VORTEX-99 Status Messages from May 3, 1999

Outlook and nowcast status messages for VORTEX-99 are provided by Principle Investigators Dr. Erik Rasmussen (NSSL) and Dr. Jerry Straka (University of Oklahoma). Erik provided realtime support via cell phone when needed and cars communicated via 2m radio using allocated government frequency. VORTEX-99 is a continuation of the Verification of the Origins of Rotation in Thunderstorms EXperiment carried out in 1994 and 1995.

VORTEX-99 10:14 am RE: MM operations on M & T
If tommorrow is a go-day it will likely be delayed by a short to medium length standby (possibly 'til as late as 1 pm departure).. There are two issues at hand to contend with:

a) the MM gps are not talking stably to the new laptops...

b) the outlook for tommorrow is not clear -- though the 06 utc ruc II run gave some hints for late supercell convection possible...Also a nice day to study the dryline...

Erik will keep you up-to-date with forcasts and the final decision via e-mail. The first outlook should come out say between 9:30 and 10:00. Thank you... ---- Jerry

VORTEX-99 STATUS MESSAGE 1023 AM CDT MON 5/3/99
STATUS STANDBY UNTIL 1130 AM UPDATE FOR POSSIBLE 1230 - 1300 CDT DEPARTURE. MOBILE MESONET GPS PROBLEM MAY BE CURED; FORECAST PROBLEMS REMAIN. MM-WAVE IS PLANNING TO OPERATE.

-NOTES- 1. This message is now being posted to a WWW site. The site can be accessed from the NSSL home page, navigation bar under "Items of Interest": http://www.nssl.noaa.gov/Or directly here: http://www.nssl.noaa.gov/projects/vortex99/ E.R.

SYNOPSES... TODAY

Much improved surface moisture is in place at 12 UTC from OK southward, and advection will continue to improve the moisture. The moist layer is deep at DFW; and upper 60's to ~ 70 F dewpoints are in SC TX moving northward. Earlier worries about deep shear were unfounded. 0-6 km shear will be about 20 m/s or a bit more; upper trop flow should be around 70 kt or so. The profile will support supercell motion from about 240 at 25 kt... fairly fast. So upper trop S-R flow will be in the neighborhood of 20-25 m/s, suggesting CL storms. If the upper trop flow does not remain in the 70 kt range, but starts decreasing, we will pay close attention to the profiler network to try to find the best pockets of strong upper flow.

Today's forecast problem concerns the location of the dryline and its ability to initiate storms. It is forecast to "jump" into the DDC-SPS area by 21 UTC, which can only happen in my opinion if deep mixing develops over W OK, W TX, W KS. Deep mixing is unlikely over the higher terrain to the west because of very wet soils and the resulting cooler low-level temps. Even if the dryline gets well into OK, it's not clear to me that convergence will be very strong along it (although at the last minute I see the ETA prog of good PVA at 500 mb over the dryline in W OK this evening... not sure about the w field but this could be enough to ensure initiation). And the flow just above the surface dryline is normal to it, meaning that rising plumes of moisture will be subject to a lot of shear and mixing. Countering that worry is the nice moisture depth of the airmass coming up out of TX. All-in-all, surface and vis satellite trends will need to be monitored very closely today to refine the target. Our strategy will probably be to head SW toward the dryline, do some data collection in clear air near the dryline, and hope for initiation. By 00 UTC, the strong W US shortwave is approaching eastern NM, and winds should back across the entire region (progressing from west to east), perhaps ending chances for initiation if storms aren't going by then.

Although supercells are likely, tornadoes are not so likely (no forecast of strongly backed surface winds) unless storms can interact with other storm's outflow boundaries. The best chances will be in areas with very large low-level dewpoints and BL RH (favoring further south). Also, we will monitor for mesoscale accidents... locally strongly backed mesoscale regions.

TOMORROW (TUE) I don't have an update on TUE yet. I do note that the ETA in successive runs is slowing tomorrow's wave considerably (very evident last night). And my gut feeling looking at the jet this morning is that it's digging a little more, and a little slower, than even last night's prog suggests. If this trend is correct, it is possible that tomorrow's severe wx will begin near the longitude of OUN or even a bit further west, instead of in the Ozarks as earlier feared.

