Alert archive / Florida / Mesoscale Discussions in 2011

Mesoscale Discussion 75

February 1, 201110 counties in Alabama; 11 counties in Florida; Early County, Seminole County, Georgia

The Storm Prediction Center issued this mesoscale discussion at Feb 1, 2011, 5:54 PM CST for 10 counties in Alabama; 11 counties in Florida; Early County, Seminole County, Georgia. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued: Feb 1, 2011, 5:54 PM CST (23:54 UTC)
Expired: Feb 1, 2011, 7:30 PM CST
In force: 96 min
Issued by: the Storm Prediction Center

All 23 counties

Butler County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Escambia County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Bay County, FL, Calhoun County, FL, Escambia County, FL, Gulf County, FL, Holmes County, FL, Jackson County, FL, Liberty County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL, Early County, GA, Seminole County, GA

The radar

The Eglin Afb radar (KEVX), 20 km from the middle of the area, began a volume at 23:53 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 11Feb 1, 6:20 PM CST

The nearest sounding before it

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 11.9 hours before the alert went out and 166 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 852 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 236 m²/s²
0-3 km storm-relative helicity: 297 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

935 
ACUS11 KWNS 012354
SWOMCD
SPC MCD 012354 
FLZ000-GAZ000-ALZ000-020130-

MESOSCALE DISCUSSION 0075
NWS STORM PREDICTION CENTER NORMAN OK
0554 PM CST TUE FEB 01 2011

AREAS AFFECTED...PORTIONS SRN AL...FL PANHANDLE...EXTREME SWRN GA.

CONCERNING...TORNADO WATCH 10...

VALID 012354Z - 020130Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 10 CONTINUES.

SVR POTENTIAL...WHILE BECOMING MRGL...WILL PERSIST FOR A FEW MORE
HOURS ACROSS THIS REGION WITHIN ERN PORTIONS WW AND EWD ACROSS
PORTIONS WRN-CENTRAL PANHANDLE OF FL.  EWD EXTENSION OF EXISTING WW
OR SMALL/SHORT-LIVED ADDITIONAL WW MAY BE ISSUED.

PRIMARY CONVECTIVE BAND CONTINUED MOVING EWD APPROXIMATELY 40-45 KT
ACROSS ERN AL AND WILL MOVE OVER WRN PORTIONS FL PANHANDLE AND OUT
OF EXISTING WW AREA PRIOR TO SCHEDULED 02Z EXPIRATION.  SFC
MESOANALYSIS SHOWS WARM FRONT INLAND...FROM NEAR TOI ESEWD BETWEEN
JAX-VLD...S OF WHICH INLAND AIR MASS WILL BE CHARACTERIZED BY SFC
DEW POINTS UPPER 50S TO LOW 60S F AND TEMPS COOLING INTO UPPER 60S
THROUGH 02Z.  CLOSER TO COAST...SHALLOW MARINE LAYER WITH RELATIVELY
HIGH STATIC STABILITY IS EVIDENT...INDUCED BY RELATIVELY COLD SHELF
WATERS...WITH TEMPS AND DEW POINTS GENERALLY LOW 60S F.  THIS AIR
MASS EXTENDS ROUGHLY 50-60 NM OFFSHORE...GRADING INTO MORE
WELL-MODIFIED MARINE AIR WITH RELATIVELY RICH THETAE...AND DEW
POINTS MID-UPPER 60S F.  MEANWHILE...CONFLUENCE LINE IS ANALYZED
FROM NEAR CEW SWD THROUGH COASTAL OKALOOSA COUNTY THEN SSWWD OVER
GULF...CORRESPONDING TO BKN BAND OF CONVECTION THAT INCLUDES
ISOLATED TSTMS.  THIS FEATURE IS MOVING NEWD 20-25 KT.  WHILE MOST
INTENSE CONVECTION SHOULD REMAIN OVER GULF...BAND OF STG TSTMS
SHOULD PERSIST AS IT MOVES EWD IN REGIME OF FAVORABLY MOIST INFLOW
SLIGHTLY ELEVATED ATOP MARINE LAYER.  WINDS AOA 50-KT SVR CRITERIA
-- EVIDENT ABOVE MARINE LAYER IN RADAR VELOCITY FIELDS -- MAY
TRANSLATE DOWNWARD ENOUGH TO GENERATE A FEW DAMAGING GUSTS IN
STRONGEST DOWNDRAFTS.  LOW-LEVEL SHEAR WILL REMAIN STG WITH ENLARGED
HODOGRAPHS...AND BRIEF/MRGL TORNADO THREAT ALSO CANNOT BE RULED OUT
TOTALLY.  A DISCRETE SUPERCELL OR TWO MAY EVOLVE FROM CONVECTION
INITIATING ON CONFLUENCE LINE...HOWEVER SUCH ACTIVITY WOULD MOVE
QUICKLY INTO AIR MASS CHARACTERIZED BY STG MLCINH...PER MODIFIED RUC
SOUNDINGS.

..EDWARDS.. 02/01/2011

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

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

LAT...LON   30308776 31238759 31908669 31698564 31368483 29948447
            29588500 29688520 29678537 29828544 29928537 30178584
            30378640 30338717 30308776

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 1, 12:00 PM CST	Mesoscale Discussion	SPC	Baldwin, Escambia, Mobile, Washington	60 min
Feb 1, 1:03 PM CST	Tornado Watch	SPC	Baldwin, Choctaw, Clarke, Conecuh, Escambia, Mobile and 3 more	7 hr
Feb 1, 3:44 PM CST	Mesoscale Discussion	SPC	Baldwin, Choctaw, Clarke, Conecuh, Escambia, Marengo and 4 more	61 min

Nearby

Mesoscale Discussions in Florida, 2011 Mesoscale Discussions in Alabama, 2011 Mesoscale Discussions in Georgia, 2011 Every mesoscale discussion in 2011

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.