A Classic Case: the June 2 Intercept Valuable data on two storms that produced violent tornadoes were obtained by VORTEX on June 2, 1995. The storms formed in a region of strongly backed low-level flow with modest westerly flow aloft, yielding strong deep shear. The target area for VORTEX for storm initiation was Clovis, New Mexico. Storms formed in this area (the boxed area below) in the late afternoon. Forecast Discussion for June 2, 1995 The first storms seemed somewhat disorganized. However, inflow quickly increased to 40-50 knots, so it was felt that the storms had a lot of potential for becoming supercells. The first target storm moved northeast along US 60 toward Friona, TX. When the storm was near Bovina, TX, inflow became so strong that visibility went to zero in blowing dust, and power lines were torn down at a distance of 15 kilometers southeast of the storm. Some surface teams were forced to turn away from the storm because of these conditions. The other teams that were closer to the developing mesocyclone reported winds of 30-50 knots flowing toward the mesocyclone from all directions. The mobile Doppler radar scanned the storm from a distance of 12 kilometers and observed very strong low-level horizontal shear. This information was reported in real-time to the field coordinator. 00Z June 3, 1995 Composite Radar (6 pm CST June 2,1995) The first violent tornado formed just southwest of Friona, moved across the southern fringes of the community, and then across the eastside of town. It traveled for several miles further northeast to the area north of Black, TX. At Friona, a large grain elevator was destroyed. The airport was completely destroyed, with the most significant damage occurring to a large steel building. The anchor bolts holding the columns of this building were ripped out of the concrete slab, with part of the slab going with the bolts. The heavy beams were left in a twisted heap. One I-beam became a missile and was thrown about 100 meters. The cemetery just north of the airport was also heavily damaged, with trees missing most of their branches. A several-ton railroad boxcar that served as a storage building bounced through the cemetery, destroying monuments and gouging a two-foot deep hole through an asphalt drive into hard-packed soil. The boxcar traveled about 100 meters. After the Friona tornado became rain-wrapped, attention shifted to a new mesocyclone just southeast of Friona. This mesocyclone was projected to move into a region with very few roads. Another mesocyclone was developing southwest of Dimmitt, TX. VORTEX targeted that storm. At times, more than a half-dozen mesocyclones were in existence over a few-county area, making the intercept very risky in terms of choosing the 'best' storm and staying safe. VORTEX Communications Summary Dimmitt, TX, tornado; 2 June 1995 In this summary, important information communicated over the VORTEX VHF frequency is summarized. A few vital transmissions are quoted. All distances are in miles unless otherwise noted. Times in UTC. [gap] indicates that NOAA-43 internal communications made it impossible to discern the VHF radio traffic. Windspeeds and motions in kt. Editor's comments are in parentheses (). Abbreviations: BD Blowing Dust BWER Bounded Weak-Echo Region CG Cloud-to-ground lightning DV Differential velocity observed on WSR-88D FC Field Coordinator FM Farm-to-Market road GTG Gate-To-Gate velocity differential on WSR-88D MT Radar-indicated maximum storm tops N1 NSSL-1 N2 NSSL-2 N4 NSSL-4 N43 NOAA-43 N43I NOAA-43 internal communication channel RFB Rain-Free Base RFD Rear-Flank Downdraft R1..R2 R1 is OU radar teams, R2 is Mobile Radar WC Wall Cloud P1..P9 PROBE1..PROBE9 88D NEXRAD WSR-88D radar Time Src Communication (hhmmss) 003010 FC "I advise operating in the Dimmitt area" 3020 FC Inflow is E ~45 kt at this location 3125 FC WC and meso SW of Dimmitt [gap] 3315 R1 Pos 2 E of FM1624 on TX86; WC is 200-210 az. 3335 FC GTG 114 located 10 NW Dimmitt 3521 FC Operations are rather disorganized, but good data are being collected. Still targeting storm moving toward Dimmitt. 