May 17, 2000 Brady Nebraska F3

The Chase:

After chasing a tremendous late evening supercell near Torrington , Wyoming the night before, we prepared for a more active severe weather chase in Central Nebraska Wednesday May 17th. The forecast models were very persistent in developing an intense surface low over southwest Nebraska , and a very strong (negatively tilted) mid-level shortwave lifting from southwest Kansas /eastern Colorado into northern Kansas and Nebraska Wednesday afternoon. A tornado outbreak looked likely, but as we noticed Tuesday, the strong cap was going to be the critical factor. If a weaker cap was in place, then the likelihood of a major damaging tornado outbreak was great. However, if the cap was going to be of the very strong, then the focus of our chase was going to have to be aimed at where the strongest forcing was going to setup, closer to the surface low.

Based on the strength of the shortwave, we believed initially the cap was going to break violently resulting in several explosive supercells. A moderate risk was forecast by the SPC ( Storms Prediction Center ) for much of Nebraska , central and eastern Kansas , northwest Missouri , and western Iowa . The mention of very damaging tornadoes was listed, especially across Nebraska , and northern Kansas . We left Torrington , Wyoming early in the morning and headed to get to our target area by late morning just in case of early development. Our initial target area was going to be the area between Kearney , Nebraska and Concordia , Kansas . This area was in the left front quadrant of the jet, and where the 850/500 mb jets were in balance. Also, this area would have incredible convergence ahead of the surface low. A very interesting note from the previous day's chase-the majority of the upper support was remaining further to the west across the High Plains, and this was a sure sign that Wednesday's main action was going to be further west than the forecast models were showing. It also indicated that the cap was going to be a lot more of a factor. We did not recognize this at first, but as the day progressed, it became very clear as to what was happening.

We made great time in getting to the Kearney , Nebraska area on I-80. Along the way, we noticed very strong warm air advection in the Ogallala, Nebraska area. Heavy drizzle and dense fog was seen between Oshkosh and Ogallala. In fact by the time we reached Ogallala, we had a ripping fog back heading west as 20-35 mph winds were blowing the very dense fog westward. This was one sure sign that things were setting up further west than the models were showing. In fact (hindsight) this should have alerted us that the probability of tornadoes was going to be as far west as the Nebraska/Colorado area near the deepening surface/850 mb lows. We were impressed by how deep the warm advection was. At the surface, winds were due east, and up above the clouds were racing west-northwest. Again in hindsight, if this area could get any heating, the tornado potential would be very high. Air temperatures were in the mid 60's with matching dew points, so there was plenty of fuel for supercells in the High Plains. By the time we reached I-80, the air temperature had risen to near 70 degrees, and there were some breaks in the cloud deck/precipitation that would make the sky very bright almost blinding at times.

We headed east on I-80 towards central Nebraska and our target area. The further east we traveled, the scarier the sky looked. Very large breaks in the clouds started occurring near North Platte , and the air temperature jumped into the lower 70's. The dew point also was higher the further east we went on I-80. I was very concerned that the North Platte area would be primed for supercells too, and I mentioned this to Brian. He agreed with me especially with the deep east flow at the surface and lower levels. To see heating already at North Platte was certainly sign that things were going to be pretty nasty later in the day. The west edge of the moderate risk was along a line from McCook-North Platte-Mullen Nebraska , and this surely represented the far west edge of low-mid 60 dew points. We had quite a discussion about the North Platte area being an interesting area later. We decided eventually this area may get pinched off from the instability, similar to what situation had occurred on April 8, 1999 when another extremely deep surface low was over Nebraska . The April 8th southwest Iowa tornado event sure gave us some pointers on how to deal with these super deep surface lows. This helped us later in the chase that's for sure!!

