6/2/97 Colorado Chase by David Shohami


From: David Shohami (davidsh@mail.geocities.com):

Hi,

I don't know if you've heard about it or not (it was in CNN) but during
October 17-18 there were huge floods in the Middle East. I chased them
as far as I could (I can't go into Egypt and Saudi Arabia,
unfortunately). So here is the report:


October 17-18 1997 Israel Chase Report

    The Red Sea Trough unleashed its most destructive power on October
17-18, when multiple supercells were the cause of 13
deaths, and dozens of people were injured, in Israel alone. Egypt and
Jordan reported damages and casualties as well.

    The scenario: during the previous days, the Red Sea Trough was
approaching Israel from central Africa. On October 16 it reached Israel,
and a few local thunderstorms occurred, nothing big. On that day, the
center of the trough, which extended all the way from Saudi Arabia to
Israel, reached the Mediterranean Sea. A low pressure area formed right
on the Mediterranean coast of Israel. A cold front developed in the sea
west from Israel. Southerly winds brought great humidity to southern and
eastern Israel, which are desert areas. Temperatures in Jerusalem were
31 C, much higher than normal. In Eilat (southern Israel) temperatures
were 37 C.

    The forecast for October 17 was local afternoon rain and
thunderstorms in eastern and southern Israel, and a chance for
localized floodings. As the day progressed, the low pressure came very
close to Israel, as well as the cold front, much earlier
than expected. The presence of cold air behind the front and extremely
hot and humid air ahead of it, caused a much more
devastating effect than what was forecasted.

    By 13:30, a single cell developed above the Dead Sea, east of
Jerusalem. I watched it rise in the clear skies, as it turned to a
large cumulonimbus with an overshooting top. After 30 minutes cumulus
clouds which developed around it made the Cb
disappear from view. By then, the Meteorological Service in Israel
issued a severe storm warning and flash flood warning for
southern, eastern and central Israel, Jerusalem included. The low
pressure hs intensified, and the cold front was now just west of Sinai.

    The Meteorological Service now began to warn people traveling in the
desert areas of flash floods and severe weather.
People in Israel are not used to severe weather, and most of them did
not heed the warnings. It was the weekend, and many
hikers and tourists were in the dangerous areas.

    In 16:00, out of nowhere, towers began to explode all around me. I
was in eastern Jerusalem at that time, with a great view
both south and north. The winds started to pick up, and I knew the cold
front is coming. This was the moment when the cool air
from the Mediterranean collided with the extremely hot air coming from
the Red Sea - the temperature difference was huge: 41
Celsius ahead of the front, and 22 behind it. Just a few minutes later,
I was gazing at a straight north-south line of massive
updrafts, starting at the Sinai Peninsula (some 700 km to the south) and
reaching about a 100 km north of Jerusalem. I took
some great pictures and videos of the updrafts which were completely
vertical, and by 16:30 I saw 3 of them developing a
cumuliform anvil. Reports coming in from Eilat in southern Israel
confirmed that storms have developed in their area as well. The
3 storms around me developed a mesocyclone in each one. The storms
rotated around me, and winds were dangerously increasing. The sun had
already set, and light was diminishing quickly. I decided to leave the
area and return home, as chasing was almost impossible because of the
darkness and the possible floodings of the roads.

    October 18 was as stormy as the previous day, but I had no chance of
chasing, because every road leading south was
blocked by the floods. So all I could do was take pictures from my
window and listen to the news.

    The human casualties and injuries were high, mainly because the
travelers didn't take the warnings too seriously.

    Here is the complete damage report for October 17-18 in Israel:
Several supercells which developed in both October 17
and 18 caused incredible amounts of rain in the Judean Desert, Negev
Desert and Arava. The annual rainfall average in these
regions is no more than 50 millimeters (2 inches), so the heavy rain
caused the usually dry streams to overflow, and floodings
occurred. 30 hikers were trapped in the Qumran stream in the Judean
Desert. Seeing the heavy rain, they took shelter in the
caves along the stream. But a sudden wave of water swept one of them
down a gorge 150 meters deep, and killed her. The
others spent the night in the caves, until help arrived.

    A car was swept away by a sudden flood near Ein Gedi, and 3 people
died, 3 others injured. 6 more died in another
accident caused by the floods. In eastern Jerusalem a young boy
disappeared in a flooding stream. More than 80 hikers in the
Negev area were rescued by helicopters, after being trapped by sudden
floods.

    In Be'er Sheva, an incredible hail storm caused 32 injuries. The
hail accumulated to over two feet deep. Wind gusts knocked
down hundreds of trees, and destroyed many roofs. The hail storm moved
west towards Gaza, and caused great damage there.
A macroburst over Eilat dropped 27 millimeters (1 inch) of rain in a few
hours, comparing to the annual average rainfall of only
32 millimeters (1.28 inches). A supercell in Ze'elim in the Negev caused
3 out of 4 trees in the area to be knocked down. Winds gusted up to 100
km/h. In Sinai more than 7,000 travelers were stranded. Damages were
estimated at millions of dollars.

David Shohami, Jerusalem Israel.

davidsh@mail.geocities.com


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