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FNUS21 KWNS 071700

FWDDY1



Day 1 Fire Weather Outlook  

NWS Storm Prediction Center Norman OK

1059 AM CST Sun Mar 07 2021



Valid 071700Z - 081200Z



...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN KANSAS...



Critical highlights have been introduced for parts of eastern Kansas

for the potential of rapid grassfire spread later this afternoon.

Visible satellite imagery depicts clear skies across much of the

central U.S., allowing for the rapid mixing of a very dry boundary

layer (as noted in OUN and TOP 12Z observed soundings). With the

onset of heating, surface RH has already dropped by 20-30% in

several locales over the last couple of hours, with sustained

southwesterly winds approaching 20 mph (and gusts reaching 30 mph

per latest METAR observations). The 12Z TOP sounding shows very dry

air above 850 mb, with the OUN sounding depicting this very dry air

even lower in altitude. METAR observations also depict a narrow

corridor of relatively drier surface air streaming from central

Oklahoma into eastern Kansas, and this trend is expected to continue

into the afternoon. Additional heating this afternoon may easily

encourage the drier air aloft to mix downward within this

aforementioned northward-streaming corridor, promoting near-critical

to critically low RH (close to 20%). Finer fuels are quite receptive

to wildfire spread, with grassland fire potential being high today

even if surface winds/RH end up falling just shy of Critical

criteria.



Portions of the southeast, northern Florida Panhandle, and the

Carolinas are still expected to see surface RH values under 30% in

spots. However, recent appreciable rainfall in the last week and the

lack of a stronger wind field precludes fire weather highlights.



..Squitieri.. 03/07/2021



.PREV DISCUSSION... /ISSUED 1228 AM CST Sun Mar 07 2021/



...Synopsis...

Broad upper-level ridging as well as a building surface high over

the central/eastern CONUS will favor mostly clear skies and limited

rain chances today. This will help support fire weather concerns for

portions of the southern and central Plains where grasses have been

drying and dry, windy conditions are expected. Conditional fire

weather threats are also noted across the Great Basin and portions

of the Carolinas where dry conditions are likely.



...Eastern Kansas and adjacent areas of Oklahoma/Missouri...

Elevated, to locally critical, fire weather conditions appear likely

this afternoon from northeast OK, across eastern KS, and into

northwest MO. Early morning observations show a surface trough

meandering eastward as a weakening surface low moves into Canada.

This trough should be draped meridionally across the Plains by

mid/late afternoon. To the east, a building surface high will help

strengthen the pressure gradient over the southern and central

Plains. 



Sustained south/southwesterly winds upwards of 15-25 mph appear

likely by mid afternoon. Mostly clear skies will aid in diurnal

heating and boundary layer mixing, which should support wind gusts

up to 30-35 mph. Dewpoint trends across eastern KS have been slowly

declining over the past 12 hours as drier air across OK and northern

TX is advected northward within a meager southerly flow regime.

However, dry air advection will likely accelerate later today as

winds increase. This factor, coupled with favorable daytime heating,

should allow relative humidity values to fall into the 20-30% range.

Reports from the region suggest that fine grassy fuels are receptive

and should support wildfire spread. Localized critical conditions

appear possible across eastern KS, and a critical delineation may be

considered if confidence increases that RH values will fall below

20% over a broad region.



...Great Basin...

Modest surface pressure falls are forecast across the Great Basin

today as an upper-level trough, noted in early-morning water-vapor

imagery approaching the Northwest Coast, gradually moves onshore.

Low-level winds will likely increase to 15-20 mph across the region,

but limited upper-level support should preclude widespread windy

conditions.  Relative humidity in the teens and low 20s has been

common over the past few days, but fuels largely remain

non-critical. One exception to this is portions of central to

western AZ where localized elevated fire weather conditions are

possible this afternoon as RH falls into the teens once again.

However, the threat is expected to remain largely localized.



...Carolinas...

Dry conditions have been noted across the western Carolinas and

west/southwest VA where recent fuel analyses suggest 10-hour fuel

moisture values are in the 5-10% range and little precipitation has

fallen in recent days. A northwesterly, post-frontal flow regime

will remain in place for today, and upstream dewpoints in the single

digits and low teens suggest another day of dry conditions is

likely. This is supported by latest guidance, which shows reasonable

probabilities for RH less than 30%. However, wind speeds will

generally remain too weak for highlights. Nonetheless,

topographically enhanced flow east of the Carolina Piedmont may

support pockets of elevated fire weather conditions this afternoon.



...Please see www.spc.noaa.gov/fire for graphic product...



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