The weather was in a rapid spin mode by late morning. A very deep surface low (29.20in) was located near Akron Colorado with a sharp warm front located east to near Concordia , Kansas , and double dry line situation developing over western Kansas . The forecast models all showed the surface low was going to deepen even further (gulp) and move towards south-central Nebraska (uh-oh). Major tornadic supercells appeared to be very likely across southern Nebraska and northern Kansas . One thing for sure, today was going to be rapidly changing and the tendency for instability wrapping westward north of the surface low was also going to be quite likely. We planned to head to Elm Creek , Nebraska to a truck stop that we went to last June to call up weather data. This was a great place because it had tables, phone jacks, eats, and gas (not related to the eats). This stop was also very near our target area on I-80, with good roads in all directions. We pulled in around 11:30 a.m., and already we saw a few chasers congregating. Later the chaser city would grow to nearly 30 at the truck stop! I had a very hard time getting a good connection, but the data I was able to pull up, showed that the cap was extending northbound from Kansas . Not good.

Chasers from all over soon gathered around trying to get on the web to pull up weather data. This was certainly a critical time for forecasting. As we struggled to get connected, the warm front over Kansas started to bow north, and would soon surge up to I-80. We knew this was both good and bad for later supercells. Good because it would get the warm front into a less capped airmass allowing for storms to erupt. The bad thing was the cap was northbound and this might possibly cap off all of Kansas and a big area of Nebraska , particularly if the warm front gets deep into Nebraska . Oddly enough (more hindsight) this situation was favoring the North Platte area even more since the cap was increasing over central Nebraska . The focus would now be west-central and southwest Nebraska where the mid- level cooling would be the strongest and able to break the cap. The shear out there would also be very strong. The majority thinking among chasers was that the cap would give way across south-central Nebraska and north-central Kansas as the negatively-tilted shortwave pivoted northeast. Jeff and I were also in agreement, but we also had in the back of our minds, that the McCook and North Platte areas may also be in great danger today. An earlier discussion with Steve Nelson ( Tulsa NWS) also helped us a great deal in considering the McCook-North Platte scenario. This made sense because it would be less capped and in the area of extreme forcing. This region would definitely be at the nose of the left front quad of the mid level jet. At any rate, we decided the best option was to hold near Holdredge in case of the cap breaking over north-central Kansas . Conditions (other than the strong cap) looked very favorable for strong tornadoes over south-central Nebraska . One item of interest that was occurring while we waited for the storms to pop. Warm air had wrapped around the north quadrant of the surface low and several tornadic supercells were forming over Morgan , Washington , and Yuma Counties in northeast Colorado . Numerous tornadoes (some damaging) were reported on the ground there. See Rich Conns' article.

We pulled over near the Furnas/Kearney Co. line in south-central Nebraska , and were later joined by other chasers. A tornado watch soon was issued by the SPC and a few damaging/destructive tornadoes were mentioned. The tornado watch was for Nebraska only, but they did advise that a tornado watch was also to be issued shortly for Kansas as well. As we waited(and waited) for storms to erupt, the surface low was moving northeast towards the McCook, Nebraska area. It was starting to "bomb-out" so it was only a matter of an hour before things got really bad for the general public across Nebraska and Kansas . A dryline bulge was very evident on satellite and surface data from the Imperial, Nebraska southeastward to near Hill City . Towering cumulus formed along the dryline that was starting to surge northeast right for us. Gundgy premature convection had fired over Kansas and the remnants were in the process of moving out as the mid-level winds strengthened. Fortunately, the cap crushed this premature stuff, otherwise it may have ruined the airmass everywhere with rain-cooled/stable air. The thermal ridge was aimed right for us and extended from near Garden City, Kansas to between McCook and Hastings , Nebraska . We were in the favorable northeast quad of this ridge, but were also capping off even more. After reviewing the data after the chase, the 850mb winds were veering majorly during the afternoon all across Kansas and central and eastern Nebraska . This was allowing the hot cap air to advect into our location.

