855
FXUS65 KPIH 141938
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
138 PM MDT SAT SEP 14 2019
DISCUSSION
TONIGHT THROUGH NEXT SATURDAY. A FLAT RIDGE OF HIGH
PRESSURE WAS POSITIONED OVER THE REGION EARLY THIS AFTERNOON AS A
DEEP BROAD UPPER LOW ADVANCED INTO THE CANADIAN COASTAL WATERS.
NUMERICAL MODELS DRIVE THE LOW SOUTH THROUGH VANCOUVER ISLAND SUNDAY
AS THE FLOW ALOFT OVER IDAHO BACKS FROM THE WEST TO SOUTHWEST AND
REMAINS DRY. THE LOW MOVES ONSHORE SUNDAY NIGHT AND EASTWARD ACROSS
OREGON AND WASHINGTON MONDAY AS ISOLATED SHOWERS LIFT NORTHWARD OUT
OF UTAH INTO THE WYOMING BORDER REGION MONDAY AFTERNOON. LAST NIGHTS
06Z NAM MODEL CYCLE WAS INDICATING A STRONGER TROUGH ADVANCING INTO
NRN NEVADA MONDAY EVENING RESULTING IN THE POTENTIAL FOR SEVERE
THUNDERSTORM ACTIVITY ACROSS THE SE IDAHO MOUNTAINS...AND THEN THE
12Z MODEL RUN CAME IN MUCH WEAKER WITH THE TROUGH AND COMPLETELY
DEVOID OF ANY ACTIVITY OVER THE SE MOUNTAINS. THUS, THE BRUNT OF THE
STORM APPEARS TO SWEEP ACROSS SE IDAHO LATE MONDAY NIGHT AND TUESDAY
WITH THUNDERSTORMS DEVELOPING OUT AHEAD OF THE TROUGH AND STRONG
WINDS TRAILING INTO THE BURLEY AND POCATELLO AREAS BEHIND THE
EXITING LOW TUESDAY AFTERNOON. WE SHOULD SEE A BRIEF DRY SPELL
TUESDAY NIGHT AND WEDNESDAY BEFORE A SECOND PACIFIC LOW ADVANCES
THROUGH THE NW STATES AND INTO SE IDAHO LATE THURSDAY AND FRIDAY
BEFORE EXITING OFF TO THE NE SATURDAY. IT LOOKS LIKE FALL HAS
ALREADY ARRIVED, WITH 15-20 DEGREE SWINGS IN DAYTIME HIGHS FROM ONE
DAY TO THE NEXT ACCOMPANIED BY SHOWERS AND GUSTY WINDS. HUSTON
AVIATION
HIGH PRESSURE CONTINUES TO EXERT CONTROL OVER SE IDAHO,
PROVIDING HIGH CONFIDENCE IN VFR CIGS/VSBYS THROUGH AT LEAST MON
EVE. AT THIS POINT, OUR AIRMASS IS TOO DRY TO SUPPORT FOG, OUTSIDE
OF VERY ISOLATED DEVELOPMENT OVER WATER. DIURNALLY BREEZY CONDITIONS
THIS AFTERNOON WILL TREND BREEZIER FOR SUN AND MON, WITH PREDOMINANT
SW TRAJECTORIES NOT FAVORABLE FOR CROSSWINDS ON MAJOR TERMINAL
RUNWAYS. TAF GROUPS LARGELY DELINEATE DIRECTIONAL WIND SHIFTS. -
01/HUSTON
FIRE WEATHER
HIGH PRESSURE WILL REMAIN THE PREDOMINANT FORCE
CONTROLLING OUR WX THROUGH MON AFTERNOON, WITH A DRYING/WARMING
TREND CONTINUING AND BREEZY CONDITIONS EACH AFTERNOON (PARTICULARLY
ACROSS THE ARCO DESERT AND MID/UPPER SLOPES OF MOST ZONES). THESE
WINDS WILL FLIRT WITH CRITICAL THRESHOLDS SUN ATOP RH VALUES
DROPPING TO 10-16% ACROSS ALL ZONES EXCEPT 411. HOWEVER, IN ADDITION
TO WINDS BEING BORDERLINE, THE BIG QUESTION REMAINS WHETHER OR NOT
FUELS (ESPECIALLY FINER FUELS/GRASSES) WILL REACH CRITICAL AND BURN
EFFECTIVELY. WITH THESE CONSIDERATIONS IN MIND, WILL CONTINUE TO
HEADLINE THE NEAR-CRITICAL WX CONDITIONS IN THE FWF, BUT NOT ISSUE
ANY RED FLAG PRODUCTS. OUR NEXT TROUGH IS STILL PROGGED TO SWING
THROUGH MON NIGHT AND TUES, WITH A MASSIVE DROP IN TEMPS AND
INCREASED HUMIDITY VALUES. WINDS MAY REMAIN BREEZY OVERNIGHT MON
NIGHT. ANOTHER TROUGH IS LIKELY THURS OR FRI. - 01/HUSTON
PIH WATCHES/WARNINGS/ADVISORIES
NONE.
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