Alert archive / Texas / Mesoscale Discussions in 2003

Mesoscale Discussion 487

April 18, 20037 counties in Oklahoma; 11 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2003, 5:36 PM CDT for 7 counties in Oklahoma; 11 counties in Texas. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued: Apr 18, 2003, 5:36 PM CDT (22:36 UTC)
Expired: Apr 18, 2003, 7:30 PM CDT
In force: 114 min
Issued by: the Storm Prediction Center

Counties Comanche County, OK, Cotton County, OK, Grady County, OK, Jackson County, OK, Jefferson County, OK, Stephens County, OK, Tillman County, OK, Archer County, TX, Baylor County, TX, Clay County, TX, Foard County, TX, Hardeman County, TX, Haskell County, TX, Jones County, TX, Knox County, TX, Throckmorton County, TX, Wichita County, TX, Wilbarger County, TX

The radar

The Altus AFB radar (KFDR), 53 km from the middle of the area, began a volume at 22:42 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

Fort Sill, OK (KFSI), launched 12:00Z, 10.6 hours before the alert went out and 104 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: 1796 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 476 m²/s²
0-3 km storm-relative helicity: 613 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.

173 
ACUS11 KWNS 182236
SWOMCD
SPC MCD 182236 
TXZ000-OKZ000-190030-

MESOSCALE DISCUSSION 0487
NWS STORM PREDICTION CENTER NORMAN OK
0536 PM CDT FRI APR 18 2003

AREAS AFFECTED...SW OK AND NWRN TX

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 182236Z - 190030Z

...TSTMS ARE EXPECTED TO DEVELOP IN THE NEXT FEW HOURS WITH LARGE
HAIL THE MAIN THREAT...

TCU ARE INCREASING ON NORTH SIDE OF SUBTROPICAL CI PLUME FROM
KNOX COUNTY TX INTO SWRN OK NEAR FDR AND APPEAR TO BE ALONG NWRN
PERIPHERY OF INCREASING SURFACE DEW POINTS. LATEST RUC SOUNDINGS
SUGGEST THAT CINH HAS NEARLY ERODED AND STRONGEST SURFACE
CONVERGENCE IS DEVELOPING ALONG THIS CLOUD LINE.  THUS...IT IS
POSSIBLE THAT ISOLD-WDLY SCATTERED TSTMS COULD INITIATE IN THE
NEXT COUPLE OF HOURS.  THE TSTMS ARE LIKELY TO BE HIGH BASED LOW
PRECIPITATION SUPERCELLS EARLY THIS EVENING GIVEN MEAGER MOISTURE
IN PLACE AND DEEP LAYER SHEAR VALUES IN EXCESS OF 45 KTS.  

MORE CONFIDENCE EXISTS FOR A MORE RAPID INCREASE IN TSTMS AFTER
SUNSET AS WARM/MOIST ADVECTION STRENGTHENS ACROSS NWRN TX INTO
SWRN/CNTRL OK.	INCREASING INSTABILITY...STRONG DEEP LAYER SHEAR
AND INCREASING ASCENT DOWNSTREAM OF APPROACHING SHORTWAVE TROUGH
WILL BRING A THREAT OF LARGE HAIL...DAMAGING WINDS AND PERHAPS AN
ISOLD TORNADO.	ANOTHER MESOSCALE DISCUSSION WILL LIKELY BE
ISSUED IN A COUPLE HOURS AFTER EVENING RAOB DATA IS ANALYZED.


..RACY.. 04/18/2003

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

ATTN...WFO...FWD...OUN...SJT...LUB...

33870025 34559979 35029863 35139788 34499761 34029780
33549848 33169901 32539982 32610019

Nearby

Mesoscale Discussions in Texas, 2003 Mesoscale Discussions in Oklahoma, 2003 Every mesoscale discussion in 2003

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.