We watched the skies clear out rapidly as the a strong southwest jet moved in. Air temperatures skyrocketed from the mid 70's under the gundgy canopy of leftover cloud debris, to the mid 80's between Hill City , Kansas and our holding spot. Two areas started to hint at developing convection. A few small storms began to develop along the dryline bulge

from Imperial, Nebraska to northeast of Goodland , Kansas . Meanwhile, towering cumulus quickly started to form on the warm front that was aligned southwest-northeast. We watched the storms closely on radar (finally connected). The storms to the south formed quickly, and the storms over southwest Nebraska slowly back built down the dryline into northwest Kansas . Both areas developed slowly, with the more rapid storm development about 20-30 miles south of us. Initially, the storms closest to us looked great. Very diffluent anvils, vertical storm towers, and inflow bands. However in the span of about an hour, these storms went from about an 8 to about a 2 on a scale from 1 to 10 with 1 being poor. Apparently the cap had this area under control, and the strong mid-level winds very quickly ripped the main updrafts apart and pushed the storms to their demise. Interestingly enough, the storms over southwest Nebraska did not have that problem. Immediately the warning bells went off to both Brian and I. Get west and get on the uncapped storms or BUST!!!

We grabbed one last radar image off the Goodland radar, and it showed the storms were holding their own. The most interesting storm to us was a small but highly sheared storm developing near Oberlin , Kansas . This storm already had signs of rotation and was on the dryline bulge immediately northeast of the intense surface low. After getting things organized, we headed west on U.S. Highway 6 towards McCook. The track was going to be well east of McCook so we figured an intercept near the town of Cambridge . Actually, we would luck out on this intercept. There was another already severe storm on the Kansas/Nebraska border moving into Red Willow County , Nebraska . Hail up to golfball sized had been reported. In this type of situation, you have to react to ongoing/sustained convection or completely bust. As favorable as the conditions may have appeared initially, things were now a lot more harsh and negative for supercells anywhere away from the dryline. The cap had surged in and squelched any hopes for at least tornadic supercells over Kansas and south-central and southeast Nebraska . We passed through Arapahoe, Nebraska and saw many chasers pulled over watching the small but intense dryline storms. A new severe thunderstorm warning was issued for the storm we targeted. Meanwhile the storm closer to Mc Cook had slowed down. I think we found the jet split! Jeff and I high fived after seeing this on the radar. Now it was time to watch these closely, very very closely!

As we closed in on the town of Cambridge , Nebraska on the Furnas-Red Willow Co. line, we had both storms bases within view. The northern storm had a fairly large updraft vault and was located about 3-4 miles west-southwest of Cambridge . The southern storm was very small, but was visibly rotating even from 8-10 miles to it's north. As with most situations with two storms in very close proximity to each other, you have to remain alert for the possibility of either a cell merger or the southern storm taking over and stealing all the inflow. We could see the large hailshaft to our west, and also started to get hailed on by the southern storm with dime-sized hail. From this point on, we lost our cellular connection and had no weather data. We listened to a good radio station out of Lexington , Nebraska that kept us informed of warnings. We pulled over for some pictures and video west of Cambridge . The cloud bases were still high, but we could see that there was some lowering of a developing wall cloud near Bartley to our northwest. This separate supercell situation continued as both lifted northward. We positioned ourselves in between the two storms and took a dirt road north to Strunk Lake . This would allow us to watch both updrafts but also would put us under the rain/hailcore of the southern storm. Both storms were now officially severe as new warnings were issued. Hail larger than golfballs was possible with the northern supercell. I classify these as legitimate supercells at this point as the bases looked to be rooted in the boundary layer now.

We progressed north with the storms and with the help of the De Lorme Nebraska Mapbook, were able to maneuver through the rural roads without losing sight of both updraft bases. We also saw a group of locals chasing near the lake. They went on west for some reason, but the storms continued to move north, possibly a little northwest at 30-35 mph. Both storms looked just like big hail storms at this point, although the southern storm had strong rotation at mid-levels based on the laminar striations. Item of note: the southern storm eventually went on to produce the Brady F3 tornado, and visually, it had the best look of rotation the whole time.

We tracked across the open country into Frontier County finally getting our first golfball hail thuds on the car. Almost the whole time we were getting rain/small hail from the southern storm up to this point. We pulled over to watch both storms again. Both were strongly rotating supercells now. In fact the storms were becoming almost aligned side by side (east-west). The now western storm was developing a large substantial wall cloud with cloud tags/scud underneath. The eastern storm had tendrils of mid-level vortices spinning around the north side of the updraft tower that was becoming barrel shaped and very laminar. We decided to head into Stockville (Frontier Co.) to get a road option north. A tornado warning was issued for a storm we could not see about 10-15 miles northwest of the Stockville supercell. We figured that if that storm was ready to produce a tornado, the storms we were watching would soon too. We had both in sight so if one supercell did become tornadic, we could see both at the same time. The roads were very muddy and tricky as far as driving, but at this stage of the game you have to stay with the updrafts. The two storms were continuing to organize and develop mature circulations.

