Fire Weather Outlook Discussion
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FNUS21 KWNS 041635
FWDDY1

DAY 1 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1134 AM CDT MON MAY 04 2015

VALID 041700Z - 051200Z

A FEW SPATIAL ADJUSTMENTS HAVE BEEN MADE FOR THIS FORECAST. THE
ELEVATED AREA IN THE NORTHEASTERN CONUS WAS EXPANDED WESTWARD TO
INCLUDE MORE OF SOUTHERN NEW YORK STATE. LATEST OBSERVATIONS
INDICATE THAT RH VALUES HAD ALREADY FALLEN BELOW MODEL GUIDANCE IN A
FEW OF THOSE AREAS...WITH 10-15 MPH SWLY LOW-LEVEL FLOW EXPECTED TO
CONTINUE THROUGH THE DAY. OVERALL...SURFACE WINDS THROUGHOUT THE
MID-ATLANTIC AND NORTHEAST ARE EXPECTED TO REMAIN JUST BELOW
CRITICAL THRESHOLDS EXCEPT FOR ON A LOCALIZED BASIS NEAR AREAS OF
FAVORABLE/ELEVATED TERRAIN...PRECLUDING CRITICAL AREA ISSUANCE FOR
THIS FORECAST.

AN ELEVATED AREA HAS ALSO BEEN INTRODUCED FOR PARTS OF THE WESTERN
AND CENTRAL FLORIDA PENINSULA FOR THIS FORECAST. 10-20 MPH LOW-LEVEL
EASTERLY FLOW...AFTERNOON RH VALUES DROPPING TO NEAR 35
PERCENT...AND SUPPORTIVE FUELS SUGGEST SOME FIRE WEATHER THREAT
THERE THROUGH THE AFTERNOON HOURS.

AREAS OF WESTERN SOUTH DAKOTA HAVE BEEN REMOVED FROM THE ELEVATED
FIRE WEATHER THREAT AREA. PERSISTENT CLOUDS AND NEARBY WETTING RAINS
WILL LESSEN FIRE WEATHER THREAT IN THAT AREA THROUGHOUT THE DAY.

..COOK/GLEASON.. 05/04/2015

.PREV DISCUSSION... /ISSUED 0302 AM CDT MON MAY 04 2015/

...SYNOPSIS...
A SPLIT-FLOW PATTERN FEATURING A SRN STREAM MIDLEVEL LOW OVER THE
SOUTHWEST AND A MORE PROGRESSIVE NRN STREAM WILL PERSIST ACROSS THE
CONUS. INCREASING LOW-MIDLEVEL FLOW WILL ACCOMPANY A SHORTWAVE
TROUGH MOVING THROUGH ERN CANADA...SUPPORTING AN ELEVATED FIRE
WEATHER THREAT OVER THE NORTHEAST AHEAD OF A WEAK COLD FRONT.
MEANWHILE...SLY FLOW WILL INCREASE ACROSS THE CNTRL/NRN HIGH PLAINS
ALONG THE WRN PERIPHERY OF A LOW-LEVEL ANTICYCLONE CENTERED OVER THE
DAKOTAS.

...MUCH OF NEW ENGLAND SWD INTO PARTS OF THE MID-ATLANTIC...
A TIGHTENING OF THE SFC PRESSURE GRADIENT IN RESPONSE TO A GRADUALLY
DEEPENING SFC LOW OVER QUEBEC WILL RESULT IN AN INCREASE IN
SUSTAINED WIND SPEEDS TO 15 TO LOCALLY 20 MPH. STRONGER GUSTS WILL
BE POSSIBLE /30-35 MPH/ IN CONJUNCTION WITH STEEPENING LOW-LEVEL
LAPSE RATES...ESPECIALLY ACROSS NRN NY INTO NWRN ME BENEATH STRONGER
850 MB FLOW. LOW-LEVEL SWLYS WILL FEATURE TRAJECTORIES GENERALLY
OVER LAND...AND WILL MAINTAIN A DRY BOUNDARY-LAYER ACROSS THE
REGION...WITH RH VALUES FALLING AS LOW AS 25 PERCENT AMIDST
TEMPERATURES IN THE UPPER 70S TO LOWER 80S F. PRIMARY UNCERTAINTY
PRECLUDING A CRITICAL FIRE WEATHER THREAT IS THE MAGNITUDE OF
SUSTAINED WIND SPEEDS...BUT LOCALLY CRITICAL CONDITIONS WILL STILL
BE POSSIBLE.

...ERN DAKOTAS INTO NERN MT...
SLY WINDS WILL INCREASE ACROSS THE HIGH PLAINS IN RESPONSE TO A
TIGHTENING SFC PRESSURE GRADIENT BETWEEN SFC HIGH PRESSURE OVER THE
ERN DAKOTAS...AND PRESSURE FALLS OVER THE NRN ROCKIES. RH VALUES
WILL GENERALLY BE IN THE 30S WHERE THE STRONGEST FLOW OCCURS...BUT
SOME OVERLAP OF SUSTAINED WIND SPEEDS OF 15-20 MPH WILL OCCUR WITH
RELATIVELY DRIER AIR /RH VALUES OF 20-25 PERCENT/ OVER THE DAKOTAS
INTO NERN MT.

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



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