FXUS65 KPIH 291654
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
954 AM MST SUN NOV 29 2009

.UPDATE...LOW CLOUDS AND FOG PERSIST THIS MORNING IN THE SNAKE
RIVER PLAIN TOWARDS THE NORTHERN AREAS OF THE MAGIC VALLEY. NICE
MICRO SCALE FEATURE THIS MORNING IN WESTERN JEFFERSON COUNTY.
BOUNDARY WINDS RUSHING DOWN THE LEMHI VALLEY AND SPREADING OUT
INTO THE SNAKE PLAIN HAVE DEVELOPED AN EDDY SWIRL IN THE STRATUS
CLOUDS CENTERED NEAR MUD LAKE. THIS DRY AIR INTRUSION IS ACTUALLY
A BLESSING AS IT WILL ASSIST IN THE ERODING OF THE CLOUD BANK.
HOWEVER FURTHER TO THE SOUTH...THE CLOUDS TO PERSIST FROM AMERICAN
FALLS TO REXBURG FOR A FEW MORE HOURS UNTIL ENOUGH MIXING ALLOWS
THE SUN TO PEAK THROUGH. THIS WILL KEEP TEMPERATURES A BIT COOLER
IN THE CLOUD LADEN AREAS. OTHERWISE FORECAST ON TRACK FOR THE REST
OF THE DAY. WILL EVALUATE THE DENSE FOG ADVISORY JUST BEFORE THE
11 AM EXPIRATION TIME...AS IT MAY NEED TO BE EXTENDED FOR AN HOUR
OR TWO IN ZONES 20 AND 21. PRESTON

&&

.PREV DISCUSSION... /ISSUED 423 AM MST SUN NOV 29 2009/ 

SHORT TERM...SUNDAY THROUGH TUESDAY.

AREA OF FOG AND STRATUS CLOUDS IN THE SNAKE RIVER PLAIN AND
EASTERN MAGIC VALLEY AGAIN THIS MORNING HAS PROMPTED THE ISSUANCE
OF ANOTHER DENSE FOG ADVISORY. AREA OF FOG/STRATUS ALSO EXTENDS
INTO THE RAFT RIVER VALLEY AND PORTIONS OF THE WOOD RIVER VALLEY.
EXPECT A PATTERN SIMILAR TO SATURDAY...WITH GENERAL IMPROVEMENT
THROUGH THE MORNING HOURS. ANTICIPATING ANOTHER ROUND OF VALLEY FOG FOR
LATE SUNDAY NIGHT/MONDAY MORNING AS HIGH PRESSURE DOMINATES THE
WEATHER PATTERN THROUGH TUESDAY AND LITTLE CHANGE IN THE BOUNDARY
LAYER AIRMASS.  DSH

LONG TERM...WEDNESDAY THROUGH SUNDAY.

ONLY MINOR CHANGES MADE TO THE EXTENDED FORECAST THIS MORNING. RIDGE 
OF HIGH PRESSURE EXPECTED TO PRODUCE DRY WEATHER FOR WEDNESDAY INTO 
THURSDAY. MODELS DIVERGE QUICKLY THEREAFTER WITH ALMOST NO 
CONTINUITY RUN TO RUN. MODELS ARE HAVING TROUBLE HANDLING THE 
STRENGTH OF THE RIDGE AND HOW FAST TO BREAK DOWN THE RIDGE. ALL 
SOLUTIONS POINT TO BREAKING DOWN THE RIDGE...ALTHOUGH PINPOINTING 
WHEN IS VERY DIFFICULT TO SAY AT THIS POINT. WILL CONTINUE SLIGHT 
CHANCES FOR PRECIPITATION IN THE MOUNTAINS FOR NOW AND GRADUALLY 
COOL TEMPS INTO NEXT WEEKEND AS MOST MODELS SHOW THE RIDGE BROKEN 
DOWN BY THAT POINT.

AVIATION...LOW STRATUS AND FOG ACROSS THE SNAKE PLAIN CONTINUES TO 
BE PROBLEMATIC. MOST LOCATIONS ARE REPORTING IFR/LIFR CEILINGS WITH 
PATCHY FOG REDUCING VISIBILITIES IN SOME AREAS TO 1/4SM. EXPECT MOST 
OF THIS MOISTURE TO MIX OUT BY AFTERNOON ONCE AGAIN. AM UNCERTAIN AS 
TO WHETHER OR NOT THE UPSLOPE BREEZE WILL ADVECT THE MOISTURE INTO 
KSUN ONCE AGAIN TODAY. FOR NOW...WILL GO WITH AN OPTIMISTIC FORECAST 
FOR ALL TAF SITES FOR THE AFTERNOON. EXPECT SOME REDEVELOPMENT 
TONIGHT WITH MODELS INDICATING MOST LIKELY LOCATION WILL BE IN THE 
UPPER HALF OF THE SNAKE PLAIN AFFECTING KIDA.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 11 AM MST THIS MORNING FOR IDZ017-
020>022-031.

&&

$$