Area Forecast Discussion
Issued by NWS Boise, 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 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KBOI 270412
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
907 PM MST FRI DEC 26 2014

.DISCUSSION...ONLY UPDATE TO THE FORECAST FOR TONIGHT WILL BE TO
ADD SOME CLOUD COVER TO THE WESTERN MAGIC VALLEY. SEEING SOME
WEAK LOW-LEVEL CONVERGENCE WHICH IS GENERATING LOW STRATUS /1-2K
AGL/ MOSTLY EAST OF TWIN FALLS AND JEROME.

FOR SATURDAY NIGHT AND SUNDAY...NEWEST GUIDANCE LOOKS TO BE
STAYING THE COURSE FROM PREVIOUS RUNS. THE 18Z AND 00Z NAM
REMAIN THE WETTEST GUIDANCE WITH THE 12Z ECMWF...HIGH RESOLUTION
MODELS AND 00Z GFS CLUSTERED TOGETHER WITH GENERALLY LOWER VALUES.
THE MODEL FORECAST LIQUID EQUIVALENT AMOUNTS IN SE OREGON AND
VALLEYS OF SW IDAHO RANGE FROM ONE TO THREE TENTHS OF AN INCH. THE
EAST-CENTRAL OREGON AND SW IDAHO MOUNTAINS STAND TO SEE FOUR TO
SIX TENTHS OF AN INCH OF LIQUID EQUIVALENT. WITH IT LIKELY TO BE
ALL SNOW TO THE VALLEY FLOORS THIS WOULD ROUGHLY TRANSLATE TO 1-3
INCHES IN VALLEYS OF SE OREGON AND SW IDAHO AND 4 TO 6 INCHES IN
THE MTNS. TIMING HASN/T CHANGED MUCH FROM EARLIER RUNS WITH THE
SNOW STARTING NORTH OF A BURNS-ONTARIO-STANLEY LINE SATURDAY
AFTERNOON...AND SOUTH OF THAT LINE AFTER 00Z SUNDAY.

TOUCH UP TO THE ADVISORY TO EXPAND THE SNOW TOTAL RANGE IN THE
VALLEYS TO 1-3 INCHES. HAVE ALSO DECIDED TO ADD THE SW IDAHO LOWER
TREASURE VALLEY ZONE AND MOVE UP THE START TIME FOR NORTHERN ZONES.

&&

.AVIATION...TONIGHT WILL BE VFR WITH AREAS OF LOW VFR STRATUS IN THE
WEST CENTRAL IDAHO MOUNTAINS. SNOW WITH MAINLY MVFR CONDITIONS WILL
SPREAD INTO BAKER COUNTY AND THE WEST CENTRAL IDAHO MOUNTAINS AFTER
12Z...REACHING KBNO AND KBOI AFTER 18Z. AFTER 00Z SNOW WILL BE
WIDESPREAD WITH TERRAIN OBSCURATION AND IFR/LIFR CONDITIONS IN THE
MOUNTAIN VALLEYS. SURFACE WINDS...VARIABLE 10 KTS OR LESS. WINDS
ALOFT...WEST 20-30 KTS UP THROUGH 10K FT MSL.

OUTLOOK FOR SUNDAY...SNOW WILL CONTINUE BUT CONDITIONS WILL IMPROVE
TO VFR ACROSS SOUTHEAST OREGON AND THE SOUTHWEST IDAHO VALLEYS BELOW
ABOUT 4000 FT MSL. SURFACE WINDS WILL INCREASE TO 15-25 KTS FROM THE
WEST.

&&

.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH SUNDAY...
QUIET WEATHER EXPECTED TONIGHT AND INTO SATURDAY MORNING AS A
TRANSITORY RIDGE MOVES OVER THE PACIFIC NORTHWEST. THE NEXT POTENT
SYSTEM MOVING THROUGH THE GULF OF ALASKA DROPS INTO THE REGION
SATURDAY MIDDAY. LIGHT SNOW IS EXPECTED TO START ACROSS THE
NORTHERN ZONES IN THE AFTERNOON AND THEN AS THE COLD FRONT SAGS
SOUTHWARD THE HEAVIER SNOW MOVES INTO THE REGION. WINTER WEATHER
ADVISORIES FOR ACCUMULATING SNOWS HAVE ISSUED FOR THIS EVENT AS IT
DIGS SOUTHWARD SATURDAY NIGHT AND INTO SUNDAY. SNOWFALL OF 4 TO 6
INCHES IN THE MOUNTAINS AND 2 TO 4 INCHES ELSEWHERE ARE EXPECTED.
AT THIS TIME ONLY LIGHT SNOW WITH LIMITED...IF ANY ACCUMULATIONS
ARE EXPECTED ACROSS HARNEY AND MALHEUR COUNTIES IN OREGON.
TEMPERATURES FOR THE WEEKEND ARE EXPECTED TO BE FAIRLY
SEASONAL...BUT THAT WILL CHANGE NEXT WEEK.


LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
UPPER LEVEL TROUGH MOVING SLOWLY SOUTH ALONG THE CONTINENTAL
DIVIDE SUNDAY NIGHT THROUGH MONDAY NIGHT. LIGHT SNOW WILL FALL
OVER THE REGION SUNDAY NIGHT AND DECREASE FROM NORTH TO SOUTH
MONDAY AND MONDAY NIGHT. AS THIS TROUGH CONTINUES TO MOVE SOUTH
FLOW ALOFT OVER SOUTHEAST OREGON AND SOUTHWEST IDAHO WILL SHIFT TO
THE NORTH AND NORTHEAST AS HIGH PRESSURE BUILDS OVER THE AREA.
THIS WILL BRING COLD AIR FROM CANADA WITH TEMPERATURES FALLING TO
AROUND 15 DEGREES BELOW NORMAL BY TUESDAY. THE NORTH TO NORTHEAST
FLOW WILL ALSO BRING IN DRY AIR AS THE RIDGE CONTINUES TO BUILD
WITH DRY CONDITIONS OVER THE FORECAST AREA TUESDAY THROUGH
THURSDAY NIGHT. FRIDAY ANOTHER UPPER LEVEL TROUGH WILL DROP SOUTH
ALONG THE CANADIAN WEST COAST FOR ANOTHER ROUND OF PRECIPITATION
WITH TEMPERATURES WARMING TO A FEW DEGREES BELOW NORMAL.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY FROM 3 PM SATURDAY TO 11 AM MST SUNDAY
     IDZ011-033.
     WINTER WEATHER ADVISORY FROM 11 PM SATURDAY TO 11 AM MST SUNDAY
     IDZ015-016-030.
     WINTER WEATHER ADVISORY FROM 8 PM SATURDAY TO 11 AM MST SUNDAY
     IDZ012-013-014-029.
OR...WINTER WEATHER ADVISORY FROM 2 PM SATURDAY TO 10 AM PST SUNDAY
     ORZ062.

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...DG
AVIATION.....JT
PREV SHORT TERM...CR
PREV LONG TERM....JA/WH



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