MESO: Mesoscale Discussion 0574

ACUS11 KWNS 281738
SWOMCD
SPC MCD 281737
GAZ000-ALZ000-281900-

MESOSCALE DISCUSSION 0574
NWS STORM PREDICTION CENTER NORMAN OK
1237 PM CDT SUN APR 28 2013

AREAS AFFECTED...PARTS OF CENTRAL/SRN AND ERN AL INTO CENTRAL GA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 281737Z - 281900Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...TSTMS WILL CONTINUE TO DEVELOP THIS AFTERNOON ACROSS
CENTRAL/SRN AL INTO CENTRAL GA...WITH AN ATTENDANT THREAT FOR
LOCALLY STRONG WIND GUSTS AND/OR A FEW STORMS PRODUCING HAIL.
OVERALL POTENTIAL FOR SEVERE STORMS SHOULD REMAIN LOW...AND THUS
PRECLUDES THE NEED FOR A SVR TSTM WATCH AT THIS TIME.

DISCUSSION...SURFACE STREAMLINE ANALYSIS SUGGESTS A CORRIDOR OF
CONVERGENCE ARCS FROM SWRN AL NEWD THROUGH CENTRAL AND EAST CENTRAL
AL TO WEST CENTRAL GA. THIS CORRIDOR IS MOST EVIDENT PER INCREASING
CLOUD DEVELOPMENT AND/OR REFLECTIVITY FROM MONROE COUNTY AL TO SRN
DALLAS/AUTAUGA COUNTIES AL...LEE COUNTY AL AND COWETA COUNTY GA. A
NW-SE ORIENTED WARM FRONT HAS MOVED INTO NRN-ERN GA THIS AFTERNOON
WITH SWLY LOW LEVEL WINDS SUPPORTING MOISTENING ACROSS THE WARM
SECTOR. THESE AFOREMENTIONED COUNTIES IN THE CONVERGENCE ZONE
RESIDE ALONG THE SRN PERIPHERY OF THICKER CLOUDS. THUS...MORE
SUNSHINE WITH SWD EXTENT HAS SUPPORTED A BOOST IN SURFACE
TEMPERATURES THROUGH THE MID-UPPER 70S. DESPITE THE ONGOING
DESTABILIZATION...WEAKER MIDLEVEL LAPSE RATES SHOULD TEND TO TEMPER
THE DEVELOPMENT OF STRONGER INSTABILITY...WITH MLCAPE AROUND 1000
J/KG. AREA WSR-88D VWP DATA INDICATED A GRADUAL DECREASE IN LOW
LEVEL WIND SPEEDS AS FORECAST...BUT 40 KT WSWLY MIDLEVEL WINDS ARE
SUPPORTING EFFECTIVE BULK SHEAR OF 30-40 KT THAT WOULD RESULT IN
STORM ORGANIZATION. HOWEVER...THE RELATIVELY MARGINAL INSTABILITY
AND MODEST MIDLEVEL LAPSE RATES AROUND 6.5 C/KM MAY LIMIT THE VIGOR
OF INDIVIDUAL UPDRAFTS.

THE STRONGER STORMS WILL BE CAPABLE OF PRODUCING LOCALLY STRONG WIND
GUSTS AND SOME HAIL...BUT OVERALL THE THERMODYNAMIC FACTORS SUGGEST
WW ISSUANCE IS UNLIKELY AT THIS TIME.

..PETERS/HART.. 04/28/2013

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

ATTN...WFO...FFC...TAE...BMX...MOB...

LAT...LON 31558801 32388666 33428486 33468375 32698298 31858348
31558477 31418587 31348710 31298762 31558801

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