Past IEM Features tagged: firewx
Red Flag Warning Duration
10 Apr 2025 05:30 AMNWS Sioux Falls issued a Red Flag Warning (Fire Weather) Wednesday for its forecast area, which includes a number of Northwestern Iowa counties. The featured chart looks into the duration of these warning events based on the office's warnings since 2006. The plotted lines represent the accumulated frequency of warning events at a given time duration value. An event is a single warning for a single county / forecast zone. The plot nicely shows these events are generally between four and eight hours in duration, which covers the windiest and least humid portion of the daylight day. Shorter duration events are typically covered by other messaging, like the Special Weather Statement and longer duration events are typically not possible with subsiding winds as the boundary layer stabilizes, cools, and increases with humidity.
Voting:
Good: 11
Bad: 1
Tags: firewx
Critical Fire Weather
18 Oct 2024 05:30 AMThe Storm Prediction Center is best known for issuing convective watches and outlooks, but they also have a fire weather program and issue a fire weather outlook akin to the convective outlook. Their "Critical" risk threshold for fire weather was forecast over western Iowa on Thursday and such thresholds are somewhat rare for the state. The featured map presents an analysis of the yearly average number of days with such a risk threshold. Areas in white would indicate no such risk over the archive of the product valid for the location. Certainly the further west you go, the greater the chance of such fire weather risks as winds generally increase, humidity decreases and drier vegetation.
Voting:
Good: 14
Bad: 0
Abstain: 1
Tags: firewx
Fire Weather Outlooks
06 Apr 2022 05:18 AMWhile the Storm Prediction Center is most widely known for its convective outlooks, watches and mesoscale discussions issued, they also issue "Fire Weather" outlooks with a similar nomenclature to the convective outlooks. The recent and numerous rounds of severe weather over the southern US have dominated the headlines, the fire weather situation over the past number of weeks has been just as extreme. The featured chart presents the daily maximum day 1 fire weather outlook category over the contiguous US. The worsening drought over the southern high plains and constant march of energetic storm systems with high winds have created the prolonged concern over unconstrained wildfire spread. Today's outlook has the highest category possible of "extremely critical" (EXTM).
Voting:
Good: 13
Bad: 0
Tags: firewx
Windy and Low Humidity
01 Oct 2013 05:45 AMA Red Flag Warning was in effect yesterday for limited parts of western Iowa. These warnings are issued when dry and windy conditions create spreading fire concerns. The featured map presents the IEM computed average number of days per year with at least one hour with sustained wind speeds at or above 25 mph and relative humidity below 25%. This combination of conditions gets more rare the further east you go in the Midwest. Dry air masses originating over the desert southwest are slowly modified as they are transported east by vegetation transpiration and evaporation. Also these events are typically with strong southwesterly winds, which means the further east you go, the more likely air originated from the Gulf of Mexico (which will have high humidities).
Voting:
Good: 35
Bad: 8
Tags: firewx