Monthly Archives: March, 2010

Moisture Missing But Fine Fuels Flourish!

Contrary to popular opinion, the ingredients for severe convective storms don’t exist in a endless supply. This Forecast Discussion (FD) from the Tulsa NWS is a good example. Reading through the FD, you will note,

“AVAILABILITY OF LOW LEVEL MOISTURE CONTINUES TO BE THE LIMITING
FACTOR WITH THIS SYSTEM. IF NOT FOR THE LACK OF MOISTURE… OTHER
FACTORS WOULD BE FAIRLY CONDUCIVE FOR SEVERE WEATHER ACROSS OUR
AREA.
AS IT IS… AM EXPECTING ISOLATED SHOWERS AND THUNDERSTORMS TO
DEVELOP SATURDAY MORNING WITHIN AREA OF WARM AIR/MOISTURE ADVECTION
AHEAD OF AN ILL-DEFINED COLD FRONT. THE FRONT SHOULD USHER IN
MORE WIDESPREAD CONVECTION DURING THE AFTERNOON AND EVENING. BASED
UPON THE SYSTEM DYNAMICS AND STEEP LAPSE RATES… THERE WILL BE A
LIMITED SEVERE THREAT… WITH HAIL AND WIND THE PRIMARY CONCERNS.”

So basically, there is a limited amount of moisture to fuel thunderstorms of severe intensity. As for the development of linear convection (aka a squall line), the cold front is unimpressive at best. Overall, there are several ingredients in place for a severe weather event. What’s not unusual is the absence of other important parameters.

More interesting and humorous is the typo (?) concerning fire weather conditions. Those conditions exists year round when dew points are low, there is an abundance of dormant vegetation that is dry, winds are strong enough to meet wind advisory criteria, and recent precipitation events have not soaked the ground and vegetation enough to prevent the initiation and spread of a grass or wild fire. I’m not sure if the same FD in discussing the fire weather potential considered this a deliberate typographical error, but the mention of the following gave me a much needed chuckle.

“THE EXPECTED WARMING TREND AND DRY SPELL FOR THE UPCOMING WEEK
CONTINUES TO LOOK LIKE A GO. FIRE DANGER WILL MOST CERTAINLY BE THE
HIGHLIGHT OF THE WEEK… WITH AVAILABLE FINE FUELS DRYING RAPIDLY.”

I’m assuming that the intended wording was to be “fire fuels drying rapidly” but with some fuels being better than others for fire weather conditions, I’m sure that describing some as “fine” is very appropriate.

Besides, what better way for a paranoid hermit to boast about his or her dilapidated double-wide being burnt to a crisp than to be gifted the opportunity to lose said abode to “fine” fuels.

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