Mesoscale Discussion 1820

Issued

Aug 27, 2012, 7:55 AM EDT (11:55 UTC)

Expired

Aug 27, 2012, 9:30 AM EDT

In force

95 min

Issued by

the Storm Prediction Center

The Miami radar (KAMX), 127 km from the middle of the area, began a volume at 11:54 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.

335 
ACUS11 KWNS 271156
SWOMCD
SPC MCD 271155
FLZ000-271330-

MESOSCALE DISCUSSION 1820
NWS STORM PREDICTION CENTER NORMAN OK
0655 AM CDT MON AUG 27 2012

AREAS AFFECTED...PORTIONS CENTRAL/SRN FL AND KEYS.

CONCERNING...TORNADO WATCH 590...

VALID 271155Z - 271330Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 590 CONTINUES.

SUMMARY...WHILE TORNADO POTENTIAL WILL REMAIN NON-ZERO...PRIND WW
MAY BE ALLOWED TO EXPIRE AS SCHEDULED...GIVEN MRGL/CONDITIONAL
NATURE OF THREAT FOR AT LEAST A FEW HOURS AFTER SCHEDULED 13Z
EXPIRATION. CONVECTIVE MODE AND TRENDS WILL BE MONITORED FOR
POSSIBILITY OF ADDITIONAL WW ISSUANCE OVER SOME PARTS OF THIS REGION
THROUGH REMAINDER MORNING.

DISCUSSION...PERSISTENT PRECIP PLUME OVER PORTIONS CENTRAL/NRN FL
HAS CONTINUED TO REINFORCE COLD POOL OVER THAT AREA...REF SPC
MESOSCALE DISCUSSION 1819 FOR MORE DETAILS ON THAT PRECIP AND
RELATED HEAVY-RAIN POTENTIAL.  SFC MESOANALYSIS INDICATED
ASSOCIATED/WAVY BOUNDARY NEAR LINE FROM NEAR CAPE CANAVERAL TO ABOUT
20 ENE VRB...SWWD ACROSS NRN/WRN PALM BEACH COUNTY...SRN/ERN HENDRY
COUNTY...NEAR APF...THEN NWWD OVER GULF.  IN NEAR TERM...TORNADO
POTENTIAL REMAINS VERY CONDITIONAL ON CONVECTIVE MODE...BUT MAY BE
RELATIVELY MAXIMIZED INVOF SRN AND ERN PORTION OF COLD-POOL
BOUNDARY.  BOUNDARY MAY REPRESENT NARROW SHEAR/BUOYANCY OVERLAP
ARCHETYPE...AND ITS BAROCLINICITY MAY INCREASE SOMEWHAT DURING
MID-LATE MORNING AS DIABATIC HEATING OCCURS IN RELATIVE CLEAR SLOT
OVER S FL.  LOW-LEVEL HODOGRAPHS WILL REMAIN MAXIMIZED ON COOL
SIDE...WITH CAPE ON WARM SIDE...AND LOW-LEVEL SHEAR GENERALLY
WEAKENING WITH SWD EXTENT OVER REGION.  ANY RELATIVELY
DISCRETE/SUSTAINED CONVECTION FORMING S OF BOUNDARY AND CROSSING ITS
BAROCLINIC ZONE MAY ENCOUNTER ENHANCED LOW-LEVEL
VORTICITY/SRH...OFFERING TRANSIENT RISK OF MESOCYCLONIC
INTENSIFICATION.

STILL...LACK OF ROBUST LIFT OUTSIDE DENSELY
CONCENTRATED/QUASI-LINEAR PRECIP BANDS HAS PRECLUDED SUBSTANTIAL
SUPERCELL DEVELOPMENT.  FURTHERMORE...TRANSLATION OF TC CENTER AWAY
FROM REGION SHOULD YIELD NET WEAKENING OF REGIONAL LOW-LEVEL SHEAR
WITH TIME.  CELL-RELATIVE HODOGRAPHS ALREADY HAVE BECOME RELATIVELY
SMALL AT EYW/MIA BASED ON VWP DATA.

..EDWARDS.. 08/27/2012

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

ATTN...WFO...MFL...MLB...KEY...TBW...

LAT...LON   28188280 28198213 28358197 28338085 27858087 27838044
            26757998 25748012 25248028 24858064 24638114 24508184
            24528218 24618217 24638195 24618180 24718163 24798147
            24798127 24778112 24788094 24898079 24988099 25158116
            25288117 25368116 25528122 25808143 25898164 25808165
            26198184 26388188 26488201 26398203 26498219 26768229
            27238254 27538278 27718273 27858289 28188280

Mesoscale Discussions in Florida, 2012Every mesoscale discussion in 2012

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.