNOON/EVENING. BERING SEA/ALEUTIANS... RELATIVELY BENIGN WEATHER FOR THE BERING SEA AND MUCH OF THE ALEUTIAN CHAIN IN TERMS OF WIND AND PRECIPITATION. THE TYPICAL FOG AND STRATUS REGIME WILL BE STRENGTHENED BY SUBSIDENCE FROM THE UPPER-HIGH BUILDING IN FROM THE SOUTH. SHIP OBS CONFIRMING THAT FOG IS DENSE WITH APPRECIABLE COVERAGE OF LOW VISIBILITY. LITTLE IMPROVEMENT CAN BE ANTICIPATED AS 850 MB TEMPERATURES OF 10 C OR HIGHER PERSIST AND KEEP THE REGION UNDER A STAGNANT AND STABLE AIRMASS. .LONG TERM FORECAST... THE FORECAST AREA SHOULD BE DOMINATED BY AN UPPER-LVL HIGH OVER THE BERING SEA...FLANKED BY A LOW OVER SE REACHES OF THE GULF OF AK AND A LOW NEAR THE FAR WESTERN CHAIN. MODELS SHOW THE RIDGE STARTING TO DAMPEN SOME AS THE LOW TO IT'S WEST BEGINS TO PUSH A BIT FURTHER NORTHEAST AND ENERGY FROM THE HIGH ARCTIC TRIES TO POKE DOWN FROM THE NORTH. INITIALLY THIS WILL RESULT IN MOSTLY DRY CONDITIONS FROM THE EASTERN BERING SEA TO SOUTHCENTRAL ALASKA WITH WARM TEMPERATURES INLAND. MODELS QUICKLY DIVERGE BY THE END OF NEXT WEEK IN DEPICTION OF AN UPPER LEVEL WAVE DROPPING OUT OF THE ARCTIC ACROSS MAINLAND ALASKA SO FORECAST CONFIDENCE DROPS SIGNIFICANTLY. .AER/ALU...WATCH/WARNING SUMMARY PUBLIC...NONE MARINE...GALE...130 FIRE WEATHER...NONE MALOY