North of Stockville, we started to notice large amounts of hail on the road. Quarter-sized hail mostly, but a few golfball-sized hailstones were on the ground. We figured that this fell from the western supercell since we were slightly ahead of the hail core from the eastern supercell. We continued north and noticed that the western storm was starting to cycle, or in better terms was about to drop a tornado. A very powerful rear flank downdraft plowed into the updraft, and numerous small circulations developed under the udraft. Some were very strong cyclonic, but the strongest were ANTI-CYCLONIC. These ringlets spun madly, and the town of Moorefield looked to be very near this violent rotation. We started noticing copious amounts of hail (mostly golfball size) on the road as we came into the town of Moorefield ( Lincoln County ). A tornado warning was issued for Lincoln County for the two circulations.

One circulation was to our northwest near Wellfleet, and the other was our storm near Moorefield. Moorefield residents were outside looking for what just hit them, an occluded circulation to the northwest of Moorefield. This was immediately west of where the RFD plowed into the storm and scalloped out the supercell's back side/south side. Very strong rotation was seen on this occlusion about three-to four miles north-northwest of Moorefield. Very quickly, a fairly wide but weak (F0) tornado came down to the ground to our west. It started with a large/broad funnel cloud, and quickly corkscrewed to the ground. The tornado remained pretty much stationary and was soon joined by another weak tornado to it's south. There were now two tornadoes on the ground and violent cloud motions above the tornadoes. Was another going to make a hat-trick? As rapid as the cloud motions were, this sure seemed possible. Another tornado tried to come down but was absorbed by the initial tornado. The tornadoes remained a pair until dissipating five minutes later. Okay now things were getting very interesting! We still watched the eastern supercell that was now growing larger, but was still nearly all rotating updraft. It was spitting golfball hail on us as we watched the western supercell's tornadoes. I guess you could say it was a notecard saying "What about me?". We directed our attention closer to that storm.

As it stood, were down to one road option through some very rugged canyon lands between Moorefield and Brady. Since the storm movement was still north, and more tornadoes were imminent, we took the road. Basically, the supercells traveled right up that road. One supercell was about three-to-five miles west of the road, and the other was about two miles east of the north-south road. Talk about a chasers dream. Only one thing might make it a nightmare though. The eastern supercell was becoming meaner and we drove through continuous hail between Moorefield and the Jeffrey Reservoir. Most of the hail was tolerable (quarter size), but as we got further north, large amounts of golfball and baseball-sized hail pounded us on northwest of the large barrel shaped updraft (eastern supercell). At this stage of the chase, you just have to gut it out and keep going!!

Both supercells had long inflow bands and we could see very violent cloud motions above us. Tornadoes looked certainly likely. The western supercell cycled again as we got blasted by 70-80 mph south RFD winds. As we got to the crest of a hill, we could see a large cone tornado coming to the ground to our southwest. There was a hilltop that it had set down on and large amounts of soil/debris were being lifted. No doubt it was a strong tornado, because our winds started abruptly switching to the northeast and gusting. I do believe this is first time I have ever seen 70 mph RFD winds back all the way to the northeast and gust at the same velocity. Jeff and I are sure the other supercell had an effect as well. About two miles east of the road, I saw some finger-like vortices forming under the updraft. This was a very serious situation now, especially with the increase in the amount of baseball-sized hail. We were pounded extremely bad by the hail but somehow avoided losing the windshield. We lost sight of the western supercell/tornado, but I quickly mentioned to Jeff that the eastern supercell was about to drop a big tornado. Very laminar collars were seen up the north side of the updraft now, and horizontal vorticity tubes were knifing into the updarft. Exciting times were starting to unfold right in front of us!

