Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 272139
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
239 PM MST TUE JAN 27 2015

.SHORT TERM...TONIGHT THROUGH THURSDAY...VISIBILITY HAS IMPROVED
OVER THE TREASURE VALLEY...BUT FOG AND LOW STRATUS REMAIN. BOISE
SOUNDING FROM THIS MORNING STILL SHOWING A STRONG INVERSION BUT
SOME UNCERTAINTY IF THE DENSE FOG WILL REDEVELOP TONIGHT AS CLOUDS
CONTINUE TO INCREASE OVER THE AREA AHEAD OF AN APPROACH WEAK UPPER
LEVEL LOW. WILL KEEP A MENTION OF PATCHY FOG IN THE FORECAST FOR
THE SNAKE RIVER VALLEY BUT THERE COULD BE ISOLATED POCKETS OF DENSE
FOG. SATELLITE AND RADAR SHOWING THE WEAK UPPER LEVEL LOW
CONTINUING TO MOVE NORTH WITH PRECIPITATION ALREADY SPREADING
INTO SOUTHWEST IDAHO ALONG THE NEVADA BORDER. BULK OF THE
PRECIPITATION WITH THIS SYSTEM WILL BE MAINLY OVER EASTERN IDAHO
WITH THE HIGHEST CHANCE OF PRECIPITATION IN THE MAGIC
VALLEY...DECREASING TO WEST AND NORTH TOWARD THE IDAHO/OREGON
BORDER WITH DRY CONDITIONS OVER SOUTHEAST OREGON. PRECIPITATION
WILL DECREASE OVER THE AREA WEDNESDAY MORNING WITH DECREASING
CLOUDS THROUGH THE DAY. SKIES WILL LIKELY CLEAR ENOUGH OVER
SOUTHEAST OREGON AND THE LOWER TREASURE VALLEY WEDNESDAY NIGHT
ALLOWING FOR FOG TO REDEVELOP. EXPECT TEMPERATURES TO REMAIN ABOVE
NORMAL THROUGH THURSDAY.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...MODELS ARE IN ABOVE-
AVERAGE AGREEMENT THROUGH SUNDAY. AN UPPER LEVEL LOW WILL MOVE
THROUGH THE DESERT SW...LEAVING US IN WEAK FLOW ALOFT THU NIGHT AND
FRI. NW FLOW ON THE EAST SIDE OF AN INCOMING RIDGE TAKES HOLD
SATURDAY...BRINGING DRY CONDITIONS INTO SUNDAY. WHILE BOTH THE EC
AND GFS BRING MOISTURE INTO THE REGION SUNDAY NIGHT...THEY DIVERGE
IN THE THICKNESS FIELD STARTING SUNDAY. FOR THE CHANCE OF PRECIP WE
ARE FORECASTING FOR SUNDAY NIGHT THROUGH TUE...THE EC INDICATES IT
MIGHT BE COLD ENOUGH FOR SNOW IN THE SNAKE RIVER VALLEY...WHILE THE
GFS INDICATES RAIN. FOR NOW...HAVE SPLIT THE DIFFERENCE AND GONE
WITH RAIN. WE HAVE NOT PUT FOG OR STRATUS IN THE VALLEYS IN THE LONG
TERM...BUT THE CHANCE FOR PATCHY FOG IS THERE. IT WILL DEPEND IN
PART ON HOW MUCH PRECIPITATION IS GENERATED BY THE SYSTEM MOVING
THROUGH TONIGHT.

&&

.AVIATION...IFR/LIFR FOG/STRATUS COVER PARTS OF SE OR AND THE SNAKE
RIVER VALLEY IN SW ID. CONDITIONS WILL DETERIORATE THIS EVENING...
BUT MID/HIGH CLOUDS WILL SLOW THE DETERIORATION. SYSTEM MOVING NORTH
IS SPREADING VALLEY RAIN AND MTN SNOW INTO THE SRN PORTION OF THE
REGION THIS AFTERNOON... AND THIS WILL CONTINUE MAINLY IN SW IDAHO
TONIGHT WITH IFR/MVFR CIGS. SFC WINDS S-W LESS THAN 10 KTS THIS
AFTERNOON BECOMING NW TONIGHT. UPPER LEVEL WINDS TO 10K FT WILL BE S
THROUGH W NEAR 10 KTS TODAY... BECOMING NW 10-20 KTS TONIGHT AND
WED.

&&

.AIR STAGNATION...INVERSION WILL WEAKEN TONIGHT AS CLOUDS AND
PRECIPITATION SPREAD OVER THE AREA. MIXING HEIGHTS WILL REMAIN
BELOW 2000 FEET AGL AT LEAST THROUGH THURSDAY. ANY RAINFALL WILL
INCREASE SURFACE MOISTURE AND WILL AID IN THE REDEVELOPMENT OF
FOG AND LOW CLOUDS ACROSS LOWER VALLEYS.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.

&&

$$

WEATHER.GOV/BOISE

SHORT TERM.......JA
LONG TERM........SP/WH
AVIATION.........SP
AIR STAGNATION...JA



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