Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 051543
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
943 AM MDT TUE MAY 5 2015

.DISCUSSION...MORNING WATER VAPOR PICS SHOWING DRIER AIR PUSHING
INTO SE OREGON. DEEPER MOISTURE IS STILL BEING PULLED INTO
S-CENTRAL IDAHO. AS THE UPPER SLIDES INTO THE PAC NW THROUGH THE
DAY THE DRY AIR WILL ADVANCE EASTWARD. THIS WILL ACT TO LIMIT
SHOWER AND THUNDERSTORM DEVELOPMENT TO THE CENTRAL ID MTNS EAST OF
YELLOWPINE AND ATLANTA. HIGHER TERRAIN SOUTH OF TWIN FALLS WILL
ALSO KEEP A CHANCE OF AFTERNOON CONVECTION. WITH THE COLD FRONT
EAST OF THE AREA...DAYTIME HEATING WILL ACT TO INCREASE WINDS
ACROSS THE FRONT. THIS WILL DRIVE A GUSTY NW WIND THROUGH THE
SNAKE PLAIN...BAKER VALLEY AND OTHER OPEN TERRAIN. FORECAST FOR
TODAY IS ON TRACK SO NO UPDATES AT THIS TIME.

&&

.AVIATION...VFR UNDER MID TO HIGH CLOUDS. ISOLATED SHOWERS AND
THUNDERSTORMS EXPECTED ALONG THE ID/NV BORDER AND BOISE MNTS THIS
AFTERNOON THROUGH EVENING...ENDING BEFORE 06/06Z. SURFACE
WINDS...GENERALLY NORTHWESTERLY 15 KTS OR LESS...WITH GUSTS UP TO
35KTS THIS MORNING THROUGH EVENING IN THE VALLEYS. WINDS ALOFT NEAR
10K FT MSL...W 10-20 KTS...BECOMING 5-15 KTS AFTER 06/06Z.

&&

.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH WEDNESDAY...STRONG AND COMPACT UPPER
LOW WAS LOCATED JUST OFFSHORE NEAR THE CANADIAN BORDER THIS
MORNING. THIS WILL HELP PUSH A COLD FRONT THROUGH THE REMAINDER OF
THE AREA THIS MORNING. FRONT WAS LOCATED FROM NEAR MCCALL TO
ONTARIO TO ROME OREGON AS OF 3 AM MDT. A FEW SHOWERS WERE STILL
MOVING THROUGH THE AREA FROM SW TO NE...BRINGING GUSTS TO 20 MPH
OR SO. WE EXPECT THE PRECIP TO MOVE EAST AS THE DAY WEARS ON AS
DRY AIR WILL PUNCH IN FROM THE SW AND ELIMINATE THE SHOWERS OVER
ALL BUT THE EASTERN FRINGE OF THE CWA....AND PERHAPS THE FAR SE
ALONG THE NV BORDER IN OWYHEE AND SRN TWIN FALLS COUNTIES. THERE
WILL BE JUST ENOUGH INSTABILITY IN THAT AREA TO CONTINUE THE
MENTION OF ISOLATED THUNDERSTORMS THIS AFTERNOON AND EVENING. AS
THE UPPER LOW ELONGATES AND STRETCHES SOUTH OVERNIGHT...OUR UPPER
FLOW WILL BACK TO SSW. THIS WILL KEEP DRY AIR OVER THE REGION AND
THERE IS ONLY A SLIGHT CHANCE OF SHOWERS IN EASTERN VALLEY
COUNTY. WED...THE LOW DROPS INTO OREGON AND MOISTURE RETURNS. WE
HAVE KEPT THE FORECAST VIRTUALLY UNCHANGED...MEANING A SLIGHT
CHANCE TO CHANCE OF SHOWERS AND THUNDERSTORMS OVER MOST OF THE
AREA WED...MAINLY IN THE AFTERNOON. TEMPS WILL SHOW SIGNIFICANT
COOLING FROM YDAY...WITH HIGHS TODAY AROUND 10 DEGREES LOWER. WE
WILL COOL ANOTHER 5 TO 10 DEGREES TOMORROW COMPARED TO TODAY.
OVERNIGHT TUE NIGHT LOWS WILL BE A FEW DEGREES BELOW NORMAL.

LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...MODELS REMAIN IN
GOOD AGREEMENT THROUGH SUNDAY AND THEN DIVERGE SUNDAY NIGHT INTO
MONDAY. UPPER LEVEL LOW WILL BE OVER OREGON WEDNESDAY NIGHT WITH
THE ASSOCIATED UPPER LEVEL TROUGH MOVING SOUTH TO SOUTHERN
CALIFORNIA BY THURSDAY NIGHT AND THEN MOVING SLOWLY EAST THROUGH
ARIZONA/NEW MEXICO OVER THE WEEKEND. EVEN THOUGH MODELS ARE IN
GOOD AGREEMENT THEY STILL DIFFER ON TIMING...PLACEMENT AND AMOUNT
OF PRECIPITATION. WILL ONLY MAKE MINOR CHANGES TO POPS WITH THE
BEST CHANCE OVER HIGHER TERRAIN. ENOUGH INSTABILITY WITH THE LOW
AND ASSOCIATED TROUGH OVER THE REGION FOR A MENTION OF AFTERNOON
AND EVENING THUNDERSTORMS. AS THE LOW MOVES EAST INTO ARIZONA/NEW
MEXICO SUNDAY...AN UPPER LEVEL RIDGE WILL DEVELOP OVER THE
INTERMOUNTAIN WEST FOR DRY CONDITIONS. SUNDAY NIGHT AND MONDAY
MODELS DIFFER ON THE TIMING OF THE NEXT UPPER LEVEL TROUGH MOVING
INTO THE PACIFIC NORTHWEST. WITH LATEST TRENDS OF THE MODELS NOT
DOING WELL THIS FAR OUT IN THE EXTENDED WENT WITH A MODEL BLEND
AND ALSO STAYED NEAR CLIMATOLOGY. TEMPERATURES THROUGH THE
EXTENDED WILL START OUT 5-7 DEGREES BELOW NORMAL THURSDAY THEN
WARM TO NEAR NORMAL SATURDAY WITH LITTLE CHANGE IN TEMPERATURES
FOR SUNDAY AND MONDAY.

&&

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

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...DG
AVIATION.....AB
PREV SHORT TERM...SP
PREV LONG TERM....JA



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