Post by Briella - Houma on Apr 6, 2014 19:10:19 GMT -6
MESOSCALE DISCUSSION 0301
NWS STORM PREDICTION CENTER NORMAN OK
0802 PM CDT SUN APR 06 2014
AREAS AFFECTED...NORTHERN MISSISSIPPI AND CENTRAL ALABAMA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 070102Z - 070300Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...THUNDERSTORMS WILL CONTINUE TO INCREASE ACROSS NORTHERN
MISSISSIPPI AND CENTRAL ALABAMA. ISOLATED LARGE HAIL WILL BE THE
PRIMARY THREAT THROUGH THE EVENING HOURS. A TORNADO THREAT MAY
DEVELOP LATE IN THE EVENING AS THE SURFACE WARM FRONT APPROACHES.
DISCUSSION...SURFACE BASED THUNDERSTORMS CONTINUE TO INCREASE IN
COVERAGE SOUTH OF A SURFACE WARM FRONT STRETCHED ACROSS SOUTHERN
LOUISIANA EASTWARD INTO THE FLORIDA PANHANDLE. THE PREDOMINANT STORM
MOTION WILL CONTINUE TO TAKE THESE STORMS NORTHEASTWARD /NORTH OF
THE WARM FRONT/...WITH A TRANSITION FROM SURFACE BASED TO ELEVATED
WITH NORTHWARD EXTENT. GIVEN THE STRONG DEEP-LAYER SHEAR /AT OR
ABOVE 50 KTS/ AND INCREASING MUCAPE...THE POTENTIAL FOR ISOLATED
ELEVATED SUPERCELLS WILL EXIST THROUGH THE EVENING. GIVEN THE
ELEVATED NATURE OF THE CONVECTION...ISOLATED LARGE HAIL WILL BE THE
PREDOMINANT THREAT.
LATER THIS EVENING...INTO THE OVERNIGHT...THE SURFACE WARM FRONT IS
EXPECTED TO APPROACH THE AREA. AS THIS OCCURS...THE POTENTIAL FOR
SURFACE-BASED CONVECTION WILL INCREASE. IF SURFACE-BASED CONVECTION
IS REALIZED THE THREAT FOR TORNADOES WOULD CONSEQUENTLY
INCREASE...REQUIRING THE ISSUANCE OF A TORNADO WATCH.
..MARSH/GUYER.. 04/07/2014
MESOSCALE DISCUSSION 0300
NWS STORM PREDICTION CENTER NORMAN OK
0748 PM CDT SUN APR 06 2014
AREAS AFFECTED...SW AND S CENTRAL LA
CONCERNING...TORNADO WATCH 64...
VALID 070048Z - 070215Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 64 CONTINUES.
SUMMARY...THE THREAT FOR TORNADOES APPEARS TO BE INCREASING SOME
COMPARED TO THE PAST FEW HOURS...WITH NEW SURFACE-BASED THUNDERSTORM
DEVELOPMENT ACROSS S CENTRAL LA.
DISCUSSION...THE 00Z LCH SOUNDING REVEALED MLCAPE NEAR 1800 J/KG
WITHIN THE WARM SECTOR...WITH SURFACE DEWPOINTS OF 70-72 F BELOW 7
C/KM MIDLEVEL LAPSE RATES. THE RECENT DEVELOPMENT OF APPARENTLY
SURFACE-BASED STORMS NEAR LAFAYETTE MAY BE SIGNALING A RELATIVE
INCREASE IN THE TORNADO RISK...COINCIDENT WITH THE WARM SECTOR
CONTINUING TO EXPAND INLAND. GIVEN THE RICH MOISTURE AND MODERATE
BUOYANCY...STORMS INTERACTING WITH THE WARM FRONT /AND ZONE OF
ENHANCED LOW-LEVEL SHEAR/ WILL HAVE THE POTENTIAL TO PRODUCE
TORNADOES...IN ADDITION TO DAMAGING GUSTS AND ISOLATED LARGE HAIL.
