Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 280419
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
919 PM MST FRI FEB 27 2015

.DISCUSSION...WATER VAPOR IMAGERY THIS EVENING SHOWING AN UPPER
LEVEL LOW CIRCULATION POSITIONED NEAR BEND OREGON. MOST OF THE
PRECIPITATION DEVELOPMENT THROUGH 04Z HAS BEEN CLOSE TO THE LOW
CENTER...OVER SE OREGON...THE OWYHEE MTNS AND HIGHER TERRAIN
ALONG THE ID/NV BORDER. THESE AREAS WILL SEE RAIN/SNOW CONTINUE
THROUGH THE NIGHT AS THE UPPER LOW CENTER TRACKS TO THE SSW.
THINKING THIS SLIGHT WESTWARD PULL ON THE LOW WILL LESSEN
PRECIPITATION CHANCES OVER THE WEST-CENTRAL AND BOISE MTNS AND
MUCH OF THE SNAKE RIVER PLAIN AND THUS HAVE LOWERED PRECIP
CHANCES IN THESE ZONES. SNOW WILL CONTINUE TO ACCUMULATE AT
HIGHER ELEVATIONS IN THE OWYHEE MTNS SO THE ADVISORY THERE LOOKS
SOLID. IN SE OREGON WILL SEE SNOW DOWN TO ABOUT 4K FEET WITH
ADDITIONAL ACCUMULATIONS OF 1-2 INCHES.

&&

.AVIATION...GENERALLY VFR. WIDESPREAD RAIN AND SNOW SHOWERS ACROSS
SOUTHEAST OREGON AND OWYHEE COUNTY IDAHO. EXPECT MVFR/LOCAL IFR/LIFR
CONDITIONS WITH SNOW SHOWERS THROUGH SATURDAY MORNING. EXPECT
ISOLATED RAIN SHOWERS IN THE TREASURE AND WESTERN MAGIC VALLEY
THROUGH SATURDAY MORNING. SURFACE WINDS...EAST-SOUTHEAST 5-15
KTS...BECOMING NORTHWEST AND INCREASING TO 15-25 KTS ACROSS EASTERN
OREGON AFTER 18Z ON SATURDAY. WINDS ALOFT...EAST 10-20 KTS.

OUTLOOK FOR SATURDAY NIGHT AND SUNDAY...PRECIPITATION ENDING
SATURDAY NIGHT. VFR ON SUNDAY EXCEPT FOR PATCHY VALLEY FOG UNTIL
ABOUT 15Z.

&&

.PREV DISCUSSION...
SHORT TERM...WE CANCELLED OUR WINTER WEATHER ADVISORY FOR SNOW IN
HARNEY COUNTY AROUND NOON PST AS SNOW DECREASED...ENDED...OR CHANGED
TO LIGHT RAIN.  SNOW ACCUMULATED AROUND 4 INCHES NEAR BURNS/OR.  A
SEPARATE ADVISORY FOR THE OWYHEE MOUNTAINS REMAINS IN EFFECT THROUGH
SATURDAY MORNING WITH THE BULK OF NEW SNOW COMING TONIGHT AND EARLY
SATURDAY MORNING.  UPPER LOW WILL MOVE SOUTH ALONG THE CASCADES
TONIGHT AND SATURDAY MORNING...INTO THE GREAT BASIN AND SWRN U.S.
SATURDAY NIGHT AND SUNDAY.  AS IT LEAVES...COLDER AND DRIER AIR
WILL COME INTO OUR CWA FROM THE NORTH.  THE UPPER LOW WILL BRING
ANOTHER COUPLE INCHES NEW SNOW TO EASTERN OREGON TONIGHT AND EARLY
SATURDAY...NOT QUITE ENOUGH FOR ANOTHER ADVISORY.  HEAVIEST SNOW IS
STILL SLATED FOR THE OWYHEE MOUNTAINS IN SWRN ID WHERE AN ADVISORY
WILL CONTINUE...WITH THE MAIN SNOWFALL OVERNIGHT.  THE TREASURE
VALLEY WILL HAVE LIGHT RAIN...POSSIBLY MIXED WITH SNOW...WITH NO
SNOW ACCUMULATION EXPECTED.  WET SNOW IN THE MAGIC VALLEY MAY
ACCUMULATE UP TO AN INCH BUT ROADS SHOULD STAY WET. INSTABILITY
STILL CALLS FOR A SLIGHT CHANCE OF THUNDERSTORMS THIS EVENING IN OUR
SRN-MOST ZONES.  AS THE UPPER LOW EXITS SOUTH...NORTHERLY SURFACE
WINDS WILL INCREASE SATURDAY.  THESE WINDS MAY CREATE A CONVERGENCE
ZONE IN THE MAGIC VALLEY AND KEEP SNOW SHOWERS GOING THERE WHILE THE
REST OF THE SNAKE BASIN CLEARS.  CLEARING AND DRYING IN ALL AREAS
SATURDAY NIGHT WILL ALLOW TEMPS TO GET AT LEAST TEN DEGREES COLDER
SUNDAY MORNING THAN ON SATURDAY MORNING.  EXPECT PATCHY FOG IN NRN
VALLEYS LATE SATURDAY NIGHT AND EARLY SUNDAY MORNING.  SUNDAY SHOULD
BE SUNNY AND COLD WITH LIGHT SURFACE WINDS UNDER NORTHERLY FLOW
ALOFT.

LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...NORTHERLY FLOW ON THE
EAST SIDE OF AN OFFSHORE UPPER LEVEL RIDGE WILL TRANSPORT ANOTHER
SHORTWAVE TROUGH FROM WESTERN CANADA SOUTH OVER THE INTERMOUNTAIN
REGION MONDAY AND MONDAY NIGHT. SCATTERED SNOW SHOWERS WILL DROP 1
TO 3 INCHES OVER THE MOUNTAINS BEFORE THE TROUGH EXITS TUESDAY
AFTERNOON. MOST OF THE PRECIPITATION IS EXPECTED TO BE OVER THE
CENTRAL IDAHO  MOUNTAINS...ENHANCED BY A CONVERGENCE ZONE BETWEEN
TWO SURFACE HIGHS MOVING SOUTH.  PRECIPITATION TOTALS IN THE VALLEYS
WILL BE MAINLY UNDER A TENTH OF AN INCH. THE AIRMASS TO OUR EAST
WILL BE ARCTIC IN ORIGIN...BUT THE COLDEST AIR WILL REMAIN EAST OF
THE CONTINENTAL DIVIDE. TEMPERATURES WILL AVERAGE 5 TO 10 DEGREES
BELOW NORMAL SUNDAY NIGHT THROUGH WEDNESDAY...THEN MODERATE TO NEAR
NORMAL BY FRIDAY AS THE UPPER LEVEL RIDGE MOVES INLAND.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY UNTIL 11 AM MST SATURDAY IDZ029.
OR...NONE.

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...DG
AVIATION.....JS
PREV SHORT TERM...LC
PREV LONG TERM....JT/WH


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