Hail in Alaska, June 9, 2010

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
1242 PM AKDT WED JUN 9 2010

.DISCUSSION...500MB RIDGE EXTENDS FROM NORTHEAST ALASKA DOWN TO
BRITISH COLUMBIA. VERTICALLY STACKED LOW REMAINS SOUTH OF THE
ALASKA PENINSULA. BROAD THERMAL TROUGH AT THE SURFACE EXTENDS FROM
NEAR FORT YUKON DOWN TOWARD ANVIK IN THE LOWER YUKON VALLEY. A
SUCCESSION OF SHORT WAVE TROUGHS ALOFT WILL EJECT FROM THE CLOSED
LOW AND MOVE NORTH INTO ALASKA'S INTERIOR...THESE TROUGHS WILL
EVENTUALLY NUDGE THE 500MB RIDGE AXIS TO THE NORTHEAST AND OUT OF
ALASKA BY THE WEEKEND. MODELS IN RELATIVELY GOOD AGREEMENT WITH
THIS IDEA.

NORTH SLOPE...VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW MAINLY
CLEAR SKIES FOR THE THIRD DAY RUNNING. RIDGE ALOFT IS PREVENTING
ANY INFLUX OF NEW MOISTURE TO THE NORTH SLOPE...ANY IFR CONDITIONS
WOULD NEED TO DEVELOP IN PLACE. WILL FORECAST MAINLY CLEAR
CONDITIONS TO PERSIST TONIGHT AND THURSDAY. WINDS WILL REMAIN SUB-
ADVISORY FOR AT LEAST NEXT COUPLE DAYS AS THE RIDGE ALOFT IS ALSO
BRINGING A WEAK GRADIENT IN THE SEA LEVEL PRESSURE PATTERN.

WEST COAST...PRIMARY CONCERN IS COASTAL FOG...WHICH WILL CONTINUE
FOR LOCATIONS WITH AN ONSHORE COMPONENT TO THE FLOW. ALSO...WIND
SPEEDS ARE BEING LOCALLY ENHANCED BY THE TOPOGRAPHY THROUGH THE
BERING STRAIT. INLAND SECTIONS WILL CONTINUE TO HAVE SOME
CONVECTIVE PRECIPITATION. NEXT OPPORTUNITY FOR SOME LEGITIMATE
BAROCLINIC WEATHER WILL COME SUNDAY AS A LOW PRESSURE SYSTEM MOVES
INTO THE BERING SEA AND AN OCCLUDED FRONT REACHES THE WEST COAST
ZONES SOUTH OF THE BERING STRAIT. THIS EVENT IS A WAYS OUT IN THE
FUTURE...BUT NOW BOTH THE GFS AND ECMWF MODELS ARE INDICATING
THIS TREND.

INTERIOR...EXPECTING ANOTHER ACTIVE CONVECTIVE AFTERNOON AND
EVENING. MORNING RAOB IN FAIRBANKS HAD A LIFTED INDEX OF -3.0C
AND ALMOST 800 J/KG OF CAPE. THIS RAOB ALSO SHOWED ENOUGH AMBIENT
WIND SHEAR TO BRING THE BULK RICHARDSON NUMBER DOWN TO 28...THIS
IS IN CONTRAST TO MOST CONVECTIVE DAYS IN ALASKA'S INTERIOR WHEN
THE BUOYANCY OVERWHELMS THE SHEAR. SO EXPECT SOME STORMS MAY BE
LONGER-LIVED THAN IS USUALLY EXPECTED...AND A FEW STORMS
COULD BECOME STRONG ENOUGH TO PRODUCE LARGER HAIL AND STRONGER
WIND GUSTS THAN IS TYPICAL FOR THE INTERIOR. CONVECTIVE REGIME IN
THE INTERIOR WILL GRADUALLY EDGE TO THE NORTHEAST OVER NEXT COUPLE
DAYS...FOLLOWING THE MOVEMENT OF THE THERMAL TROUGH. THEN
TRANSITIONING TO A MORE STRATIFORM REGIME BY THE WEEKEND.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.FIRE WEATHER...WILL CONTINUE RED FLAG WARNINGS FOR ZONES 219 AND
220 DUE TO LOW HUMIDITY THROUGH THIS EVENING. BUT DO NOT EXPECT A
REPEAT OF THIS RED FLAG ON THURSDAY...DUE TO THE NORTHWARD DRIFT OF
THE THERMAL TROUGH AND ASSOCIATED INFILTRATION OF HIGHER DEWPIONT
AIR INTO THE NORTHEAST INTERIOR. EXPECT ANY THUNDERSTORMS FOR THE
FORESEEABLE FUTURE TO BE WET.

&&

.HYDROLOGY...NAM AND GFS MODELS ARE BOTH MODERATELY AGGRESSIVE WITH
STRATIFORM PRECIPITATION IN ZONES 211 AND 222 ON FRIDAY ASSOCIATED
WITH THE PASSAGE OF A SHORT WAVE TROUGH ALOFT. FOR NOW...THIS DOES
NOT APPEAR TO BE AN OPTIMAL MECHANISM TO PRODUCE ENOUGH
PRECIPITATION FOR FLOODING GIVEN THE TRAJECTORY OVER THE ALASKA
RANGE. BUT WILL NEED TO KEEP AN EYE ON THIS SINCE UNLIKE THE
CONVECTIVE REGIME THAT HAS BEEN IN PLACE OVER THE LAST SEVERAL
DAYS...THIS NEW SHORT WAVE OFFERS THE POTENTIAL FOR WETTING RAINS
OVER A BROADER AREA.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FOR AKZ219-AKZ220.
&&

ES JUN 10

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE FAIRBANKS AK
338 PM AKDT WED JUN 09 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0545 PM     HAIL             4 N FAIRBANKS           64.89N 147.65W
06/08/2010  E0.75 INCH                          AK   CO-OP OBSERVER

            TSTORM INCLUDED SHRA, FREQUENT LIGHTNING, STRONG GUSTY
            WINDS, HAIL 3/8 INCH TO 3/4 INCH - COVERED THE GROUND

&&

CB