000
FXUS65 KPIH 061007
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
307 AM MST TUE JAN 6 2009
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT. NEXT WAVE IS
CURRENTLY STREAKING DOWN FROM CANADA THROUGH WA/OR AND REACHING AS
FAR AS NRN UTAH AS IT MOVES THROUGH RIDGE OF HIGH PRESSURE THAT IS
CENTERED OFF CALIF COAST. AT THE MOMENT...LOW CLOUDS TRAPPING
MOISTURE OVER MANY AREAS OF SNAKE RIVER PLAIN ALLOWING SOME FOG TO
FORM ACROSS I-15/I-86/I-84 CORRIDOR WITH SOME VERY LIGHT SNOW.
THUS...INCLUDED PATCHY FOG IN FORECAST...AM EXPECTING FOG TO LIFT
BY LATE MORNING BUT LOW CLOUDS TO REMAIN MOST OF THE DAY. AS FAR
AS LARGE SCALE PATTERN...GFS/NAM12 IN FAIRLY GOOD SYNOPTIC
AGREEMENT FOR NEXT FEW DAYS...THOUGH GFS A LITTLE WETTER. WIND
FLOW FAVORING UPSLOPE CONDITIONS ALONG CENTRAL MTNS AND ERN/SRN
HIGHLANDS THIS AFTERNOON THROUGH THURSDAY THOUGH BULK OF MOISTURE
EXPECTED TO FALL LATE TONIGHT INTO TOMORROW MORNING. QPF AMTS ON
THE LOW SIDE FOR AREA WITH SNOWFALL TOTALS BELOW WARNING CRITERIA.
ERN HIGHLANDS AND CENTRAL MTNS COULD SEE 4 TO 6 INCHES TOTAL
SNOWFALL BY WED MORNING WHILE HIGHER ELEVATIONS OVER WASATCH MTNS
MIGHT GET UP TO 10 INCHES. THE VALLEYS AND LOWER ELEVATIONS FOR
SRN HIGHLANDS WILL POSSIBLY SEE 4 TO 5 INCHES OF NEW SNOW. ONE
CONCERN IN FORECAST IS TEMPERATURES AS ALL MODELS SHOWING
CONSIDERABLE WARMING THROUGH WEDNESDAY. NOT COMPLETELY SOLD ON
IDEA AS WARM AIR ALOFT WILL CREATE STRONG INVERSION KEEPING SOME
COLD AIR IN PLACE. WENT A FEW DEGREES COOLER THAN GUIDANCE...EVEN
SO...CHC FOR RAIN/SNOW BY WED MORNING FOR ALMOST ENTIRE SNAKE
RIVER PLAIN AND EVEN SRN HIGHLANDS BY WED EVENING. THURSDAY
APPEARS TO BE RELATIVELY CALM DAY AS VERY SCATTERED SNOW/RAIN
SHOWERS POSSIBLE FOR FORECAST AREA. NEXT SYSTEM HAS SLOWED DOWN
CONSIDERABLY IN ALL MODELS AND WILL MOVE THROUGH LATE THURSDAY
NIGHT/EARLY FRIDAY MORNING. RENWICK
&&
.LONG TERM...FRIDAY THROUGH TUESDAY. GFS HAS MADE A MOVE TOWARD THE
SLOWER ECMWF TIMING WITH UPPER TROUGH AXIS OVER SE IDAHO FRIDAY
MORNING AND EXITING THE REGION BY LATE AFTERNOON. UPPER RIDGE THEN
BUILDS ALONG THE COAST WHILE WEAK PAC FEATURES ROLL OVER THE TOP OF
THE RIDGE AND DIG SE ALONG THE DIVIDE FROM TIME TO TIME. THUS
GENERALLY HAVE HIGHEST PRECIPITATION POTENTIAL DURING THE PERIOD
FAVORING THE SE/ERN HIGHLANDS ON FRIDAY WITH EXITING WAVE. MUCH
LOWER PCPN POTENTIAL FOLLOWS SATURDAY THROUGH TUESDAY GENERALLY
FAVORING THE NE/ERN HIGHLANDS TO CATCH THE OFF CHANCE THAT ONE OF
THE OVER-TOPPING WAVES IS ACTUALLY STRONG ENOUGH TO PENETRATE REGION
AND PRODUCE SOME LIGHT SNOW. SCREAMING MESSAGE WILL BE DRIER
CONDITIONS WITH DEVELOPMENT OF VALLEY INVERSIONS UNDER THE RIDGE
SCENARIO THROUGHOUT MOST OF THE PERIOD. HAVE GENERALLY TRIED TO
STRAY TOWARD THE COOLER GUIDANCE ESPECIALLY IN THE VALLEY REGIONS.
HUSTON
&&
.AVIATION...LOW LEVEL STRATUS AND FOG (LIFR/IFR CONDITIONS) WITHIN
THE SNAKE RIVER PLAIN REMAINED TRAPPED UNDER A MOIST NW FLOW ALOFT
THIS MORNING WHILE KSUN WAS FAR ENOUGH UP THE WOOD RIVER VALLEY TO
REMAIN OUT OF THE SOUP AND IN VFR CONDITIONS. BOTH MODELS INDICATE
LITTLE IF ANY RELIEF ACROSS THE SNAKE RIVER PLAIN AND WE WILL LIKELY
BE STRUGGLING WITH IFR/LIFR CONDITIONS THROUGH AT LEAST 21Z WED. AS
FOR KSUN...VFR CIGS WILL LIKELY CONTINUE UNTIL LATE THIS MORNING
(APPROX 16Z) BEFORE LOWERING UNDER THE INCREASINGLY MOIST NW FLOW
ALOFT WHICH WILL LIKELY BRING LIGHT SNOW AND POSSIBLY MVFR/IFR
CIGS/VIS AT TIMES THROUGHOUT THE AFTERNOON/EVE. IMPROVING CONDITIONS
SHOULD FOLLOW AFTER 06Z TONIGHT AS DRIER AIR ALOFT SHIFTS OVERHEAD.
MODELS HOWEVER STILL HOLD ONTO A VERY MOIST LOWER LAYER AT KSUN
WHICH MAY BE INDICATIVE OF THE STRATUS IN THE SNAKE RIVER PLAIN
SPREADING INTO THE WOOD RIVER VALLEY. HUSTON
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
