FXUS65 KPIH 111037 AFDPIH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE POCATELLO ID 337 AM MST THU FEB 11 2016 .SHORT TERM...TONIGHT THROUGH SATURDAY. UPPER RIDGE AXIS CONTINUES OVER EAST IDAHO. SFC BASED INVERSIONS REMAIN BUT MOST FOG APPEARS TO BE LIMITED TO SOUTHERN HIGHLAND AREAS SOUTH OF POCATELLO. LATEST VIIRS IMAGERY SHOWS THIS REGION EXTREMELY WELL WITH ANOTHER SMALL POCKET ALONG INTERSTATE 15 NORTH OF IDAHO FALLS. VERY WEAK SHORTWAVE OVER SOUTHEAST OREGON TRIES TO SLIDE INTO THE RIDGE EARLY TODAY AND MAY BE ENOUGH ASSOCIATED MIXING TO PREVENT FOG FROM SPREADING TOO FAR FROM CURRENT LOCATIONS. STRONGER SHORTWAVE AXIS STILL SHIFTING INTO THE CA/OR COAST THIS MORNING AND EXPECTED TO TOP RIDGE ALONG DIVIDE LATE TODAY AND OVERNIGHT. LATEST GFS SPREADS PRECIP JUST INTO NORTHERN ZONES THIS EVENING WHILE LATEST NAM KEEPS MOISTURE NORTH. HAVE ALLOWED WEAK POPS TO DROP INTO THE NORTHEAST CORNER OVERNIGHT WITH VERY WEAK QPF/SNOW. OTHERWISE BELIEVE SFC INVERSIONS TO REMAIN IN PLACE ESPECIALLY SOUTHERN PORTIONS OF THE FCST AREA AND WILL KEEP MENTION OF AT LEAST PATCHY FOG OVERNIGHT PER PERSISTENCE. RIDGE AXIS CONTINUES TO WEAKEN INTO FRIDAY WITH NEXT SYSTEM ARRIVING AS EARLY AS FRIDAY NIGHT. GFS SLIGHTLY FASTER WITH SHORTWAVE AXIS DROPPING THROUGH WA/OR FRIDAY NIGHT BUT BOTH GFS AND NAM SPREAD PRECIP INTO WESTERN EDGES OF CENTRAL MTN REGION BY SATURDAY MORNING. SHORTWAVE AXIS DRIVES THROUGH EAST IDAHO DURING THE DAY SATURDAY WITH PRECIP GENERALLY SAGGING SOUTHEAST BUT REMAINING FOCUSED OVER HIGHER ELEVATIONS. HAVE WEAKENED POPS SLIGHTLY IN THE SOUTH BASED ON 00Z RUNS BUT EARLY LOOK AT 06Z RUNS HAVE NAM BRINGING INTRODUCING MORE QPF INTO THE SOUTHERN HIGHLANDS THAN THE GFS. REGARDLESS...QUICK MOVING SYSTEM WITH LIMITED MOISTURE DOES MEAN TOTAL SNOW AMOUNTS FOR SYSTEM REMAIN ON THE LOW SIDE WITH LESS THAN 3IN TOTALS EVEN AT HIGHER ELEVATIONS. SFC FRONT DRIVES ACROSS THE REGION EARLY IN THE DAY WITH FAVORABLE SFC GRADIENT AND 30-40KT 700MB WINDS. HAVE KEPT INCREASED WINDS DURING THE DAY BUT ESPECIALLY IN THE AFTERNOON ACROSS THE SNAKE PLAIN AND HIGHER ELEVATIONS. DMH .LONG TERM...SUNDAY THROUGH THURSDAY...OVERALL DISTURBED WEATHER PATTERN FOR SUNDAY EXPECTED TO LEAD TO WIDELY SCATTERED TO NUMEROUS SNOW SHOWERS WITH RAIN IN THE EASTERN MAGIC VALLEY/LOWER SNAKE RIVER PLAIN. WINDS IN EXCESS OF 15-25MPH REMAIN IN THE FORECAST WITH LIKELY HIGHER SPEEDS. HIGH PRESSURE RIDGE TO BUILD IN EARLY WEEK WHICH WILL BRING WARMER TEMPERATURES...PERHAPS THE WARMEST WE'VE SEEN IN A WHILE. TIMING DIFFERENCES EXIST BETWEEN GFS...EUROPEAN AND CANADIAN MODEL SOLUTIONS REGARDING WEDNESDAY/THURSDAY SYSTEM. EUROPEAN SOLUTION NOT SHOWING ANY RAIN/SNOW UNTIL EARLY THURSDAY (CANADIAN FOLLOWING SUITE). GFS MORE AGGRESSIVE AND BRINGING WIDESPREAD PRECIP LATE WEDNESDAY. DID NOT WANT TO AMEND FORECAST AND LEFT PREVIOUS WIDESPREAD ACTIVITY AS IS AT THIS TIME. NP/DMH && .AVIATION...AREAS OF MIST AND LOW STRATUS EXPECTED THIS MORNING AT VALLEY LOCATIONS...PATCHY FOG CANNOT BE RULED OUT OCCASIONALLY AS WELL. FOG MAY ONCE MORE REDEVELOP AGAIN TONIGHT WITH NO CHANGE IN ATMOSPHERIC CONDITIONS. CEILINGS SHOULD BE IMPROVING MID-MORNING TO VFR CONDITIONS AND IF THEY ARE TO REDUCE TONIGHT WOULD BE AFTER 00Z. BURLEY COULD REDUCE EARLIER THAN THIS IN THE MID-AFTERNOON HOURS TO IFR STRATUS DECKS - VERY LOW CONFIDENCE IN THAT BUT IT IS POSSIBLE. SUN VALLEY WILL PERSIST WILL LIGHT WINDS AND MID TO HIGH LEVEL CLOUDS THE NEXT 24 HOURS WITH VFR CONDITIONS. NP/DMH && .AIR STAGNATION...HIGH PRESSURE AND SURFACE INVERSIONS CONTINUE THIS MORNING WITH FOG SETTLING IN LOWER ELEVATION AREAS MAINLY SOUTH OF POCATELLO. POOR AIR QUALITY CONTINUES IN THE CACHE VALLEY. DESPITE WEAK FEATURE TOPPING THE RIDGE TONIGHT...AND GRADUAL WEAKENING OF RIDGE THROUGH FRIDAY...SURFACE BASED INVERSIONS ARE EXPECTED TO CONTINUE THROUGH FRIDAY. DIMINISHED AIR QUALITY AND AT LEAST PATCHY FOG SHOULD CONTINUE. A STRONGER SYSTEM WILL FINALLY TOPPLE THE RIDGE SATURDAY BRINGING SOME PRECIPITATION BUT MORE IMPORTANTLY INCREASED WINDS TO THE REGION. THEREFORE AIR QUALITY IS EXPECTED TO IMPROVE OVER THE WEEKEND. