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FNUS21 KWNS 061652

FWDDY1



Day 1 Fire Weather Outlook  

NWS Storm Prediction Center Norman OK

1051 AM CST Sat Mar 06 2021



Valid 061700Z - 071200Z



Much of the previous forecast remains on track. Current visible

satellite imagery depicts clear skies across much of the central and

northern High Plains. Continued diurnal heating through the

afternoon should foster enough boundary-layer mixing for surface RH

to drop into the 20-25% range, as also suggested by the latest model

guidance consensus. Latest guidance also suggests that RH will drop

to 15% along the Colorado Front Range into the Nebraska Panhandle.

However, sustained southerly winds across the High Plains is

expected to remain within the 15-20 mph range, and given the

sparsity of the 15-20% RH, Critical highlights have been withheld,

though locally Critical conditions may still occur across portions

of the central High Plains.



Across the eastern U.S., late morning boundary-layer mixing has

already resulted in surface RH dropping at/below 30% across much of

Virginia into North Carolina. RH may drop even further by afternoon

peak heating, however, guidance consensus currently suggests that

surface winds will likely remain at/below 10-15 mph on a widespread

basis, precluding an Elevated delineation. However, given lack of

recent rainfall and near single-digit 10/100 hr fuel moisture

values, localized wildfire potential exists, especially across

southern Virginia into northern North Carolina.



..Squitieri.. 03/06/2021



.PREV DISCUSSION... /ISSUED 0100 AM CST Sat Mar 06 2021/



...Synopsis...

An upper-level shortwave trough, noted in morning water-vapor

imagery moving onshore across northern California, will continue to

progress to the northeast into the northern Rockies by this

afternoon. In response, a deepening lee trough will strengthen

pressure-gradient winds and support elevated fire weather conditions

across the Plains as well as the Great Basin. Elsewhere across the

CONUS, rain chances across the Southeast and weak winds over

southwestern TX will limit additional fire weather concerns. 



...High Plains...

The overall forecast remains on track and confidence in widespread

elevated fire weather conditions from eastern CO northward into

western SD is high based on recent observations. Regional 00 UTC

soundings and recent surface observations reveal a dry boundary

layer already in place, which will help relative humidity values

fall into the 15-20% range later today. Sustained winds near 20 mph

are expected, and steepening low-level lapse rates will help

downward mixing of 30-35 mph gusts by late afternoon. 



Recent hi-res ensemble guidance continues to show high probabilities

in elevated conditions, and suggests that sustained winds near 20

mph and RH values between 20-25% may extend as far north as western

ND/eastern MT (though slightly higher boundary-layer moisture is

noted in the 00 UTC BIS sounding). Transient critical conditions are

possible across northeast CO and western NE where the potential for

RH near 15% and frequent gusts to 30 mph is highest. Confidence in

sustained, widespread critical conditions is currently not high

enough to warrant a delineation, though trends will continue to be

monitored.



...Great Basin...

Lee troughing to across MT/WY with gradual surface pressure rises

across CA will help strengthen the pressure gradient across the

Great Basin this afternoon. Winds increasing to 15-20 mph are likely

and may coincide with areas of 15-20% RH - especially across

southeast UT where the overlap of favorable wind/RH is highest per

recent guidance. However, ERC values across this region remain below

critical thresholds, suggesting a muted fire weather concern.



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



$$