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000
FXUS65 KPIH 052053
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
155 PM MST THU DEC 5 2013

.SHORT TERM...TONIGHT THROUGH SUNDAY. LATEST SATELLITE IMAGERY
SHOWING AN AREA OF LOW CLOUDS/STRATUS WEST OF POCATELLO WITH REPORTS
OF LIGHT SNOW FLURRIES. MODELS SUGGEST THAT THE STRATUS FIELD WILL
WORK BACK UP THE VALLEY TONIGHT AND THUS HAVE ADDED A MENTION OF
FLURRIES WITHIN THE SNAKE RIVER PLAIN. IN ADDITION TO THE
STRATUS...AN INFLUX OF MOISTURE IS EXPECTED FROM THE NNW AS A
DISTURBANCE DIGS SOUTH THROUGH VANCOUVER ISLAND AND ALONG THE
WASHINGTON/OREGON COAST. THE DISTURBANCE TURNS INLAND FRIDAY
AFTERNOON/NIGHT DIGGING SE ACROSS OREGON INTO NRN NEVADA. FAIRLY
MODEST DIFFERENCES IN THE TRACK OF THE WAVE SHOWING UP BETWEEN THE
NAM AND GFS WITH THE FORMER TAKING THE WAVE A BIT FURTHER SOUTH AND
WEST OF THE GFS TRACK AND CONSEQUENTLY A BIT DRIER. HAVE LEANED
TOWARD THE WETTER GFS SOLUTION IN THIS REGARD WITH INCREASINGLY
STRONGER CHANCES OF PRECIPITATION EXPECTED FRIDAY NIGHT INTO
SATURDAY AS THE TROUGH DIGS INTO NRN NEVADA. ANTICIPATING UPWARDS OF
1 TO 3 INCHES ACROSS THE CNTRL MOUNTAINS...1 TO 2 INCHES IN THE
SNAKE PLAIN AND 3 TO 5 INCHES ACROSS THE SE HIGHLANDS UNDER THE
WETTER GFS SOLUTION BY SATURDAY EVENING. AS THE UPPER TROUGH SHIFTS
EAST INTO UTAH SATURDAY EVENING PRODUCING A CONVERGENT LOW LEVEL
UPSLOPE FLOW IN THE POCATELLO AREA WHICH IS TYPICALLY NOT HANDLED
WELL BY THE MODELS AND CAN PRODUCE 1 TO 2 INCHES OF ADDITIONAL
ACCUMULATION IN A LOCALIZED AREA. THUS WILL CONTINUE TO WATCH THE
EVOLUTION OF THE SYSTEM AND MODEL CONSOLIDATION FOR A POTENTIAL
WINTER WEATHER ADVISORY LATE FRIDAY NIGHT INTO SATURDAY.
TEMPERATURES REMAIN COLD...BUT WITH SOME MODERATION SATURDAY DUE TO
THE INFLUX OF CLOUDS. HUSTON

.LONG TERM...SUN NIGHT THROUGH NEXT THU NIGHT. 500MB LONGWAVE PROG
INDICATES THAT THE PACIFIC RIDGE/NORTHERN CANADA POLAR VORTEX
PATTERN ACTUALLY STRENGTHENS THROUGH TUE...THEN SHOWS SOME
DE-AMPLIFYING BY WED MORNING. THUS EXPECT THE VERY COLD TEMPERATURES
TO CONTINUE.  SOME SHORTWAVES DO MOVE THROUGH THE MEAN
NORTH-NORTHWEST AND NORTHERLY FLOW. THE 05/00Z GUIDANCE WAS VERY
MUCH IN AGREEMENT AS FAR AS TIMING...BUT THE 05/12Z GFS HAS SHOWN
THE SOLUTION FOR THIS TIME TO BE UNSTABLE IN TIMING...WITH THE GFS
SPEEDING UP THE SHORTWAVE APPROACH AND THUS BEING WETTER
EARLIER...AND DRIER IN THE LATER PERIODS COMPARED TO THE ECMWF. HAVE
TRIED TO SPLIT IT DOWN THE MIDDLE AFTER TUE.  DO NOT AT THIS TIME
SEE ANY SIGNIFICANT WIND...ESPECIALLY EARLY. CANNOT RULE OUT LATE
NIGHT AND EARLY MORNING FOG PROBLEMS DURING THE EARLY PART OF THIS
PERIOD...BUT UPPER LEVEL TROUGHING WOULD TEND TO KEEP THAT A LOW
PROBABILITY WITH STRONG UPPER LEVEL AIR FLOW AND A LACK OF A LARGE
AREA OF SUBSIDENCE. MESSICK
&&

AVIATION...STRATUS PROBLEMS WILL BE LIMITED TO THE KPIH VICINITY AS
MID-LEVEL MOISTURE STARTS TO MOVE IN TONIGHT.  THIS IS IN ADVANCE OF
AN UPPER LEVEL TROUGH EXPECTED FRI AFTERNOON THROUGH SAT. LIGHT
NORTHEAST TO EASTERLY SURFACE WIND EXPECTED AT THE LOWER AIRDROMES.
SHOWERS EXPECTED TO POP UP OVER THE WOOD RIVER BASIN...WHICH COULD
POTENTIALLY CAUSE TEMPORARY CLOSURE OF KSUN...BUT THE WEAKNESS OF
THE INSTABILITY INDICATES THE PROBABILITY VERY LOW. THUS ONLY VCSH
COMMENT IN THE TAF. MESSICK
&&

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

$$