146
FXUS65 KPIH 190357
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
957 PM MDT MON MAY 18 2026
KEY MESSAGES
- A VERY CHILLY OVERNIGHT TONIGHT IN THE SNAKE RIVER PLAIN AND
EASTERN MAGIC VALLEY. FROST AND FREEZE BULLETINS HAVE BEEN
ISSUED.
- SOME PRECIPITATION, INCLUDING THURSDAY AFTERNOON
THUNDERSTORMS, IS POSSIBLE STARTING TUE EVENING AND CONTINUING
THROUGH THU AFTERNOON.
- WEAKER WIND UNTIL THE WEEKEND.
DISCUSSION
ISSUED AT 143 PM MDT MON MAY 18 2026
TONIGHT THROUGH THU AFTERNOON...SAVE FOR SOME SHOWERS IN THE
EXTREME SOUTHEAST CORNER OF THE FORECAST AREA, THE NEXT 24 HOURS
WILL CONTINUE TO BE DRY, COOL TO COLD, AND WINDY. THIS IS DUE TO
AN UPPER LEVEL TROUGH CURRENTLY IN WY STILL PUSHING SLOWLY
EASTWARD. THE CLEAR SKIES AND CONTINUED NORTHERLY AIRFLOW MEANS
A QUITE COLD OVERNIGHT TONIGHT, WITH 20 TO 30 DEGREES EXPECTED
IN THE SNAKE RIVER PLAIN. WITH THE NORTHERLY FLOW NOT AS STRONG
IN THE EASTERN MAGIC VALLEY, TEMPERATURES ARE ONLY EXPECTED TO
BOTTOM OUT TONIGHT IN THE MIDDLE 30S. THESE TWO REASONS ARE WHY
A FROST ADVISORY HAS BEEN ISSUED FOR THE TWO MAGIC VALLEY ZONES
AND A FREEZE WARNING ONCE AGAIN FOR ALL ZONES IN THE SNAKE RIVER
PLAIN. THE START TIME WAS MOSTLY BASED ON WHEN THE AFFECTED
ZONES FINALLY LOSE THIS STRONG WIND TONIGHT, WHICH IS STILL
ACTUALLY FAIRLY LATE. BY 19/15Z 19/0900MDT THE TEMPERATURES
SHOULD SURGE BACK ABOVE FREEZE AND FROST THRESHOLDS.
THE NORTH WIND IS EXPECTED TO SHIFT TO A SOUTHWEST WIND AND NOT
BE AS PROBLEMATIC FOR THE SNAKE RIVER PLAIN FOR TUE. THE LIGHT
NORTHERLY WIND IN THE MORNING WILL SHIFT TO A SOUTH TO SOUTHWEST
WIND FOR THE AFTERNOON, ENDING THE NEED FOR A LAKE WIND
ADVISORY ON TUE. THIS LIGHTER SOUTH TO WEST WIND CONTINUES WED,
THEN A NORTHERLY WIND RETURNS FOR THU. IT DOESN'T TAKE MUCH FOR
A LAKE WIND ADVISORY TO BE NEEDED IN THE NORTH FLOW REGIME, SO
IT MAY RETURN.
FINALLY, IMPULSES MOVING THROUGH THE NORTHWEST TO WEST UPPER AIR
FLOW WILL RETURN ON TUE NIGHT. THIS WILL MEAN SHOWERS OVER THE
NORTH END OF THE FORECAST AREA THAT NIGHT, THEN A FURTHER
DIGGING SOUTHWARD WILL SPREAD PRECIPITATION FROM A CLOSE LOW IN
CENTRAL MT FOR HEAVIER RAINFALL ON WED NIGHT AND THU MORNING.
THE PRECIPITATION WILL BE MAINLY FOCUSED ON THE CENTRAL IDAHO
MOUNTAINS AND THE SOUTHERN AND EASTERN HIGHLANDS, WITH THE
NORTHERN END OF THE SNAKE RIVER PLAIN MOST LIKELY TO SEE
PRECIPITATION IN THE LOWER ELEVATIONS. WHILE ISOLATED
THUNDERSTORMS ARE POSSIBLE TUE AND WED, THU INCLUDES THE
ASSOCIATED COLD FRONT WITH THIS MT LOW ACTUALLY COMING THROUGH
AND GENERATING HIGH CHANCE OF THUNDERSTORMS. SINCE THE AFTERNOON
HAS MORE UNSTABLE AIR, THE BEST THREAT IS IN THE EASTERN THIRD
OF THE FORECAST AREA.
THU NIGHT THROUGH NEXT MON...THE LOW CLEARS OUT EARLY ENOUGH ON
THU THAT WHILE IT IS COLDER, THE SUNNY SKIES OF FRI SHOULD ALLOW
A WARMING TREND TO DEVELOP QUICKLY. BY SAT AFTERNOON
TEMPERATURES SHOULD SOAR ABOVE NORMAL AFTER A NEAR NORMAL FRI
AFTERNOON. A GRADUAL WARMING TREND CONTINUES AT LEAST INTO MON,
FOR BOTH HIGHS AND LOWS. WEAK TROUGHING GETS REPLACED BY WEAK
UPPER LEVEL RIDGING, WHICH WILL ALLOW SOME BREEZY WESTERLY WIND,
BUT DOESN'T APPEAR TO BRING AN SIGNIFICANT PRECIPITATION. IT
APPEARS TO BE FAIRLY LIMITED TO HIGHER ELEVATIONS THAT CAN
PROVIDE LIFTING WITH WEST-FACING SLOPES IN THE ZONAL FLOW,
ESPECIALLY FRI AND SAT. ONLY A MINORITY OF THE SOLUTIONS CLUSTER
AROUND A WET SCENARIO FOR EASTERN IDAHO. THIS ACCOUNTS FOR THE
WARMING TREND. THE ZONAL FLOW TIGHTENS STARTING SAT, SO IT WILL
LIKELY BE BREEZY TO WINDY FOR SAT/SUN/MON, AT LEAST IN THE
AFTERNOON.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 957 PM MDT MON MAY 18 2026
WINDS LOOK LIGHT THROUGH TOMORROW. SOME MID CLOUD AROUND
SUN, BYI AND PIH SHOULD DISSIPATE OVERNIGHT. SUN WILL PROBABLY
SWITCH TO UPVALLEY AROUND MIDDAY, THINK A CROSSWIND IS UNLIKELY IN
THE AFTERNOON WITH WINDS AS LIGHT AS THEY ARE.
PIH WATCHES/WARNINGS/ADVISORIES
FROST ADVISORY FROM 3 AM TO 9 AM MDT TUESDAY FOR IDZ051-055.
FREEZE WARNING UNTIL 9 AM MDT TUESDAY FOR IDZ052>054.
DISCUSSION...MESSICK
AVIATION...13
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