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000
FXUS65 KPIH 140234
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
834 PM MDT MON MAY 13 2013

.UPDATE...UPPER TROUGH SLIDING THROUGH THE PACNW THIS EVENING PER
SAT IMAGERY. SURFACE FRONT INTO WESTERN IDAHO EARLY THIS
EVENING PER OBSERVATIONS AND SURFACE PRESSURE CHANGES...ON TRACK
TO PASS THROUGH THE REGION OVERNIGHT TONIGHT. WEAK CONVECTION
OCCURRED EARLIER ACROSS THE SOUTHERN/EASTERN HIGHLANDS ALREADY
DISSIPATING. MESONET OBSERVATIONS THROUGH THE UPPER SNAKE PLAIN
SHOWING WINDS ALREADY DECREASING AS WELL THIS EVENING. THUS WILL
CANCEL THE ADVISORY EARLY. STRONG SURFACE GRADIENT STILL EXPECTED
JUST BEHIND PASSAGE OF THE FRONT...CURRENTLY INDICATED BY GUSTY
SURFACE WINDS THROUGH EASTERN OREGON. EARLYLOOK AT 00Z NAM
INDICATES THAT BEST MID LEVEL SUPPORT FOR WINDS WELL NORTH INTO
MONTANA AND SURFACE LOW EJECTS WELL INTO THE PLAINS OVERNIGHT AS
WELL. COMBINED WITH BEST GRADIENT OCCURING DURING OVERNIGHT
HOURS...BELIEVE WINDS WILL REMAIN BELOW ADVISORY CRITERIA.
MOISTURE REMAINS WELL NORTH INTO MONTANA AS WELL SO THREAT FOR
CONVECTION DISSIPATES RAPIDLY OVERNIGHT EVEN IN NORTHERN ZONES.
CURRENT FORECAST GRIDS COVER THESE SCENARIOS WELL SO ONLY UPDATES
WILL BE TO THE TEXT PRODUCTS FOR EARLY CANCELLATION OF WIND
ADVISORY. DMH


&&

.PREV DISCUSSION... /ISSUED 136 PM MDT MON MAY 13 2013/

SHORT TERM...FOCUS IS ON SHORT WAVE DISTURBANCE MOVING INTO THE
WASHINGTON AND OREGON COAST AS IT LIFTS AND MOVES THROUGH NORTHERN
IDAHO. A 110 KT 300 MB JET STREAK CROSSES NORTH
IDAHO...POSSIBILITY OF THUNDERSTORMS WITH SEVERE DOWN DRAFT GUSTS
NEAR 60 MPH DEVELOPING THIS AFTERNOON. PRECIPITABLE WATER VALUES
OF .6 TO .7 INCH...55 TO 65 KT VERTICAL SHEER AND CAPE UP TO 1000
J/KG COULD SUPPORT SOME HAIL AS WELL. MODELS SUGGEST FOCUS OF
ACTIVITY WILL BE JUST NORTH OF NORTH FORK AND MISSING THIS
FORECAST AREA...BUT WILL HAVE TO MONITOR THE SITUATION. WIND
ADVISORY REMAINS IN EFFECT FOR THE UPPER AND LOWER SNAKE PLAIN
THIS AFTERNOON AND EVENING. FRONT IS PRESENTLY NEAR MULAN PASS.
THE JET STREAK COULD DEVELOP A SURFACE WAVE IN SOUTHWEST MONTANA
THIS AFTERNOON...SLOWING THE PROGRESSION OF THE FRONT. THE RAPID
UPDATE MODEL IS NOW DELAYING THE FRONT INTO POCATELLO UNTIL ALMOST
10 PM. SUN WILL BE DOWN BY THEN AND WINDS JUST MIGHT BE LIGHTER
THAN EXPECTED. SURFACE PRESSURE GRADIENT WILL STILL BE STRONG AND
WINDS MAY STAY UP THROUGH TUESDAY MORNING. WILL KEEP THE WIND
ADVISORY OUT A LITTLE LONGER AND SEE HOW THINGS DEVELOP. TUESDAY
CONTINUES TO LOOK PROGRESSIVELY DRIER IN CONFLUENT FLOW WITH THE
SHORT WAVE QUICKLY MOVING THROUGH EASTERN MONTANA BY TUESDAY
MORNING. A NEW DISTURBANCE OFF THE PACIFIC BRINGS A SURFACE COLD
FRONT INTO THE IDAHO CENTRAL MOUNTAINS BY THURSDAY MORNING. MODELS
AGREE THIS ONE WILL HAVE MORE AMPLITUDE AND A BETTER CHANCE OF
SCATTERED SHOWERS.

LONG TERM...THURSDAY THROUGH MONDAY. MODELS CONTINUE TO SHOW
AGREEMENT WITH TIMING OF UPPER TROUGH MOVING ACROSS THE AREA ON
FRIDAY. INCREASED MOUNTAIN POPS FOR FRIDAY AFTERNOON...ESPECIALLY
OVER THE CENTRAL MOUNTAINS. GFS ENSEMBLE SUITE SHOWS SOME
UNCERTAINTY BEYOND FRIDAY AS THE AMPLITUDE AND SPEED OF THE UPPER
WAVE. MADE LITTLE CHANGES TO POPS FOR DAYS 6 AND 7. WINDS DURING
THIS EVENT WILL BE GUSTY...BUT STILL REMAIN BELOW WIND ADVISORY
CRITERIA.  HINSBERGER

AVIATION...MAIN CONCERN WILL BE WINDS THROUGH THE PERIOD AS A COLD
FRONT PASSES THROUGH THIS EVENING. FORECAST SOUNDINGS INDICATE
POSSIBLE LLWS FOR KPIH AND KIDA AS 30KT WINDS SETTLE JUST ABOVE THE
SURFACE...BUT EXPECT TO SEE SURFACE WINDS STRONGER THAN BUFR
SOUNDINGS PREDICT. CONVECTION SHOULD REMAIN WELL NORTH OF THE
TERMINALS THIS AFTERNOON/EVENING AND SHOULD CONTINUE TO SEE VFR
CONDITIONS PREVAIL.  HINSBERGER

&&

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

$$