Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 221953
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
153 PM MDT FRI MAY 22 2015

.SHORT TERM...TONIGHT THROUGH MONDAY.

LOW PRESSURE WILL MOVE OUT OF SOUTHERN CALIFORNIA INTO SOUTHERN
UTAH TONIGHT. SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED
THIS AFTERNOON. THESE STORMS ARE MOVING RATHER SLOWLY...SO HEAVY
RAINFALL IS THE MAIN THREAT ALONG WITH SOME SMALL HAIL. MUCH OF
THE CONVECTION WILL DIMINISH THIS EVENING. HOWEVER THE MODELS
CONTINUE TO SHOW A BAND OF SHOWERS MOVING OUT WYOMING INTO
SOUTHEAST IDAHO AFTER MIDNIGHT AND PERSISTING THROUGH SATURDAY
MORNING. THESE SHOWERS ARE PART OF A SPIRAL BAND ASSOCIATED WITH
THE LOW PRESSURE SYSTEM. EXPECT MORE SHOWERS TO DEVELOP OUTSIDE OF
THE BAND AREA ONCE AGAIN SATURDAY AFTERNOON ACROSS MUCH OF THE
REGION. ONCE AGAIN HEAVY DOWNPOURS AND SMALL HAIL ARE POSSIBLE.
THE LOW WILL MOVE INTO THE NORTHERN PLAINS ON SUNDAY. THERE WILL
STILL BE ENOUGH MOISTURE AROUND TO SUPPORT A FEW SHOWERS AND
THUNDERSTORMS...HOWEVER THE COVERAGE SHOULD BE MUCH LESS ON
SUNDAY. YET ANOTHER LOW PRESSURE SYSTEM WILL APPROACH THE AREA ON
MONDAY...THIS TIME FROM THE NORTHWEST. THIS WILL PRODUCE A GOOD
CHANCE FOR SHOWERS AND THUNDERSTORMS ONCE AGAIN ON MONDAY.

VALLE

.LONG TERM...MON NIGHT THROUGH NEXT FRI NIGHT. THE LONGWAVE 500MB
FORECAST INDICATES THAT BY WED THE GEM STATE MAY BE IN MORE OF A
WESTERLY UPPER LEVEL FLOW RATHER THAN THE SOUTHERLY FLOW THAT HAS
BEEN BRINGING UP THE UNSTABLE SUBTROPICAL AIR. THIS IS WHY THE
CHANCE FOR PRECIPITATION LOWERS FOR THU AND FRI. THERE IS HOPE TO
BELIEVE THIS AS BOTH THE ECMWF AND GFS ARE EXPECTING THIS. NOT THAT
THERE IS ZERO CHANCE...BUT THAT THE THREAT IS REDUCED. DECREASED
CLOUDINESS BY WED WILL ALLOW TEMPERATURES TO WARM UP DESPITE THE
SHIFT FROM SOUTHERLY FLOW. NO SIGNIFICANT WIND EXPECTED OTHER THAN
FROM THUNDERSTORM ACTIVITY. MESSICK

&&

.AVIATION...SKIES SHOULD CLEAR ENOUGH IN BY LATE MORNING TO ALLOW
CONVECTIVE TEMPERATURES TO BE REACHED AND CONTINUE THE ROUND OF
AFTERNOON AND EVENING -TSRA. SHOWERS WILL NOT TAPER OFF DURING THE
EVENING AS A MASSIVE MOIST AIR MASS MOVES IN FOR THE LATE NIGHT
HOURS THROUGH MOST OF SAT. WOULD EXPECT AT LEAST A CIG IMPACT FOR
THE AIRDROMES...MAINLY FOR THE MORNING HOURS AS THE MOISTURE TENDS
TO THIN BY MID-AFTERNOON...JUST IN TIME FOR THE INCREASED HEATING TO
ONCE AGAIN DEVELOP -TSRA. MESSICK

&&

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

$$


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