FXUS65 KPIH 120307
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
907 PM MDT SUN MAY 11 2008

.DISCUSSION...THE 00Z NAM12 MODEL RUN MAINTAINS THE STRENGTH OF
THE SURFACE PRESSURE GRADIENT IN THE LOWER SNAKE PLAIN THROUGH THE
NIGHT. WINDS MAY SLOW FOR A COUPLE OF HOURS CLOSE TO MIDNIGHT BUT
OVER ALL WINDS SHOULD REMAIN STRONG ENOUGH TO CONTINUE THE LAKE
WIND ADVISORY THROUGH MORNING. RS

&&

.PREV DISCUSSION... /ISSUED 757 PM MDT SUN MAY 11 2008/

DISCUSSION...IN SATELLITE IMAGERY THE SHORT WAVE MOVING IN FROM
THE PACIFIC IS CATCHING UP WITH THE MOIST BAROCLINIC BAND NOW OVER
SOUTHEAST IDAHO. EXPECTED AS THE 700 MB SHORT WAVE PROGRESSES EAST
WILL SEE SOME ENHANCEMENT OF SHOWERS. POPS ACROSS THE THE SOUTH
CENTRAL AND CARIBOU HIGHLANDS WERE PUSHED UP A BIT AND SNOW LEVELS
WERE LOWERED SOME AFTER MIDNIGHT TONIGHT TO 6500-6900 FEET. HIGHER
ELEVATIONS AROUND BEAR LAKE MAY PICK UP AN INCH OF SNOW LATE
NIGHT. BLOWING DUST ADVISORY WILL BE ALLOWED TO EXPIRE AT 800 PM
AS WINDS ARE DROPPING OFF SOME AND THERE HAVE BEEN A FEW LIGHT
SPRINKLES OF RAIN TO SETTLE THE DUST. LAKE WIND ADVISORY IS IN
EFFECT UNTIL 900 PM FOR AMERICAN FALLS RESERVOIR AND COULD BE
MARGINAL THROUGH THE NIGHT. RS

PREV DISCUSSION... /ISSUED 205 PM MDT SUN MAY 11 2008/

SHORT TERM...TONIGHT THROUGH WEDNESDAY. UPPER TROF MOVING INTO THE
PAC NW THIS AFTN HAS INTENSIFIED THE SW FLOW ALOFT OVER THE FCST
AREA. THIS IS DRIVING THE BREEZY CONDITIONS THRU THE SNAKE RIVER
PLAIN. MID LVL MSTR MOVING INTO THE AREA IS PRODUCING MAINLY MID
CLDS...ALONG WITH SOME VIRGA. SOME SHOWERS ARE OCCURRING OVER THE
CEN MTNS AND NE HIGHLANDS THIS AFTN...AND AN ISOLD TSTM IS ALSO
POSSIBLE IN THE NE HIGHLANDS. THE INSTABILITY IS VISIBLE IN THE MID
CLDS. THE COLD FRONT IS ALREADY MAKING ITS WAY THRU THE CEN MTNS...
BUT THE REAL COLD PUSH WILL COME TONIGHT. PRECIP WILL BECOME
WIDESPREAD IN THE MTNS TONIGHT IN THE WAKE OF THE COLD FRONT...AND
WILL REMAIN MAINLY IN THE EASTERN PARTS OF THE FCST AREA ON MONDAY.
PRECIP WILL BE MAINLY RAIN IN THE VALLEYS AND SNOW IN THE MTNS. RAIN
MAY MIX WITH SNOW TONIGHT IN THE UPPER SNAKE RIVER PLAIN. THERE MAY
BE A BREAK IN THE POST FRONTAL PRECIP IN THE MORNING ACROSS THE
SNAKE RIVER PLAIN...BUT INSTABILITY BENEATH THE UPPER LOW OVER SCEN
ID WILL SET OF SHOWERS IN THE AFTN.

PRECIP MOVES OUT OF THE AREA BY TUE MORNING AS THE UPPER RIDGE
DOMINATES THE PAC NW. THE UPPER RIDGE WILL BE ORIENTED SUCH THAT THE
FLOW OVER MUCH OF THE NW WILL BE WRLY. THIS MAY ALLOW SOME PAC MSTR
TO SPILL OVER THE RIDGE INTO THE FCST AREA TUE NIGHT AND WED. THIS
WILL SET OFF SOME SHOWERS IN THE MTNS.

AFTER A COLD MONDAY AND BELOW FREEZING TEMPS AGAIN TUE MORNING...
TEMPS WILL WARM AGAIN UNDER THE RIDGE. HEDGES

LONG TERM...WED NIGHT THROUGH NEXT SUN NIGHT.  LAST SHORTWAVE GOES
THROUGH IN FIRST 24 HOURS OF PERIOD.  IT MOVES FROM NORTH TO SOUTH
OVER EASTERN IDAHO SO ITS ORIGIN OF CENTRAL CANADA MEANS NOT A WHOLE
LOT OF MOISTURE AND MAINLY INCREASED POP AT HIGHER ELEVATIONS.
PACIFIC UPPER LEVEL RIDGE CONTINUES TO BUILD AND LEAVES A NUMBER OF
DAYS OF NEARLY CLEAR SKIES WITH ZERO POP.  TEMPERATURES SHOULD WARM
INTO THE UPPER 70S AND LOWER 80S AT SNAKE RIVER PLAIN ELEVATIONS.
INCOMING WAVE APPEARS TO BREAK DOWN RIDGE IN LAST 24 HOURS BUT HAVE
DELAYED ITS ARRIVAL BY 12 HOURS.  SHOULD BE MONITORED AS A DISTINCT
POSSIBILITY AS 500MB 5-WAVE DOES INDICATE THAT THE BLOCKING HIGH HAS
BECOME A WAVE BY THAT TIME.  MESSICK

AVIATION...SO FAR ONLY LIGHT SHOWERS WITH NO LIGHTNING YET.  HAVE
BACKED OFF TSRA ACTIVITY UNTIL AFTER 11/22Z WHEN INSTABILITY IS AT A
MAXIMUM.  EXPECT SHOWERS LATER TONIGHT WITH SECOND COLD FRONT THAT
IS CURRENTLY SLIDING THROUGH PANHANDLE AND EASTERN OREGON.  INCOMING
FRONT IS KEEPING WIND GUSTY THIS AFTERNOON EVEN WITH A WIND SWITCH.
THIS SECOND FRONT WILL ALSO ALLOW WIND TO STAY UP FOR MUCH OF THE
NIGHT BUT DO EXPECT GUSTING TO SUBSIDE WITH SOME DIURNAL COOLING.
SKY SHOULD CLEAR AFTER MIDNIGHT WITH MORE SHOWERS POSSIBLE MAINLY
OVER MOUNTAINS FOR MON AFTERNOON.  THE FRONT TONIGHT COULD BRING IN
SOME MARGINAL VFR FOR VALLEY AIRDROMES KPIH AND KIDA.  MAIN MOISTURE
PRETTY MUCH STAYS AWAY FROM KBYI AND KSUN AREAS.  MESSICK

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 6 AM MDT MONDAY FOR IDZ021.

&&

$$