... DAY 1 SEVERE WEATHER OUTLOOK AND FIRE WEATHER OUTLOOK...

DAY 1 SLIGHT RISK FOR SEVERE STORMS TODAY AND TONIGHT!

SPC AC 151251

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0751 AM CDT Fri Oct 15 2021

   Valid 151300Z - 161200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   ARKANSAS ACROSS THE OHIO VALLEY INTO WESTERN NEW YORK...

   ...SUMMARY...
   Isolated severe gusts and hail, along with a marginal tornado
   threat, are expected today from parts of Arkansas across the Ohio
   Valley into western New York.

   ...Synopsis...
   In mid/upper levels, a progressive synoptic-scale trough will cross
   the central CONUS through the period, from its present position over
   the High Plains.  By 12Z tomorrow, the trough should arc across
   Lower MI to the lower Ohio Valley and southwestern AR.

   At the surface, 11Z analysis showed an occluded/cold front from
   southwestern QC across Lake Ontario, northern OH, through a weak low
   near HUF, another near HRO, another between MWL-ADM, then
   southwestward across the TX Big Bend and across eastern Chihuahua. A
   warm front was drawn from central/northern OH southwestward over
   northern/central MS.  The warm front should move northeastward over
   the inland Mid-Atlantic and lower Great Lakes through the period. 
   By 00Z, the northern low should deepen and move to Lake Erie, with
   cold front southwestward over western portions of OH/KY/TN,
   northwestern MS, and southeast to deep south TX.  By 12Z, the cold
   front should extend from Lake Ontario over western PA, WV,
   northeastern TN, northern GA, eastern AL, and the north-central/
   west-central Gulf.

   ...AR to western NY...
   Episodes of scattered frontal and prefrontal thunderstorms are
   expected today up and down this corridor, offering damaging to
   severe gusts, potential for a few tornadoes, and isolated,
   marginally severe hail.

   As the mid/upper trough moves eastward, expect falling heights
   aloft, strengthening (but largely front-parallel) mid/upper winds
   and deep shear, as well as shots of DCVA within the southwest flow. 
   A northeastward shift of the strongest part of the LLJ also should
   occur, toward OH/PA and western NY by late this afternoon, with
   accompanying warm advection and moisture advection/transport from
   the higher-theta-e air mass now over the lower Ohio Valley and
   Mid-South.  Also, the ongoing Ozarks activity that started last
   night west-southwest of OKC has generated a well-defined MCV
   initially near FLP.  This feature should move east-northeastward to
   northeastward toward the PAH area and perhaps beyond, across parts
   of KY and up the lower Ohio Valley.

   All those factors, as well as areas of warm-sector diurnal heating/
   destabilization in cloudiness gaps, will support thunderstorm
   development today.  Activity largely should assume quasi-linear to
   clustered configurations, though sufficient deep shear will exist to
   support supercell potential -- either embedded in a line or in the
   warm sector.  Outflow/differential-heating zones will be the most
   probable foci for warm-sector potential.  Despite the rich low-level
   moisture, modest midlevel lapse rates should help to limit MLCAPE to
   the 500-1000 J/kg range from KY-NY, and 1000-1500 J/kg range around
   the Mid-South and AR where stronger heating and greatest moisture
   are expected.  Wind profiles will be mostly unidirectional, except
   for some better-curved hodographs under the northeastern LLJ segment
   or in mesoscale areas where the wind profile is altered by a passing
   MCV.

   ..Edwards/Leitman.. 10/15/2021

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
   CURRENT UTC TIME: 1444Z (10:44AM), RELOAD THIS PAGE TO UPDATE THE TIME

MARGINAL AND SLIGHT RISK 

PROBABILITY OF TORNADO 2-5% CHANCE

PROBABILITY OF HAIL 5%

PROBABILITY OF DAMAGING WINDS 5-15% CHANCE

DAY 1 EXCESSIVE RAINFALL OUTLOOK 5-10%

SPC DAY 1 FIRE WEATHER OUTLOOK (ELEVATED)

FNUS21 KWNS 150529

FWDDY1

Day 1 Fire Weather Outlook  

NWS Storm Prediction Center Norman OK

1229 AM CDT Fri Oct 15 2021

Valid 151200Z - 161200Z

...Synopsis...

An upper-level trough will continue eastward from the Plains into

parts of the Midwest today. Across the West, an upper-level ridge

will build. At the surface, a high pressure system will strengthen

within the Great Basin and persist into Saturday.


...Southern California...

Winds have already begun to turn offshore this evening across

southern California. Winds should continue to increase through the

overnight into Friday morning. Winds will peak sometime between

early morning and early afternoon. Poor overnight RH recovery is

expected which means elevated conditions are likely for much of the

period. Winds of 15-20 mph are expected broadly with

terrain-enhanced areas potentially seeing 25-30 mph during the peak

of the event. The most likely areas for critical conditions will be

the higher terrain of Los Angeles/Ventura Counties. However, the

general lack of mid-level wind support, combined with a marginally

critical surface pressure gradient, suggest critical conditions will

be localized.


..Wendt.. 10/15/2021


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