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FNUS28 KWNS 202047
FWDD38

DAY 3-8 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0346 PM CDT MON APR 20 2015

VALID 221200Z - 281200Z

VERTICALLY-STACKED LOW IS EXPECTED TO BE CENTERED OVER ONTARIO AT
THE BEGINNING OF THE PERIOD WITH STRONG MID/UPPER LEVEL FLOW
EXTENDING THROUGH THE BASE OF THE TROUGH -- FROM THE NRN PLAINS EWD
ACROSS THE OH VALLEY AND THROUGH THE MID-ATLANTIC. THIS LOW IS
EXPECTED TO REMAIN RELATIVELY IN PLACE UNTIL D5/FRI WHEN A SHORTWAVE
TROUGH MOVING THROUGH ITS BASE INDUCES AN EWD SHIFT AND SOME
ELONGATION OF THE SYSTEM. FARTHER W...LOW OFF THE SRN CA COAST IS
EXPECTED TO GRADUALLY MOVE EWD INTO THE SOUTHWEST ON D4/THU AND INTO
THE SRN PLAINS ON D5/FRI. RECENT RUNS OF THE GFS HAVE TRENDED MORE
PROGRESSIVE WITH THE SYSTEM WHILE THE ECMWF RUNS HAVE REMAINED MORE
CONSISTENT IN FAVORING A SLOWER SOLUTION. UPPER RIDGING IS EXPECTED
OVER THE SOUTHWEST ON D6/SAT AS THE REGION SITS IN BETWEEN THE
EXITING SHORTWAVE TROUGH AND ANOTHER APPROACHING FROM THE SRN GREAT
BASIN.

...D3/WED - D5/FRI: SOUTHWEST/SRN HIGH PLAINS...
THE PROGRESSION OF THE UPPER LOW FROM THE SRN CA EWD ACROSS THE
SOUTHWEST AND INTO THE SRN PLAINS WILL PLACE MUCH OF THE SOUTHWEST
AND SRN HIGH PLAINS UNDER SWLY FLOW ALOFT. THE AIRMASS OVER THE
REGION ON D3/WED IS STILL EXPECTED TO BE DRY ENOUGH TO SUPPORT A
LARGE AREA OF RH VALUES BELOW 10 PERCENT. RECENT GUIDANCE KEEPS WIND
SPEEDS AROUND 15-20 MPH WITH THE POTENTIAL FOR CRITICAL CONDITIONS
REMAINING HIGH ENOUGH TO LEAVE THE 40 PERCENT THREAT AREA LARGELY
UNCHANGED. WIND SPEEDS ARE EXPECTED TO INCREASE OVER THE AREA ON
D4/THU AS THE SURFACE PRESSURE GRADIENT TIGHTENS AND MID/UPPER FLOW
INCREASES. HOWEVER...LOW-LEVEL MOISTURE AND CLOUD COVER ARE ALSO
EXPECTED TO INCREASE. AS A RESULT...THE CHANCE FOR CRITICAL
CONDITIONS REMAINS HIGH ENOUGH TO KEEP THE 40 PERCENT THREAT AREA
BUT TOO LOW TO INTRODUCE 70 PERCENT PROBS ATTM.

WIND SPEEDS WILL LIKELY INCREASE EVEN MORE ON D5/FRI BUT PREVIOUSLY
MENTIONED TIMING DIFFERENCES AMONGST THE GUIDANCE REGARDING WHEN THE
LOW MOVES INTO THE SRN PLAINS ON D5/FRI LIMIT OVERALL
PREDICTABILITY. EVEN WITH THESE TIMING DIFFERENCE...CONFIDENCE IS
HIGH THAT THE SRN HIGH PLAINS WILL BE BEHIND THE LOW BY THE LATE
MORNING WITH THE CHANCE OF CRITICAL CONDITIONS IN THE AFTERNOON.
PROBABILITY REMAINS TOO LOW TO DELINEATE A 70 PERCENT AREA WITH THIS
FORECAST BUT IF CURRENT MODEL TRENDS CONTINUE -- I.E. A PORTION OF
THE AREA REMAINS PRECIPITATION FREE AND STRONG WINDS AND LOW RH
REMAIN FAVORABLY ALIGNED -- A 70 PERCENT AREA WILL LIKELY BE NEEDED
IN SUBSEQUENT FORECASTS.

...D6/SAT - D7/SUN: SOUTHWEST/SRN HIGH PLAINS...
UPPER RIDGING IS ANTICIPATED OVER THE REGION ON D6/SAT BEFORE
ANOTHER SHORTWAVE MOVES THROUGH LATE D7/SUN. GUIDANCE SUGGESTS
CONDITIONS WILL CONTINUE TO SUPPORT AT LEAST SOME FIRE WEATHER
THREAT ON BOTH OF THESE DAYS.

..MOSIER.. 04/20/2015

...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...




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