VORTEX STATUS MESSAGE AND FORECAST DISCUSSION
NATIONAL SEVERE STORMS LABORATORY
1130 AM CDT APRIL 19 1995


OPERATIONAL STATUS AT 1130 CDT: GO
TARGET AREA:  NORTH TX  
SUPPLEMENTAL SOUNDING/ARCHIVE II REQUESTS: SELS has reques-
ted 18Z soundings at AMA,OUN,FWD,SHV,MAF,DRT,CRP.  VORTEX
requested 21Z soundings at all the sites in the VORTEX ops
area.  Level II archives at FWD, LBB, DYS, KFDR are likely
to be very important. 

DAILY FORECAST DISCUSSION:

Interesting situation, with a lot of positives and some neg-
atives.  Positives include increasing instability, with 700-
500 mb delta-ts having increased markedly overnight, as H500
cooling and H700 warming has occurred in advance of the sig-
nificant short wave trough over southern AZ at 12Z.  Progs
show a mixed bag of expectations.  Looks like a compromise
among them will have the vort max entering west TX at about
00Z and a surface low somewhere near ABI, with a strong dry
push developing south from the surface low.  Very strong
winds through most of the troposphere and backed low-
level winds even south of the surface boundary in north TX
bode well for helicities today.  With increasing moisture in
south easterly flow in southeast TX, expect significant CAPE
values as upward motion continues development of hi lapse 
rates, perhaps as high as 2500-3000 j kg-1.  Helicities in
the 400-600 j kg-1 range are also possible.

Some problems:  in order to put good storms in the VORTEX
ops area, the surface boundary has to give way and retreat
some towards the Red River.  The pesky northeasterly winds
and cool temperatures in central TX seem to be relenting by
16Z, so this may be all right.  Another issue is the cap.
In order to keep the warm moist air at low levels moving 
northward, convection should be suppressed as long as pos-
sible ... it appears so far to be held in check.  The cap 
then needs to be broken, preferably in the vicinity of the
dryline, to get good storms up.  It appears with the vigor-
ous trough approaching that the latter will happen.

Thus, expect storms to develop somewhere near ABI and south-
ward from there and move rapidly northeastward. With the 
strong flow through most of the troposphere, the storms will`
be moving smartly, and only modest right turns are expected,
on the order of 20 deg.  If everything works out right, this
could be a major tornadic event in north TX.

Have not looked at tomorrow very much, but it appears from
the progs that things will be pretty much suppressed as the
major wave continues to lift out pretty much as the last one
did, toward the Great Lakes with severe thunderstorms into
the Ohio Valley, as well.

	Doswell/Janish

PROBABILITIES OF OCCURRENCE IN VORTEX OPS AREA THRU 04Z (DAY1) 
AND 12-04Z (DAY2)...
                           DAY1    DAY2
LIGHTNING                   90      10
SEVERE                      80      05
TORNADOES                   70      02
TARGETABLE STORM            80      02

FCST STORM MOTION - TARGETABLE STORMS ONLY
PRE-SUPERCELL             250/40   -N/A-
SUPERCELL                 270/30   -N/A-

FCST INITIATION TIMES (LT) - TARGETABLE STORMS ONLY 
LIGHTNING                 1530    -N/A- 
1ST SEVERE RPT            1630    -N/A-
1ST TORNADO               1700    -N/A-