130
FXUS65 KPIH 230807
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
207 AM MDT SAT OCT 23 2021
SHORT TERM
TONIGHT THROUGH MONDAY NIGHT.
ATMOSPHERIC RIVER EVENT SETTING UP FOR THE WEEKEND.
SHOULD SEE THE FIRST PUSH OF SHOWERS ACROSS THE REGION TODAY. SNOW
LEVELS TODAY ARE SITTING ABOVE 6500FT. RAIN/SNOW AMOUNTS TODAY LOOK
LIGHT. THE STRONG PUSH OF MOISTURE ARRIVES BY SUNDAY AFTERNOON.
WE'LL SEE A WARM FRONT PUSH THROUGH THE REGION SUNDAY AFTERNOON AND
EVENING. SNOW LEVELS ARE COMPLICATED FOR THIS EVENT. ACROSS THE
CENTRAL MOUNTAINS WHERE THE HEAVIEST RAINFALL/SNOWFALL IS EXPECTED,
SNOW LEVELS WILL START AT 6500 FT RISING SUNDAY NIGHT INTO MONDAY
MORNING TO 7000-7500 FT. SNOW LEVELS ACROSS THE REST OF EAST IDAHO
CLIMB MUCH HIGHER, PERHAPS OVER 9000 FT EVEN. STRONG SOUTHERLY WINDS
ARE EXPECTED TO DEVELOP SUNDAY AFTERNOON AND EVENING WHICH MAY CUT
INTO RAIN CHANCES AND AMOUNTS AROUND AMERICAN FALLS, POCATELLO, AND
BLACKFOOT. HOWEVER, THE REAL FOCUS IS THE CENTRAL MOUNTAINS WHERE
UPWARDS OF 2 INCHES OF LIQUID IS POSSIBLE. SNOW AMOUNTS OF UP TO 2
FEET ARE POSSIBLE ABOVE 7000FT. ONCE AGAIN, SNOW AMOUNTS ARE HIGHLY
DEPENDENT UPON WHERE SNOW LEVELS ACTUALLY FALL, AND THERE IS A FAIR
AMOUNT OF UNCERTAINTY THERE. NOT SURPRISINGLY, WILL CONTINUE THE
WINTER STORM WATCH FOR THE CENTRAL MOUNTAINS.
ON MONDAY, THE TRAILING COLD FRONT POWERS THROUGH THE REGION AND WE
SHOULD SEE THE BRUNT OF THE HEAVY PRECIPIATION SHIFT EAST WITH THE
FRONT. THAT FRONT SHOULD PASS THROUGH EAST IDAHO MONDAY AFTERNOON
AND MONDAY EVENING. RIGHT NOW, WE EXPECT MOST OF THE HEAVY
PRECIPITATION TO FALL IN THE WARM SECTOR AS SNOW LEVELS FALL MONDAY
AFTERNOON AND EVENING TO 6000-6500 FT. AS A RESULT, THIS IS EXPECTED
TO MAINLY BE A RAIN EVENT FOR EAST IDAHO. STORM TOTAL RAINFALL
AMOUNTS STARTING TODAY THROUGH MONDAY NIGHT ARE IMPRESSIVE WITH A
1.00-1.50 INCHES POSSIBLE FOR EAST IDAHO AND THE MAGIC VALLEY AREA.
ONCE AGAIN, THE CENTRAL MOUNTAINS, ESPECIALLY ALONG THE BIG WOOD AND
UPPER SALMON AREAS, SHOULD DO VERY WELL WITH UP TO 2 INCHES LIQUID
WITH THIS EVENT. SOME AREAS MAY EVEN OVERACHIEVE, ESPECIALLY ALONG
SOME OF THE HIGHER RIDGES AND PEAKS. IN TERMS OF SNOWFALL, A STORM
TOTAL OF 2 TO 3 FEET IS POSSIBLE ABOVE 7000 FT, WITH THE MORE
IMPRESSIVE NUMBERS ON THE UPPER SLOPES AND RIDGELINE. ACROSS THE
REMAINDER OF THE AREA, ONLY LOOKING AT 1 TO 6 INCHES MAINLY ALONG
THE RIDGELINE.
13
LONG TERM
(TUESDAY - NEXT SATURDAY).
