Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 310250
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
850 PM MDT WED JUL 30 2014

.DISCUSSION...CONVECTION HAS BEEN SIMILAR TO LAST NIGHT IN
STRENGTH AND COVERAGE...ALBEIT IN DIFFERENT AREAS FOR THE MOST
PART. A LARGE OUTFLOW BOUNDARY MOVED THROUGH THE TREASURE VALLEY
FROM NE TO SW THIS EVENING...KNOCKING DOWN SOME SMALL BRANCHES AND
ISOLATED TREES. THE RED FLAG WARNING CONTINUES FOR BURNS BLM
BECAUSE A SHORT WAVE TROUGH IS STILL HEADED INTO THE AREA THIS
EVENING. THE WARNING MAY NEED TO BE EXTENDED PAST MIDNIGHT IF
ACTIVITY GETS GOING WITH THE APPROACHING WAVE.

THE IMMEDIATE CONCERN IS THE CONVECTION OVER THE OWYHEES. THE
OUTFLOW BOUNDARY THAT MOVED THROUGH THE TREASURE VALLEY IS HEADED
THERE SHORTLY...AND MAY ACT TO AMPLIFY THE STORMS OR HELP INITIATE
NEW ONES. WE WILL DECIDE WHAT TO UPDATE OVER THE NEXT HOUR AND
THEN GET A NEW FORECAST OUT.

&&

.AVIATION...VFR. SCATTERED THUNDERSTORMS MAINLY SOUTH OF THE SNAKE
RIVER PLAIN THIS EVENING. ISOLATED RAIN SHOWERS ACROSS THE WEST
CENTRAL AND BOISE MOUNTAINS. EXPECT THUNDERSTORMS TO DIMINISH AFTER
SUNSET EXCEPT ACROSS HARNEY COUNTY OREGON WHERE A SHORTWAVE SHOULD
KEEP STORMS GOING THROUGH 12Z THURSDAY. BASES 8K-10K FEET AGL.
SURFACE WINDS...VARIABLE 10 KTS OR LESS EXCEPT GUSTS TO 30 KTS OR
MORE NEAR THUNDERSTORMS. WINDS ALOFT...NORTH AROUND 10 KTS UP
THROUGH 10K FEET MSL.

&&

.PREV DISCUSSION...
SHORT TERM...GREATEST INSTABILITY AND CAPE THIS AFTERNOON ARE IN
HARNEY COUNTY AND THUNDERSTORMS ARE ALREADY FORMING NEAR THERE
WITH MORE STORMS UPSTREAM IN NERN CALIF.  A WEAK PACIFIC SHORT WAVE
TROUGH IS ALSO COMING INLAND.  0 TO 6 KM BULK SHEAR IS WEAK.  WE
HAVE DESIGNATED HARNEY COUNTY FOR THE MAIN THUNDERSTORM ACTIVITY
THIS EVENING WITH LESSER ACTIVITY ELSEWHERE.  STORMS SHOULD BE
PULSE TYPE WITH LOCAL HEAVY RAIN AND GUSTY WINDS.  ACTIVITY SHOULD
WIND DOWN LATE THIS EVENING THROUGH THURSDAY MORNING THEN REDEVELOP
THURSDAY AFTERNOON/EVENING AND AGAIN FRIDAY AFTERNOON/EVENING.
LITTLE DAY-TO DAY CHANGE IN TEMPERATURES THROUGH FRIDAY.

LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...ALTHOUGH MODELS
CONTINUE TO DECREASE THE AMPLITUDE OF THE UPPER LEVEL RIDGE OVER
WESTERN NORTH AMERICA...WARM TEMPERATURES ARE EXPECTED TO
CONTINUE...AVERAGING 3-5 DEGREES ABOVE NORMAL. VERY MOIST AND
UNSTABLE AIR IN THE RIDGE CIRCULATION WILL FUEL ISOLATED
THUNDERSTORMS MAINLY AFTERNOONS AND EVENINGS EACH DAY. MODELS AGREE
ON BRINGING A SHORTWAVE TROUGH NORTH OVER THE GREAT BASIN SUNDAY
NIGHT AND MONDAY. THIS FEATURE WILL HELP SUPPORT CONVECTION OVER OUR
AREA BEFORE MOVING EAST INTO COLORADO TUESDAY NIGHT. WITH
PRECIPITABLE WATER AS MUCH AS HALF AN INCH ABOVE NORMAL...LOCAL
HEAVY RAIN IS POSSIBLE WITH THUNDERSTORMS.

AVIATION...VFR. SCATTERED TO BROKEN MID LEVEL AND HIGH CLOUDS.
ISOLATED THUNDERSTORMS MAINLY BEFORE 06Z. BASES 8K-10K FEET AGL.
SURFACE WINDS...VARIABLE 10 KTS OR LESS EXCEPT GUSTS TO 30 KTS OR
MORE NEAR THUNDERSTORMS. WINDS ALOFT...NORTH AROUND 10 KTS UP
THROUGH 10K FEET MSL.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING ORZ636.

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...SP
AVIATION.....JS
PREV SHORT TERM...LC
PREV LONG TERM....JT/AB


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