BEYOND

Tranquil, mild weather. Plant your gardens.

TARGET TODAY

#1 (still vague)
ABI-CDS-GAG-DDC-RSL-SLN-OUN-MWL-ABI
P(convection) 30%
P(severe | convection) 90%
P (any tornado *) 10%
P (sig tornado *) 8%

* Using SPC format of probability of event with 25 mi of a point; my outline would be an SPC-like probability contour at my value.

VORTEX99 STATUS MESSAGE 11:10 AM CDT VORTEX-99 STATUS MESSAGE 1023 AM CDT MON 5/3/99

STATUS GO... MEET 1215 CDT for 1300 DEPARTURE

PLEASE NOTE: MEET AT THE NSSL BALLOON BARN (there won't be time to ferry the MM's to the NSSL parking lot). ALSO: Please email Jerry (jstraka@pig.ou.edu) and tell him if you intend to participate. This will help him configure teams for today.

-NOTES- 1. This message is now being posted to a WWW site. The site can be accessed from the NSSL home page, navigation bar under "Items of Interest": http://www.nssl.noaa.gov/

Or directly here: http://www.nssl.noaa.gov/projects/vortex99/ E.R.

SYNOPSES...
TODAY {A nowcast will be issued just prior to departure}

TOMORROW (TUE)
Operations likely along dryline in OK. Possible severe weather outbreak.

BEYOND
Tranquil, mild weather. Plant your gardens. Maybe next weekend can be ruined by supercells again.

TARGET TODAY
#1 (still vague... update in 1.5 h) ABI-CDS-GAG-DDC-RSL-SLN-OUN-MWL-ABI
P(convection) 30%
P(severe | convection) 90%
P (any tornado *) 10%
P (sig tornado *) 8%

* Using SPC format of probability of event with 25 mi of a point; my outline would be an SPC-like probability contour at my value.

VORTEX-99 NOWCAST 1145 AM CDT

I have been monitoring the regional surface products at SPC. There has been a persistent, and strengthening, convergence bullseye in the SPS area. MUCAPES are > 5000 J/kg in that area and southward.

A growing/thickening plume of CI is forming over NM and advecting NE. Currently, this plume has a S edge, which appears to be near the jet maximum on the profiler network. As upper flow backs over the next several hours, this CI should head toward W OK and KS, possibly reducing insolation enough to prevent/delay initiation.

Current SPC CIN is < 25 J/kg over a large area of OK and N TX. Plugging in SW OK surface parcels into the OK sounding (p-adjusted) shows that CIN has been removed unless the lid has strengthened.

Upper trop jet is along S NM -> Purcell axis. 5-6 km winds may be > 50 kt in about 3 h along this same axis or slightly southward. In addition, 3 km profiler winds show strong WSW flow developing over W TX.

The feeling here is that the veered winds ahead of the dryline are reducing the moisture convergence over W OK. The convergence zone is well ahead of the dryline as indicated in the surface winds and MCON plot from SPC.

VORTEX-99 will be heading SW on I-44 shortly toward the SPS area, where the best CAPE, least CI, and strongest MCON are. Options back to NW will be kept in mind in case the area to the south of the developing jet experiences so much subsidence that it remains capped.

Cu

VORTEX-99 NOWCAST
I am analyzing a true dryline from GLD - E BGD - W LBB - E MAF. With some cooling aloft and continued slow warming at the surface, I expect this feature to move to the east edge of the Caprock/elevated terrain, but not much further.

I am analyzing a west edge to the deep moisture HLC-DDC-E GAG- Erick- Spur.

I am not seeing pronounced convergence anywhere along either of these features. I think we're very close to initiation, but there is no strong focus at the surface.

Something else has caught my eye... a very strong jet at 6+ km has moved into NM and W TX on the 18Z profilers. Winds are 70-80 kt and VERY diffluent across W TX and E NM, with the diffluent axis from SW LBB to around Erick, expected to shift slowly SE with the falling heights through the afternoon.

