Alert archive / Florida / Mesoscale Discussions in 2017
Mesoscale Discussion 1639
The Storm Prediction Center issued this mesoscale discussion at Sep 10, 2017, 10:33 PM EDT for 43 counties in Florida; 7 counties in Georgia. It was in force for 87 min.
The area
The outline as issued.
The facts
- Issued
- Sep 10, 2017, 10:33 PM EDT (02:33 UTC)
- Expired
- Sep 11, 2017, 12:00 AM EDT
- In force
- 87 min
- Issued by
- the Storm Prediction Center
All 50 counties
Alachua County, FL, Baker County, FL, Bradford County, FL, Brevard County, FL, Charlotte County, FL, Citrus County, FL, Clay County, FL, Columbia County, FL, DeSoto County, FL, Dixie County, FL, Duval County, FL, Flagler County, FL, Gilchrist County, FL, Glades County, FL, Hamilton County, FL, Hardee County, FL, Hernando County, FL, Highlands County, FL, Hillsborough County, FL, Indian River County, FL, Lafayette County, FL, Lake County, FL, Lee County, FL, Levy County, FL, Manatee County, FL, Marion County, FL, Martin County, FL, Nassau County, FL, Okeechobee County, FL, Orange County, FL, Osceola County, FL, Pasco County, FL, Pinellas County, FL, Polk County, FL, Putnam County, FL, Saint Johns County, FL, Saint Lucie County, FL, Sarasota County, FL, Seminole County, FL, Sumter County, FL, Suwannee County, FL, Union County, FL, Volusia County, FL, Brantley County, GA, Camden County, GA, Charlton County, GA, Clinch County, GA, Echols County, GA, Glynn County, GA, Ware County, GA
The radar
The Tampa radar (KTBW), 77 km from the middle of the area, began a volume at 02:35 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.
The nearest sounding before it
Tampa Bay, FL (KTBW), launched 00:00Z, 2.6 hours before the alert went out and 77 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
- 1120 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 29 m²/s²
- 0-3 km storm-relative helicity
- 63 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
736
ACUS11 KWNS 110233
SWOMCD
SPC MCD 110233
FLZ000-GAZ000-110400-
Mesoscale Discussion 1639
NWS Storm Prediction Center Norman OK
0933 PM CDT Sun Sep 10 2017
Areas affected...Central Florida northward into far southeastern
Georgia
Concerning...Tornado Watch 483...
Valid 110233Z - 110400Z
The severe weather threat for Tornado Watch 483 continues.
SUMMARY...The tornado threat associated with Hurricane Irma should
gradually shift northward in tandem with northward progress of the
center of circulation. A new Tornado Watch will likely be
coordinated around 0330Z.
DISCUSSION...Irma continues northward progress across southwestern
Florida. The tornado threat over the past several hours has
continued within the northeastern quadrant of the circulation, with
a few brief tornadoes reported especially along eastern portions of
the Peninsula where buoyancy remains the strongest. Scattered
bands/cells (exhibiting occasional strong rotation) continue to
rapidly migrate northwestward into the discussion area from open
Atlantic waters at this time, and observations/models suggest that
this regime should persist well into the mid-morning Monday -
especially near coastal areas along and east/northeast of Irma's
track.
Given the continued tornado threat, a new Tornado Watch will be
coordinated at around 0330Z.
..Cook/Grams.. 09/11/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CHS...MFL...MLB...TBW...JAX...TAE...
LAT...LON 27087925 26928039 26958122 26568181 26398274 27088354
27338363 27618372 28858405 30638330 31458162 31458162
31118027 27297912 27087925SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 10, 11:50 PM EDT | Tornado Watch | SPC | Alachua, Baker, Bradford, Clay, Duval, Flagler and 5 more | 14 hr |
| Sep 11, 4:58 AM EDT | Mesoscale Discussion | SPC | Alachua, Baker, Bradford, Clay, Duval, Flagler and 5 more | 2 hr |
| Sep 11, 8:49 AM EDT | Mesoscale Discussion | SPC | Baker, Duval, Nassau, Saint Johns | 116 min |
| Sep 11, 1:46 PM EDT | Tornado Watch | SPC | Bryan, Bulloch, Burke, Candler, Chatham, Effingham and 7 more | 10 hr |
Nearby
Mesoscale Discussions in Florida, 2017Mesoscale Discussions in Georgia, 2017Every mesoscale discussion in 2017
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.