We approached the Jeffrey Reservoir area with caution as the hail increased in intensity. Little did we know that immediately east of the road through Conroy Canyon a developing strong tornado was about to touchdown. We passed the reservoir dam area, and could see alot of rapid cloud motions overhead and to our east. As we turned to go east on Brady Road., the tornado quickly started to organize. We were due north of the tornado that was developing over the rough terrain on the Platte River bluffs. About a mile east of the dam at an intersection, we pulled over for one of the best tornado spectacles we have ever seen. Our timing could not have been any better as the truncated cone started to come down to the ground about six miles south-southeast of Brady in eastern Lincoln County Nebraska. It was 5:15 p.m. when the Brady tornado officially came to the ground. Jeff called 911 to warn them of the tornado and that it may affect the town of Brady. Jeff and I scrambled out towards the road to get an unobscured view of the tornado that was approaching from the south. The width of the tornado grew from about 100 yards to over 300 yards wide as it moved into the valley. At first, we were in the direct path of the tornado, but the diffluence took over and directed the tornado to the northwest! We were safe from the tornado, but not from the inflow jets and occasional baseball hail that pounded Jeff and I in the neck and back. I even had some welts on his back from the hail. Winds were rapidly on the increase, with gusts to 75 mph. The tornado was about a mile to our south and heading right for the Jeffrey Reservoir dam. Power line "pops" were seen as it moved across the open field, and into some high tension lines. I was doing the video and Jeff was clicking of pictures like mad!

The tornado close encounter grew even more up close and personal as the winds roared from the east-northeast with gusts well over 80 mph. The tornado passed within 1/2 to 1/4 of a mile from us. The utility poles were beginning to lean hard to the north as the tornado plowed across the open field. The width of the tornado was continuing to increase and was over 400 yards across. Based on the appearance, the tornado was likely in the strong F2 to weak F3 range as it moved just east of the dam. The unmistakable roar was heard as the tornado moved to the northwest. Several farmsteads were hit by the tornado as it moved out of the bluffs into the valley. Large debris was picked up as it hit these homes and farms. We continued to hold our position as the tornado crossed Brady Road and moved towards the Platte River. It was at this point, when the tornado maxed out. The width was now approaching 1/2 mile, and large amounts of soil and now water were being drawn up into the vortex. This made the color of the tornado change to a brown and white swirl. This very interesting "blend" of colors made for some spectacular shots of the tornado that was moving away about 1.5 miles from us. We continued to shoot pictures and video, but also stood there in awe as this strong and impressive tornado crossed the Platte River valley. Interesting note: as the F3 tornado and the inflow jets moved away from our location, the loud roar had subsided, and we could no longer hear the tornado. Up until this point we could hear the impressive roar. This maybe something to be researched in the future.

The contrast of the tornado was starting to lower so we packed up quickly and headed for I-80. The tornado was moving northwest and west towards the town of Maxwell. The town of Brady was spared from the tornado, but Maxwell was now in the path, as was the rest area on I-80. We made it to I-80, and lots of weekday traffic was present. A few motorists had heard the warning apparently and had pulled over. Many did not seem to notice the tornado about 1-2 miles south of the highway. We were surprised to see how many motorists were still on the road. We could see the rest area about two miles to our west, and lots of people were stopped there. As the tornado moved west-northwest, it looked like this rest area was going to be hit. We continued west, and the tornado starting to weaken slowly. The tornado eventually shifted to more westerly component as the rope stage was beginning. Fortunately this happened before it approached that crowded rest area. We watched the dramatic rope stage start about two miles to the south of I-80 very near the Platte River. Ironically the tornado dissipated very near the Fort McPherson National Cemetery. The last sign of the tornado was a thread vortex that disappeared under the shearing out wall cloud. This was yet another chase where we watched the tornado from start to finish, only this time it was from a close perspective!