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... NONE. && $$  FXUS65 KPIH 161000 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 300 AM MST Mon Jan 16 2017 .SHORT TERM...Today through Wednesday night. Forecast is status quo for today and tomorrow as upper ridging keeps things quiet for us. Low-level stratus should remain present in the valleys, and is depicted this morning on VIIRS spectral imagery over the Eastern Magic Valley. Temperature profile supports ice nucleation within the stratus layer, and is resulting in light flurries in some areas. This should end late this morning. The upper ridge will pass Tuesday night opening us up to increasing moisture transport from the Pacific. Models are a bit out of sync with the timing of the onset of precipitation, but generally the best chances will be Wednesday afternoon. Models are suggesting a warm layer developing over the Eastern Magic Valley possibly extending to Pocatello throughout the day Wednesday. Temperature profiles support the potential for freezing rain during this period. Low to moderate confidence levels for freezing rain at this time. Snow accumulation will begin for the Central Mountains Wednesday afternoon, and we have better confidence on snow intensity, though timing may vary over the course of the next few model runs. Hinsberger LONG TERM...Thursday through Monday. Medium range models in good agreement this cycle. Amplified shortwave trough deepens across PacNW and intermountain region during the day Thursday, spreading precipitation across Idaho. Weak cold front slides across Idaho, with temp profiles supportive of snow all areas. Break break Thursday night behind front. Models start to diverge somewhat with southern stream supporting faster shortwave feature undercutting slower and slightly retrograding northern stream. Thus weakest confidence in precipitation, with both GFS and ECMWF in relative dry but cooler period Friday through Sunday. Flow consolidates over Pacific again with deep trough off west coast. Both models, with some agreement with GFS ensembles, indicating next significant feature rotating around trough to reach coast and spread inland by Monday. Details remain fuzzy thus kept to broadbrush blend late in the period. DMH && .AVIATION...IFR conditions in place early this morning in region stretching from KIDA to west of KBYI, and including many valleys south of the Snake River. Stratus layer lies within favored temp zone for snow, and seeing light snow continue in some locations so will keep temp conditions for snow going until after sunrise. Ridge remains intact with inversions so will keep persistent forecast with brief afternoon improvement to VFR then a return to marginal or worse conditions after sunset as inversions strengthen and stratus/fog return for overnight. DMH && .HYDROLOGY... All current flood headlines remain in place this morning: An Areal Flood Advisory will remain in effect for Cassia and southern Minidoka county through the weekend. Floodwaters on roads has frozen over and several county roads remain closed. A Flood Warning continues at Antelope Creek in Darlington due to an ice jam on this creek along with runoff from early-week rainfall and snowmelt has resulted in some homes being flooded in Darlington. The Flood Advisory for the Challis River Bridge south of Challis will continue at the request of the BLM and local law enforcement. Citizens are urged to avoid this area. Dry conditions remain forecast through Tuesday. Frozen flooded areas continue to pose a threat to drivers. Ice jams will remain a threat with sub-zero lows in many areas through Tuesday morning, and ice build-up already present in many river channels. Another storm system arrives mid week. This system is expected to bring a warm-up to near or just above freezing to Cassia, Minidoka, Power and Oneida counties, where frozen flooded areas exist. At least partial melting of these areas is possible, along with the added concerns of additional precipitation which could fall as rain in lower elevations. Current headlines are expected to be evaluated again during daylight hours, in consultation with emergency management officials. DMH && .PIH WATCHES/WARNINGS/ADVISORIES...None. && $$