Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 221456
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
856 AM MDT TUE APR 22 2014

.UPDATE...ENERGETIC PACIFIC STORM MOVING INTO WESTERN IDAHO THIS
MID MORNING. SURFACE WINDS ON TRACK TO INCREASE AS THE MORNING
WEARS ON AND BY MID DAY WE WILL BE WINDY...ESPECIALLY ACROSS THE
SNAKE PLAIN. WOULD NOT BE SURPRISED TO SEE THE TYPICAL SPOTS IN
BLOWING DUST WHICH IS TO SAY KEEP AN EYE ON I-15 NEAR ROBERTS.

CONVECTION CONCERN REMAINS AS DRY SLOT WORKS INTO AREA AND ENOUGH
SUN IS EXPOSED TO GENERATE THUNDERSTORMS. SPC OUTLOOK HAS AREA
FROM POCATELLO NORTH TO MONIDA AND POINTS EAST IN THE SLIGHT RISK
AREA. HAIL AND GUSTY WINDS THE THREAT. ONCE THE FRONT PASSES
THROUGH BY THIS EVENING...THAT THREAT ENDS AND WE ARE LEFT WITH
THE WIND.

FORECAST HAS THESE DETAILS HANDLED SO NO CHANGES MADE TO GOING
PACKAGE SO FAR. DITTMANN

&&

.PREV DISCUSSION... /ISSUED 228 AM MDT TUE APR 22 2014/

SHORT TERM...TODAY THROUGH FRIDAY. SATELLITE IMAGERY SHOWING A DEEP
UPPER TROUGH MAKING LANDFALL INTO WA/OR/CA COASTLINES THIS MORNING.
NEGATIVE TILT TO THE TROUGH IS RESULTING IN COLD CLOUD TOPS. ALREADY
SEEING SOME RAIN ON THE STERLING WEBCAM ALONG A THETA-E
RIDGE...AHEAD OF THE MAIN COLD FRONT. MODELS SHOWING MAIN BAND OF
PRECIP WILL BE JUST BEHIND THE COLD FRONT WHICH SHOULD ENTER OUR
WESTERN BORDER BETWEEN 15Z TO 18Z AND PUSH OUT OF THE AREA BY 00Z
TONIGHT. TRIMMED THE POPS FOR THE MORNING HOURS A BIT EXCEPT FOR THE
WASATCH RANGE. INSTABILITY BECOMES A FACTOR LATER THIS AFTERNOON
WITH LIFTED INDICES DROPPING BELOW ZERO AHEAD OF THE FRONT. SPC
OUTLOOK FOR TODAY EXPANDED THUNDERSTORM COVERAGE INTO MOST OF THE
FORECAST AREA. KEEPING THUNDER MENTION FOR THIS AFTERNOON. MODELS
ARE SHOWING A TIGHT GRADIENT BEHIND THE FRONT...AND A GOOD POTENTIAL
FOR STRONG WINDS THROUGH TOMORROW. CURRENT HEADLINES COVER THIS
WELL.  HINSBERGER

LONG TERM...FRIDAY THROUGH TUESDAY NIGHT. THE GFS AND ECMWF ARE IN
AGREEMENT WITH A MAJOR UPPER TROF OVER THE W COAST ON FRI. THE TROF
ROTATES TO A NEG TILT BY SAT AS IT MOVES OVER THE GREAT BASIN. THE
GFS HAS DEPARTED FROM THE PREVIOUS SOLUTION OF A SPLIT FLOW PATTERN
TO MORE WHAT THE ECMWF WAS SUGGESTING. THE END RESULT IS PRECIP
SPREADING ACROSS THE FCST AREA ON FRI AND REMAINING FAIRLY
WIDESPREAD THRU SAT. SNOW LEVELS REMAIN HIGH...BUT SNOW MAY
OCCASIONALLY MIX WITH RAIN OVERNIGHT AT LOWER ELEVATIONS. NO SNOW
ACCUMULATION EXPECTED AT THE LOWER ELEVATIONS. THE UPPER TROF DOES
NOT SHOW MUCH EASTWARD PROGRESSION ON SUN...SO THE THREAT OF PRECIP
REMAINS. THE SYSTEM IS BECOMING LESS ORGANIZED...SO WOULD EXPECT
SHOWERS TO DIMINISH SOMEWHAT IN COVERAGE. BY MON...BOTH MODELS BUILD
UPPER RIDGING INTO THE WEST...BUT THE ECMWF IS A LITTLE MORE
STUBBORN WITH MOVING THE UPPER TROF OUT OF THE AREA. WILL KEEP LOW
CHANCES FOR PRECIP IN THE MTNS ON MON...THEN DRY EVERYTHING OUT MON
NIGHT AS BOTH MODELS SHOW UPPER RIDGING BEING THE DOMINANT FEATURE
THRU TUE NIGHT. HEDGES

AVIATION...A DEEP UPPER TROF MVING INTO THE WEST COAST TODAY WILL
SPREAD SHOWERS AND ISOLD TSTMS ACROSS THE REGION BY THIS AFTN. CIGS
ARE EXPECTED TO DROP TO LOW VFR...WITH OCNL MVFR CIGS TONIGHT. SW
WINDS ARE EXPECTED TO BECOME STRONG THIS AFTN AND TONIGHT ACROSS THE
SNAKE RIVER PLAIN/EASTERN MAGIC VALLEY. HEDGES

HYDROLOGY...EXPECT TO SEE IN-BANK RISES IN RIVERS AND STREAMS OVER
THE NEXT FEW DAYS DUE TO RUNOFF FROM PRECIP AND SNOWMELT. CURRENT
HYDROGRAPH PROJECTIONS ARE NOT INDICATING FLOODING AT THIS TIME.
HINSBERGER

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM NOON TODAY TO 9 PM MDT WEDNESDAY
IDZ017-020-021.

WIND ADVISORY FROM NOON TODAY TO 9 PM MDT THIS EVENING
IDZ022>025.

&&

$$







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