Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 240142
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
742 PM MDT SAT APR 23 2016

.UPDATE...UPPER LOW CONTINUING TO SLIDE EAST INTO SW WYOMING THIS
EVENING PER SATELLITE IMAGERY. SFC LOW REMAINS OVER IDAHO/MONTANA
BORDER WITH SHOWERS SLIDING SOUTHEAST ACROSS THE FORECAST AREA.
SFC GRADIENT WEAKER THAN ANTICIPATED AND SHOWER ACTIVITY HELPING
TO PRECLUDE DEVELOPMENT OF THE STRONG WINDS. WIND TREND FROM RAP
AND HRRR INDICATING SLOW DECREASE OF WINDS REMAINDER OF THIS
EVENING...SUPPORTED BY EARLIER GUIDANCE. THUS HAVE LET ADVISORY GO
EARLY. HAVE ADJUSTED WIND FORECAST DOWN SLIGHTLY REMAINDER OF
TONIGHT PERIOD OTHERWISE REMAINDER OF FORECAST IN GOOD SHAPE AND
NO OTHER CHANGES ANTICIPATED. DMH


&&

.PREV DISCUSSION... /ISSUED 221 PM MDT SAT APR 23 2016/

SHORT TERM...CURRENT RADAR IMAGERY HAS THE CENTER OF CIRCULATION
OF THESE SHOWERS ROUGHLY WHERE INTERSTATE 84 CROSSES THE IDAHO
AND UTAH STATE LINE. THIS DISTURBANCE TRACKS INTO SOUTHERN WYOMING
TONIGHT WITH WRAP AROUND EXPECTED OVER THE EASTERN HIGHLANDS.
SURFACE WINDS ARE GUSTING TO AROUND 45 MPH JUST WEST OF BURLEY AND
WILL LIKELY PICK UP ALONG I84/I86 AS SOME OF THE SHOWERS BREAK OFF
THE NEXT COUPLE OF HOURS. WILL KEEP THE CURRENT WIND ADVISORY IN
EFFECT FOR THIS EVENING. THINK THE SHOWERS ARE DELAYING THE ONSET
OF THE WINDS. SNOW LEVELS DROP TO ABOUT 7000 FEET ELEVATION OVER
THE EASTERN HIGHLANDS TONIGHT...THEN REBOUND UP TWO TO THREE
HUNDRED FEET DURING THE DAY. SNOW SHOULD ACCUMULATE UP TO 5 INCHES
OVER THE MOUNTAINS AROUND DRIGGS THROUGH MONDAY AFTERNOON. TETON
PASS MOST AT RISK FOR ACCUMULATION. TRANSITORY RIDGE BUILDS IN
SATURDAY NIGHT AND EARLY SUNDAY PROVIDING A BREAK FROM SHOWERS FOR
MOST OF THE VALLEY AREAS. OROGRAPHICS FAVOR SOME SHOWERS BETWEEN
DRIGGS AND ISLAND PARK. MODELS FAVOR THE NEXT DISTURBANCE TRACKING
ACROSS NORTHERN NEVADA AND UTAH MONDAY AND TUESDAY. 700 MB WINDS
SHOW SOME POTENTIAL FOR BANDING OF PRECIPITATION OVER THE
INTERSTATE 86 STRETCH FROM POCATELLO TO BURELY...BUT SNOW LEVELS
SHOULD BE AT OR ABOVE ABOUT 6200 FEET ELEVATION. ALSO HAVE
PROBLEMS WITH LIQUID WATER CONTENT...GFS APPEARS TO HAVE SOME
CONVECTIVE FEED BACK PRESENT IN THE MODEL AT TIMES. WILL PROBABLY
TAKE A COUPLE OF MODEL RUNS TO PLACE PRECIPATION AMOUNTS. RS

LONG TERM...TUESDAY THROUGH SATURDAY NIGHT. LOOK FOR A LINGERING
SYSTEM EARLY TUESDAY BRINGING GOOD PRECIPITATION CHANCES
PARTICULARLY FOR OUR EASTERN AREAS. MOUNTAINS IN THE SOUTHEAST
HIGHLANDS WILL LIKELY SEE 1 TO 2 INCHES OF SNOW. THE GFS MODEL
CONTINUES TO SHOW MORE PRECIPITATION THAN THE ECMWF MODEL. THE ECMWF
MODEL SHOWS STRONGER RIDGING THAN THE GFS ON WEDNESDAY. THUS..THE
ECMWF MODEL IS DRIER. THE GFS MODEL SHOWS AFTERNOON MOUNTAIN SHOWERS
DEVELOPING ON WEDNESDAY. THURSDAY INTO FRIDAY BOTH MODELS BRING AN
UPPER LEVEL LOW OVER UTAH BRINGING SHOWERS ACROSS THE AREA...
PARTICULARLY OUR SOUTHERN AREAS. THE ECMWF MODEL THEN BRINGS IN HIGH
PRESSURE RIDGING QUICKER THAN THE GFS MODEL BRINGING DRY CONDITIONS
BY SATURDAY AFTERNOON. THE GFS KEEPS LINGERING PRECIPITATION ACROSS
THE AREA INTO SATURDAY EVENING PARTICULARLY FOR OUR EASTERN AREAS.
EXPECT BELOW NORMAL TEMPERATURES EARLY IN THE PERIOD SLOWLY RISING
TO NEAR NORMAL BY THE END OF THE PERIOD. WYATT

AVIATION...AN UPPER LEVEL LOW IS MOVING OVER THE AREA TODAY. EXPECT
VICINITY THUNDERSTORMS FOR THE TAF SITES THIS AFTERNOON PARTICULARLY
FOR KPIH AND KIDA. LOOK FOR SHOWERS FOR THE SNAKE RIVER PLAIN TAF
SITES BRINGING MVFR CONDITIONS THIS AFTERNOON INTO THE EVENING. CIGS
WILL GO DOWN TO IFR DURING PERIOD OF RAIN SHOWERS ON STATION. KSUN
SHOULD REMAIN VFR WITH VICINITY SHOWERS THIS AFTERNOON AND EVENING.
HOWEVER...MVFR CIGS ARE POSSIBLE FOR KSUN WITH HEAVIER SHOWERS ON
STATION. EXPECT BREEZY TO MODERATE WINDS BY MID TO LATE AFTERNOON.
WINDS SHOULD CONTINUE THROUGH MOST OF THE NIGHT AND START TAPERING
OFF BY EARLY TO MID TOMORROW MORNING. WYATT

&&

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

$$


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