Flood in Alaska, May 28, 2012

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
428 AM AKDT MON MAY 28 2012

.DISCUSSION...
UPPER LEVELS...A 532 DM LOW 75 MILES WEST OF CAPE LISBURNE AT 12Z
THIS MORNING WILL MOVE INTO THE GULF OF ANADYR TUE MORNING AND
ELONGATE OUT. THE LOW SPLITS INTO TWO CENTERS TUE NIGHT. ONE
CENTER REMAINS ACROSS CHUKOTKA WHILE THE OTHER CENTER DIVES SOUTH
TO THE CENTRAL ALEUTIANS ON WEDNESDAY. A STRONG 567 DM RIDGE
CENTERED BETWEEN THE GREAT SLAVE AND GREAT BEAR LAKES WILL REMAIN
QUASI-STATIONARY TROUGH TUE AND THEN BEGIN TO SLOWLY WEAKEN AND
MOVE EAST WHILE THE NORTHERN PORTION OF THE RIDGE SLOWLY BUILDS
INTO THE BEAUFORT SEA.

SFC...A WEAK THERMAL TROUGH EXTENDS FROM 75 MILES NORTH OF MCGRATH-
TANANA-FORT YUKON EARLY THIS MORNING. THE TROUGH REMAINS NEARLY
STATIONARY TODAY AND WILL STRENGTHEN SOME DURING THE DAY WITH
STRONG DAYTIME HEATING. THE TROUGH IS EXPECTED TO BE EVEN BETTER
DEFINED AND STRONGER TUE PM FROM GALENA-STEVENS VILLAGE-CHALKYITSIK
WITH A SECONDARY TROUGH EXTENDING FROM GALENA SOUTH INTO THE LOWER
KUSKO VALLEY. THE MOST UNSTABLE AIR WILL RESIDE NEAR THE THERMAL
TROUGH WHERE THERE WILL BE THE BEST CHANCE OF THUNDERSTORMS. A
RIDGE OF HIGH PRESSURE EXTENDS FROM THE NORTHEAST BERING SEA AND
INTO THE CHUKCHI SEA. THE RIDGE WILL SLOWLY WEAKEN TROUGH TUE. A
WEAK TROUGH IS EXPECTED TO DEVELOP TODAY IN THE EASTERN BEAUFORT
SEA.

INTERIOR...A SERIES OF SHORTWAVE TROUGHS WILL ROTATE TROUGH THE
INTERIOR OVER THE NEXT TWO DAYS. ONE TROUGH WEAKENS TODAY ACROSS
THE EASTERN INTERIOR ALONG THE ALCAN BORDER TO NEAR DELTA
JUNCTION. SOUTHEAST FLOW ALOFT INCREASES TUE WITH A COUPLE OF MORE
SHORTWAVES TO MOVE FROM SOUTHEAST TO NORTHWEST ACROSS THE
INTERIOR. A SHORTWAVE RIDGE BUILDS BRIEFLY ACROSS THE EASTERN
INTERIOR TUE NIGHT INTO WEDNESDAY. SHOWERS AND EVEN SOME AREAS OF
STRATIFORM RAIN WILL ACCOMPANY THE SHORTWAVE TROUGHS WITH THE
PRECIPITATION BEING THE MOST SHOWERY IN NATURE DURING THE
AFTERNOON AND EVENING HOURS. THE 12Z PAFA SOUNDING WAS SLIGHTLY
UNSTABLE WITH A LIFTED INDEX OF -2 AND 600 J/KG OF CAPE. BASED ON
THE MORNING SOUNDING DID HAVE SOME ISOLATED THUNDERSTORMS THIS
AFTERNOON INTO THE CENTRAL INTERIOR...BUT LEFT THEM OUT OF THE
KUSKO VALLEY AS THE MORNING SOUNDING AT MCGRATH WAS MUCH DRIER AND
MORE STABLE THAN THE PAFA SOUNDING.

