Area Forecast Discussion
Issued by NWS Pocatello, ID

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000
FXUS65 KPIH 231950
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
150 PM MDT SAT AUG 23 2014

.SHORT TERM...TONIGHT THROUGH TUESDAY. THE LATEST SATELLITE IMAGERY
WAS SHOWING A LOW PRESSURE SYSTEM OVERHEAD WITH SEVERAL WELL DEFINED
VORT FEATURES EMBEDDED IN THE FLOW. CURRENT RADAR TRENDS ARE SHOWING
A RAPID INCREASE IN SHOWER ACTIVITY EARLY THIS MORNING AND CURRENTLY
ANTICIPATE THIS CONTINUE AND BECOME MORE LINEARLY FOCUSED THROUGH
THE AFTERNOON AS ONE OF THE EMBEDDED VORT FEATURES PLUNGES SOUTH
THROUGH THE SNAKE RIVER PLAIN AND THE SURFACE WINDS BEGIN TO FORM A
CONVERGENCE AREA WITH THUNDERSTORMS ACROSS THE UPPER VALLEY THAT
DRIFTS SOUTH LATE THIS AFTERNOON BEFORE DISSIPATING LATER THIS
EVENING AS THE UPPER LOW BEGINS TO LIFT NE INTO SRN MONTANA.
ANTICIPATING A BRIEF BRAKE IN THE ACTION SUNDAY MORNING BEFORE THE
NEXT PAC THROUGH DIGS INTO THE NW STATES SUNDAY AFTERNOON FURTHER
WEST THAN PREVIOUS PROGS SPINNING UP A SHALLOW CLOSED LOW OVER THE
NRN GREAT BASIN SUNDAY AFTERNOON/NIGHT WITH AN INCREASE IN SHOWER
ACTIVITY WHICH LINGERS THROUGH MONDAY NIGHT/TUESDAY AS THE LOW
SLOWLY FILLS AND GRADUALLY SWINGS EAST ALONG THE NEVADA/UTAH BORDER
BEFORE EXITING EAST OF THE REGION TUESDAY EVENING.

.LONG TERM...TUESDAY NIGHT THROUGH NEXT SATURDAY. DRIER AND WARMER
CONDITIONS DEVELOP ACROSS SRN IDAHO WEDNESDAY THROUGH FRIDAY AS A
TRANSIENT UPPER RIDGE MIGRATES EAST ACROSS THE AREA AHEAD OF THE
NEXT APPROACHING PAC STORM SYSTEM. THE 12Z GFS CONTINUES TO TAP INTO
THE REMNANTS OF HURRICANE MARIE AS IT LIFTS NE OUT OF THE
SUB-TROPICAL ERN PACIFIC WATERS OFF THE MEXICAN COAST TO A POSITION
WELL OFF THE CALIFORNIA COAST FRIDAY AHEAD OF THE INCOMING TROUGH.
AS THE TROUGH MOVES INLAND SATURDAY...THE GFS BEGINS TO INTERACT
WITH THE SUB-TROPICAL MOISTURE PRODUCING WIDESPREAD SHOWER ACTIVITY
ACROSS IDAHO. THE 12Z ECMWF TAKES MARIE ON A MORE NWRLY TRAJECTORY
PREVENTING THE INCOMING TROUGH FROM TAPPING INTO THE MOIST
SUB-TROPICAL SYSTEM WITH DRIER CONSEQUENCES. WE WILL CONTINUE TO
MONITOR THE MODEL TRENDS FOR ANY CHANGE IN EITHER MODEL. HUSTON
&&

.AVIATION...UPPER LOW IS SLOWLY DRIFTING ACROSS SOUTHEAST IDAHO THIS
AFTERNOON. ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE IN THE
COLD CORE REGION WITH MOST OF THE STRATIFORM PRECIP WRAPPING AROUND
THE LOW INTO THE SALMON/CHALLIS AREA. STARTING TO SEE CEILINGS AT
KIDA LIFT FROM IFR TO MVFR...AND SHOULD SCATTER OUT IN THE EARLY
AFTERNOON. HRRR SIGNALS INCREASING SHOWER ACTIVITY AROUND
MID-AFTERNOON AND INTO THE EVENING AS LOW MOVES INTO THE YELLOWSTONE
AREA. FORECAST SOUNDINGS FAVORING 6000 FT TO 10000 FT CEILINGS
OVERNIGHT INTO TOMORROW.  HINSBERGER
&&

.FIRE WEATHER...A LITTLE LESS COVERAGE OF SHOWERS AND THUNDERSTORMS
TODAY AS UPPER LOW SLOWLY DRIFTS ACROSS SOUTHEAST IDAHO TODAY.
HEAVIER PRECIP IS BEING WRAPPED AROUND THE LOW INTO LEMHI COUNTY.
DRIER WEATHER IS EXPECTED SUNDAY AS INFLUENCE OF LOW WANES...BUT
MODELS ARE PROJECTING ANOTHER UPPER LOW TO DROP INTO OR/ID SUNDAY
NIGHT. IMPULSES OF ENERGY AROUND THE LOW WILL BRING MORE SHOWERS AND
THUNDERSTORMS TO THE AREA DURING THE DAY MONDAY...AND MAY LINGER
INTO TUESDAY MORNING. UPPER RIDGING WILL BRING DRIER WEATHER TO THE
REGION LATER ON TUESDAY AND SHOULD LAST THROUGH FRIDAY. A PACIFIC
TROUGH WILL APPROACH THE WEST ON FRIDAY. REMNANTS OF HURRICANE MARIE
MAY BE POSITIONED TO CONTRIBUTE ITS TROPICAL MOISTURE THOUGH THERE
IS STILL SOME UNCERTAINTY WITH ITS TRACK IN RELATION TO THE PACIFIC
TROUGH...BUT SIGNS POINT TO ANOTHER WET WEEKEND.  HINSBERGER
&&

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

$$









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