Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 211956
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
156 PM MDT TUE JUL 21 2015

.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT. TSTMS DEVELOPING
ACROSS THE CENTRAL MTNS THIS AFTN IN RESPONSE TO A MINOR UPPER
TROF. TSTMS DEVELOPING OVER SOUTHERN ID AND NORTHEAST NV DUE TO
THE TROPICAL MOISTURE FROM DELORES. THIS TROPICAL MOISTURE WILL
THE THE FOCUS OF ATTENTION. AS A DEEPER UPPER TROF DIGS INTO THE
PAC NW...INCREASING SW FLOW ALOFT WILL PULL THE TROPICAL MOISTURE
INTO ID. THIS WILL RESULT IN INCREASING COVERAGE OF SHOWERS AND
TSTMS TONIGHT THRU WED NIGHT. HIGH MOISTURE CONTENT ALSO BRINGS
THE POSSIBILITY OF LOCALLY HEAVY RAINFALL AMOUNTS WED AFTN AND
NIGHT. ACTIVITY DIMINISHES SOMEWHAT BY THU MORN...BUT PICKS UP
AGAIN THU AFTN AS ANOTHER MINOR UPPER WAVE IS EJECTED FROM THE
MAIN UPPER TROF STILL OVER THE W COAST. SOME OF THESE TSTMS MAY
PRODUCE GUSTY WINDS AND SMALL HAIL THU AFTN. ACTIVITY WILL
CONTINUE THROUGH THE EVENING AS THE MAIN UPPER TROF MOVES THRU.
ACTIVITY WILL DIMINISH BY FRI MORN OVER THE WESTERN PART OF THE
FCST AREA...BUT SCATTERED SHOWERS AND TSTMS WILL LINGER IN THE
EASTERN AND SOUTHERN HIGHLANDS.

.LONG TERM...FRIDAY THROUGH TUESDAY. SHOWERS AND TSTMS WILL
CONTINUE TO DIMINISH IN COVERAGE OVER THE EAST AS THE UPPER TROF
MOVES OFF TO THE EAST. DRIER AIR MOVING IN WILL END PRECIP BY
MIDNIGHT...CONTINUING THRU SUN MORN. A BROAD UPPER TROF MOVES INTO
THE PAC NW...PRODUCING A SLIGHT CHANCE FOR ISOLD TSTMS OVER THE
CENTRAL MTNS AND NEAR THE DIVIDE SUN AFTN AND EVE. THIS REPEATS ON
MON...WITH DRY AGAIN ON TUE. TEMPS WILL RUN A LITTLE COOLER MON
AND TUE. HEDGES

&&

.AVIATION...A WEAK UPPER LEVEL DISTURBANCE WILL COMBINE WITH
INCREASING MOISTURE TO PRODUCE ISOLATED TO SCATTERED THUNDERSTORMS
THIS AFTERNOON AND EVENING ACROSS THE REGION. HAVE VCTS IN AT ALL
SITES THROUGH 03-04Z EXCEPT PIH...WHICH STANDS THE LOWEST CHANCE TO
SEE CONVECTION...WITH THE GREATEST CHANCES AT SUN. GUSTY W-SW WINDS
SHOULD OCCUR ACROSS THE SNAKE RIVER PLAIN BETWEEN ABOUT 21 AND 03Z
WITH GUSTS TO AROUND 20 KTS LIKELY. A BREAK IN PRECIPITATION IS
EXPECTED THIS EVENING WITH RENEWED CONVECTION SPREADING FROM SW-NE
ACROSS THE REGION TOMORROW...APPROACHING BYI AND SUN BY AROUND 12Z
AND IDA BY MID MORNING. WIDESPREAD SHOWERS AND THUNDERSTORMS SHOULD
BE COMMON BY TOMORROW AFTERNOON...ALTHOUGH VFR CONDITIONS SHOULD
PERSIST. WINDS TOMORROW SIMILAR TO TODAY IN BOTH MAGNITUDE AND
DIRECTION WITH GUSTINESS AGAIN DEVELOPING ACROSS THE SNAKE RIVER
PLAIN BY 21Z. HIGHER GUSTS POSSIBLE IN AND NEAR STORMS. AD/HEDGES

&&

.FIRE WEATHER...A BROAD UPPER TROUGH CENTERED OVER BRITISH COLUMBIA
WILL STRENGTHEN AS IT MIGRATES EASTWARD THROUGH THE PACNW THROUGH
THURSDAY NIGHT. ABUNDANT MOISTURE AHEAD OF THE TROUGH WILL STREAM
NORTHEASTWARD INTO SE IDAHO SETTING THE STAGE FOR INCREASING SHOWER
AND THUNDERSTORM ACTIVITY. ISOLATED SHOWERS AND THUNDERSTORMS TODAY
WILL BECOME WIDESPREAD TOMORROW AND LINGER THROUGH THURSDAY. THE
AFOREMENTIONED TROUGH LIFTS OUT OF THE AREA BY FRIDAY...HOWEVER SOME
LINGERING MOISTURE WILL BE AVAILABLE FOR ADDITIONAL SHOWER AND
THUNDERSTORM ACTIVITY...MAINLY ACROSS THE EASTERN HIGHLANDS. DRY
SOUTHWESTERLY FLOW TAKES HOLD SATURDAY BEFORE THE NEXT BROAD TROUGH
ENTERS THE PACNW SUNDAY INTO EARLY NEXT WEEK...PROVIDING RENEWED
SHOWER AND THUNDERSTORM ACTIVITY FOR LATE SUNDAY INTO
TUESDAY...THOUGH MORE LIMITED MOISTURE WILL LIMIT THE SCOPE OF
ACTIVITY WHEN COMPARED TO WED AND THU OF THIS WEEK. A FEW PERIODS OF
GUSTY WINDS ARE EXPECTED THE NEXT COUPLE OF DAYS...STRONGEST IN THE
SNAKE RIVER PLAIN DURING THE AFTERNOON AND EARLY EVENING HOURS...
20-25 MPH AT TIMES...WITH GUSTY WINDS IN HIGHER TERRAIN AREAS AS
WELL. ABUNDANT MOISTURE WITH MINIMUM RELATIVE HUMIDITY VALUES
PEAKING IN THE 45-55 PERCENT RANGE THU...HIGHEST ACROSS THE EASTERN
HIGHLANDS... SHOULD PRECLUDE THE NEED FOR A RED FLAG. DRIER
CONDITIONS TAKE HOLD THIS WEEKEND. WINDS DECREASE SOME THIS WEEKEND
BEFORE INCREASING AGAIN EARLY NEXT WEEK AHEAD OF THE NEXT TROUGH.
AD/HEDGES

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$



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