Alert archive / Montana / Red Flag Warnings in 2021

Red Flag Warning 14, NWS Missoula, MT

August 17, 20214 counties in Montana

NWS Missoula, MT issued this red flag warning at Aug 17, 2021, 9:47 AM MDT for 4 counties in Montana. It took effect at Aug 17, 2021, 12:00 PM MDT. It was in force for 9 hr. 5 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
Aug 17, 2021, 9:47 AM MDT (15:47 UTC)
In effect from
Aug 17, 2021, 12:00 PM MDT
Expired
Aug 17, 2021, 9:00 PM MDT
In force
9 hr
Issued by
NWS Missoula, MT

Counties Beaverhead County, MT, Jefferson County, MT, Madison County, MT, Silver Bow County, MT

The radar

The Missoula radar (KMSX), 200 km from the middle of the area, began a volume at 15:47 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Aug 17, 2:45 PM MDTTSTM WND GST 603 Sw Dillon, MTIMET RELAYED THAT GUSTY WINDS FROM A THUNDERSTORM ROLLED THROUGH THE ICP FOR THE ALDER CREEK FIRE AND KNOCKED DOWN ALL OF THE PORTABLE TOILETS.
Aug 17, 2:45 PM MDTTSTM WND GST 695 Ne Dillon, MT
Aug 17, 3:34 PM MDTTSTM WND GST 534 Nne Mcallister, MTNORRIS HILL MDT.
Aug 17, 6:00 PM MDTNON-TSTM WND GST 5512 Se Boulder, MT
Aug 17, 6:16 PM MDTNON-TSTM WND GST 503 Ssw Ennis, MTENNIS RAWS.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 3.8 hours before the alert went out and 246 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.

Skew-T log-pSkew-T log-p diagram, Great_falls, MT at 12:00Z on 2021-08-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Great_falls, MT at 12:00Z on 2021-08-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 15 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2898 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
15 m²/s²
0-3 km storm-relative helicity
155 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

994 
WWUS85 KMSO 171547
RFWMSO

URGENT - FIRE WEATHER MESSAGE
National Weather Service Missoula MT
947 AM MDT Tue Aug 17 2021

MTZ111-180300-
/O.NEW.KMSO.FW.W.0014.210817T1800Z-210818T0300Z/
East Beaverhead-
947 AM MDT Tue Aug 17 2021

...RED FLAG WARNING IN EFFECT UNTIL 9 PM MDT THIS EVENING...

* Affected area: Fire Zone 111 (East Beaverhead). 

* Impacts: A combination of gusty winds and low humidity will
  produce critical fire weather conditions this afternoon and
  evening. 

* Winds: Southwest 25 to 30 mph with gusts to around 40 mph.

* Minimum humidities: 15 to 20 percent. 

&&

$$
1 follow-up statement
829 
WWUS85 KMSO 180240
RFWMSO

URGENT - FIRE WEATHER MESSAGE
National Weather Service Missoula MT
840 PM MDT Tue Aug 17 2021

MTZ111-180345-
/O.EXP.KMSO.FW.W.0014.000000T0000Z-210818T0300Z/
East Beaverhead-
840 PM MDT Tue Aug 17 2021

...RED FLAG WARNING WILL EXPIRE AT 9 PM MDT THIS EVENING...

Although breezy winds continue, RHs will continue to rise.  

&&

$$

The office that day

Everything else NWS Missoula, MT issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 17, 2:55 PM MDTSpecial Weather StatementMSOSilver Bow50 min
Aug 17, 3:26 PM MDTSpecial Weather StatementMSOPowell49 min

Nearby

Red Flag Warnings in Montana, 2021Every red flag warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.