I still like the best CAPE, MCON, sunshine, lack of CIN in the SPS area. In N OK the upper flow right now would not even support supercells, let alone HP (30-40 kt upper trop). This will change rapidly over the next 6 h however.

SPC surface MCON last updated 16Z. HUBCaps 18Z moisture convergence still bullseyes near SPS. This many-hour persistence max is probably the best bet for initation. (NOTE: Howie just pointed out to me that this max _may_ be spurious owing to a suspciously backed ob in N TX. Eyeballing the surface map, I see that ADM is similarly backed, but Howie may be right about this bad ob messing up the analysis)

I have no idea what VORTEX99 is doing. They last called an hour ago and have not called back. Eri*

VORTEX-99 NOWCAST/STATUS
An echo has been cycling near Crowell, TX for the last 30 min or so. It briefly reached 45 dBZ at 1515 CDT. It is very strung-out E-W, suggestive of an LP-type CB.

Backing is evident in surface winds across the SW 1/4 of OK at this time.

Teams are headed toward the SPS area with options to work SW OK as well. Eri*

VORTEX-99 STATUS 1545 CDT
STATUS The armada is now just S of Lawton, and observing a small new CB NE of Grandfield. It does not yet have good structure. They will now "hang out" in the area just SW of Lawton and let one or two storms become a bit more interesting before intercepting.

Erik

VORTEX-99 STATUS/NOWCAST 1610 CDT
The armada is at Geronimo OK (S of Lawton) observing very strong CB growth W and SW, with very hard anvils and light rain.

OK mesonet shows a band of backed surface winds from S of ADM to the Lawton area.

The teams are going to continue to watch for one storm to become dominant. Erik

VORTEX-99 STATUS
TORNADO! The Armada is intercepting a tornado at close range approx 2 E of Apache OK at 1720 CDT

Erik*

VORTEX-99 STATUS
URGENT REPORT I cannot reach NWS... their phone number is not avble from CO.

At 1734, the armada is reproting a tornado doing a lot of damage, lofting large debris...

0.5 mi WNW of lat 34.96N 98.26 W (decimal degrees)

Someone in Norman plz convey this to NWS

Thanks Erik

VORTEX-99 STATUS
2nd tornado forming; first has dissipated

The armada has observed a possible brief large cone tornado 2.5 NNE of Cement at 1751 CDT. At this moment it is a large rotating wall cloud; not a tornado. Condensation is occasionally to the ground.

Erik

VORTEX-99 STATUS
Large tornado W of Chickasha

VORTEX99 is intercepting a large tornado at this time (1800 CDT) to the west of Chickasha, OK.

Erik

VORTEX-99 STATUS 1844 CDT
The armada is now heading for Anadarko; there is an intense near-ground meso SW of town.

The pursuit of the Chickasha storm ended at a point where the road was so clogged with debris that a bulldozer will be required to clear it. I do not know exactly where this damage path is.

erik 1844 CDT

VORTEX-99 STATUS
STATUS and request for obs/video/photos

All chasers,

For our research, we will need extensive documentation (esp. photographic) of the supercell from Lawton to Chickasha, and the storm from SW of Anadarko up to E of El Reno. Several tornadoes were intercepted on these supercells by the mobile mesonet. More details to follow in the next several days. For tonight, please scribble down notes or transcribe tapes while your memory is fresh.

ATTM the status of the MM teams is still unknown, but it is possible that there are no easy routes to Norman from the NW across the several damage swaths.

FYI... Neal Rasmussen (my brother) intercepted both of these storms and obtained video and large-format still photography of both. His video is being uploaded on the Fox network right now. One of the more interesting segments apparently has one tornado rotating around a larger tornado, a la Allison???

Erik

VORTEX-99 STATUS
Jerry Straka is home; I have spoken with him by phone. Absolutely amazing tails of TORNADO ALQDS, etc. And, from what I gather, unprecedented mobile mesonet obs of tornadoes, all sides, at various ranges. Amazing obs too numerous to mention. I've asked Jerry to post when he has a chance and fill everyone in.

I will try to get some sort of forecast out by around 0930 CDT tomorrow; with the STATUS MESSAGE at 1030 CDT.

Erik