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
000
FXUS65 KPIH 312124
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
224 PM MST SAT JAN 31 2015

.SHORT TERM...TONIGHT...LOW LEVEL STRATUS CLOUDS AND PATCHY FOG
WILL BE THE MAIN PROBLEM IN THE SNAKE PLAIN AND LOWER VALLEY
AREAS. BY SUNDAY AFTERNOON WE WILL BEGIN TO SEE A CHANGE IN THE
WEATHER WITH INCREASING MIDDLE AND HIGH LEVEL CLOUDS APPROACHING
FROM THE WEST. MOIST AIR OFF THE PACIFIC WILL BEGIN TO BRING SOME
SNOW TO THE MOUNTAINS THE NEXT FEW DAYS. ACCUMULATIONS ABOVE 5500
FEET OF 2 TO 5 INCHES IS POSSIBLE THROUGH TUESDAY MORNING. FOR THE
LOWER VALLEYS...SNOW LEVELS OF 4500 TO 5000 FEET DURING THE DAY
WILL MEAN SOME MIXED RAIN AND SNOW IN THE LOWER VALLEYS DURING
THE AFTERNOON. SUNDAY NIGHT...ANY ACCUMULATION SHOULD BE LIMITED
TO LESS THAN AN INCH ON THE VALLEY FLOORS...BENCH AREAS ON THE
EAST SIDE OF THE SNAKE PLAIN SUNDAY NIGHT AND MONDAY 1 TO 2 INCHES.
WINDS IN THE SNAKE PLAIN MONDAY NIGHT AND EARLY TUESDAY INCREASE
TO 15 TO 25 MPH...ALONG WITH SNOW LEVELS RISING TO AROUND 6000
FEET ON TUESDAY...AND AFTERNOON HIGHS FROM THE UPPER 30S TO MIDDLE
40S. RS

.LONG TERM...TUE NIGHT THROUGH NEXT SAT NIGHT. 500MB 5-WAVE HAS THE
GEM STATE CAUGHT BETWEEN A GULF OF ALASKA TROUGH AND A GULF OF
CALIFORNIA HIGH...SLIGHTLY CLOSER TO THE HIGH THAN THE TROUGH. BUT
THE STORM TRACK DOES CUT THROUGH NORTHERN IDAHO AND THUS EXPECT AN
UNSETTLED EXTENDED FORECAST. THE PATTERN OVER THE WESTERN STATES AND
EASTERN PACIFIC ACTUALLY AMPLIFIES...KEEPING THE FORECAST AREA IN
GENERAL WARM SOUTHWESTERLY AIR FLOW...ESPECIALLY EARLY IN THIS
PERIOD. THIS EXPLAINS THE WARM TEMPERATURES IN THE SECOND HALF OF
THE FORECAST TIME. GFS AND ECMWF HAVE STRONG MAGNITUDE AND TIMING
DIFFERENCES IN THE SHORTWAVES THAT ARE PUSHED THROUGH. THE GFS IS
DRIER IN THE FIRST HALF...THEN WETTER THAN THE ECMWF IN THE SECOND
HALF OF THIS PERIOD. HAVE ATTEMPTED TO COMPROMISE BETWEEN THE TWO.
THE ONLY DAY THAT SEEMS VERY SURE IS FRI NIGHT WHEN MODERATE TO
HEAVY PRECIPITATION IS BROUGHT IN BY BOTH SOLUTIONS. HAVE GENERALLY
MADE IT CLOUDIER WITH HIGHER POP THAN PREVIOUS FORECAST. WINDS WITH
THE FRI NIGHT STORM COULD BE FIRST SIGNIFICANT IN A WHILE...BUT
SHOULD GENERALLY BE BREEZIER THAN LATELY WITH NO REAL CHANCE FOR
HIGH PRESSURE TO DOMINATE THE GEM STATE. MESSICK

&&

.AVIATION...USED CONDITIONAL CLIMATOLOGY TABLES TO ATTEMPT TO FIGURE
OUT A STRATUS LIFTING TIME...AS MOS GUIDANCE CONTINUES TO BE SUSPECT
AND AT TIMES THE GFS IS THE EXACT OPPOSITE OF THE NAM OUTPUT.
CONDITIONAL CLIMATOLOGY HAS A PRETTY GOOD HISTORY WITH BREAKOUT
OCCURING LATE THIS AFTERNOON/THIS EVENING FOR KIDA AND KPIH. AFTER
01/06Z...NO CLIMATOLOGY-BASED INFORMATION...SO AS FAR AS SUN MORNING
GOES...HAVE LOOKED AT TIME-HEIGHT CROSS SECTIONS. KBYI AND KPIH
AIRDROMES APPEAR TO CLEAR OUT EARLIER THAN THIS MORNING...DURING THE
EARLY TO MID-MORNING HOURS ON SUNDAY. KIDA APPEARS THE MOST STUBBORN
OVERNIGHT...BUT STILL EXPECTED TO ACTUALLY CLEAR SUNDAY
MORNING...WHICH THEY WILL NOT THIS AFTERNOON. WIND CONTINUES
NEGLIGIBLE AT THE SURFACE. A MID-LEVEL DECK WITH SOME WIND ALOFT
WILL HELP TO BREAK UP THE STRATUS SITUATION IN ADVANCE OF A TROUGH
EXPECTED MON AFTERNOON/EVENING. KSUN IS ONLY AT RISK FOR STRATUS IF
A GOOD SOUTHERLY WIND DEVELOPS IN THE AFTERNOON WITH ABUNDANT
STRATUS IN THE LOWER PARTS OF THE WOOD RIVER VALLEY. IT CAME VERY
CLOSE TODAY...BUT DO NOT BELIEVE THE STRATUS WILL EXTEND AS MUCH AS
IT DID THIS MORNING AND THE KSUN AIRDROME SHOULD ONLY HAVE TO
CONTEND WITH MID-LEVEL CIGS AND POSSIBLE SHOWERS IN THE VCNTY.
MESSICK

&&

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

&&

$$






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