242
FXUS65 KBOI 161500 CCA
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
900 AM MDT WED OCT 16 2013
.DISCUSSION...CLOUDS FROM WEAK FRONTAL BAND NOW PASSING THROUGH
OUR CWA FROM NW-SE. ANY RAIN SHOULD STAY NORTH AND EAST OF OUR
CWA. CLEARING FROM THE NORTHWEST THIS AFTERNOON AND EVENING.
STRONG NORTHERLY FLOW ALOFT THURSDAY AND FRIDAY FOR CLEAR COOL
WX. NO UPDATES.
&&
.AVIATION...VFR. HIGH CLOUDS OVER AREA THIS MORNING. CLEARING FROM
NORTHWEST TO SOUTHEAST AND SUNNY AFTER 21Z. VISIBILITY SENSORS
CONTINUE TO BE AFFECTED BY SPIDER WEBS. LIGHT SURFACE WINDS. WINDS
ALOFT WEST TO NORTHWEST 10 TO 15 KT AT 10K FEET MSL.
&&
.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH THURSDAY...UPPER LEVEL TROUGH OVER SW
CANADA HAS A BUBBLE OF SURFACE HIGH PRESSURE ASSOCIATED WITH IT. AS
IS COMMON IN THE COOL SEASON THE HIGH SPLITS AND DRAINS MOST OF ITS
COLD AIR EAST OF THE CONTINENTAL DIVIDE. SOME TEMPERATURE MODIFIED
HIGH PRESSURE WILL ALSO FILTER INTO THE COLUMBIA BASIN AND SE OREGON
LATE TONIGHT THROUGH THURSDAY. NO PRECIPITATION IS EXPECTED OVER SW
IDAHO OR SE OREGON WITH THE UPPER TROUGH AND COLD FRONT BECAUSE THE
FRONT TRACKS MAINLY OVER MONTANA. EXPECT PASSING CLOUDS WHICH WERE
OVER NORTHERN ZONES INCLUDING BAKER TO VALLEY COUNTIES AS OF 3 AM TO
REACH BOISE BY SUNRISE AND EXIT THE TREASURE VALLEY BY EARLY
AFTERNOON...AND MAGIC VALLEY EARLY THIS EVENING. TEMPERATURES
AVERAGE 5 DEGREES BELOW NORMAL IN THE SHORT TERM. ABUNDANT SUNSHINE
AND LIMITED MIXING WILL PERSIST INTO THE LONG TERM DUE TO THE WEST
COAST RIDGE.
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...MODEL CONSISTENCY AND
CONTINUITY ARE ABOVE AVERAGE THROUGH THE PERIOD...SHOWING A HIGH
AMPLITUDE PATTERN WITH A WEST COAST UPPER LEVEL RIDGE AND AN EASTERN
NORTH AMERICA UPPER LEVEL TROUGH. BETWEEN THESE MAJOR FEATURES OVER
OUR AREA THROUGH MONDAY...NORTHWEST FLOW ALOFT WITH RELATIVELY HIGH
500 MB HEIGHTS WILL MAINTAIN DRY WEATHER WITH NEAR NORMAL
TEMPERATURES. ON TUESDAY MODELS SHOW THE CENTER OF THE UPPER LEVEL
RIDGE SHIFTING INLAND OVER THE NORTHWEST STATES. DURING SUMMER THIS
WOULD MEAN EVEN WARMER SURFACE TEMPERATURES...BUT IN LATE OCTOBER...
LACKING GOOD MECHANISMS FOR VERTICAL MIXING...THE LOWER VALLEYS DO
NOT RESPOND AS MUCH TO WARMING ALOFT. MODEL SOUNDINGS FOR TUESDAY
AFTERNOON INDICATE MIXING ONLY THROUGH THE LOWEST 2500 FEET...
BENEATH AN ISOTHERMAL LAYER EXTENDING UP TO 550 MB. SO WE ARE
STAYING WITH PERSISTENCE FOR TEMPERATURES.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...LC
AVIATION.....CD
PREV SHORT TERM...VM
PREV LONG TERM....JT