Area Forecast Discussion
Issued by NWS Boise, ID

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000
FXUS65 KBOI 270357
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
857 PM MST MON JAN 26 2015

.DISCUSSION...MID AND HIGH CLOUDS ARE STREAMING IN FROM THE
SOUTHWEST IN ADVANCE OF AN UPPER LEVEL SYSTEM. THIS IS STILL
EXPECTED TO MOVE INTO SE OREGON AND SW IDAHO TUE AFTERNOON...AND
THEN SPREAD NE INTO MUCH OF SRN IDAHO TUE NIGHT. LOW CLOUDS AND
FOG PERSIST THIS EVENING IN MUCH OF MALHEUR COUNTY...ALTHOUGH IT
IS NOW LARGELY OBSCURED FROM SATELLITE OBSERVATION BY THE MID AND
HIGH CLOUDS MENTIONED PREVIOUSLY. HAVE DONE A SMALL UPDATE TO
MODIFY THE SKY GRIDS TO ALLOW FOR THE INCOMING CLOUDS. HAVE ALSO
LOWERED THE MIN TEMP FORECAST FOR FAIRFIELD...WHICH IS ALREADY
DOWN TO 14 DEGREES. UPDATE OUT SHORTLY.

&&

.AVIATION...VFR WITH SCATTERED HIGH CLOUDS EXCEPT FOR MVFR
CONDITIONS IN STRATUS ACROSS SE OREGON. EXPECT THE MAIN AREA OF
STRATUS AND PATCHY FOG TO BE ACROSS THE LOWER TREASURE
VALLEY/WEISER BASIN AND LONG VALLEY LATER TONIGHT THROUGH TUESDAY.
WINDS AND HIGH/MID CLOUDS WILL INCREASE AHEAD OF AN UPPER LOW OFF
THE SOUTHERN CA COAST WHICH SHOULD LIFT ACROSS THE GREAT BASIN ON
TUESDAY. RAIN WILL REACH THE NV/ID BORDER TUESDAY AFTERNOON AND
SHIFT NORTHEAST TUESDAY NIGHT. PRECIPITATION SHOULD REMAIN
SOUTHEAST OF A KREO-KBOI- KMYL LINE. SURFACE WINDS LIGHT AND
VARIABLE...EXCEPT IN MAGIC VALLEY NE WINDS 15 KTS. WINDS ALOFT
NEAR 10K FT MSL...SW 15-20 KTS...THROUGH 21Z TUES.


&&

.AIR STAGNATION...CONTINUED INVERSION CONDITIONS THROUGH TUESDAY.
UPPER LEVEL RIDGE WILL BEGIN TO BREAK DOWN LATER TONIGHT AS A
TROUGH APPROACHES THE AREA FROM THE SOUTH. INVERSION WILL WEAKEN
SLIGHTLY AS COOLER TEMPS ALOFT MOVE OVER THE AREA TUESDAY INTO
WEDNESDAY BEFORE A RETURN TO INVERSION CONDITIONS LATER IN THE
WEEK.

&&

.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH WEDNESDAY...UPPER LEVEL RIDGE IS
BEGINNING TO MOVE EAST. TEMPERATURES ALOFT WILL SLOWLY COOL IN
RESPONSE TO A SYSTEM MOVING UP THE CALIFORNIA COAST INTO THE GREAT
BASIN TONIGHT. PATCHY FOG IS EXPECTED TO FORM ONCE AGAIN TONIGHT
IN SIMILAR AREAS AS LAST NIGHT. THE DENSE FOG THAT WAS IN THE
LOWER TREASURE VALLEY OVERNIGHT HAS LIFTED INTO A LOW STRATUS DECK
AND COULD LIMIT FOG DEVELOPMENT UNDER THIS AREA. PATCHY DENSE FOG
REMAINS IN SHELTERED VALLEYS OF MALHEUR COUNTY. NEXT SYSTEM
ARRIVES FROM THE SOUTH TUESDAY AFTERNOON. THE STRONGEST DYNAMICS
OF THIS SYSTEM WILL MOVE ACROSS EASTERN IDAHO INTO WYOMING...THUS
EXPECT THE HIGHEST PRECIPITATION CHANCES IN THE MAGIC VALLEY AND
AREAS EASTWARD WITH MINIMAL PRECIPITATION CHANCES NEAR BAKER
COUNTY. SNOW LEVELS WILL LOWER TO AROUND 5000 TO 6000 FT MSL WITH
THIS SYSTEM. PRECIPITATION WILL MOVE OUT OF THE REGION BY
WEDNESDAY MORNING WITH PATCHY FOG DEVELOPING IN THE SHELTERED
VALLEY LOCATIONS OF WEST CENTRAL AND BOISE MOUNTAINS...AND TREASURE
AND MAGIC VALLEYS...AS UPPER LEVEL RIDGING BRINGS WARMER TEMPERATURES
ALOFT ONCE AGAIN.

LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...TRANSIENT RIDGE
WEDNESDAY NIGHT WILL SHIFT EASTWARD. SPLIT FLOW WILL THEN DOMINATE
THE NW BUT A WEAK MOIST UPPER LEVEL TROUGH IS NOW EXPECTED OVER THE
AREA THURSDAY NIGHT TO FRIDAY MORNING. REX BLOCK OVER WESTERN
NORTH AMERICA IS EXPECTED LATER FRIDAY THROUGH MONDAY...WITH HIGH
PRESSURE ALOFT OVER IDAHO AND LOWER PRESSURE OVER ALOFT OVER OLD
MEXICO THOUGH MODEL AGREEMENT IS STILL LOW BY LATE MONDAY WITH
THE OPERATIONAL EC MORE ZONAL AND THE GEFS/ENSEMBLE EC AND 12Z GFS
HOLDING ON TO MORE RIDGING. THOUGH DISAGREEMENT THAT SOME MOISTURE
MAY REACH NORTHERN TIER ZONES SO WILL HAVE LOW POPS ACROSS THE NE
OREGON/CENTRAL IDAHO MTNS LATE IN THE EXTENDED. TEMPERATURES 5-10
DEGREES ABOVE NORMAL FRIDAY-SUNDAY AND NEAR TO A LITTLE ABOVE
NORMAL EARLY NEXT WEEK.

&&

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

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...SP
AVIATION.....JS
AIR STAGNATION...KA
PREV SHORT TERM...KA
PREV LONG TERM....VM/WH



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