FXUS65 KPIH 230305
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
815 PM MST TUE DEC 22 2009

.SHORT TERM...TONIGHT THROUGH FRIDAY. A QUICK UPDATE TO FOLLOW THIS 
EVENING...REMOVING ALL REMAINING ADVISORIES (ACROSS THE SRN 
HIGHLANDS) AND ADDING MENTION OF AREAS OF FOG (AND PATCHY DENSE 
FOG). KDIJ AND KSUN WERE REPORTING 1/4SM FZFG BUT LOOKING AT 
SURROUNDING WEB CAMS IT APPEARS THAT THE FOG IS ISOLATED AT BEST AT 
THIS TIME. HIGHLIGHTS MAY FOLLOW ON THIS ITEM OVERNIGHT...BUT ARE 
NOT WARRANTED AT THIS TIME DUE TO LIMITED COVERAGE AND OBVIOUS LOW 
CLOUD COVER NOTED IN SATELLITE IMAGERY. SEE PREVIOUS DISCUSSION 
BELOW. HUSTON 

THE LATEST SATELLITE IMAGERY WAS SHOWING A BROAD LOW CIRCULATION 
ACCELERATING SSE THROUGH ERN OREGON THIS AFTERNOON WITH SEVERAL WELL 
DEFINED CIRCULATIONS ROTATING ABOUT THE LOW. ONE SUCH CIRCULATION 
WAS LIFTING NNE ALONG THE NEVADA/UTAH BORDER AND IS EXPECTED TO LIFT 
INTO SRN IDAHO LATE THIS AFTERNOON/EARLY THIS EVENING HELPING TO 
SUSTAIN CONTINUED SNOWFALL ACROSS THE REGION THROUGH THE EVENING. 
HENCE...THE WARNINGS AND ADVISORIES CURRENTLY POSTED ACROSS THE SRN 
HIGHLANDS/SNAKE PLAIN WILL CONTINUE INTO THE EVENING HOURS BEFORE 
ENDING AROUND MIDNIGHT. AFTER MIDNIGHT...THE LOW WILL HAVE SHIFTED 
INTO WRN ARIZONA WITH RAPIDLY DECREASING CLOUD COVER AND 
PRECIPITATION POTENTIAL. TEMPERATURES SHOULD COOL SHARPLY ACROSS THE 
CNTRL MOUNTAINS TONIGHT WHERE THE BEST CLEARING IS EXPECTED TO OCCUR 
WHILE THE SNAKE PLAIN AND SE HIGHLANDS REMAIN UNDER A PARTIALLY 
PROTECTIVE LOW CLOUD COVER. A SECONDARY LOW...CURRENTLY LOCATED OVER 
THE CANADIAN ROCKIES...WILL DIG SSE INTO/THROUGH MONTANA 
WEDNESDAY/WEDNESDAY NIGHT WHICH SHOULD PROVIDE A WEAK NW UPSLOPE 
FLOW FOR THE ERN HIGHLANDS DURING THE DAY WEDNESDAY. MUCH DRIER AND 
COLDER CONDITIONS WILL FOLLOW WEDNESDAY NIGHT THROUGH FRIDAY AS A 
SHARP RIDGE OF HIGH PRESSURE BUILDS ALONG THE PAC COAST. HUSTON

.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY. COLD BUT DRY RIDGING 
PATTERN REMAINS IN PLACE ACROSS THE GREAT BASIN THROUGH THE WEEKEND. 
MODELS STILL HAVING PROBLEMS WITH CONSISTENCY BEGINNING SUNDAY NIGHT 
AS THE NEXT SYSTEM APPROACHES THE WEST COAST.  THE GFS COMPLETELY 
SPLITS THE SYSTEM...LEAVING A BUBBLE HIGH OVER IDAHO AND STEERING 
SYSTEMS NORTH AND SOUTH OF THE AREA.  THE ECMWF MEANWHILE DOES A 
BETTER JOB BREAKING DOWN THE RIDGE AND MOVING THE SYSTEM...ALBEIT 
WITH A SPLIT...OVER EASTERN IDAHO.  THE MOST RECENT MODEL RUNS ARE 
AT ODDS WITH RUNS FROM 24 HOURS AGO...SO THEREFORE CONFIDENCE IS LOW 
AT THIS TIME.  HAVE LEFT BULK OF FORECAST INTACT...WITH ISOLATED 
POPS IN THE HIGHER ELEVATIONS SUNDAY AND BEYOND.  OTHERWISE... 
TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE PERIOD. 
&&

.AVIATION...A SLOW MOVING BAND OF LIGHT TO MODERATE SNOW CONTINUES 
TO DRIFT EASTWARD ACROSS EASTERN IDAHO THIS AFTERNOON. THIS BAND 
WILL GRADUALLY FALL APART THROUGH THE EVENING HOURS AS DRIER AIR 
WORKS ITS WAY INTO THE REGION.  EXPECT ALL TAF LOCATIONS TO CONTINUE 
SEEING IFR CONDITIONS THROUGH 00Z. VISIBILITY WILL IMPROVE THIS 
EVENING AS THE SNOW COMES TO AN END FROM WEST TO EAST...HOWEVER 
MOISTURE AND CLOUDS WILL KEEP LOW CEILINGS AND POSSIBLY SOME 
FLURRIES IN PLAY TONIGHT.  CEILINGS IMPROVE WEDNESDAY MORNING. 
&&

.PIH WATCHES/WARNINGS/ADVISORIES...NONE.
&&

$$