Technical weather discussion forecast for Lincoln, NE

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fxus63 koax 251959
afdoma


Area forecast discussion
National Weather Service Omaha/valley NE
255 PM CDT Friday Apr 25 2003


Forecast challenges onset of thunderstorms and rain late Sat/sun...temperatures during the
period...chance of precipitation in the extended.


Synopsis...the latest surface analysis had high pressure over much
of the plains. The strong surface low was over southern Illinois...with weak surface troughs
moving through Missouri and Arkansas. Surface winds were NE at 10 to 20
miles per hour...with some stronger gusts near 30 at lnk and Clarinda Iowa.
Dewpoints were in the 30s.


Forecast...tonight...expect winds to decouple as the surface ridge moves
into the area. Have lows in the 40s with mostly clear skies.
Despite clear skies and light winds...do not expect mentionable fog
in the grids/public zones with relatively dry low levels and decent
dewpoint spreads. South return flow is forecast for Saturday with
increasing south winds 15 to 30 miles per hour. With the middle level ridge over
the forecast area...have 70s forecast with dewpoints in the 40s.
Meanwhile...surface pressure falls are occurring over The Rockies and Western
Plains. Will maintain mainly dry forecast through Sat and introduce
slight chance - for western zones Sat night. Sunday...a weak
shortwave...returning deeper moisture...and convergence along the
front to increase chance of precipitation central and southeast zones and have left
slight chance in north. Lifted index values in the 0 to - range in the southeast portion
of the forecast area sun and sun evening. Some storms could become
strong southeast where thermal/wind fields support stronger storms. Storm Prediction Center
currently has southeast corner in outlook area for day3.


The extended forecast hinges on the location of the surface front and
impulses ejecting eastward from the main middle level trough out west. The GFS
is a bit more aggressive with the development of an mesoscale convective system Monday am
compared to the ETA model. For now continue chance probability of precipitation. Pattern does not
significantly change and cannot rule out chance or slght chance probability of precipitation in
the extended. Temperatures to be dominated by the 60s to lower 70s across
the forecast area.