Winter Storm Watch 2, NWS Boise, ID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
904 AM MST MON JAN 16 2012

.DISCUSSION...12Z BOI RAOB WAS MUCH COLDER THAN 12Z YESTERDAY ABOVE
THE BOUNDARY LAYER BUT CLOUDS HELD TEMPS UP DURING THE NIGHT.  MAX
TEMPS TODAY WILL BE NOTICEABLY COLDER THOUGH. WITH COLD AIR NOW IN
PLACE ATTENTION TURNS TO THE MOISTURE HEADED OUR WAY FROM THE
MID-LATITUDES IN THE PACIFIC...DUE INTO OUR ZONES TUESDAY NIGHT
THROUGH FRIDAY.  PROGS INDICATE A LOT OF PCPN WILL COME IN WEDNESDAY
BUT THE SNOW LEVEL WILL ALSO BE RISING AS A STRONG WARM FRONT MOVES
THROUGH.  FOR NOW WE CAN SAFELY SAY THAT SNOW WILL FALL THE WHOLE
TIME THROUGH FRIDAY IN MOUNTAINS ABOVE 6000 FEET IN THE NORTH AND
7000 FEET SOUTH.  LOWER ELEVATIONS...INCLUDING THE VALLEYS...WILL
START AS SNOW WHICH AND IT MAY BE SIGNIFICANT WEDNESDAY.  12Z MODEL
DATA WILL GIVE US A BETTER IDEA.  HEAVIEST PCPN SHOULD COME WITH THE
WARM FRONT...NOW EXPECTED IN SWRN IDAHO WEDNESDAY AFTERNOON.  WINTER
STORM WATCH WILL BE ISSUED SHORTLY FOR ZONES LISTED BELOW...OTHER
ZONES MAY BE ADDED IN AFTERNOON PACKAGE.

&&

.AVIATION...ISOLATED SNOW SHOWERS WITH LOCAL MVFR CEILINGS AND
TERRAIN OBSCURATION WILL CONTINUE THROUGH TODAY...MAINLY OVER THE
MOUNTAINS...AS AN UPPER TROUGH CROSSES THE REGION. WESTERLY SURFACE
WINDS 10-20 KTS BECOMING MORE SOUTHERLY AFTER 00Z. WINDS ALOFT WILL
BE WEST TO NORTHWEST UP TO 25 KTS AT 12K FEET MSL.

WIDESPREAD MVFR/IFR CONDITIONS EXPECTED TUESDAY NIGHT THROUGH EARLY
THURSDAY WITH HEAVY SNOW IN THE MOUNTAINS AND A RAIN/SNOW MIX IN THE
VALLEYS.

&&

.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH WEDNESDAY...THE BLUE MOUNTAINS IN
OREGON...AND WEST CENTRAL AND BOISE MOUNTAINS IN IDAHO WILL SEE
SCATTERED SNOW SHOWERS TODAY THANKS TO A WEAK SHORTWAVE TROUGH
EMBEDDED WITHIN A BROAD UPPER TROUGH ENCOMPASING THE ENTIRE PACIFIC
NORTHWEST. ANOTHER IMPULSE CURRENTLY POSITIONED NEAR 140W LAT IS
EXPECTED TO BRUSH OUR NORTHERN MOUNTAIN ZONES ON TUESDAY FOR
ADDITIONAL LIGHT PRECIPITATION. BY WEDNESDAY THE STAGE WILL BE SET
FOR A MUCH DEEPER MOISTURE FETCH. A WET UPSLOPE PATTERN WILL BEGIN
WEDNESDAY AND CONTINUE THROUGH AT LEAST FRIDAY. LATEST MODELS
CONTINUE TO FAVOR THE BOISE MOUNTAINS FOR THE BULK OF THE
PRECIPITATION...THOUGH THE ENTIRE CWFA STANDS TO GET IN ON THE
ACTION WITH MODELS CONSISTENTLY ADVERTIZING WINDS AND MOISTURE AT 3
TO 4 STANDARD DEVIATIONS ABOVE NORMAL ACCORDING TO THE GEFS ANOMALY
TABLES. THE GFS HAS NOW SLOWED THE TIMING OF A WARM AIR INTRUSION TO
FOR LATER ON WEDNESDAY THAN PREVIOUS RUNS WHICH COULD MAKE FOR A
SNOWY AFTERNOON COMMUTE IN THE TREASURE VALLEY METRO AREA. THE
COMBINATION OF WINTER PRECIPITATION AND STRONG WINDS MAY NECESSITATE
A WINTER WEATHER ADVISORY AND/OR WATCH DEPENDING ON WHAT THE DAY
SHIFT DEEMS NECESSARY WITH THE AFTERNOON FORECAST PACKAGE.

