Fire Weather Outlook Discussion

Days 3 - 8 Storm Prediction Center Norman, Oklahoma

FNUS28 KWNS 122121
FWDD38

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0320 PM CST Wed Dec 12 2018

Valid 141200Z - 201200Z

A strong upper jet will be in place around a strong mid-level cutoff
low in the southern Plains at the beginning of the period. The
combination of dry air and strong winds may lead to elevated fire
weather conditions across much of Texas and critical conditions in
some locations. Lee cyclogenesis and a strengthening gradient on
Saturday may lead to elevated to locally critical fire weather
conditions in eastern New Mexico into the Texas Panhandle. Beyond
Saturday, fire weather conditions are expected to be mostly benign.
There may be occasional fire weather concerns in the southern High
Plains next week, but model uncertainty is still too great to
highlight any areas.

...D3/Friday - Western Oklahoma and the Texas Panhandle southward to
far south Texas...
The overall wind field from the strong upper low will be weakening
on Friday, but the northerly low-level jet will still be 40 to 50
mph during the afternoon hours when mixing will reach its peak.
There is high confidence in winds of 20 to 30 mph in much of the
state of Texas and Oklahoma. The greatest question concerning fire
weather will be the relative humidities. Typically the GFS model is
the driest model due to its tendency to overmix the boundary layer,
but in this case, the ECMWF is much drier than the GFS. Therefore,
this is leading to much uncertainty about where relative humidity
values will drop to below 15 percent for an extended period on
Friday afternoon. Closer to the surface low in eastern Texas, cloud
cover, cooler temperatures, and higher dewpoints will alleviate fire
weather concerns despite the strong winds. The drier air will be on
the periphery of this system which has been roughly highlighted by
the 40 percent contour. If the moisture profile suggested by the
ECMWF is correct, critical fire weather conditions are likely across
much or all of this 40 percent area. At this time, the 70 percent
area indicates where both the GFS and ECMWF agree in relative
humidities less than 15 percent.

Another uncertainty with regard to the critical fire weather risk
will be wetting precipitation in west central Texas. Significant
precipitation is expected to fall between Abilene and Wichita Falls
which will likely limit fuel receptiveness in these locations,
especially where it falls as snow and significant accumulation
occurs. Therefore, this portion of the 40 percent area will likely
need to be adjusted in future outlooks to account for wetting
rains/accumulated snowfall.

...D4/Saturday - Eastern New Mexico into the Texas Panhandle...
Made only minor changes to the 40 percent area for Saturday in
eastern New Mexico and the Texas Panhandle. There is a chance a
70%/critical area may need to be added in future outlooks given the
forecast relative humidities and winds, but there is still some
uncertainty as to where the greatest fire weather conditions are
most likely.

..Bentley.. 12/12/2018

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

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