Alert archive / Georgia / Mesoscale Discussions in 2015

Mesoscale Discussion 2021

December 17, 2015Henry County, Houston County, Alabama; 9 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Dec 17, 2015, 3:21 AM CST for Henry County, Houston County, Alabama; 9 counties in Georgia. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued: Dec 17, 2015, 3:21 AM CST (09:21 UTC)
Expired: Dec 17, 2015, 5:15 AM CST
In force: 114 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Henry County, AL, Houston County, AL, Calhoun County, GA, Clay County, GA, Early County, GA, Miller County, GA, Quitman County, GA, Randolph County, GA, Seminole County, GA, Terrell County, GA, Webster County, GA

The radar

The Ft Rucker radar (KEOX), 54 km from the middle of the area, began a volume at 09:21 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 nearest sounding before it

Tallahassee Rgnl, FL (KTLH), launched 00:00Z, 9.4 hours before the alert went out and 125 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: 186 J/kg
Mixed-layer CIN: -65 J/kg
Mixed-layer LCL: 728 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 79 m²/s²
0-3 km storm-relative helicity: 107 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

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

056 
ACUS11 KWNS 170921
SWOMCD
SPC MCD 170921 
GAZ000-FLZ000-ALZ000-171115-

MESOSCALE DISCUSSION 2021
NWS STORM PREDICTION CENTER NORMAN OK
0321 AM CST THU DEC 17 2015

AREAS AFFECTED...EXTREME SERN AL / SWRN GA / N-CNTRL FL PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 170921Z - 171115Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A LOW-PROBABILITY RISK FOR A BRIEF/WEAK SUPERCELL TORNADO
OR WIND DAMAGE WILL SEEMINGLY BE CONFINED TO SERN AL AND SWRN GA
OVER THE NEXT 2-4 HOURS.

DISCUSSION...KEOX RADAR IMAGERY DURING THE PAST HOUR HAS SHOWN A
WEAK SUPERCELL OVER HENRY CO. AL MOVING INTO SWRN GA.  A MARITIME
WARM FRONT EXTENDS EWD ACROSS SERN AL INTO SWRN GA WHILE A WEAK
SURFACE LOW SLOWLY DEVELOPS NEWD INTO S-CNTRL AL EARLY THIS MORNING.
 SHORT-TERM MODEL FORECAST SOUNDINGS ARE NOTABLY TOO COOL/DRY AT THE
SURFACE /I.E. NAM...RAP/ ACROSS THE FL PANHANDLE AND SWRN GA WITH 2
DEG C TEMP/DEWPOINT DISCREPANCIES NOTED.  ADDITIONALLY...UNREALISTIC
BOUNDARY-LAYER MOISTURE PROFILES IMPLIED BY THE RAP SOUNDINGS LEND
UNCERTAINTY IN THE DEPICTION OF OBJECTIVELY-ANALYZED THERMODYNAMIC
FIELDS.  WITH THOSE CONCERNS MENTIONED...OBSERVATIONS SHOW THE 
MOISTURE-RICH AIRMASS --CHARACTERIZED BY LOW 70S DEWPOINTS-- IS
LOCATED S OF THE MARITIME FRONT AND WEAK SURFACE-BASED BUOYANCY OF
250 J PER KG IS ESTIMATED.  WHILE THE THREAT FOR A BRIEF/WEAK
TORNADO AND WIND DAMAGE SEEMS LIMITED...WILL CONTINUE TO MONITOR
CONVECTIVE TRENDS FOR A POSSIBLE UPTICK IN STRONG STORM POTENTIAL.

..SMITH/MEAD.. 12/17/2015

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

ATTN...WFO...FFC...TAE...

LAT...LON   30898538 31378533 31948499 32148445 31968423 31288447
            30738489 30898538

Nearby

Mesoscale Discussions in Georgia, 2015 Mesoscale Discussions in Alabama, 2015 Every mesoscale discussion in 2015

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.