Alert archive / Montana / Severe Thunderstorm Warnings in 2002
Severe Thunderstorm Warning 1, NWS Glasgow, MT
NWS Glasgow, MT issued this severe thunderstorm warning at May 21, 2002, 6:22 PM MDT for Petroleum County, Montana. It was in force for 53 min. 2 reports came from inside the area while it was in force.
The area
The counties it named, with what was reported inside it.
The facts
- Issued
- May 21, 2002, 6:22 PM MDT (00:22 UTC)
- Expired
- May 21, 2002, 7:15 PM MDT
- In force
- 53 min
- Issued by
- NWS Glasgow, MT
- Area
- Counties, with a storm outline in the text
County Petroleum County, MT
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| May 21, 6:30 PM MDT | Thunderstorm Wind 55 M | Flatwillow, MT | |
| May 21, 6:44 PM MDT | Thunderstorm Wind 50 M | Winnett, MT |
NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.
The nearest sounding before it
Great_falls, MT (KTFX), launched 00:00Z, 0.4 hours before the alert went out and 181 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 829 m above ground
- 0-6 km bulk shear
- 60 kt
- 0-1 km storm-relative helicity
- 110 m²/s²
- 0-3 km storm-relative helicity
- 328 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
What forecasters said that day
The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Glasgow, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at May 21, 2:30 PM MDT, 3 hours 52 minutes earlier.
Area forecast discussion, May 21, 2:30 PM MDT, 3 hours 52 minutes before
NORTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
230 PM MDT TUE MAY 21 2002
.SHORT TERM...WATER VAPOR IMAGERY SHOWS HIGHLY AMPLIFIED FLOW WITH
VIGOROUS TROUGH LIFTING NORTHEAST OVER THE GREAT BASIN REGION. THE
SURFACE REFLECTION OF THIS TROUGH IS A LOW THAT WILL TRACK EAST
ACROSS EASTERN MONTANA TONIGHT AND TOMORROW. HOWEVER EACH MODEL
DEVELOP DIFFERENT TRACKS WITH THE AVN TAKING A NORTHERN ROUTE ALONG
THE CANADIAN BORDER WHILE THE ETA TAKES THE LOW EAST INTO
SOUTHWESTERN NORTH DAKOTA. BOTH MODELS PRODUCE HIGHEST QPF AMOUNTS
ACROSS SOUTHERN SASKATCHEWAN WITH MAIN SYSTEM. MAIN PROBLEM FOR
PRECIP WILL BE HOW MUCH MOISTURE IS AVAILABLE...SINCE OMEGA VALUES
WILL BE DECENT WITH PASSAGE OF FRONT. WILL HOLD OFF PRECIP
DEVELOPING UNTIL MIDNIGHT TONIGHT AND INCREASE POP VALUES FOR
TOMORROW NIGHT WHEN A WEAK VORTMAX MAY CONTINUE TO PRODUCE RAIN
ACROSS THE CWA. OTHERWISE POPS LOOK REASONABLE.
THERE WILL BE A COOL DOWN OF 15 TO 20 DEGREES FOR TOMORROW AFTER
FRONT/LOW HAVE PASSED. HOWEVER BELIEVE INHERITED TEMPERATURES FOR
TONIGHT AND TOMORROW ARE TOO LOW AND WILL INCREASE THEM AND GO MORE
IN LINE WITH GUIDANCE. COOLEST DAY WILL BE THURSDAY WITH A CANADIAN
HIGH CENTERED OVER EASTERN MONTANA. THIS HIGH MOVES OFF TO THE EAST
FOR FRIDAY STARTING A WARMING TREND.
WINDS ARE MAJOR DIFFERENCE BETWEEN MODELS BECAUSE OF MODEL TRACKS.
ETA TAKES WINDS EAST TO NORTHEAST TO NORTHWEST WHILE THE AVN GOES
SOUTHEAST TO SOUTHWEST TO NORTHWEST. RIGHT NOW WINDS ARE NORTH
NORTHEAST IN WINNETT AND LEWISTOWN AND CURRENT SURFACE ANALYSIS GOES
ALONG BETTER WITH ETA. SO WILL FAVOR THE ETA SOLUTION. OVERALL WIND
SPEEDS WILL CONTINUE TO BE BREEZY UNTIL THURSDAY AFTERNOON INTO
THURSDAY NIGHT WHEN HIGH SETTLE IN OVER REGION.
.LONG TERM...SOUTHERN BRANCH OF SPLIT JET CONTINUES TO SET UP OVER
NEMONT FOR THE EXTENDED PERIOD WITH ZONAL FLOW ALOFT. WEAK RIDGE
KEEPS SATURDAY DRY HOWEVER BY SUNDAY...A TROUGH DIGS SOUTHEAST
ACROSS THE PACNW. THIS TURNS THE FLOW SOUTHWEST BRINGING WEAK
SHORTWAVES ACROSS THE MONTANA. WILL INCREASE POPS SLIGHTLY BEYOND
DAY 4 HOWEVER WILL NOT MAKE ANY MAJOR CHANGES. BERDES
KGGW RWB 046/055 034/053 040/058 77665322
BEEE 040/062 042/066 044/068 044/070 7711222222
KGDV WRB 046/060 036/053 039/058 77335322
BEEE 040/062 042/067 045/071 045/073 7711222222
.GGW...FIRE WEATHER WATCH FOR ALL ZONES UNTIL 03Z.Nearby
Severe Thunderstorm Warnings in Montana, 2002Every severe thunderstorm warning in 2002
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive.