Area Forecast Discussion
Issued by NWS Pocatello, ID

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
000
FXUS65 KPIH 281036
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
336 AM MST SUN DEC 28 2014

.SHORT TERM...TODAY THROUGH TUESDAY. WE ARE IN THE THROES OF THE
LATEST STORM AFFECTING EASTERN IDAHO. THE HEAVIEST AND MOST
PERSISTENT SNOW OVERNIGHT HAS BEEN ALONG AND EAST OF THE I-15
CORRIDOR DUE TO UPSLOPE FLOW. THERE HAS BEEN LIGHTER SNOW
ELSEWHERE...ALTHOUGH THE STRONG SOUTH WIND HAS PREVENT A LOT OF
ACCUMULATION ALONG I-86 FROM POCATELLO WEST TOWARD BURLEY. SNOW IS
ACTUALLY INCREASING ESPECIALLY FARTHER WEST AND THE STORM
CONTINUES TO MOVE INTO THE AREA. WE ARE SEEING BLOWING AND
DRIFTING IN SEVERAL AREAS...EVEN WITH LIGHTER WINDS AS THE SNOW
FALLING AND LEFT OVER FROM CHRISTMAS IS FLUFFY. FOR THE REST OF
TODAY...THE FOCUS OF THE PERSISTENT SNOW SHIFTS TO ACROSS THE
SOUTHERN AND EASTERN HIGHLANDS...INCLUDING SOME BENCH AREAS FROM
REXBURG TO NEAR POCATELLO. IN FACT...THE HEAVIEST SNOW IS LIKELY
IN FROM NEAR ASHTON TO ALMOST IDAHO FALLS AS IT APPEARS WE MIGHT SEE
SOME ENHANCED SNOWFALL DUE TO A COMBINATION OF UPSLOPE AND A WEAK
CONVERGENCE BAND. THE REST OF THE AREA WILL SEE SNOW BUT LESS
WIDESPREAD. WE ARE ALSO LOOKING AT A SECOND CONVERGENCE TYPE BAND
DEVELOPING ACROSS THE SNAKE PLAIN SOMEWHERE BETWEEN IDAHO FALLS
AND POCATELLO...EXTENDING OUT TO AROUND CRATERS. THIS WILL LOCALLY
ENHANCE SNOWFALL AS WELL. FOR THIS EVENING AND TONIGHT...POCKETS
OF SNOW WILL REMAIN ACROSS EASTERN IDAHO. THIS IS WHERE THE
FORECAST GETS TRICKY FOR THE SNAKE PLAIN AND ADJACENT
FOOTHILLS/MOUNTAINS. THE MODELS ARE SHOWING ANYWHERE FROM 1 TO 3
ADDITIONAL BANDS DEVELOPING AND SLOWLY DROPPING SOUTHWEST. WHILE
WE ARE CONFIDENT THERE WILL BE SOME BANDING...WE AREN`T SURE WHERE
TO PLACE ANY OF THEM PRECISELY OR AMOUNTS INVOLVED. THEREFORE...WE
WENT A BROADER APPROACH AND PUT HIGHER SNOW CHANCES OVER MOST OF
THE PLAIN AND ADJACENT AREAS. THE DAY AND EVENING SHIFTS SHOULD
HAVE A BETTER HANDLE ON WHERE THEY WILL DEVELOP. AS OF RIGHT
NOW...ALL HEADLINES FOR SNOW AND BLOWING SNOW REMAIN IN PLACE FOR
TODAY.

