4/13/98 Chase Summary by Jeff Wear


From: Jeff Wear (jwear@compuserve.com):

The latest in a series of cold Gulf of Alaska lows moved into California
early Monday morning. Showers and thunderstorms popped up all over the
San Joaquin Valley by the noontime hour, with the strongest extending
from NE Merced County to SW Fresno County/Kings County. At 1400, I left
Turlock to get a look at these storms.

My plan was to take I-5 out of Patterson in Stanislaus County, then
drive southbound along the west side of the valley, where I would have a
good panoramic view of the storms to my east. If I saw a cell I wanted
to get a closer look at, I would have turned off at the nearest exit and
head east. If the storms failed to materialize, I planned to turn left
at Hwy 198, head east on Hwy 198 to Hwy 99, then take Hwy 99 back to
Turlock.

The drive down I-5 wasn't anything too exciting - just driving in and
out of scattered showers with sunny breaks in between. The cells I had
gone out to see had weakened - I heard about 4 crackles on the AM radio
between 1400 and 1600. It wasn't until I got into southwestern Fresno
County that things started to look promising. The news radio station out
of Fresno I was listening to was reporting heavy showers in SW Fresno
County and SW and NW Tulare County. A few minutes later, I passed by a
sign that said "CAUTION. HEAVY RAIN AHEAD. SLOW DOWN." But the sky
straight ahead didn't look too dark. Then I looked east and saw what
they were talking about - a fairly large, disorganized area of
stratiform-type precip. At the southern tip of this area (around
Lemoore) was a well-developed Cb, with a flanking line of Cu extending
to the SW towards Avenal and Kettleman City. By this time I was close to
the intersection of I-5 and Hwy 198. Hwy 198 led directly towards this
developing storm, so I turned left there and headed towards Lemoore.

Once I was eastbound on Hwy 198, the storm began to take off. The first
CG strike hit at 1610. White streamers began descending from the Cb.
Most of the hail appeared to be falling north of the highway, so it
looked I would just miss the hailshaft. Less than a mile west of Lemoore
Naval Air Station (NLC), I got into some 1/4 to 1/2 inch hail - with a
few stones as large as 5/8 inch. At one point there was just enough hail
to cover the road - but nothing like what I saw SE of Merced on Mar 28.
I was out of the hailshaft by the time I was east of NLC.

At 1630, a wall cloud briefly developed SW of Lemoore near Stratford. I
didn't observe any rotation with this wall cloud. CG activity with this
storm rapidly decreased as it passed over Lemoore, and ceased by the
time it got to Hanford. I stayed at the corner of 19th Ave and Idaho Rd
from 1630 to 1715 to watch the storm as the core passed just to my north
and rained itself out. I did have some brief 1/8 inch hail at this
location around 1635, however. After that, I took Hwy 198 back to Hwy
99, then headed home.

There was one highlight on my trip back. In SE Merced County, I spotted
a non-severe but photogenic squall line at 1900. There was a spectacular
blue-violet shelf cloud which appeared to be right over Merced - but the
heart of the storm appeared to be to the N and NE off towards Lake
Yosemite. Still, I encountered some heavy rain just SE of Merced - but
no hail or gusty winds. I didn't see any lightning with this storm - nor
hear any crackles on the radio.

After getting home, I went onto CompuServe and the Internet to check
reports. I got home too late to get the METARs and SPECIs for NLC
between 23z-00z. If anyone has these observations, I'd be most
appreciative to see them.

In summary.....

* 5/8 inch hail on Hwy 198 about 1/2 mi W of NLC at 1620. One of 860-AM's=

  listeners in Lemoore called the station with a report of nickel-sized
  hail. A nickel is roughly 7/8 inch in diameter. The same station later
  reported that there was "quite a hailstorm" at the intersection of I-5
  and Hwy 198.

* Wall cloud 5 mi SW of Lemoore at 1630.

* Temps unseasonably cool in the valley for April - especially in areas
  where convection dragged cool air to the surface. Warmest temp I
  measured was 59F near the intersection of I-5 and Hwy 198. I measured
  temps as low as 44F in Turlock at 1410 and 42F between Merced and
  Atwater at 1910. Merced Airport (MCE) reported 43F at 1919. Average
  afternoon temps in the valley in mid-Apr are in the mid 70s. Quite a
  turnaround from the mid to upper 90s this area has seen this time of
  year in recent years (87, 88, 89, 90, 94).

The cold weather is getting on a lot of people's nerves here, but as
long as it comes with some good t'storms, I have no gripes. At least
we're not getting the low stratus my parents have been getting in TX the
past couple of days. :-)


Jeff


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