WEST COAST...MAINLY DRY WEATHER THE NEXT COUPLE OF DAYS.  SCATTERED
INLAND SHOWERS AND ISOLATED THUNDERSTORMS BY TUE PM MAINLY FROM THE
NULATO HILLS EAST IN ASSOCIATION WITH THE THERMAL TROUGH.  SCATTERED
SHOWERS WILL LIKELY MAY THEN SPREAD WEST TOWARD THE COAST WEDNESDAY
AS AN UPPER TROUGH BUILDS NORTH TO NEAR KOTZEBUE BY WED PM.

NORTH SLOPE...WEAK EAST TO NORTHEAST FLOW ALONG MOST OF THE ARCTIC
COAST THE NEXT COUPLE OF DAYS.  A WEAK TROUGH IN THE EASTERN
BEAUFORT SEA IS PRODUCING A PERIOD OF W-NW WIND FROM PRUDHOE BAY
EAST TODAY THAT WILL TURN BACK INTO THE EAST TONIGHT AS THE TROUGH
LIFTS FURTHER OFFSHORE AND THE TROUGH IN THE INTERIOR STRENGTHENS.
AREAS OF STATUS AND PATCHY FOG AND FLURRIES ARE EXPECTED ALONG THE
COAST THROUGH WEDNESDAY WITH SEASONABLE TEMPS. ISOLATED SNOW
SHOWERS TODAY ALONG THE BEAUFORT SEA COAST IN ASSOCIATION WITH THE
SURFACE TROUGH. AREAS OF RAIN AND SNOW LIKELY ALONG PARTS OF THE
NORTHERN AND WESTERN ARCTIC COAST ON WEDNESDAY AS A SHORTWAVE
TROUGH LIFTS NORTH TO THE WESTERN ARCTIC COAST.

&&

.FIRE WEATHER....80 LIGHTNING STRIKES YESTERDAY IN ZONE 220 EAST OF FT
YUKON AND IN ZONE 224 FROM ABOUT CHICKEN EAST. ISOLATED THUNDERSTORMS
ARE POSSIBLE TODAY AND TUESDAY ALONG AND NEAR THE THERMAL
TROUGH...BUT ANY THUNDERSTORMS WILL BE WET. MUCH OF THE INTERIOR
FROM FAIRBANKS EAST HAS HAD SIGNIFICANT RAINFALL DURING THE LAST
COUPLE OF DAYS. RELATIVE HUMIDITIES WILL REMAIN ABOVE CRITICAL
LEVELS THIS WEEK...AND LIKELY THE LOWEST IN THE WESTERN INTERIOR.

&&

.HYDROLOGY...THE FIRST CREST MOVING DOWN THE CHENA RIVER REACHED
FAIRBANKS OVERNIGHT. THE NEXT SURGE OF WATER IS NOW MOVING DOWN
THE UPPER CHENA BASIN AND WILL BEGIN TO FLOW TOWARD FAIRBANKS OVER
THE NEXT 36 HOURS. ADD'L RAINFALL YESTERDAY OF 0.50-1.00" IN THE
BASIN IS BEGINNING TO SHOW UP EARLY THIS MORNING WITH RISES NEAR
TWO RIVERS. THE SALCHA LEVELED OFF AND IS NOW SLOWLY RISING AGAIN
DUE TO ADD'L RAINFALL. THE GOODPASTER IS ALSO SEEING SOME SMALL
RISES THIS MORNING. THE TANANA AT FAIRBANKS CRESTED SUN PM AND IS
NOW FALLING. AS RAIN COMES DOWN THE GOODPASTER AND SALCHA AN
ADDITIONAL RISE IS LIKELY TUE. A SMALL STREAM FLOOD ADVISORY IS IN
EFFECT UNTIL NOON TODAY FOR THE STEESE HIGHWAY FROM MP 80 TO
CIRCLE. AROUND 1 INCH OF RAIN FELL SUNDAY AND MANY STREAMS AND
CREEKS THAT CROSS THE STEESE HIGHWAY ARE RUNNING NEAR BANKFULL.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
BRISK WIND ADVISORY FOR PKZ210-PKZ225.

FLOOD ADVISORY AKZ220-AKZ222-AKZ223.

&&

CB MAY 12