FOR MONDAY AND TUESDAY...WE WILL SEE POCKETS OF LIGHT SNOW
AREAWIDE ON MONDAY AS WEAK WAVES IN THE MAIN FLOW INTERACTS WITH
COLDER AIR AND WHATEVER MOISTURE IS LEFT IS SQUEEZED OUT. WINDS
WILL REMAIN BREEZY HEADING INTO TUESDAY...LOW PRESSURE DEEPENS TO
OUR SOUTH AND WEST...BRINGING DRIER AIR AND TURNING THE FLOW FROM
THE NORTH AND NORTHEAST. WE WILL CONTINUE TO SEE GUSTY WINDS...SO
POCKETS OF BLOWING SNOW AND ALSO LOW WIND CHILLS WILL BE AN
ISSUE...ESPECIALLY THE LATTER MONDAY NIGHT AND TUESDAY. THIS PATTERN
SHOULD PULL MUCH COLDER AIR INTO IDAHO. THE QUESTION REMAINS HOW
COLD WILL IT GET. THE NAM AND THE ECMWF WANT TO KEEP THE REALLY
REALLY COLD AIR ON THE OTHER SIDE OF THE DIVIDE...PERHAPS SNEAKING
SOME IF IT INTO THE UPPER SNAKE PLAIN AND HIGHLANDS. THE GFS WANTS
TO PULL IT MUCH FARTHER INTO EASTERN IDAHO. WE TRIED TO SPLIT THE
DIFFERENCE BY THE END OF THE SHORT TERM PERIOD UNTIL WE SEE HOW
DEEP THE ARCTIC AIRMASS. IT ALSO MAY BE A CASE OF THE REALLY COLD
AIR STAYS AWAY...BUT WE SEE VERY COLD TEMPERATURES DUE TO FRESH
SNOW COVER AND CLEARING SKIES. KEYES


.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. COLD AND DRY CONDITIONS
TUESDAY NIGHT AND WEDNESDAY WITH NORTH WINDS BRINGING COLD AIR ACROSS
THE DIVIDE INTO IDAHO. WIND FLOW LOOKS PRETTY FAVORABLE FOR THIS ON
TUESDAY AND TUESDAY NIGHT...BY WEDNESDAY THOSE WINDS BEGIN TO
DECREASE IN STRENGTH. MODEL SOUNDINGS FROM THE GFS MODEL ARE NOT
REAL CONVINCING THAT THE DEPTH OF THE COLD AIR IS ENOUGH TO
CONTINUE COLD AIR ACROSS THE DIVIDE AS THE WINDS LOOSE STRENGTH. GFS
NUMERICAL GUIDANCE STILL FAVORS MINUS 18 AT IDAHO FALLS WEDNESDAY
MORNING AND 31 BELOW IN YELLOWSTONE. PROBLEM IS NOT ALL THE MODELS
ARE IN AGREEMENT ON HOW MUCH COLD AIR THERE WILL BE. WE HAVE FRESH
WHITE SNOW ON THE GROUND AND IDAHO FALLS DROPPED TO MINUS 4
YESTERDAY MORNING. WITH CLEARING SKIES WEDNESDAY AND THURSDAY...WILL
KEEP TEMPERATURES TO THE COLD SIDE. ANOTHER DISTURBANCE DROPS SOUTH
FROM CANADA FRIDAY AND SATURDAY THAT APPEARS TO HAVE LIMITED
MOISTURE ASSOCIATED WITH IT...ENOUGH TO GO WITH A CHANCE OF SNOW IN
THE MOUNTAINS AND SLIGHT CHANCE IN THE SNAKE PLAIN. RS

&&

.AVIATION...MVFR CEILINGS IN STRATUS AND LIGHT SNOW AT MOST TAF
SITES THIS MORNING EXPECTED TO BE MOVING OUT THROUGH THE EASTERN AND
SOUTH HIGHLANDS BY NOON TIME. DRIER AIR ALREADY BEGINNING TO WORK
INTO IDAHO ON THE WEST SIDE THIS MORNING. RS

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 5 PM MST THIS AFTERNOON IDZ018>021-31.

WINTER STORM WARNING UNTIL 11 PM MST THIS EVENING IDZ023-025.

WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING IDZ022-024.

WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON IDZ017-032.

&&

$$







USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.