TUESDAY MORNING LOOKS TO SEE THE FINAL REMNANTS OF AN UPPER LEVEL
TROUGH THAT BROUGHT WIDESPREAD PRECIPITATION AND HIGH ELEVATION
SNOWFALL TO SOUTHEAST IDAHO AS IT CONTINUES ITS PASSAGE FURTHER
SOUTHEAST OF OUR REGION. PRECIPITATION THROUGHOUT THE DAY TUESDAY
STAYS MOSTLY CONFINED TO OUR SOUTHERN AND EASTERN LOCATIONS, AS WELL
AS THROUGH THE CENTRAL MOUNTAINS. SNOW LEVELS DROP TO VALLEY FLOORS
IN THE CENTRAL MOUNTAINS TUESDAY MORNING, WHILE ELSEWHERE 5,500-
6,000FT IS MORE LIKELY WITH MARGINAL WET BULB TEMPERATURES. CLUSTER
ANALYSES MIDWEEK NEXT WEEK SHOW AGREEMENT AMONGST LONG TERM ENSEMBLE
MODELS HAVING HIGH PRESSURE MAKING A PUSH FURTHER NORTH ASSOCIATED
WITH A BUILDING RIDGE. CHANCES FOR LIGHT RAIN AND HIGH ELEVATION
SNOW SHOWERS PERSIST MIDWEEK, WITH WIDESPREAD PRECIPITATION LIKELY
OUT OF THE AREA BY WEDNESDAY. LINGERING SHOWERS ARE LIKELY MOSTLY
FOR OUR NORTHERN LOCATIONS AND AREAS AT ELEVATION, WITH
ACCUMULATIONS STAYING LIGHT. THIS IS COURTESY OF A FEW SHORTWAVE
TROUGHS THAT PASS BY UP INTO MONTANA, KEEPING THOSE VERY SLIGHT
CHANCES FOR PRECIPITATION THROUGH THE WEEK AND ELEVATED WINDS
LIKELY. LOOKING TOWARDS THE START OF THE WEEKEND, THERE IS SLIGHT
DISAGREEMENT AS TO WHEN THIS UPPER LEVEL RIDGE IS EXPECTED TO BREAK
DOWN, WITH THE GFS BRINGING AN UPPER LEVEL CLOSED LOW IN FOR
SATURDAY AND THE ECMWF LAGGING A BIT BEHIND FOR SUNDAY. TEMPERATURES
FOR NEXT WEEK REMAIN SEASONABLE WITH HIGHS IN THE 40S AND 50S,
WARMING UP TO AROUND 60 DEGREES NEXT FRIDAY ASSOCIATED WITH THAT
BUILDING HIGH PRESSURE TREND DURING THE WEEK. CONDITIONS ARE
EXPECTED TO SLIGHTLY COOL BY A FEW DEGREES NEXT WEEKEND, ASSOCIATED
WITH THAT NEXT SYSTEM WHEN IT ARRIVES. MACKAY
AVIATION
VFR REMAINS THE PREDOMINANT GROUP TO START OFF TODAY,
WITH INCREASED CHANCES OF SCATTERED SHOWERS BUILDING SOUTHWEST TO
NORTHEAST THROUGHOUT THE DAY FOR MUCH OF THE SOUTHERN AND EASTERN
PORTIONS OF THE FORECAST AREA. MARGINAL VFR CIGS ARE EXPECTED
ACROSS ALL TAF SITES AT TIMES DURING THE DAY ASSOCIATED WITH THESE
RAIN SHOWERS EXCEPT AT KSUN. HERE, PRECIPITATION IS EXPECTED TO
STAY LIGHT AND OUTSIDE OF THE TERMINAL UNTIL THE OVERNIGHT HOURS
WHEN THE OUTER FRINGES OF THE NEXT LARGE SYSTEM MOVES IN. CHANCES
FOR PRECIPITATION TAPER OFF DURING THE AFTERNOON AND EVENING
HOURS. SOUTHWEST WINDS REMAIN ELEVATED TODAY WITH GUSTS AT KPIH,
KIDA, AND KDIJ UP TO AROUND 20-25KTS. THIS AFTERNOON AND INTO
TONIGHT, CEILINGS BEGIN TO IMPROVE SLIGHTLY BEFORE LOWERING INTO
THE MVFR/IFR CATEGORIES AS THE NEXT LARGE SYSTEM BEGINS IMPACTING
THE REGION SUNDAY INTO THE START OF NEXT WEEK, KEEPING WINDS
ELEVATED AS THIS SYSTEM PASSES THROUGH. MACKAY
PIH WATCHES/WARNINGS/ADVISORIES
WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING
FOR IDZ069-071>074.
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