000
FXUS65 KPIH 210939
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
339 AM MDT TUE MAY 21 2013

.SHORT TERM...TODAY THROUGH THU NIGHT. A BRIEF BREAK BEFORE
A RATHER STRONG SHORTWAVE ENTERS THE GEM STATE AND AFFECTS THE
WESTERN PART OF THE FORECAST AREA WED AFTERNOON. IN THE UNSTABLE
AIR LEFT BEHIND FROM THE SUNDAY TROUGH...SOME AFTERNOON AND EARLY
EVENING SHOWERS ARE POSSIBLE...BUT SHOULD BE MAINLY DRY
THUNDERSTORMS AND ONLY EXPECTED TO BE ISOLATED. AS THE NEXT TROUGH
MOVES IN LATE WED AFTERNOON...IT COULD BRING MODERATE TO STRONG
WIND...WHICH IS ENOUGH FOR A LAKE WIND ADVISORY. 90KT-PLUS JET...50KT-
60KT WINDS AT 500MB...AND ABOUT A 10MB PRESSURE GRADIENT ACROSS
SOUTHERN IDAHO WILL ALL WORK TO BOOST THE WIND. HOWEVER 700MB
WINDS ARE WEAK AND MAINLY FROM THE SOUTH...AND WINDS AT HIGHER
LEVELS ALSO FROM THE SOUTH AND SOUTHWEST...WHICH DO NOT SUPPORT
THE SURFACE WINDS. THE COLD AIR ADVECTION IS ALSO WEAK. THUS DO
NOT THINK A WHOLE SALE WIND ADVISORY IS NEEDED...JUST LAKE WIND.
WIND SHOULD BE SIMILAR ON THU. THE STRONG PRECIPITATION BAND
MOVES SLOWLY THROUGH THE FORECAST AREA...MAINLY AFFECTING THE
NORTHERN AND WESTERN ZONES FROM WED NIGHT THROUGH THU NIGHT. THE
CLOUD UP AND COLDER AIR MASS BEHIND THE FRONT WILL MEAN COOLER
TEMPERATURES AFTER TODAY. SOME SNOW IS POSSIBLE IN THE HIGH
ELEVATIONS...BUT TREND IS FOR LIGHTER PRECIPITATION AMOUNTS ON THE
NAM. GFS IS MUCH WETTER WITH AS MUCH AS 0.40 INCH LIQUID WATER
EQUIVALENT IN THE MOUNTAINS. HOWEVER THE SNOW LEVEL SHOULD RISE
DURING THE AFTERNOON EVEN IN THIS PATTERN AND SNOW BELOW 8000 FEET
ELEVATION SHOULD BE RARE. MESSICK

.LONG TERM...FRI THROUGH MON NIGHT. STORM DURING THE NEAR TERM
DEPARTS FRI MORNING...BUT AN ANCHOR LOW STILL SITS OVER THE
PACIFIC NORTHWEST WITH MORE SHORTWAVES EXPECTED TO ENTER THE BASE
OF THE UPPER LEVEL TROUGH AND EJECT NORTHEASTWARD. HOWEVER THE
TRAJECTORY IS NOT AS SOLID A STRIKE ON EASTERN IDAHO. THE CENTRAL
IDAHO MOUNTAINS BEAR THE BRUNT OF IT FOR THE FORECAST AREA...WITH
OTHER AREAS RECEIVING LITTLE PRECIPITATION. THE MAIN SHORTWAVE
DURING THIS PERIOD IS ON SUN/SUN NIGHT. THIS NEXT SHORTWAVE DOES
NOT PACK MUCH IN WIND...AND PRECIPITATION IS FAIRLY LIGHT.
FORECAST CONFIDENCE IS LOW...AS THE ECMWF DOESNT REALLY EVEN HAVE
THIS TROUGH. IT BRINGS IN A WEAKER TROUGH ON TUE. SO HAVE REALLY
BROAD-BRUSHED TOWARDS THE END OF THE EXTENDED FORECAST. MESSICK

&&

.AVIATION...TRANSITORY RIDGE PUSHES ACROSS EASTERN IDAHO TODAY. DEEP
PACIFIC LOW ALREADY ENCROACHING ON PACNW COAST WITH MOISTURE
PUNCHING THROUGH SOUTHERN OREGON THIS MORNING...EXPECTED TO REACH
EASTERN IDAHO THIS AFTERNOON. CONVECTION POSSIBLE AGAIN MAINLY OVER
CENTRAL MOUNTAINS AND FAR NORTHEAST CORNER THIS AFTERNOON AND
EVENING WITH MVFR CONDITIONS. DMH

&&

.FIRE WEATHER...A WEAK RIDGE WILL PASS BY THE FIRE DISTRICT THIS
MORNING. THE NEXT PACIFIC TROUGH ALREADY ALONG THE PACNW COAST WILL
PUSH MOISTURE BACK INTO EASTERN IDAHO TODAY WITH ANOTHER THREAT OF
AFTERNOON AND EVENING CONVECTION MAINLY IN THE CENTRAL MOUNTAINS AND
ALONG THE NORTHEAST PORTIONS OF THE DISTRICT. A COLD FRONT TO PASS
THROUGH THE REGION EARLY WEDNESDAY MORNING WITH GUSTY WINDS THROUGH
THE DAY AND ANOTHER ROUND OF SHOWERS AND ISOLATED THUNDERSTORMS. DMH

&&

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

$$