Alert archive / Florida / Mesoscale Discussions in 2012
Mesoscale Discussion 2250
The Storm Prediction Center issued this mesoscale discussion at Dec 29, 2012, 4:00 AM EST for 10 counties in Florida. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 29, 2012, 4:00 AM EST (09:00 UTC)
- Expired
- Dec 29, 2012, 6:00 AM EST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
Counties Citrus County, FL, Dixie County, FL, Gilchrist County, FL, Hernando County, FL, Hillsborough County, FL, Levy County, FL, Manatee County, FL, Pasco County, FL, Pinellas County, FL, Sumter County, FL
The radar
The Tampa radar (KTBW), 114 km from the middle of the area, began a volume at 09:00 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
Tampa Bay, FL (KTBW), launched 00:00Z, 9.0 hours before the alert went out and 114 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 610 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 298 m²/s²
- 0-3 km storm-relative helicity
- 408 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted, in the capitals the NWS used until 2016.
988
ACUS11 KWNS 290900
SWOMCD
SPC MCD 290900
FLZ000-291100-
MESOSCALE DISCUSSION 2250
NWS STORM PREDICTION CENTER NORMAN OK
0300 AM CST SAT DEC 29 2012
AREAS AFFECTED...W-CNTRL FL PENINSULA
CONCERNING...01Z OUTLOOK UPGRADE
VALID 290900Z - 291100Z
SUMMARY...A THREAT FOR LOCALIZED DAMAGING WINDS AND PERHAPS A BRIEF
TORNADO SHOULD DEVELOP BETWEEN 10-12Z PRIOR TO THE EXPIRATION OF THE
01Z CONVECTIVE OUTLOOK.
DISCUSSION...BROKEN LINE OF PRE-FRONTAL TSTMS EXTENDED FROM NEAR
APALACHEE BAY SWWD ACROSS THE NERN GULF. 08Z SURFACE ANALYSIS PLACED
A 1007 MB CYCLONE JUST E OF TLH WITH A WAVY WARM FRONT THAT HAD
ADVANCED NWD ACROSS N-CNTRL FL. WITH THE SPATIAL EXTENT OF THE WARM
SECTOR HAVING INCREASED ACROSS MOST OF THE PENINSULA...CONCERN IS
INCREASING FOR AT LEAST A MARGINAL SEVERE THREAT TO BECOME MORE
PREVALENT...INITIALLY ALONG THE GULF COAST OF W-CNTRL FL.
MODIFIED 00Z TBW RAOB AND NAM/GFS FORECAST SOUNDINGS SUGGEST 68-69
DEG F SURFACE DEW POINTS ARE NEEDED FOR SURFACE-BASED CONVECTION.
WITH LOWER 70S DEW POINTS NOW JUST OFFSHORE IN THE NERN GULF...IT
APPEARS THAT WEAK SURFACE-BASED BUOYANCY WILL EXIST INLAND. ALTHOUGH
RELATIVELY POOR TROPOSPHERIC LAPSE RATES WILL LIMIT UPDRAFT
ACCELERATION...THE FRINGE OF THE STRONG DEEP-LAYER SWLYS/WLYS SHOULD
RENDER SUFFICIENT SHEAR FOR A RISK OF LOCALIZED DAMAGING WINDS AND
POSSIBLY A BRIEF TORNADO. AFTER 12Z...GUIDANCE IS CONSISTENT THAT
LOW-LEVEL FLOW WILL SUBSIDE/VEER AS THE CNTRL APPALACHIANS SHORT
WAVE TROUGH PULLS FARTHER AWAY FROM THE PENINSULA...WHICH SHOULD
HELP TEMPER THE OVERALL THREAT.
..GRAMS.. 12/29/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MLB...TBW...JAX...TAE...
LAT...LON 29708354 29768282 29458223 28868197 28178186 27428221
27448273 27738284 28428279 29068299 29708354SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 29, 12:02 AM EST | Mesoscale Discussion | SPC | Bay, Franklin, Gulf | 88 min |
Nearby
Mesoscale Discussions in Florida, 2012Every mesoscale discussion in 2012
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.