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| Science Forum Index » Geology - Meteorology Forum » October 2009 30-Day Forecast... |
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| Jim... |
 Posted: Sat Oct 03, 2009 9:59 am |
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Guest
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OCTOBER 2009 30-DAY OUTLOOK
420 PM EDT Wed. Sep. 30, 2009
Atmospheric patterns, 700 MB and 500 MB height anomalies, statistical
data, and various models, along with observed cases from past such
months and also data from 1895-2000 were used in this forecast.
A weak El Nino persisted during the past month, with monthly sea
surface temperature ranging from +0.5C to +1.5C above normal across
the equatorial Pacific Ocean. The latest
Nino4, Nino3.4, and Nino3 regional are indicating sea surface
temperature indices of +0.8C, +0.8C, and +0.7C respectively with very
slight decreases observed during the past two weeks. There remains a
reservoir of above average subsurface oceanic heat content
anomalies and the pattern of anomalous tropical convection and low and
upper-level winds that are consistent with an El Nino. Convection was
suppressed during across Indonesia. Impacts across the United States
from the El Nino were weak and are forecast to remain so in October.
Coastal sea surface temperatures remain near normal along the U.S.
West coast, but cold anomalies were developing along the coasts of
Washington and southern California.
The NAO index is currently slightly negative and is forecast to remain
negative during the first 14 days of the month. The PNA index is
positive and is forecast to remain generally positive during the same
period. Models are in good agreement on the predicted 500-HPA
circulation across North America. The GFS, the European and the
Canadian ensembles all predict an upper-level ridge over southern
Alaska and western Canada, extending into the Northwest. An upper-
level trough is forecast in the West with a ridge over the Southeast
at the start of the month. The pattern is forecast to shift eastward
with an upper-level trough forecast west of Alaska, an upper-level
ridge near the West coast, and a trough over the Southwest and the
Great Lakes and the Northeast.
Above normal temperatures are forecast across the Northwest. The
probability of above normal temperatures across this region is 56
percent. Above normal temperatures are also forecast across the
Southeast. The probability of above normal temperatures across this
region is 57 percent. Below normal temperatures are forecast across
portion of the upper Mississippi Valley, the Great Lakes, the upper
Ohio Valley, the Northeast and a large portion of the mid-Atlantic.
The remainder of the nation is expected to be near normal with no
significant deviation from climatology.
Below normal precipitation is forecast along the West coast. The
probability of below normal precipitation across this region is 56
percent. Below normal precipitation is also forecast across the
Southeast and portion of the lower mid-Atlantic. The probability of
above normal precipitation across this region is 57 percent. Above
normal precipitation is forecast across the upper Mississippi and Ohio
Valley, the Northeast and the northern mid-Atlantic. The probability
of above normal precipitation across this area is 58 percent. The
remainder of the nation is expected to be near normal with no
significant deviation from climatology.
Jim Munley Jr.
http://www.jimmunleywx.com |
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