We pulled over and watched the dissipating tornado, and watched a new tight circulation form about a mile to our east. This circulation formed just as the Brady tornado dissipated. We watched this closely, but it apparently moved north into cooler more stable air. We decided this one did not appear that it was a threat, even though a tornado warning had been issued for this newly developed circulation. We followed it for about ten minutes, but it had the sign of gusting out so we called it a chase. Just then, we started to see many other chasers, some of which were with us southwest of Holdrege. We were fairly well blitzed by the intensity of the chase, and decided we had best get the video to the Weather Channel so it could be fed by satellite to the other media outlets. We knew our video was good, but later on could not believe some of the shots we actually got. The media frenzy was on and we had a long drive back to Tulsa which would put us into town by dawn the next morning. The media frenzy rolled on all day long Thursday with multiple national media interviews and zero sleep. I even had to work that day...so that much needed sleep did not happen until about 10pm that night. This means that I have been awake since Wednesday morning around 6:30am or about 39 hrs. straight.

Edited Aug. 7, 2006...very few changes needed on this wild but enjoyable chase.

SPC Day 1 Severe Wx Outlook - 1630z

‑MKC AC 171643
STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK
DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWBC.
VALID 171630Z - 181200Z

THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF CENTRAL/ERN NEB AND
CENTRAL/ERN KS TO THE RIGHT OF A LINE FROM 10 S JLN BVO 30 S ICT 35
N HLC 15 W LBF 10 S MHN 20 WSW ANW 20 NW OFK 25 E OMA 30 N STJ 50
SSE OJC 10 S JLN.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM
30 ENE SEP 40 NE ABI 25 WNW SPS 35 ESE CSM 30 NNE P28 15 SW RSL
20 W HLC DEN 10 SSW LAR 40 SE 4DG 35 SSE PHP 10 W HON MSP
30 NE MSN 50 NNW LAF 25 NE HUF 25 NNW EVV VIH 10 SSW SGF MKO
10 ESE DUA 30 ENE SEP.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 85 SSE MRF
30 SSE CDS 35 WNW CSM 45 NE DDC 35 SSW HLC GLD 40 SSW FMN 60 S SGU
TPH 40 WSW U31 40 NE WMC S80 50 NE 63S ...CONT... 50 NW HVR LWT
65 ENE BIL 20 ESE Y22 30 SSE IMT OSC ...CONT... MSS 35 WSW GFL
15 NE POU ISP ...CONT... 10 E JAX ABY MSL 40 N MEM 60 E FSM ACT
DRT.

...SEVERE THUNDERSTORM FORECAST DISCUSSION...
SATELLITE IMAGERY SHOWS UPPER LOW NEAR THE UT/CO BORDER MOVING EWD
IN RESPONSE TO UPSTREAM SHORT WAVE TROUGH MOVING ONSHORE ALONG THE
PACIFIC COAST. STRONGEST WINDS ALOFT OVER THE SRN ROCKIES ARE
FORECAST TO SPREAD ENEWD ACROSS OK THIS AFTERNOON AND CONTINUE INTO
THE MIDDLE MS VALLEY TONIGHT. DEEP SURFACE LOW OVER ERN CO WILL
MOVE TOWARD SWRN NEB THIS AFTERNOON...THEN IS FORECAST TO FILL
TONIGHT AS IT MOVES EWD ACROSS SRN NE. COMPLEX SERIES OF EAST/WEST
ORIENTED BOUNDARIES EXTEND EWD FROM THE LOW ACROSS PARTS OF THE
CENTRAL PLAINS...WITH MODELS SUGGESTING PRIMARY SURFACE WARM FRONT
WILL BECOME ESTABLISHED ALONG THE KS/NEB BORDER INTO NRN MO THIS
AFTERNOON. DRY LINE EXTENDING SWD FROM THE LOW INTO WRN TX IS
EXPECTED TO BEGIN ACCELERATING EWD THIS AFTERNOON IN RESPONSE TO
BOUNDARY LAYER MIXING AND INCREASING SWLY LOW LEVEL MOMENTUM AS
MID/UPPER LEVEL JET STREAK MOVES TOWARD OK.