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0805 PM CDT SUN APR 06 2014
VALID 070100Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PART OF THE LOWER MS
VALLEY AND CENTRAL GULF COAST STATES...
...LA/MS/AL/WRN FL PANHANDLE...
60-90 METER 500 MB HEIGHT FALLS SPREADING INTO THE LOWER MS VALLEY
AND LOW LEVEL WAA WILL CONTINUE TO SUPPORT TSTM DEVELOPMENT THIS
EVENING INTO THE OVERNIGHT PERIOD ACROSS THE LOWER MS VALLEY AND
CENTRAL GULF COAST STATES...AS A SHORTWAVE TROUGH TRACKS FROM THE
SRN PLAINS TO THE OZARKS REGION. THIS WILL SUPPORT AN AREA OF LOW
PRESSURE DEEPENING AS IT TRACKS FROM THE UPPER TX COAST TO WRN OR
MIDDLE TN BY 12Z MONDAY. 00Z SOUNDINGS INDICATED RELATIVELY
SUBSTANTIAL LOW LEVEL MOISTENING HAS OCCURRED FROM LA INTO MS AND AL
SINCE 12Z TODAY...WHILE SURFACE OBSERVATIONS SHOWED SURFACE
DEWPOINTS IN THE LOWER 70S HAVE MOVED INLAND ACROSS SRN PARTS OF LA.
A CONTINUED RETURN OF HIGHER THETAE AIR IS EXPECTED INTO THE LOWER
MS VALLEY AND CENTRAL GULF COAST STATES THROUGH THIS FORECAST PERIOD
RESULTING IN LOW LCLS. ALTHOUGH INSTABILITY WILL TEND TO REMAIN
MARGINAL WITH NWD EXTENT AWAY FROM THE COAST...LOCATIONS WITH
SURFACE DEWPOINTS INTO THE MIDDLE 60S COMBINED WITH STRENGTHENING
DEEP LAYER WIND FIELD WILL HAVE AN INCREASED TORNADO THREAT AS LOW
LEVEL AND DEEP LAYER SHEAR INCREASE. A FEW STRONG TORNADOES WILL BE
POSSIBLE THIS EVENING AND OVERNIGHT INTO EARLY MONDAY MORNING ACROSS
SERN LA...SRN MS...AND SWRN AL WHERE MOISTENING WILL BE THE GREATEST
AND LARGE HODOGRAPH CURVATURE IS EXPECTED AS THE SLY LLJ
STRENGTHENS.
...ERN AR/FAR NRN MS INTO WRN TN...
AN INCREASE IN FORCING FOR ASCENT LATE IN THIS FORECAST PERIOD IS
EXPECTED ACROSS ERN AR INTO FAR NRN MS AND WRN TN WITHIN THE EXIT
REGION OF A STRENGTHENING SSWLY 500 MB JET ACCOMPANYING THE NEWD
MOVING SHORTWAVE TROUGH. THIS...COMBINED WITH DPVA...STEEPENING
MIDLEVEL LAPSE RATES /7-7.5 C PER KM/...MUCAPE 700-900 J/KG AND
RELATIVELY STRONG CLOUD-BEARING SHEAR SUGGEST A FEW STRONGER CORES
WILL BE CAPABLE OF PRODUCING MARGINALLY SEVERE HAIL. THIS ACTIVITY
WILL BE ELEVATED WITH POINT FORECAST SOUNDINGS SHOWING THE BASES
ROOTED BETWEEN 700-850 MB.
...PARTS OF THE NRN/CENTRAL PLAINS TO THE PERMIAN BASIN IN TX...
LOSS OF DAY TIME HEATING IS EXPECTED TO SUPPORT AN OVERALL DECREASE
IN TSTM POTENTIAL ACROSS THE MIDDLE PART OF THE LOWER 48 STATES.
FOR SHORT TERM FORECAST DETAILS FOR THE PERMIAN BASIN WHERE THERE
HAVE BEEN A FEW STRONGER STORMS...REFER TO SPC MESOSCALE DISCUSSION
#299.
