Area Forecast Discussion
Issued by NWS Pocatello, ID

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000
FXUS65 KPIH 200950
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
250 AM MST SAT DEC 20 2014

.SHORT TERM...TODAY THROUGH MONDAY NIGHT.
HAVE ISSUED A WINTER STORM WARNING FROM 5 PM THROUGH SUNDAY NIGHT
FOR THE CENTRAL MOUNTAINS ABOVE 6 THOUSAND FEET. KEPT THE WINTER
STORM WATCH IN EFFECT FOR THE SAME TIME PERIOD IN THE EASTERN
HIGHLANDS. VERY STRONG JET STREAM IN THE PACIFIC WILL DRIVE IN
EXTENSIVE MOISTURE TO SOUTHEAST IDAHO THROUGH THE WEEKEND AND
EXPECT HEAVY SNOW TO DEVELOP THIS AFTERNOON AND CONTINUE THROUGH
SUNDAY. SNOW LEVELS WHICH WILL START OUT AT ABOUT 5 THOUSAND FEET
TODAY WILL GRADUALLY RISE TO ABOVE 7 THOUSAND FEET BY SUNDAY
AFTERNOON. THIS SHOULD LIMIT SNOW AMOUNTS BELOW 6500 FEET THROUGH
THE PERIOD...BUT ALL LOCATIONS EARLY TONIGHT ABOVE 5 THOUSAND FEET
SHOULD SEE SOME ACCUMULATION. GENERALLY EXPECTING 5 TO 10 INCHES
ABOVE 6 THOUSAND FEET AND POSSIBLE OVER A FOOT ABOVE 7 THOUSAND
FEET THROUGH SUNDAY NIGHT. STRONG WESTERLY WINDS WILL LIKELY
ACCOMPANY THE STORM DURING THE DAY ON SUNDAY ESPECIALLY OVER
MOUNTAIN PASSES WHERE BLOWING AND DRIFTING ARE LIKELY. EXPECT RAIN
THROUGHOUT THE ENTIRE EVENT IN THE SNAKE RIVER PLAIN WITH STRONG
GUSTY WINDS ON SUNDAY AND A WIND ADVISORY MAY BE NECESSARY.
PRECIPITATION SHOULD TAPER OFF SUNDAY NIGHT AS A COLD FRONT MOVES
THROUGH THE REGION WITH MAINLY DRY CONDITIONS MONDAY AND MONDAY
NIGHT. TEMPERATURES WILL REMAIN WELL ABOVE NORMAL BOTH TODAY AND
SUNDAY WITH COOLING EXPECTED MONDAY BEHIND THE FRONT.
GK

.LONG TERM...TUESDAY THRU SATURDAY. MODELS STILL AGREE ON GENERAL
PATTERN BUT GFS/PARALLEL GFS/ECMWF STILL ALL DIFFER ON DETAILS
THROUGH THE HOLIDAY TRAVEL WEEK. RIDGE IN PLACE TUE FOR DRIEST DAY
OF THE WEEK. CHRISTMAS SYSTEM DROPS THROUGH PACNW ACROSS EAST IDAHO
CHRISTMAS EVE/CHRISTMAS DAY. GFS SLIGHTLY SLOWER AND REMAINS FURTHER
NORTH WITH SFC/700MB FEATURES. ECMWF FASTEST AND FURTHEST SOUTH WITH
PARALLEL GFS SOMEWHERE IN THE MIDDLE. STILL QUITE A BIT OF
UNCERTAINTY REGARDING TIMING OF THE COLD FRONT AND PRECIP. ECMWF AND
TO SOME EXTENT THE PARALLEL GFS FAVOR SNOW REACHING VALLEY FLOORS BY
CHRISTMAS MORNING. GFS HOLDS ON TO WARMER AIR WITH COLD TEMPS
ARRIVING DURING CHRISTMAS DAY. ALL MODELS FAVOR TRANSITORY RIDGE FOR
FRI/SAT AHEAD OF ANOTHER SYSTEM DIVING INTO THE PACNW LATER IN THE
WEEKEND. OPTED TO MAINTAIN CURRENT FCST FOR CHRISTMAS HOLIDAY WHICH
HOLDS BEST CHANCE FOR PRECIP CHRISTMAS EVE NIGHT...AND AT LEAST A
CHANCE OF SNOW TO VALLEY FLOORS. DMH

&&

.AVIATION...VFR/MVFR CONDITIONS IN PLACE MOST AREAS THIS MORNING.
VERY MOIST PACIFIC SYSTEM PUSHING THROUGH PACNW AS ADVERTISED TODAY.
PRECIP RETURNS TO CENTRAL MTNS BY LATE MORNING THEN SPREADS ACROSS
REMAINDER OF EAST IDAHO THIS AFTN/EVE. STRONG WEST/NORTHWEST FLOW
ALOFT WILL FOCUS PRECIP IN LEADING EDGES OF CENTRAL MTNS AND EASTERN
HIGHLANDS. WARM TEMPS KEEP SNOW LEVELS HIGH AND HEAVIEST PRECIP
ARRIVES OVERNIGHT. KSUN LIKELY ALL SNOW WITH CONDITIONS REMAINING
BELOW FIELD MINIMUMS ONCE PRECIP STARTS. KIDA SHIFTING FROM VFR/MVFR
TO RAIN/SNOW MIX AND IFR CEILINGS OVERNIGHT. KBYI/KPIH BOTH STAY
RAIN THROUGH TONIGHT BUT MAY OCCASIONALLY FLIRT WITH IFR CEILINGS
DURING PERIODS OF HEAVIER PRECIP. DMH

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 5 PM THIS AFTERNOON TO 5 AM MST MONDAY
ABOVE 6000 FEET FOR THE IDZ031-032.

WINTER STORM WATCH FROM THIS AFTERNOON THROUGH LATE SUNDAY NIGHT
ABOVE 6000 FEET FOR THE IDZ019-023-025.

WINTER STORM WARNING FROM 5 PM THIS AFTERNOON TO 5 AM MST MONDAY
IDZ018.

&&

$$






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