Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 052001
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
201 PM MDT TUE MAY 5 2015

.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT. WV SAT IMAGERY SHOWS
CENTER OF UPPER LOW DRIVING ALONG LENGTH OF VANCOUVER ISLAND
TODAY. STRONG SHORTWAVE DIVING SOUTHEAST THROUGH BASE OF TROUGH
INTO OREGON/CALIFORNIA COASTAL REGION...HELPING TO DEEPEN TROUGH.
SHORTWAVE ADVECTING EAST AHEAD OF MAIN TROUGH THROUGH IDAHO THIS
AFTERNOON AND EVENING...DRIVING COLD FRONT THROUGH THE REGION.
FRONTAL PASSAGE CONTINUES THROUGH THIS AFTERNOON AND EARLY
EVENING...HELPING TO MAINTAIN CURRENT CONVECTION. MODELS PUSH
CONVECTIVE FOCUS EAST ACROSS THE REGION THROUGH THE EVENING MAINLY
AHEAD OF FRONT/SHORTWAVE AXIS. MODERATE INSTABILITY WITH LIFTEDS
AROUND -2 AND VERY WEAK CAPE. RAP/HRRR BOTH GENERATE OUTFLOWS
ROUGHLY 40KTS IN NORTHERN CONVECTIVE REGIONS LATER THIS
AFTERNOON...PROPAGATING EAST AHEAD OF THE FRONT. SHOULD SEE
CONVECTIVE ACTIVITY WEAKEN AFTER SUNSET AND COULD END COMPLETELY
AFTER 06Z THOUGH KEPT WEAK POPS ALONG WYOMING BORDER FOR LINGERING
OROGRAPHIC INFLUENCE.

CLOSED LOW SAGS INTO THE PACNW DURING THE NIGHT AND ROTATES SOUTH
TOWARD CENTRAL CALIFORNIA BY THURSDAY MORNING. BOTH GFS AND NAM
ROTATE ANOTHER SHORTWAVE NORTH ACROSS THE REGION DURING THE DAY.
BEST CHANCES FOR CONVECTION APPEAR TO BE IN THE SOUTHERN HIGHLANDS
AND CLOSE TO THE DIVIDE BUT KEPT WEAK POPS THROUGH THE REMAINDER
OF THE REGION FOR ISOLATED MENTION. BY THURSDAY MORNING...ANOTHER
STRONG SHORTWAVE WORKS AROUND THE TROUGH INTO EAST IDAHO BUT GFS
AND NAM DIFFER ON BEST PLACEMENT OF PRECIP. NUDGED POPS AND
HUMIDITIES HIGHER FOR WHAT LOOKS TO BE THE WETTEST PERIOD OF THE
WEEK. BY THURSDAY NIGHT...CENTER OF UPPER LOW SHIFTS WELL SOUTH
TOWARD POINT CONCEPTION CALIFORNIA. MOISTURE SHOULD BECOME MORE
LIMITED BUT SOUTH MOIST FLOW WITH UPPER LEVEL DIVERGENCE LIKELY TO
KEEP POTENTIAL FOR SOME SHOWERS AND AFTERNOON THUNDERSTORMS IN
PLACE. DMH

.LONG TERM...FRIDAY THROUGH NEXT TUESDAY. GFS/ECMWF SHOW NO MAJOR
DIFFERING FROM SOLUTIONS WITH THE TRACK/INTENSITY OF THE CUT OFF LOW
DROPPING INTO THE DESERT SOUTHWEST. BY 18Z SATURDAY...THE LOW WILL
BE POSITIONED OVER THE FOUR CORNERS AREA WITH STRONG MOISTURE
TRANSPORT FROM THE EASTERLY FLOW. FOCUSED GREATEST POPS OVER EASTERN
HIGHLANDS FOR MUCH OF SATURDAY...INCREASING SLIGHTLY FROM PREVIOUS
FORECAST. MODELS ARE SIGNALING DRIER WEATHER ON SUNDAY AS RIDGING
BUILDS IN. KEEPING SLIGHT CHANCE POPS TO ACCOUNT FOR CONVECTIVE
ACTIVITY AS WE DESTABILIZE THROUGHOUT THE DAY. ECMWF IS COMING MORE
IN LINE WITH THE GFS WITH UPPER LOW PUSHING INTO WA/OR COAST MONDAY
AND LIFTING IT INTO BC...THOUGH BOTH MODELS FAVOR SPREADING
ASSOCIATED PRECIP SHIELD OVER MUCH OF IDAHO...SO WILL KEEP POPS
GOING INTO THE EXTENDED PERIODS. HINSBERGER


&&

.AVIATION...SHOWERS AND ISOLATED THUNDERSTORMS ARE RETURNING EARLIER
THAN YESTERDAY AS AIRMASS DESTABILIZES AHEAD OF A COLD FRONT.
CONVECTION SHOULD BECOME MORE WIDESPREAD THROUGH THE AFTERNOON AT
KPIH AND KBYI. DRIER AIR WILL MOVE IN BEHIND OF THE FRONT AND SHOULD
CURTAIL CONVECTION LATER THIS EVENING...THOUGH WINDS WILL REMAIN
HIGH THROUGH THE NIGHT. HINSBERGER


&&

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

$$


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