MAY 2008 30-DAY OUTLOOK
400 PM EDT Wed. April 30, 2008
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.
The current cool episode weakened to moderate strength as negative sea
surface temperature anomalies weakened across the central and east-
central equatorial Pacific. The latest weekly surface sea temperatures
are more than 1.0 C below normal in the area between 160 E and 120W.
All indices warmed during March, with only the westernmost regions
having values nearly 1.0 C below average. Above normal remained
restricted to the far eastern equatorial Pacific. Models indicate
that the cold episode in the tropical Pacific should remain at a
moderate strength through the spring and will influence the
circulation across North America.

NAO is currently in a positive phase and is forecast to trend negative
to neutral during the first 14 days of the month. The PNA is also
positive and should remain positive to near neutral during the same
period. Models are in poor agreement with the 500-HPA pattern for May.
The European Ensembles show troughs over the Bering Sea and the
western part of the nation and off the Southeast coast. The GFS
depicts a flatter pattern with generally a zonal flow across the
nation. Heights are forecast to be near to above normal across the
West. Near to below normal heights are forecast across the center of
the nation

Above normal temperatures are expected across the West coast onto the
Rockies and the Southwest. The probability of above normal
temperatures in this region is 55 percent. Below normal temperatures
are expected across the upper Mississippi Valley and the Ohio Valley,
Northeast and mid-Atlantic. The probability of above normal
temperatures occurring across this area is 56 percent. The remainder
of the nation is expected to average near normal with no significant
deviation from normal climatology.
Below normal precipitation is expected from the Plains to the West
coast. The probability of below normal precipitation in this area is
58 percent. Above normal precipitation is expected across the eastern
Plains eastward across the Mississippi Ohio and Tennessee Valleys. The
probability of above normal precipitation in this region is 57
percent. The remainder of the nation is expected to be near normal
with no significant deviation from climatology.
Jim Munley Jr.
http://www.geocities.com/jimmunleywx