Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 290303
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
903 PM MDT FRI AUG 28 2015

.DISCUSSION...LOTS OF MID AND HIGH CLOUDS MOVING NE ACROSS THE
REGION THIS EVENING IN ADVANCE OF A SHORTWAVE TROUGH THAT IS
EXPECTED TO MOVE THROUGH TOMORROW. RADAR INDICATES LIGHT SHOWERS
BRINGING PERHAPS A HUNDREDTH OR TWO TO EASTERN OWYHEE COUNTY AND
SRN TWIN FALLS COUNTY. NAM STILL INDICATES A CHANCE FOR LIGHT
SHOWERS IN THE UPPER TREASURE AND WESTERN MAGIC VALLEYS LATE
TONIGHT...SO WILL NOT CHANGE THE FORECAST AT THIS TIME. WINDY
TOMORROW AS A FRONT MOVES THROUGH...THEN TURNING COOLER FOR THE
COMING WEEK.

&&

.AVIATION...VFR WITH MOSTLY SCT-BKN HIGH CLOUDS. OCCASIONAL MVFR
FROM WILDFIRE SMOKE NORTH OF A KBNO-KSNT LINE. SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS BETWEEN 29/09Z-18Z AHEAD OF SATURDAY/S
FRONTAL PASSAGE IN IDAHO WEST CENTRAL AND BOISE MOUNTAINS...MAGIC
VALLEY AND SOUTHERN HIGHLANDS. SHOWER AND THUNDERSTORM ACTIVITY
EXPECTED OVER MOST OF THE REGION WITH W TO E FRONTAL PASSAGE
BETWEEN 29/18- 30/06Z. VARIABLE GUSTY WINDS NEAR 30 KTS CAN BE
EXPECTED NEAR STRONGER THUNDERSTORMS. SURFACE WINDS...GENERALLY 12
KTS OR LESS...AFTER 29/18Z SURFACE WINDS INCREASING FROM W TO
E WITH FRONTAL PASSAGE. STRONGEST WINDS ARE EXPECTED IN SE
OREGON...WITH FORECAST GUSTS TO AROUND 40 KTS BEFORE 30/00Z...THEN
TAPERING OFF OVERNIGHT. WINDS ALOFT NEAR 10K FT MSL...SW 15-25
KTS...THEN BY 29/12Z SSW 35-55 KTS...THEN DECREASING AFTER 30/00Z
TO WSW 20-25 KTS.

FOR SUNDAY...DRIER CONDITIONS AND CALMER WINDS WITH PASSING CLOUDS.


&&

.PREV DISCUSSION...
SHORT TERM...AT 2 PM MDT CONVECTIVE CLOUDS WERE FORMING IN ERN
OWYHEE COUNTY AND SOUTHERN TWIN FALLS COUNTY...NEAR WHERE MODELS
PUT ISOLATED SHOWERS AND THUNDERSTORMS TONIGHT.  PACIFIC COLD FRONT
WILL COME INLAND OVERNIGHT AND ACROSS OREGON ZONES MIDDAY SATURDAY
AND IDAHO ZONES LATE SATURDAY/SATURDAY EVENING.  FRONT WILL BRING
GUSTY WINDS ESPECIALLY TO SOUTHERN PARTS OF HARNEY AND MALHEUR
COUNTIES SATURDAY.  FRONT WILL ALSO BRING SIGNIFICANT COOLING TO
THE OREGON SIDE LATE SATURDAY...BUT IDAHO WILL HAVE TIME TO GET
WARM AGAIN SATURDAY BEFORE THE FRONT ARRIVES.  EVEN WITH COLD
ADVECTION SATURDAY NIGHT...CLOUDS WINDS AND SHOWERS WILL KEEP TEMPS
MILD...BUT SUNDAY WILL BE SIGNIFICANTLY COOLER IN ALL ZONES.  MODELS
KEEP OREGON ZONES DRY SATURDAY BUT AS THE FRONT MOVES EAST IT WILL
MOISTEN AND IDAHO ZONES WILL HAVE A CHANCE OF SHOWERS ESPECIALLY
SATURDAY NIGHT.  FRONTAL ZONE WILL BE EAST OF OUR CWA SUNDAY AND WE
SHOULD BE DRY AGAIN EXCEPT ALONG NRN BORDER ZONES IN THE HEART OF
THE UPPER TROUGH.

LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY. LONGWAVE TROUGH
CONTINUES TO SIT OFF THE PACNW COAST AND IS EXPECTED TO DO SO FOR
THE MID AND LONG TERM. AS NEXT WEEK PROGRESSES MODELS INDICATING A
SHORTWAVE TROUGH WITHIN THE FLOW SLOWLY MOVING INLAND...BUT WITH
LITTLE IF ANY IMPACT ON THE CWA. MOUNTAIN SHOWERS AND THUNDERSTORMS
ARE POSSIBLE BUT CONFIDENCE IS LOW. HOWEVER...THIS FEATURE WILL BE
ENOUGH TO CONTINUE TO KEEP TEMPERATURES BELOW NORMAL DURING THIS
TIME.

WEDNESDAY NIGHT THROUGH FRIDAY....NEXT SYSTEM PUSHES INTO WASHINGTON
THURSDAY MORNING. MOISTURE AHEAD OF THIS SYSTEM WILL MAKE ITS WAY
INTO THE FORECAST AREA DURING THIS PERIOD. ECMWF SHOWS THIS LOW
PASSING WELL NORTH OF THE FORECAST AREA WHILE GFS SHOWS THIS SYSTEM
STALLING OUT AND NOT MAKING PASSAGE DURING THE PERIOD. MODELS DIFFER
ON HOW MUCH PRECIPITATION AND EXACT TIMING. BECAUSE OF THIS
DISAGREEMENT...WENT WITH A MODEL BLEND OF THE ECMWF AND GFS AND
LIMITED THE HIGHER POPS TO HIGHER ELEVATIONS. EXPECTED TEMPS DURING
THE PERIOD WILL BE BELOW NORMAL.

&&

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

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...SP
AVIATION.....AB
PREV SHORT TERM...LC
PREV LONG TERM....EP/JC


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