Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 021943
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
143 PM MDT SUN AUG 2 2015

.DISCUSSION...A NUMBER OF LOCATIONS ALREADY BREAKING INTO THE 90S
THIS AFTERNOON. SOME CLOUD BUILD UPS ALSO NOTED OVER THE MOUNTAINS
NORTH OF SUN VALLEY...A LITTLE DIFFICULT TO TELL IF ANY OF THOSE
WILL BE ABLE TO TURN INTO A THUNDERSTORMS. MAIN FOCUS IS ON SUB
TROPICAL MOISTURE ACROSS NEVADA AND UTAH GRADUALLY MAKING A SWING
THIS WAY. TIMING MOSTLY FAVORS DAY TIME MONDAY WITH POTENTIAL FOR
SHOWERS AND ISOLATED THUNDERSTORMS DURING THE MORNING HOURS IN THE
SOUTH CENTRAL HIGHLANDS. THE NAM MODEL IN PARTICULARLY IS SUGGESTING
THE FLOW STRETCHES WEST AND EAST AS THE BAND MOVES UP TO IDAHO AND
FAVORS THE WETTER THUNDERSTORMS FOCUSED OVER THE BEAR LAKE AREA AND
CARIBOU HIGHLANDS. IN FACT THE GENERAL TREND SEEMS TO FAVOR THE BULK
OF THE ACTIVITY MOVING NORTH ALONG THE EASTERN HIGHLANDS ALL THE WAY
TO ISLAND PARK THROUGH ABOUT MIDNIGHT. ALONG THE EAST SIDE THROUGH
THE CARIBOU HIGHLANDS AND BEAR LAKE AREA...WOULD NOT BE SURPRISED TO
SEE SOME .25 TO .5 INCH RAIN AMOUNTS FROM A FEW THUNDERSTORMS.
TEMPERATURES WILL PROBABLY DROP 10 TO 12 DEGREES MONDAY WITH ALL THE
CLOUD COVER AND SHOWERS AROUND. TUESDAY WE HAVE INCREASING SOUTHWEST
FLOW WITH EMBEDDED LITTLE DISTURBANCES TO TRIGGER SOME AFTERNOON
THUNDERSTORMS. A STRONGER DISTURBANCE COMES THROUGH ON WEDNESDAY AND
THE CHANCE OF SHOWERS AND THUNDERSTORMS WAS INCREASED. MODELS SO FAR
HAVE THURSDAY AS THE DRIEST DAY AND THAT COULD BE SHORT LIVED. THE
GFS IS VERY QUICK WITH ANOTHER DISTURBANCE OFF THE PACIFIC ON
FRIDAY....WHILE OTHER MODELS ARE SLOWER AND FAVOR FRIDAY NIGHT AND
SATURDAY. RS

&&

.AVIATION...MOISTURE WILL CONTINUE TO INCREASE IN THE NEXT 24 HOURS
AS A STORM APPROACHES FROM THE SOUTHWEST. WE ARE STILL WAITING TO
SEE IF WE GET ISOLATED MOUNTAIN STORMS ESPECIALLY NEAR KSUN.  RIGHT
NOW...NOT MUCH IS HAPPENING OTHER THAN SOME CUMULUS DEVELOPMENT.
SHOWERS AND THUNDERSTORMS WILL INCREASE FROM SOUTH TO NORTH STARTING
BETWEEN 12-15Z MONDAY. WE HAVE VCSH IN FOR KBYI AND KPIH DURING THAT
TIMEFRAME SHIFTING TO -SHRA VCTS OR -TSRA IN THE AFTERNOON. IT LOOKS
LIKE KIDA AND KSUN SHOULD HOLD OFF UNTIL AFTER 18Z. EXPECT VFR
WEATHER ALTHOUGH WITH HEAVIER CELLS...WE COULD SEE A DROP IN
VISIBILITY AND CEILINGS AS WELL WINDS OVER 30KTS. BY LATE IN THE
DAY...15-25KT WINDS WILL DEVELOP AROUND KBYI AS THE SYSTEM CLEARS TO
THE NORTHEAST. KEYES

&&

.FIRE WEATHER...THE MAIN PUSH FOR SHOWERS AND STORMS IS STILL ON
TRACK FOR MONDAY AS THE STORM ITSELF MOVES OVER IDAHO. ACTIVITY
SHOULD DEVELOP IN EARNEST AROUND 15Z IN THE SOUTHERN MOUNTAINS AND
SPREAD NORTH AFTER THAT. SCATTERED OR GREATER COVERAGE IS FORECAST
ACROSS THE SOUTHERN AND EASTERN MOUNTAINS WITH LESS ACROSS THE SNAKE
PLAIN AND CENTRAL MOUNTAINS. THE FIRE WEATHER WATCH FOR ZONES 4278
AND 413 WILL BE UPGRADED TO A RED FLAG WARNING FROM 9AM TO 9PM.
BASED ON SOME OF THE TRENDS...THE HIGHEST COVERAGE COULD END UP
BEING CONFINED ACROSS THE SOUTHEAST CORNER UNDER THE STRONGEST PART
OF THE SYSTEM. IF THAT ENDS UP BEING THE CASE...WE MAY NEED TO
ADJUST THE RED FLAG TONIGHT OR TOMORROW. GUSTY WINDS OVER 30MPH ARE
POSSIBLE WITH STRONGER STORMS. MOST STORMS WILL BE DRY IN THE
BEGINNING BUT LATER IN THE DAY WE SHOULD SEE A MIX AND TRANSITIONING
TO MOSTLY WET BY EVENING. WHERE WE GET HEAVIER CELLS TO DEVELOP AND
WHERE WE GET MULTIPLE STORMS IN THE SAME LOCATION...AMOUNTS OF 0.20-
0.50 INCHES OF RAIN IS POSSIBLE AND EVEN LOCALLY HIGHER THAN THAT.
STORM COVERAGE SHOULD BE LOWER ON TUESDAY BUT STILL AROUND AS WE
WILL BE IN-BETWEEN STORMS. THERE WILL BE AN UPTICK ON WEDNESDAY AS
THE NEXT LOW MOVES IN...BUT STILL SOME QUESTIONS ON WHERE THE HIGHER
COVERAGE AREAS WILL BE. ONE MODEL SUGGEST EVERYTHING WILL BE FROM
THE SNAKE PLAIN NORTH AND EAST...WHILE OTHERS SUGGEST ALL OF THE
MOUNTAINS WILL GET HIT PRETTY GOOD BUT NOT MUCH IN THE PLAIN. WE
SHOULD HAVE THAT SORTED IN THE NEXT 36-48 HOURS. KEYES

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM 9 AM TO 9 PM MDT MONDAY FOR IDZ413-427.

&&

$$


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