Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 291028
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
328 AM MST MON DEC 29 2014

.SHORT TERM...TODAY THROUGH WEDNESDAY. A BROAD AREA OF LOW
PRESSURE REMAINS ENTRENCHED ACROSS THE REGION THIS MORNING. THERE
ARE SEVERAL WEAK DISTURBANCES EMBEDDED IN THIS PATTERN...LEADING
TO POCKETS OF VERY LIGHT SNOW OR FLURRIES ACROSS EASTERN IDAHO.
THIS ESPECIALLY THE CASE WHERE WE HAVE LOW/MID CLOUDS AND GETTING
THE SEEDER FEEDER PROCESS GOING. WE ALSO HAVE SOME BREAKS IN THE
CLOUDS AS WELL. FOR THE REST OF THE DAY...EXPECT MORE OF THE SAME
WITH LIGHT SNOW PAINTED THROUGHOUT EASTERN IDAHO. IT IS REALLY
HARD TO PINPOINT WHERE WE MIGHT SEE POCKETS OF ENHANCED SNOWFALL
MORE THAN A HANDFUL OF HOURS OUT...SO WE OPTED WITH A BROAD
APPROACH TO THE FORECAST. IF WE GET ENHANCED SNOWFALL IN
SPOTS...THERE COULD BE AROUND AN INCH OF NEW FLUFFY SNOW.
OTHERWISE...EXPECT NOTHING MORE THAN A DUSTING. TEMPERATURES WILL
CONTINUE TO TREND COLDER TODAY...AND IN SOME SPOTS WE HAVE LIKELY
SEE HIGHS FOR THE DAY. AS THE PATTERN SHIFTS SOUTH AND A DOMINANT
STORM DEVELOPS ACROSS UTAH AND NEVADA....WE WILL SEE CLOUDS AND
SNOWFALL QUICKLY ENDING TONIGHT AND NORTH/NORTHEAST FLOW
DEVELOPING. THIS WILL HELP BRING COLDER AIR TO EASTERN IDAHO ALONG
WITH STRONGER WINDS IN MANY AREAS. THIS WILL DROP LOWS TONIGHT
INTO 0-10 DEGREE RANGE FOR THE SOUTHWEST HALF OF THE FORECAST
AREA. THE REST OF US WILL BE BELOW ZERO...WITH TEMPS COLDER THAN
-20 ALONG THE MONTANA BORDER AND ALSO THE HIGHER VALLEYS OF THE
CENTRAL MOUNTAINS. WITH WINDS PICKING UP...WIND CHILLS WILL BE
BELOW ZERO FOR EVERYBODY. IN MANY PLACES...VALUES WILL BE -20 TO
-40. WHERE WE HAVE THE LOW WIND CHILLS COMBINED WITH 10+MPH
WINDS...WE HAVE ISSUED WIND CHILL WARNINGS FOR THIS EVENING
THROUGH TUESDAY MORNING. EVEN WHERE WE DON`T HAVE WIND CHILL
WARNINGS AND THEY ARE GOING TO BE AT -20 OR COLDER...THE SAME
IMPACTS WILL BE THERE IN TERMS OF QUICK ONSET OF FROSTBITE AND
HYPOTHERMIA.

COLD TEMPERATURES WILL BE WITH US THROUGH MIDWEEK AS HIGH PRESSURE
BUILDS OVER IDAHO AND WE KEEP A NORTHERLY FLOW. BECAUSE OF THE
COLD START TOMORROW...HIGHS IN THE SINGLE DIGITS AND TEENS ARE
FORECAST. WE WOULDN`T BE SURPRISED IF SOME PLACES DON`T GET ABOVE
ZERO. TUESDAY NIGHT WILL BE EVEN COLDER AS WINDS RELAX AND THE
ARCTIC AIR IS IN PLACE. RIGHT NOW...IT APPEARS ANY HIGH CLOUDS
MOVING OVER THE STATE WILL NOT HAVE ANY EFFECTS ON KEEPING
TEMPERATURES A BIT WARMER. LOWS OF -10 TO -30 ARE FORECAST EXCEPT
FOR THE MAGIC VALLEY AND SOUTH CENTRAL HIGHLANDS...BUT STILL
EXPECT THOSE AREAS TO BE BELOW ZERO. WIND CHILLS WILL BE DANGEROUS
LOW AGAIN AND LIKELY IN MORE AREAS VERSUS TONIGHT. BY
WEDNESDAY...WE WILL SEE MID AND UPPER SLOPES WARMING A BIT. MOST
VALLEYS WILL STAY COLD DUE TO INVERSIONS AND A COLDER START. THOSE
AREAS WILL ONLY REACH THE SINGLE DIGITS AND PERHAPS LOW TEENS.
ABOVE THE INVERSION...WE MAY PLACES IN THE UPPER TEENS FOR HIGHS. KEYES

.LONG TERM...THURSDAY NIGHT THROUGH SUNDAY.
GFS LOOKS TO BE FOLLOWING THE EUROPEAN MODELS WITH THE CLOSED LOW
OVER SOUTHERN CALIFORNIA AND ARIZONA WEDNESDAY/THURSDAY...FOLLOWED
BY A FLATTENING OF THE RIDGE IN THE EASTERN PACIFIC FRIDAY THROUGH
SUNDAY. DRY AIR IS EXPECTED OVER SOUTHEAST IDAHO WEDNESDAY AND
THURSDAY WITH LINGERING COLD TEMPERATURES. TEMPERATURES BEGIN TO
MODIFY WARMER WITH MORE WESTERLY FLOW...INCREASING CLOUD COVER AND A
CHANCE OF PRECIPITATION MAINLY OVER THE MOUNTAINS AND ALONG THE
MONTANA AND IDAHO BORDER. PRECIPITATION IN THE CENTRAL MOUNTAINS AND
EASTERN HIGHLANDS COULD BECOME MORE SIGNIFICANT AROUND SUNDAY IF
DEEPER MOISTURE OFF THE PACIFIC ARRIVES LIKE THE GFS SUGGESTS. RS

&&

.AVIATION...THE MAIN PROBLEM IS LOW STRATUS IN THE SNAKE PLAIN
PERSISTING OVER KIDA...KPIH AND KBYI. WITH THE TROUGH MOVING
SOUTHWARD TODAY THE 700 MB WINDS BECOMING EASTERLY WHICH WILL HELP
TRANSPORT THE STATUS DOWN VALLEY TO THE WEST. WE SHOULD SEE SOME
LIFTING OF THE CEILINGS TO AROUND 3000 FEET AGL AT KIDA/KPIH BY
18Z...THEN A GRADUAL CLEARING AFTER MIDNIGHT. KPIH/KBYI MAY TAKE
UNTIL TUESDAY MORNING TO CLEAR. SNOW SHOULD FAVOR THE MOUNTAINS
WHERE OROGRAPHIC LIFT IS AVAILABLE. SOME TEMPORARY WIND CONVERGENCE
IN THE SNAKE PLAIN COULD SUPPORT SOME LIGHT SNOW...BUT IT IS REALLY
HARD TO COUNT ON FOR TIMING. FOR KSUN...WILL BE WATCHING
SOUTHEASTERLY SURFACE WINDS THIS AFTERNOON AND LOOKING FOR LOW
STRATUS TO BE DRAWN INTO THE THE AIRPORT AREA. RS


&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WIND CHILL WARNING FROM 10 PM THIS EVENING TO 11 AM MST TUESDAY
IDZ020-021-025-032.

WIND CHILL WARNING FROM 5 PM THIS AFTERNOON TO 11 AM MST TUESDAY
IDZ019.

&&

$$






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