Local Forecast Discussion
000 FXUS65 KPIH 032030 AFDPIH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE POCATELLO ID 230 PM MDT FRI SEP 3 2010 .SHORT TERM...TONIGHT THROUGH MONDAY AFTERNOON. A DRY COLD FRONT IS EXPECTED SAT LATE AFTERNOON/EARLY EVENING OVER SOUTHERN IDAHO. WHILE MOST OF THE PRECIPITATION IS LIGHT AND LIMITED TO MOUNTAIN ELEVATIONS...THE ASSOCIATED WIND IS EXPECTED TO BE STRONG. THE FRONT IS ACCOMPANIED WITH A 110KT-PLUS JET MAX AT 250MB AND HAS VERY UNSTABLE AIR THAT SHOULD ALLOW DEEP VERTICAL MIXING. THE PATTERN SCORES NEAR WIND ADVISORY ON THE WACHTER WIND STUDAY FOR SAT AFTERNOON AND CONTINUES EVEN STRONGER ON SUN...WHEN THE PATTERN SCORES NEAR HIGH WIND WARNING ON WACHTER WIND SCHEME. THUS EXPECT AT LEAST A WIND ADVISORY FOR SUN. AT THIS TIME...HAVE ISSUED A SPECIAL WEATHER STATEMENT DESCRIBING THE NUMEROUS WEATHER CHANGES EXPECTED FOR THE HOLIDAY WEEKEND. STRONG WIND AND LOW HUMIDITY ALSO MEANS SOME EXTREME FIRE DANGER AS OUTLINED BELOW. THE WARM SURGE AHEAD OF THE FRONT MEANS VERY WARM TEMPERATURES FOR MOST OF THE AREA ON SAT AFTERNOON...IN THE SEVENTIES TO NEAR 90. BUT THE COLD AIR MASS MOVING IN WILL LOWER THE HIGHS FOR SUN AS MUCH AS 25 DEGREES. SNOW LEVELS WILL LOWER TO APPROXIMATELY THE 7500 FOOT ELEVATION...MAKING SOME HIGH ELEVATION SNOW POSSIBLE. AS THE FRONT MOVES AWAY AND THE GRADIENT RELAXES SUN NIGHT...THE COLD AIR WILL BE ALLOWED TO SETTLE AND PUT TEMPERATURES INTO THE TEENS IN THE ALPINE BASINS OF CENTRAL IDAHO AND TEMPERATURES EVEN IN THE SNAKE RIVER PLAIN WILL FLIRT WITH RECORD LOWS AND A POSSIBLE FROST ADVISORY FOR SUN NIGHT. WEAK UPPER LEVEL RIDGING FOR MON MAKES IT A SALVAGEABLE DAY FOR THE HOLIDAY...ALTHOUGH TEMPERATURES WILL REMAIN COOL. MESSICK .LONG TERM...MON NIGHT THROUGH NEXT FRI NIGHT. WEAK UPPER LEVEL RIDGING CONTINUES UNTIL AN UPPER LEVEL TROUGH MOVES IN BY MID WEEK. ECMWF IS SLOWER WITH PRECIPITATION THREAT RETURNING THU NIGHT...WHILE GFS HAS PRECIPITATION AS EARLY AS WED NIGHT...THOUGH MUCH LIGHTER AMOUNTS THROUGHOUT THE FORECAST PERIOD. THE DRY PERIOD IS ENOUGH TO WARM TEMPERATURES BACK TO NORMAL UNDER THE UPPER LEVEL SOUTH TO SOUTHWEST FLOW. GFSX MOS IS CATCHING THE OVERLY AGRESSIVE NATURE OF THE GFS AND ACTUALLY ONLY HAS SIGNIFICANT POP ON THU NIGHT. CONDITIONS REMAIN CLOUDY WITH DIMINISHED THREAT OF PRECIPITATION ON FRI/FRI NIGHT WITH ONLY A SLIGHT COOL DOWN IN TEMPERATURES DUE TO THE CLOUDS AND PRECIPITATION. WIND DOES NOT LOOK ANYWHERE NEAR AS STRONG AS THE SAT/SUN STORM MENTIONED IN THE SHORT TERM. MESSICK && .AVIATION...VFR CONDITIONS WILL PERSIST THROUGH