Brisk Wind Advisory 121, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
251 AM ADT FRI JUN 29 2007

.DISCUSSION...

GOES IR LOOP IS SHOWING THE UPPER LEVEL HIGH IS CURRENTLY
CENTERED OVER THE UPPER YUKON VALLEY. THIS HIGH PRESSURE
SUPPRESSED CONVECTION OVER THE EASTERN INTERIOR THURSDAY...WITH
ONLY A SMALL NUMBER OF STRIKES OCCURRING IN THE CENTRAL INTERIOR
ALONG THE NORTH-SOUTH BOUNDARY BETWEEN THE DRY AIR UNDER THE HIGH
AND MOIST AIR FARTHER TO THE WEST.

FOR TODAY THROUGH SUNDAY...THE NAM40 SURFACE CAPES AND LIFTED
INDEXES ARE RUNNING MUCH HIGHER THAN THE GFS40. THIS MAY
LIKELY TO BE THE HIGHER SURFACE DEW POINTS AND LOW LEVEL
MOISTURE ON THE NAM40. THE NAM40 MOS IS ALSO INDICATING
HIGHER SURFACE DEW POINTS IN THE CENTRAL AND SOUTHERN INTERIOR
THAN THE GFS...BUT THE GFS IS TRENDING TO HIGHER DEW POINTS
THROUGH THE WEEKEND.

MODELS RUNS ARE CHANGING THE PATTERN ALOFT FROM A CLOSED
HIGH TO A RIDGE...WITH THE RIDGE AXIS DRIFTING NORTHWARD
A BIT THROUGH THE WEEKEND. THE FLOW ALOFT OVER THE INTERIOR
WILL BECOME MORE EASTERLY...ALLOWING MOISTURE FROM
NORTHWEST CANADA TO GRADUALLY INFILTRATE WESTWARD. THIS
MOISTURE IS SHOWING UP WELL ON THE GOES IR AND WATER
VAPOR LOOPS. A WEAK LOW ALOFT IS PROGGED TO MOVE WESTWARD
INTO THE SOUTHEAST INTERIOR SATURDAY AFTERNOON ...
LIKELY ENHANCING CONVECTION IN THAT AREA.

AT THE SURFACE...A BROAD THERMAL TROUGH WITH THE AXIS
EXTENDING FROM THE NORTHWAY AREA TO NEAR TANANA AND NORTHWESTWARD
INTO ZONE 208 WILL PERSIST THROUGH THE WEEKEND...STRENGTHENING
A LITTLE OVER THE WEEKEND.

THE INCREASE IN MOISTURE AND THE SLIGHT NORTHWARD SHIFT OF
THE UPPER RIDGE AXIS SHOULD RESULT IN AN INCREASE IN THUNDERSTORM
ACTIVITY OVER MUCH OF THE INTERIOR AND BROOKS RANGE OVER
THE WEEKEND...WITH THE MOST ACTIVITY BEING ALONG AND NEAR THE
SURFACE TROUGH.

OVER THE WESTERN INTERIOR AND MUCH OF THE WEST COAST...
SCATTERED SHOWERS ARE EXPECTED THROUGH THIS EVENING
IN A BROAD NORTH-SOUTH BAND OF MOISTURE. THE TAIL OF A VORT
CENTER LIES OVER MARINE ZONE 210...IT MAY MOVE A BIT MORE EAST
BEFORE STALLING OUT AND DIMINISHING IN INTENSITY.

HIGH PRESSURE WILL PERSIST OVER THE ARCTIC OCEAN.
EAST WINDS 15-25 MPH...AND LOW CLOUDS AND PERIODS OF
FOG WILL CONTINUE ALONG THE ARCTIC COAST.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.FIRE WEATHER...
THUNDERSTORM ACTIVITY IS EXPECTED TO INCREASE OVER
THE WEEKEND...MEANING A SUBSTANTIAL INCREASE IN THE
NUMBER OF LIGHTNING STRIKES.

&&

.HYDROLOGY...
BOTH GFS AND NAM ARE SHOWING AN INCREASE IN PRECIPITABLE
WATER...TO AN INCH OR MORE...OVER THE CENTRAL AND SOUTHERN
INTERIOR OVER THE WEEKEND. THIS MEANS AN INCREASED POTENTIAL
FOR LOCALLY HEAVY RAINFALL AMOUNTS IN THUNDERSTORMS.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR PKZ230-PKZ235.

BRISK WIND ADVISORY FOR PKZ235-PKZ240-PKZ245.
&&

RF JUN 07