Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 160229
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
829 PM MDT MON SEP 15 2014

.DISCUSSION...UPPER LEVEL SHORT WAVE WAS PROVIDING THE LIFT NEEDED
IN AN OTHERWISE MARGINALLY MOIST/UNSTABLE ENVIRONMENT FOR ISOLATED
SHOWERS/THUNDERSTORMS IN HARNEY AND MALHEUR COUNTIES. LATEST
RADAR AND SATELLITE DATA SHOW THE EASTERN EDGE OF THE CONVECTION
JUST TO THE WEST OF THE IDAHO/OREGON BORDER. NEW MODEL GUIDANCE
SUPPORTS THE IDEA THAT THIS AREA OF CONVECTION WILL CONTINUE TO
MOVE TO THE NORTHEAST...BUT WILL LIKELY BYPASS THE BOISE AREA TO
THE WEST. ALSO...EXPECTING THE CONVECTION TO WEAKEN SOMEWHAT SINCE
WE HAVE LOST DAYTIME HEATING...MEANING THE THUNDERSTORMS WILL
LIKELY END BY MIDNIGHT. HOWEVER...ISOLATED SHOWERS SHOULD CONTINUE
AND MOVE INTO BAKER COUNTY TONIGHT...THEN CROSS THE UPPER WEISER
AND WEST CENTRAL MOUNTAINS LATE TONIGHT THROUGH TUESDAY MORNING.
THE SHORT WAVE AND ATTENDANT MOISTURE WILL SHIFT INTO THE CENTRAL
IDAHO MOUNTAINS FOR A SLIGHT CHANCE OF THUNDERSTORMS TUESDAY
AFTERNOON. MEANWHILE...DRIER STABLE AIR WILL MOVE INTO THE
REMAINDER OF SW IDAHO AND SE OREGON. NEAR RECORD HIGH OF 92F
/RECORD IS 93F/ IN BOISE IS STILL ON TRACK FOR TUESDAY. FORECAST
WAS UPDATED EARLIER TO ACCOUNT FOR THE CONVECTION IN MALHEUR
COUNTY. FOR NOW...NO ADDITIONAL UPDATES ARE NEEDED.

&&

.AVIATION...VFR. SCT-BKN HIGH AND MID LEVEL CLOUDS AND LOCAL
SMOKE LAYERS ALOFT. EXPECT ISOLATED THUNDERSTORMS ACROSS SOUTHEAST
OREGON UNTIL ABOUT 06Z...AND AFTER 18Z OVER THE CENTRAL IDAHO
MOUNTAINS EAST OF KMYL AND IDAHO CITY AND OVER THE HIGHLANDS SOUTH
OF KTWF. SURFACE WINDS...VARIABLE 10 KTS OR LESS BECOMING
SOUTHWEST 10-15 KTS ACROSS SOUTHEAST OREGON AFTER 18Z. WINDS
ALOFT...SOUTHWEST UP TO 25 KTS AT 10K FT MSL.

&&

.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH WEDNESDAY...INCOMING UPPER LEVEL
DISTURBANCE IS BRINGING MID AND HIGH CLOUDS TO S CENTRAL OREGON AS
WELL AS SOME HIGH BASED CU TO THE MOUNTAINS OF CENTRAL AND SW
IDAHO. THUNDERSTORM DEVELOPMENT SO FAR WAS ACROSS EAST CENTRAL
NV. COMPARING A FEW FORECAST SOUNDINGS FOR THIS EVENING...SE
OREGON IS LESS FAVORABLE THAN NV FOR THUNDER...DUE TO MINIMAL CAPE
LESS THAN 100 J/KG ACROSS SE OREGON /LKV-BNO/ VERSUS AROUND
200 J/KG AT ELKO. ALSO A /50-200/ CAP WAS NOTED ACROSS SE OREGON.
SO WILL KEEP THE THUNDERSTORM THREAT THIS EVENING ACROSS THE
HIGHEST TERRAIN WHERE CAP IS WEAKEST AND TREND TO ISOLATED
MOUNTAIN SHOWERS LATER TONIGHT ACROSS THE HIGHER MTNS WELL N AND
W OF BOISE.

UPPER LEVEL FORCING SHIFTS THROUGH CENTRAL IDAHO AS TUESDAY
PROGRESSES...LEAVING SE OREGON AND MOST OF SW IDAHO IN MILD
LOCALLY BREEZY SW FLOW. THIS WILL COMBINE WITH EAST DOWNSLOPE
WINDS FOR NEAR RECORD HIGHS AT BOISE TUESDAY AFTERNOON. SOME
MOISTURE AND LIGHT SE TO S WINDS ARE EXPECTED LATE TUESDAY
AFTERNOON ACROSS CENTRAL IDAHO TO THE FAR NW MAGIC VALLEY.
LIMITED MOISTURE ACROSS THE HIGHER TERRAIN OF CENTRAL IDAHO
WARRANTS LOW POPS THERE LATE TUESDAY AND MOISTURE MAY LINGER INTO
LATE WEDNESDAY BEFORE THE UPPER TROUGH/COLD FRONT COME IN FOR THE
EARLY LONG TERM.

LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...PACIFIC UPPER TROUGH
WILL SPLIT AND WEAKEN AS IT COMES INLAND WEDNESDAY NIGHT.  SRN
PORTION WILL FORM A WEAK UPPER LOW IN CALIF WHILE NRN PORTION
SHEARS OFF INTO MONTANA. WEAK COLD FRONT WILL PASS THROUGH OUR
ZONES WEDNESDAY NIGHT COOLING TEMPS 5-10F FOR THU AND FRI BUT EVEN
THEN REMAINING A LITTLE ABOVE NORMAL. FROPA WILL ALSO BRING A
CHANCE OF SHOWERS AND SLIGHT CHANCE OF THUNDERSTORMS TO IDAHO
ZONES MAINLY THURSDAY AS A SMALL PART OF TROPICAL MOISTURE FROM
ODILE WILL BE DRAWN NWD FROM ARIZ. NEXT PACIFIC UPPER RIDGE WILL
COME IN LATE NEXT WEEK WITH ANOTHER WARMING AND DRYING TREND...MIN
TEMPS WARMING MORE SLOWLY THAN MAX TEMPS.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...BW
AVIATION.....JT
PREV SHORT TERM...VM
PREV LONG TERM....LC/LC


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