4/22/98 Chase Summary by Steve Sponsler


From: Steve Sponsler (vortex2@brevard.net)
Subject:      Florida Desperation Chase with A Lesson Learned

Logging in at work...first thing..check out the Day 1 SPC DISC...now the
AVN/ETA...local obs and NWS forecast discussion.. (of course..I'm supposed
to be doing "work" related activities)

It appears the quasi-stationary boundary stretched across S-C Florida will
remain basically "in place" until the upper level 'kicker' passes through
after 22/08Z  (the current time is 21/12Z)...nothing new...but this
time...according to the MLB forecast discussion...forecasted extrapolated
LIs of -4 to -7 were in the picture for XMR (where I work...Kennedy Space
Center)...with CAPES in the 2000 J/kg range at max heating...sfc temps in
the upper 70s-lwr 80s and  DPs near 70 (which reminds me...the sfc moisture
convergence was great...with a differential of 10-15 degrees north and south
of the stationary boundary)...more impressive..zero wet bulb temps at
11.5K...not bad for Florida..where I anticipated max tops in the 30-40K
range...plenty of room for rare Florida hail over pea-sized...and this time
of year in Central to South Florida (based on 15 years experience) is
notorious for prolific, lowly publicized, hail events!!! (golf balls had
occurred the night before near Kissimmee ..did YOU HEAR ABOUT THIS HAIL?
(gasp...already devastated by the tornado this year)!!)

Sfc winds are NE north of the Boundary...and S-SW south of the boundary
generally in the 10-20 kt range...with isolated pockets of "variable at
5"!!"

Okay, so many features were already in place...but what about the
timing?!...Both the AVN and ETA were in close agreement...a  somewhat neg.
tilted 850mb trough would form over the Gulf just off SW Florida
...hmm...why was there NO DISCUSSION of this in any of the NWS or SPC
forecasts...no matter..that's what the models showed...and satellite imagery
was verifying this!   (latest satellite imagery was verifying this as a
cluster of storms was developing nicely by 1pm and moving Steadily  just
North of East )...not only this...a distinguishable (but not necessarily
strong ) pocket of PVA would pass over in sync with the 850mb trof according
to the ETA and AVN. (of course, it is all one in the same)

Based on the loops downloaded from Intellicast (taking desperate measures
here)...timing would place this concentrated area EAST of Florida's east
coast  by 00Z (8pm local).....so when would it be in the CHASEABLE LOCATION?
(having to extrapolate a 12 hr time frame here based on the model time
frames)..my best guess was somewhere around Fellsmere to Vero at 5-6pm based
on the timing of radar loops and all the other info available!  (also
anticipating a seabreeze convergence to come into play)  Would it be a one
shot deal or a training affect? Could spouts form near the coast with all
these factors in play despite no upper level/jet stream support? Certainly
possible...it happens more often than not!!

BUT...I thought not..no spouts today..not enough heat!..No matter...

I prayed for a 'training' affect...given the time I had to leave work to
arrive at the target  area...if it came in as one "neat package" I'd be too
late.  No matter, off we go!!!! We'll play the Northern edge of the frontal
boundary and hope that the forecasted Southern tip of the AVN/ETA progged
850mb trough would NOT swipe all the CAPE out to sea with it!! (swoosh)

I left Cape Canaveral under virtually clear but very hazy skies with a
healthy NE 12mph wind ....knowing that just 40 miles to the south the wind
was out of the opposite direction and temps were 8-12 degrees warmer...very
adrenalating....  Dark..convective SC were already beginning to race
northward, entering the "stable zone",  as I started south on I-95.  Listing
to MegaDeth's latest release ("Cryptic Writings")...then switching to YES's
("Relayer" Cd)...cruising..getting hyped...(knowing I'd be in the Plains in
one short month)...:-)

I'll delete all the road /route details...basically went straight South
toward the front then migrated West and South...entered the Fellesmere area
and broke out of a low, rapidly NE ward progressing SC deck to
encounter......gackkk...drizzle...AND WORSE...

The sun shone through revealing a sheared off tower  moving swiftly off to
the East...(ESE of me)...and heading rapidly toward the coast...to the west
of that...NOTHING!

ANYTHING ELSE?!  Wx radio blares..The Short Term Forecast: "a chance of
showers...isolated thunderstorms"... for the area I was in...only a mention
of occasionally CGs...stopped at a state park..out in the middle of nowhere
near Fellsmere..to video soothing swamp waters...and the quiet and solitude
I hadn't expected to encounter 2 hours after leaving a busy office building.

Continued WX-RADIO monitoring verified my fear...it was a one-cell event
(which did drop dimes-quarters in SW Fl as it made land fall)...Okay..so I
didn't strike it rich...(but then again..you wouldn't expect to hit it 100%
on lottery scratch-offs anyway)...

What did I learn? The progged 850mb shortwave trough was the ticket! It
rippled along the sfc trough already in place and swooped all the CAPE right
out to sea with it.  Temps dropped a good 8 degrees after it's passage.
(probably no sfc obs to verify this..but I could sure feel it)....and all
shower activity quickly dissipated in it's wake.

A harsh lesson learned...BUT IT SURE WAS FUN TO GO FOR A CHASE!

LESSON 2: Do you like to Chase AND enjoy all the secondary benefits? If
so...you had a good time :-)

Share Knowledge and Experience. That's the ticket.
Steve :-)


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