Area Forecast Discussion


821 
FXUS65 KBOI 130255
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
855 PM MDT MON AUG 12 2013
.DISCUSSION...AS OF 830 PM MDT MAIN CONVECTIVE ACTIVITY WAS IN 
NORTHERN MALHEUR COUNTY AND BAKER COUNTY...MOVING NORTH.  SUMPTER 
AND BAKER CITY WERE IN THE PATHS OF THE STRONGEST STORMS.  THE
STORMS IN MALHEUR COUNTY APPEARED TO BE HEAVY RAIN-MAKERS ACCORDING 
TO RADAR ESTIMATES.  RELATIVELY LITTLE LIGHTNING THERE.  IN IDAHO
ONLY ISOLATED WEAK CONVECTION...CERTAINLY NOTHING SEVERE.  WE PLAN
TO LET RED FLAG WARNINGS FOR LIGHTNING EXPIRE AS SCHEDULED AT
10 PM MDT/ 9 PM PDT/.  WE HAVE SEEN A COUPLE OF WEAK THUNDERSTORM
OUTFLOWS PASS THROUGH THE TREASURE VALLEY FROM WEST TO EAST.  THE
BENEFIT OF THESE OUTFLOWS WOULD BE TO PUSH SOME OF THE SMOKE BACK 
OUT OF THE TREASURE VALLEY THIS EVENING.  AFTERNOON FORECAST HAS 
KEPT MAX TEMPS FOR TUESDAY A LITTLE LOWER THAN GUIDANCE DUE TO 
SMOKE... STILL A GOOD IDEA AS LAST TWO DAYS WERE A LITTLE COOLER 
THAN FORECAST.  NO UPDATES EXCEPT TO EXPIRE THE RED FLAG WARNINGS 
LATER THIS EVENING.
&&
.AVIATION...WILDFIRE SMOKE WILL CAUSE REDUCED VISIBILITIES AND 
MOUNTAIN OBSCURATION FROM UPPER TREASURE VALLEY ACROSS THE CENTRAL 
IDAHO MOUNTAINS THROUGH THURSDAY. SOME IMPROVEMENT IS EXPECTED
THIS EVENING IN THE TREASURE VALLEY FROM WEAK THUNDERSTORM 
OUTFLOW...HOWEVER EXPECT TO SEE THE SMOKE RETURN FOR REDUCED 
VISIBILITIES AFTER MIDNIGHT. ISOLATED THUNDERSTORMS WILL DIMINISH 
ACROSS SE OREGON BY 05Z. LIGHT SURFACE WINDS...EXCEPT IN THE 
VICINITY OF STORMS. SOUTH WINDS ALOFT UP TO 10 KTS AT 10K FT MSL.
 
&&
.AIR STAGNATION...00Z BOI RAOB HAD LIGHT TO MODERATE NORTHWEST WINDS 
FROM THE SURFACE TO ABOUT 6000 FEET AGL...AND SOUTHERLY WINDS ABOVE
THAT.  THESE WINDS SHOULD KEEP MOST OF THE SMOKE FROM ELMORE COUNTY 
FIRES OUT OF THE TREASURE VALLEY. HOWEVER...NIGHTTIME DRAINAGE WINDS 
ARE USUALLY FROM THE EAST WHICH WOULD TEND TO BRING SMOKE IN AT THE
LOWEST LEVELS. AROUND 4 PM MDT THE IDAHO DEPARTMENT OF ENVIRONMENTAL 
QUALITY ISSUED AN ORANGE AIR QUALITY ADVISORY FOR THE TREASURE 
VALLEY. THIS ADVISORY WILL REMAIN IN EFFECT UNTIL AIR QUALITY 
IMPROVES.
&&
.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH WEDNESDAY...SHOWERS AND THUNDERSTORMS 
FORMING OFF THE HIGHER TERRAIN THIS AFTERNOON WILL CONTINUE INTO
THE EVENING. A SHORT WAVE TROUGH SWINGING INTO THE PACNW WILL KEEP 
ISOLATED ACTIVITY OVER SE OREGON AND MTNS OF SW IDAHO OVERNIGHT. 
DYNAMICS ALOFT ARE WEAK SO THUNDERSTORMS WILL PULSE AND THE DRY 
BOUNDARY LAYER WILL SUPPORT GUSTY OUTFLOW WINDS TO 45 MPH. LEVEL 
WINDS OUT OF THE NORTH-NORTHEAST THIS MORNING TRANSPORTED QUITE A 
BIT OF SMOKE INTO THE SNAKE VALLEY BETWEEN MOUNTAIN HOME AND BOISE. 
WHILE SURFACE WINDS HAVE SHIFTED TO THE NW...VISIBLE SATELLITE PICS 
THIS AFTERNOON STILL SUGGEST AN EAST-NORTHEAST WIND ALOFT. WITH 
CONTINUED PRESENCE OF SMOKE...HAVE LOWERED HIGH TEMPERATURES FOR THE 
UPPER TREASURE VALLEY TUESDAY AND WEDNESDAY /CLOSER TO THE COOLER 
MAV GUIDANCE/. OTHERWISE A GENERAL WARMING TREND THE NEXT COUPLE OF 
DAYS AS SOUTHWEST FLOW CONTINUES THROUGH WEDNESDAY UNDER A BUILDING 
UPPER LEVEL RIDGE. ISOLATED AFTERNOON THUNDERSTORMS WILL DEVELOP 
AGAIN TUESDAY AND WEDNESDAY WITH THE FOCUS OF ACTIVITY OVER THE 
EAST-CENTRAL OREGON AND WEST-CENTRAL AND BOISE MOUNTAINS. 
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...STILL EXPECT A VERY 
HOT RIDGE TO REAMPLIFY OVER SE OREGON AND SW IDAHO FOR LATER THIS 
WEEK...FOLLOWED BY ANOTHER FLAT TROUGH /OR LOW/ PASSAGE TO OUR NW 
THIS WEEKEND. LOW-ELEVATION VALLEY HIGH TEMPERATURES WILL BE AT 
LEAST 90 THROUGH NEXT MONDAY...AND ARE LIKELY TO REACH 100 LATE 
THURSDAY. SOUTH CENTRAL IDAHO MAY END UP JUST AS WARM FRIDAY AS 
THURSDAY AS THE HIGH AMPLITUDE PATTERN IS SLOW TO BREAK DOWN. 
GENERALLY SOUTH OF A BURNS OREGON TO IDAHO CITY LINE...LATE 
AFTERNOONS LOOK HOT AND UNSTABLE WEDNESDAY THROUGH FRIDAY. BY 
SATURDAY EXPECT A BREAKDOWN OF THE UPPER RIDGE FOR ALL AREAS AND 
SOME PRECIPITATION FROM THE NE OREGON BLUES INTO NORTH-CENTRAL IDAHO 
AS A TROUGH TRACKS FROM WEST TO EAST ALONG THE CANADIAN BORDER. 
MODELS HAVE TRENDED TOWARDS A STRONGER PACNW RIDGE SUNDAY AND MONDAY 
SO ABOVE NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION CHANCES 
ARE ON TRACK INTO EARLY NEXT WEEK. 
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...RED FLAG WARNING UNTIL 10 PM MDT THIS EVENING IDZ401>403.
OR...RED FLAG WARNING UNTIL 10 PM MDT /9 PM PDT/ THIS EVENING ORZ636-
     637.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...LC
AVIATION.....JDS
AIR STAGNATION....LC
PREV SHORT TERM...DG
PREV LONG TERM....VM/KA