VORTEX STATUS MESSAGE AND FORECAST DISCUSSION NATIONAL SEVERE STORMS LABORATORY 1130 AM CDT APRIL 29 1995 OPERATIONAL STATUS AT 1130 CDT: GO TARGET AREA: SErn OK and NErn TX SUPPLEMENTAL SOUNDING/ARCHIVE II REQUESTS: 18Z and 21Z spe- cial soundings at MAF and FWD, Level II archive at KTLX, FWD and KFDR DAILY FORECAST DISCUSSION: Situation as analyzed here looks pretty much as described in the morning SELS AC. A shortwave trough moving through the basically zonal flow has produced an MCS overnight with an associated outflow boundary that has been moving southward across OK this morning. That movement has been slowing down and the boundary will end up in southern and southeastern OK this afternoon. A cold front has moved into northwestern OK this morning and a dryline trails south-southwestward from the surface low in southwestern OK. Enough cold advection is seen to expect the cold front to continue to advance to the southeast today, but it should slow down. High mid-tro- pospheric lapse rates and sufficient moisture are present to yield CAPES in excess of 2500 J kg-1. Strong turning of the hodograph, even with the decay of the nocturnal "jet" should give helicities of at least 300 J kg-1, so supercells are a reasonable bet. 700 flow is increasing, at least according to the 12Z RUC H700 height gradient. Big question is the speed of the flow in the upper troposphere. It appears that by this evening, there should be 55-65 kts at H300 somewhere in the vicinity of the Red River, which ought to be just enough to prevent storms from being excessively outflow dom- inated. Storms should develop near the surface low in the vicinity of the cold front-dryline-outflow boundary inter- section and move relatively slowly for April. Tomorrow looks promising as well. The NGM and ETA differ as to the details ... which often are critical ... but it appears that the surface low and associated boundaries is not going very far from today's positions and the H500 progs show an increase in the flow and a significant shortwave trough affecting the area tomorrow. As always, a big ques- tion are mesoscale boundaries associated with today's action but will have to wait and see about those, of course. Doswell/Crisp PROBABILITIES OF OCCURRENCE IN VORTEX OPS AREA THRU 04Z (DAY1) AND 12-04Z (DAY2)... DAY1 DAY2 LIGHTNING 95 80 SEVERE 80 70 TORNADOES 40 30 TARGETABLE STORM 70 60 FCST STORM MOTION - TARGETABLE STORMS ONLY PRE-SUPERCELL 270/25 270/30 SUPERCELL 315/15 300/20 FCST INITIATION TIMES (LT) - TARGETABLE STORMS ONLY LIGHTNING 1545 1600 1ST SEVERE RPT 1630 1645 1ST TORNADO 1645 1715