...KS/NEB AREA...
VISIBLE IMAGERY SHOWS CLEARING SPREADING NEWD ACROSS NWRN TX/ERN CO
INTO WRN KS AND SWRN NEB. THIS WILL PERMIT STRONGER HEATING TO
SPREAD NEWD ALONG THE DRY LINE THIS AFTERNOON WITH ADDITIONAL
DESTABILIZATION EXPECTED NEAR THE WARM FRONT/DRY LINE TRIPLE POINT.
12Z SOUNDINGS SHOW VERY STEEP MID LEVEL LAPSE RATES ABOVE THE LOW
LEVEL CAP...WHICH IS LIKELY TO WEAKEN THIS AFTERNOON AS DYNAMIC
COOLING OVERSPREADS THE AREA FROM THE WEST. IT APPEARS THAT ETA
MODEL IS CONTINUING TO EXCESSIVELY DRY THE LOW LEVELS AHEAD OF THE
DRY LINE...AND CURRENT TRENDS SUGGEST THAT LOW LEVEL MOISTURE WILL
BE SLOW TO DIMINISH BENEATH CLOUD SHIELD OVER THE CENTRAL PLAINS
WITH SURFACE DEW POINTS IN THE MID 60S PERSISTING THIS AFTERNOON.
THIS WILL CONTRIBUTE TO STRONG INSTABILITY WITH MUCAPE OF 2000-3000 J/KG
THUNDERSTORMS ARE EXPECTED TO REDEVELOP BY MID AFTERNOON ALONG AND
NORTH OF THE WARM FRONT OVER PARTS OF NEB WHERE LOW LEVEL
CONVERGENCE AND WARM ADVECTION WILL BE MAXIMIZED. ADDITIONAL
CONVECTION IS EXPECTED TO DEVELOP SWD ALONG THE DRY LINE IN KS
WITHIN LEFT EXIT REGION OF MID/UPPER LEVEL JET STREAK. WINDS ALOFT
ARE FORECAST TO BE STRONG AND VEER WITH HEIGHT INDICATING FAVORABLE
POTENTIAL FOR SUPERCELLS TO DEVELOP. LARGE HAIL AND DAMAGING WIND
GUSTS ARE LIKELY WITH STRONGER CELLS. IN ADDITION...A FEW TORNADIC
SUPERCELLS ARE POSSIBLE NEAR THE WARM FRONT AND DRY LINE INTO THE
EVENING HOURS. ACTIVITY IS EXPECTED TO SPREAD ENEWD TONIGHT WITH
A CONTINUED THREAT FOR HAIL AND DAMAGING WIND GUSTS.

...OK/NRN TX...
ELEVATED CONVECTION IS MOVING NEWD ACROSS THIS AREA AS STRONG CAP
REMAINS IN PLACE ACCORDING TO 12Z SOUNDINGS. PRIMARY CONCERN
CONTINUES TO BE EVOLUTION OF LOW LEVEL MOISTURE FIELD...WHICH IS
FORECAST BY THE 12Z ETA TO DIMINISH RAPIDLY TODAY. AGAIN...IT
APPEARS THE MODEL IS DRYING THE LOW LEVELS TOO QUICKLY AHEAD OF THE
DRY LINE AND THERE REMAINS THE POSSIBILITY OF SURFACE-BASED
CONVECTIVE DEVELOPMENT ALONG THE DRY LINE THIS AFTERNOON IF SURFACE
DEW POINTS REMAIN IN THE 60S. ALTHOUGH IT APPEARS THAT CONVECTIVE
DEVELOPMENT WILL REMAIN ISOLATED AT BEST...VERY FAVORABLE WIND
PROFILES INDICATE POTENTIAL FOR SUPERCELLS TO FORM WITH THREAT FOR
LARGE HAIL...DAMAGING WIND GUSTS...AND ISOLATED TORNADOES. SEVERE
THREAT WILL CONTINUE INTO THE EVENING HOURS WITH WEAKENING OF
STORMS EXPECTED AFTER DARK.

...ERN SD ACROSS SRN MN/NERN IA...
ISOLATED SMALL CLUSTERS OF ELEVATED STRONG/SEVERE STORMS HAVE
CONTINUED THIS MORNING WITH OCCASIONAL LARGE HAIL/STRONG WIND GUSTS
REPORTED. STORMS MAY CONTINUE INTO THE AFTERNOON ALONG NRN/ERN
EDGE OF UNSTABLE LAPSE RATES WITH CONTINUED POTENTIAL FOR ISOLATED
SEVERE ACTIVITY.


..WEISS.. 05/17/00