SATURDAY. SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP MAINLY OVER THE CENTRAL AND EASTERN MOUNTAINS TOMORROW AFTERNOON. BREEZY WEST TO SOUTHWEST WINDS WILL DEVELOP AS WELL AND AFFECT ALL TAF SITES. THE ONLY SITE THAT MAY BE AFFECT THUNDERSTORMS TOMORROW WOULD BE KSUN. A COLD FRONT WILL PUSH THROUGH SATURDAY NIGHT AND SUNDAY. STRONG WINDS WILL CONTINUE THROUGH SUNDAY EVENING. SHOWERS AND THUNDERSTORMS WILL CONTINUE WITH THE HIGHEST CHANCES CONTINUING ACROSS THE CENTRAL AND EASTERN MOUNTAINS. THE REST OF THE AREA WILL SEE A SLIGHT CHANCE ON SUNDAY. THE WIND AND SHOWER/STORM THREAT WILL AFFECT ALL TAF SITES DURING THIS PERIOD. KEYES && .FIRE WEATHER...A POTENT STORM SYSTEM BEGIN AFFECTING EASTERN IDAHO TOMORROW AND CONTINUE INTO SUNDAY EVENING. SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP TOMORROW AFTERNOON ACROSS THE CENTRAL AND EASTERN MOUNTAINS...AND CONTINUE THROUGH SUNDAY. THOSE AREAS WILL SEE THE HIGHEST CHANCES. EVERYWHERE WILL SEE THEIR BEST CHANCE...AND NOT A BIG ONE...AS THE FRONT PASSES SATURDAY NIGHT AND SUNDAY. THE BIGGEST STORY IS THE WIND...DRY AND VERY WARM AIR AHEAD OF THE FRONT AND THE VERY STRONG WINDS CONTINUING ON SUNDAY. JUST ABOUT EVERYONE WILL SEE STRONG SOUTHWEST WINDS OF 20 TO 30 MPH SUSTAINED SATURDAY AFTERNOON AND EVENING. THE STRONGEST WINDS WILL BE AT RIDGETOP AND ACROSS THE SNAKE PLAIN WHERE GUSTS COULD BE APPROACHING 40 MPH. HAINES INDICES OF 5 AND 6 ARE FORECAST IN ALL AREAS EXCEPT THE WESTERN PART OF THE CENTRAL MOUNTAINS. WINDS SHOULD DIE DOWN A BIT SATURDAY NIGHT BE PICK UP ON SUNDAY MORNING AND LAST INTO THE EVENING. SUSTAINED OF 15 TO 25 MPH ARE FORECAST IN THE CENTRAL MOUNTAINS AND UPPER SNAKE HIGHLANDS. SUSTAINED WINDS OF 20 TO 35 MPH ARE LIKELY ACROSS THE REST OF EASTERN IDAHO. THIS WILL PUT GUSTS OF 25 TO 35 MPH IN THE FORECAST FOR MOST AREAS. ACROSS THE SNAKE PLAIN...WIND GUSTS OF 40 TO 45 MPH ARE LIKELY. HAINES VALUES WILL DROP SHARPLY BY SUNDAY AND THE CENTRAL MOUNTAINS AND THE UPPER SNAKE HIGHLANDS WILL SEE HIGHER RH VALUES. HOWEVER...FARTHER SOUTH WHERE LESS CLOUDS AND PRECIPITATION ARE GOING TO EXIST...THE AIR WILL CONTINUE TO BE QUITE DRY EXCEPT AT RIDGETOP. AFTER LOOKING AT CRITICAL FUELS AND COORDINATING WITH LOCAL OFFICES...WE ARE UPGRADING THE FIRE WEATHER WATCH TO A RED FLAG WARNING FOR ZONES 409/410/411/412/413 FROM NOON SATURDAY THROUGH 6PM SUNDAY. KEYES && .PIH WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM NOON SATURDAY TO 6 PM MDT SUNDAY BELOW 7000 FEET FOR THE IDZ411-413. RED FLAG WARNING FROM NOON SATURDAY TO 6 PM MDT SUNDAY IDZ409-410-412. && $$
NWS PIH Office Area Forecast Discussion