3635 R2 Loc 9 W Dimmitt 3650 FC Go for it, R2 3655 FC Core is 50 dBZ 5 WSW Dimmitt 3725 P3 At 540-186; wind 120/35-40 [gap] 3805 N43 BWER, MT 19 km, hook, ~10 SW Dimmitt 3815 FC Round, lowered base SW of Dimmitt 3855 N4 Intense updraft visible 4000 N43I "tight little hook" (storm unknown) 4030 FC Another meso is SE of Summerfield [gap] 4140 P3 In Nazareth 4200 FC Another persistent meso is near Tulia 4240 P3 R- ended as they entered Nazareth 4250 FC P3: do N-S transects at longitude of Nazareth 4300 FC 100 GTG 10 SW of Dimmitt moving from SW 4340 FC Core 7 SW of Dimmitt, 50 dBZ 4355 FC Bottom two tilts of 88D have 100 GTG 4405 N43 Hook SW of Dimmitt 4420 N1 In Dimmitt [gap] 4520 P6 Just E of Summerfield 4540 FC Meso near Summerfield has decreased somewhat 4610 FC Another meso 340/8 from Dimmitt, just SW of the bend in US385 4620 P6 Loc just N of the bend; R+; vis ~0 4635 FC P6: hold up or make a U-turn now 4720 FC Est motion from 240 on Dimmitt storm; moving toward 5-6 E of Dimmitt 4728 FC TVS SW of Dimmitt 4800 FC TVS report is incorrect; TVS is 15 SW of Dimmitt mesoscyclone on another mesocyclone. 5 mesocyclones currently in existence 4837 N43I A cloud to the east of the aircraft goes to the ground 4900 FC Baroclinic zone may be S of Nazareth; runs E-W about 5 S of TX86 based on visual obs 4915 P3 Going under E-W cloud band now 4948 P1 "Big meso to our south-southwest" 5010 FC Meso is 3-4 S of Dimmitt 5020 FC Project meso to move to about 5-6 E of Dimmitt 5102 P4 Loc 527-289; Hail up to 1" [gap] 5235 P9 3/4" hail 5245 P1 At 503-303; rotating WC immediately S 5300 FC WC is 3-3.5 due S of the center of Dimmitt 5310 R2 Loc 2 N of the WC 5315 N43 BWER, MT 19 km 5 SW Dimmitt 5345 FC Another big lowering ~10 N Dimmitt 5420 T2 At Summerfield; finished picking up turtles 5505 FC Cloud base lowering toward ground near Dimmitt meso 5510 P1 Dust, funnel nearby 220. Loc 489-303 5538 FC Funnel is 5 S Dimmit 5542 P1 Dust continues 5550 FC Projects crossing close to Nazareth based on tracking 5638 FC Clear slot all the way around WC (W-S-ENE) 5650 FC A significant tornado is about to form 5 SSE of Dimmitt 5655 N43I "Dire predictions from FC" 5705 P1 "There's rapid motion just to our SW; dust on the ground; I don't know what it's connected to" 5708 FC "We see what's a big, broad funnel-looking thing down in that same area, Probe1, with a slot wrapped around the east side of it" 5811 FC Large funnel 1/2 way to ground SE of Dimmitt 5840 P1 "FC, Probe1!" 5841 FC "Probe1, FC, we see the tornado" 5845 FC Calls P1 for 50 seconds before requesting other volunteers to give reports of azimuths for triangulation [gap] 010005 P1 At 516-303. Tornado ~1S, to W of the road, moving ENE 0032 FC Tornado is 3 S of 86, 1 E of Dimmitt 0050 FC Project a crossing near FM 2567 and TX86 0107 P6 2nd tornado is just S of them; it just formed. 0126 N43I "has a good donut now" 0136 P1 Just crossed the road ~ 1 S (US385) 0155 FC 2nd tornado is 11 N of Dimmitt 0215 N43 BWER and hook with the Dimmitt tornado 0220 FC Large, violent tornado 0247 P2 Tornado is translating slowly left to right; loc 540-162 0305 P6 2nd tornado is large, W of US385, about 2 SW of 728-343; becoming rain-wrapped 0337 P2 New rotation on leading edge of RFD ahead of the tornado 0410 P4 Wind 2524; theta-e fell 2 degrees, T=2? C 0500 P5 Tornado SSE (155) from 551-304 0543 FC Tornado will pass 4 E Dimmitt 0620 P1 Tornado ENE from 523-382. Very big. 0635 FC Tornado is 2 SE Dimmitt on TX194. 0640 P4 Just now crossing TX194 just to the north. 0730 P2 Another lowering to the NNW of the tornado 0742 P1 Tornado to the NE; very rapid rotation in the wall cloud around it 0800 FC We're in TOR-S (whew! now we all know what to do!) 0825 FC Lowering on the gust frint between Dimmitt and Nazareth [gap] 0903 P9 TX86 is impassable (why?) 0911 FC Estimated diameter 1/2 mile 0950 FC Tornado 1.5 E Dimmitt on TX86 1000 P4 Wind variable and gusty; no drop in theta-e 1033 P2 Wind direction 050; theta-e 348 1045 FC Tornado has ended its S->N translation 1107 P9 No apparent motion 1125 P9 At 526-287 1150 P4 Another WC SW 1155 FC We will commit to the Dimmitt tornado until its demise 1310 FC RFD nose 8E, 2S Dimmitt 1325 P1 Tornado seems to be moving back to the SW; loc 459-297 [gap] 1400 P1 Tornado is stationary 1410 FC Tornado 1-1.5 NE Dimmitt; stationary or perhaps drifting SW 1444 P1 Incredible motion NE 1518 P8 At 539-155; rotation forming 2 S (?) 1558 P1 Downward motion in the tornado 1620 P5 Tornado continues to the NE 1630 ? Tornado roping; very rapid rotation 1650 P8 Directly beneath rapid rotation 1720 P2 At 509-107; new rotation due west 1740 P1 Tornado roping, condensation detached 1755 FC Strong cloud base rotation 3 SW Nazareth 1805 P1 Tornado dissipated Chapter 3 continued on page 6..... 5