MESOSCALE DISCUSSION 0117
NWS STORM PREDICTION CENTER NORMAN OK
0515 PM CST SAT FEB 20 2016
AREAS AFFECTED...PARTS OF CNTRL/E CNTRL MO AND ADJACENT SWRN IL
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 202315Z - 210115Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...WITH SEVERE WEATHER POTENTIAL EXPECTED TO BE LIMITED TO
MOSTLY MARGINAL SEVERE HAIL...AND PROBABLY CONFINED IN BOTH AREA AND
TIME...A WATCH IS NOT CURRENTLY ANTICIPATED. BUT TRENDS WILL
CONTINUE TO BE MONITORED.
DISCUSSION...CONVECTIVE CELLS ARE DEEPENING ACROSS THE LOWER
MISSOURI VALLEY...WITHIN AN APPARENT ZONE OF BROADER LARGE-SCALE
ASCENT ASSOCIATED WITH WARM ADVECTION BASED AROUND 700 MB. MOISTURE
RETURN TO THIS ZONE...AT LEAST NORTH OF A VICHY/FARMINGTON LINE...IS
ELEVATED ABOVE RELATIVELY DRY BOUNDARY LAYER...BUT STILL
CONTRIBUTING TO INCREASING CAPE WHICH MODELS SUGGEST WILL BECOME
SUPPORTIVE OF INCREASING THUNDERSTORM ACTIVITY THROUGH THE 00-03Z
TIME FRAME.
BENEATH 40-50 KT WESTERLY MID/UPPER FLOW...DEEP LAYER SHEAR IS
POTENTIALLY SUPPORTIVE OF SUPERCELL STRUCTURES...WHICH WILL ENHANCE
POTENTIAL FOR MAINLY SEVERE HAIL IN THE MORE SUSTAINED STORMS. THIS
THREAT IS PROBABLY HIGHEST WITHIN A NARROW CORRIDOR WEST THROUGH
EAST OF VICHY...INTO AND EAST OF THE FARMINGTON AREA. THIS COINCIDES
WITH THE NORTHERN GRADIENT OF THE HIGHER PRECIPITABLE WATER...WHERE
SURFACE DEW POINTS IN THE MID 50S ARE CONTRIBUTING WEAK BOUNDARY
LAYER BASED INSTABILITY...AND CLOUD-BEARING LAYER SHEAR IS LIKELY
MAXIMIZED.
WARMER MID-LEVEL TEMPERATURES AND WEAKER LARGE-SCALE ASCENT MAY
CONTINUE TO PRECLUDE CONVECTIVE DEVELOPMENT TO THE SOUTH OF THIS
REGION.
..KERR/HART.. 02/20/2016
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PAH...LSX...SGF...EAX...
LAT...LON 39399271 39179129 38688970 37918958 37469046 37759149
37859252 38319292 39399271
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