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...THE WET PATTERN
CONTINUES AS TEMPS AND SNOW LEVELS GRADUALLY RISE THROUGH THE WEEK
BEFORE AN UPPER LEVEL TROUGH BRINGS A COLDER AIRMASS BACK INTO THE
AREA BEGINNING SATURDAY. PRECIP THROUGH THE END OF THE WORK WILL BE
ALL RAIN IN THE VALLEYS BUT STILL SNOW IN THE MOUNTAINS. ONLY THE
HIGHER PEAKS WILL SEE SNOW FRIDAY EVENING AS SNOW LEVELS RISE
DRAMATICALLY TO NEAR 6200 FEET MSL NORTH OF A KBNO-KBOI LINE AND
NEAR 7500 FEET MSL SOUTH. FRIDAY LOOKS TO BE THE WARMEST DAY OF THE
WEEK AS WARM ADVECTION SETS IN UNDER RISING HEIGHTS AHEAD OF THE
DIGGING UPPER LEVEL TROUGH THAT WILL AFFECT THE AREA OVER THE
WEEKEND. SOME NUMERICAL GUIDANCE IS EVEN SUGGESTING TEMPS UP INTO
THE 50/S IN THE LOWER VALLEYS ON FRIDAY. HAVE INCREASED THOSE TEMPS
A BIT TO BE 10-12 DEGREES F ABOVE NORMAL. A STRONG SURFACE PRESSURE
GRADIENT ACROSS HARNEY...MALHEUR...AND OWYEE COUNTIES CONTINUES
THROUGH FRIDAY WITH GUSTY AFTERNOON WINDS IN THOSE AREAS. MODELS
STRUGGLE TO PINPOINT THE DETAILS OF THE COLDER TROUGH FOR THE
WEEKEND AND INTO MONDAY...THOUGH THE PATTERN LOOKS TO REMAIN
RELATIVELY WET AND UNSETTLED THROUGH THE END OF THE FORECAST PERIOD.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...WINTER STORM WATCH FROM LATE TUESDAY NIGHT THROUGH THURSDAY
        AFTERNOON IDZ011-013-028-033.
     WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY
        EVENING IDZ029.
OR...WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY
        EVENING ORZ062.

&&

WEATHER.GOV/BOISE

DISCUSSION...LC
AVIATION.....JDS
PREV SHORT TERM...CD
PREV LONG TERM....CB

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE BOISE ID
929 AM MST MON JAN 16 2012

IDZ012-014>016-030-ORZ061-063-064-171245-
LOWER TREASURE VALLEY ID-UPPER TREASURE VALLEY-
SOUTHWEST HIGHLANDS-WESTERN MAGIC VALLEY-
SOUTHERN TWIN FALLS COUNTY-HARNEY COUNTY-MALHEUR COUNTY-
LOWER TREASURE VALLEY OR-
929 AM MST MON JAN 16 2012 /829 AM PST MON JAN 16 2012/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL
IDAHO...SOUTHWEST IDAHO AND SOUTHEAST OREGON.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A VERY MOIST WEST FLOW FROM ACROSS THE PACIFIC WILL BRING A VERY
WET WEEK TO THE AREA WITH THE POSSIBILITY OF LIGHT WET SNOW IN THE
VALLEYS WEDNESDAY AFTERNOON BEFORE TURNING TO RAIN LATE WEDNESDAY
NIGHT AND FOR THE REMAINDER OF THE WEEK. THIS COULD CAUSE
HAZARDOUS DRIVING CONDITIONS WITH SLICK ROADS.

.SPOTTER INFORMATION STATEMENT...

REPORTS OF SIGNIFICANT SNOWFALL AND ANY ADVERSE DRIVING CONDITIONS
WOULD BE GREATLY APPRECIATED.

IDZ011-013-028-029-033-ORZ062-171245-
WEST CENTRAL MOUNTAINS-BOISE MOUNTAINS-CAMAS PRAIRIE-
OWYHEE MOUNTAINS-UPPER WEISER RIVER-BAKER COUNTY-
929 AM MST MON JAN 16 2012 /829 AM PST MON JAN 16 2012/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST
IDAHO...WEST CENTRAL IDAHO AND NORTHEAST OREGON.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A WINTER STORM WATCH IS IN EFFECT FROM TUESDAY EVENING THROUGH
WEDNESDAY EVENING FOR THE POTENTIAL OF HEAVY SNOW. PLEASE SEE THE
LATEST WINTER STORM STATEMENT /WSWBOI/ FOR FURTHER DETAILS.

.SPOTTER INFORMATION STATEMENT...

REPORTS OF SIGNIFICANT SNOWFALL AND ANY ADVERSE DRIVING CONDITIONS
WOULD BE GREATLY APPRECIATED.