A southerly flow of moisture was favorable for thunderstorm development. One such thunderstorm developed and produced hail just under one inch in size near Bonners Ferry, Idaho on September 30,2016.
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The episode as NWS OTX wrote it up.
A southerly flow of moisture was favorable for thunderstorm development. One such thunderstorm developed and produced hail just under one inch in size near Bonners Ferry, Idaho on September 30,2016.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Spokane, WA wrote its last area forecast discussion before the first event at Sep 30, 1:18 PM PST, 58 minutes earlier.
Area Forecast Discussion National Weather Service Spokane WA 218 PM PDT Fri Sep 30 2016 .SYNOPSIS... Another round of scattered showers and isolated thunderstorms is possible tonight into Saturday morning. Breezy and cooler conditions can be expected on Saturday, followed by drier and seasonal weather for Sunday and Monday. A return to more unsettled and cooler weather is forecast by mid week. && .DISCUSSION... Tonight through Monday: The weather around the Inland NW will be influenced by an upper trough of low pressure off the coast and as it moves inland. For tonight, the trough axis will be off the coast and starts to pivot inland. This will keep a moist and slightly unstable southwest flow over Oregon and into the Inland NW. A disturbance in the flow over Oregon will ripple northeast and bring another round of mid level clouds and instability to the region this evening and overnight. The track of the moisture band has been extrapolated mainly by satellite and radar as the models have been wavering on solutions, especially how far west this convection will spread. As the flow backs to a more southerly orientation, the moisture should advect mainly to the north, and even creep as far west as the east slopes of the cascades, but mainly across the Columbia Basin and into the northern mountains overnight. Mid level instability looks adequate to support embedded high based thunderstorms with the showers overnight into early Saturday morning. The convection will lift to the northeast during the morning hours on Saturday with a dry slot moving in by midday. This will be just temporary as the next disturbance lifts toward the Cascades and helps generate surface based convection across the east slopes of the Cascades and into the Okanogan Highlands by mid afternoon into early evening. Could see some isolated lightning in the higher terrain of mainly Okanogan county. Snow levels will lower to near 5k ft, and could see some light snow showers near the crest late Saturday afternoon. Meanwhile, westerly surface winds will become breezy Saturday afternoon across the lowlands as temperatures cooldown by about 10 degrees from today, topping out in the 60s. Showers, winds and clouds will decrease Saturday night as the upper trough axis finally moves inland, south of the region across northern California. This will advect drier air from the south and east for Sunday. Overnight lows will dip into the 30s with some freezing temperatures possible in the sheltered northern valleys mainly north and east of Spokane, but also radiational cooling under the clearing skies will lean toward the development of patchy fog. There is a small chance of orographic convection in the northern Cascades, but for the most part, expect a dry day on Sunday with lighter winds and seasonal temperatures in the mid 60s to lower 70s. By Sunday night into Monday, the upper trough pinches off to a closed low over CA/NV and leaves a broad col over the region. After another round of chilly near freezing temperatures with patchy fog, expect Monday to have light winds, drier conditions and more seasonal temperatures. /rfox. Monday night through Friday: An active fall weather pattern will be in place throughout the week bringing several rounds of rain and near to below normal temperatures. Overall, model guidance is in good agreement of a progressive and active storm track aimed at the Pac NW but timing of each round of rain does carry some uncertainty. At this time, there are no signs of any major storm systems capable of high winds or flooding rains...just your typical October weather pattern. Snow levels will reside between 6000-7000 feet with little to no concern for snow on mountain passes. Loose agreement of the 00z/12z model suites indicate the first round of showers associated with a weak frontal band passing through on Tuesday. Showers, mainly in the mountain linger into Wednesday. Thereafter, focus will turn toward Friday into the weekend with the potential for a wetter and more widespread rain event. The latter system will carry the highest probabilities for rainfall amounts near 0.25" or greater with a richer fetch of moisture tied into it...however it is too early to say how widespread these amounts would be. /sb && .AVIATION... 18Z TAFS: Narrow bands of showers and isolated thunderstorms moving south to north can be expected through the early afternoon. There will be a brief break in the pcpn threat around 21Z. Then another round of showers is expected 03z/Sat for KMWH and KEAT, and aft 07Z for the rest of the TAF locations. Pcp should be north of the TAF locations by 15Z Sat. Ceilings are expected to remain VFR. && .PRELIMINARY POINT TEMPS/POPS... Spokane 47 62 39 67 41 65 / 70 10 0 10 10 10 Coeur d'Alene 48 61 37 66 38 64 / 70 20 0 10 10 10 Pullman 45 62 36 68 37 63 / 50 20 0 0 10 10 Lewiston 52 68 42 72 44 67 / 40 20 0 0 10 10 Colville 46 64 36 67 35 67 / 70 30 10 10 0 10 Sandpoint 49 60 35 64 36 62 / 70 60 0 10 10 10 Kellogg 46 58 37 64 37 61 / 60 50 0 10 10 10 Moses Lake 46 67 37 71 41 70 / 20 10 0 10 0 10 Wenatchee 50 66 43 67 45 69 / 20 10 10 10 10 10 Omak 46 67 39 68 41 69 / 20 20 10 10 0 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SPOKANE WA 548 AM PDT FRI SEP 30 2016 IDZ001>004-026-027-WAZ031>038-041>044-011300- NORTHERN PANHANDLE-COEUR D'ALENE AREA-IDAHO PALOUSE- CENTRAL PANHANDLE MOUNTAINS-LEWISTON AREA- LEWIS AND SOUTHERN NEZ PERCE COUNTIES-NORTHEAST BLUE MOUNTAINS- LOWER GARFIELD AND ASOTIN COUNTIES-WASHINGTON PALOUSE- MOSES LAKE AREA-UPPER COLUMBIA BASIN-SPOKANE AREA- NORTHEAST MOUNTAINS-OKANOGAN HIGHLANDS-WENATCHEE AREA- EAST SLOPES NORTHERN CASCADES-OKANOGAN VALLEY-WATERVILLE PLATEAU- 548 AM PDT FRI SEP 30 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH IDAHO... NORTH CENTRAL IDAHO...CENTRAL WASHINGTON...EAST CENTRAL WASHINGTON...NORTH CENTRAL WASHINGTON...NORTHEAST WASHINGTON AND SOUTHEAST WASHINGTON. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE SPOKANE WA 248 PM PDT FRI SEP 30 2016 IDZ001-302230- NORTHERN PANHANDLE ID- 248 PM PDT FRI SEP 30 2016 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN BOUNDARY AND WEST CENTRAL BONNER COUNTIES UNTIL 330 PM PDT... AT 247 PM PDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 13 MILES SOUTHEAST OF NORDMAN...OR 17 MILES NORTHWEST OF SANDPOINT... MOVING NORTHEAST AT 30 MPH. NICKEL SIZE HAIL WILL BE POSSIBLE WITH THIS STORM AS WELL AS WINDS UP TO 45 MPH. LOCATIONS IMPACTED INCLUDE... BONNERS FERRY. LAT...LON 4842 11670 4849 11685 4885 11650 4868 11623 TIME...MOT...LOC 2147Z 220DEG 24KT 4851 11671 LN
The Spokane radar (KOTX), 149 km away, was scanning. The volume nearest the first event began at 22:15 UTC.
2 hail. Local standard time, as filed.
A trained weather spotter reported 0.75 inch hail one mile northwest of Bonners Ferry, Idaho.
A member of the public reported 0.88 inch hail 3 miles north northwest of Bonners Ferry, Idaho.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2016Every state in 2016This day in weather historyWarnings in Idaho, September 2016
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 654524, 654525.