Area forecast discussion
National Weather Service North Platte NE
644 am CDT Thursday may 23 2013
Synopsis...
issued at 345 am CDT Thursday may 23 2013
At 08z...the mean sea level data showed low pressure centered over southwest
Wyoming with a warm front across western Colorado. Another low was
centered over eastern New Mexico with a warm front extending into
southwest Kansas. The stratus clouds were clearing as high pressure
forced its way into northern Nebraska.
&&
Short term...(today and tonight)
issued at 345 am CDT Thursday may 23 2013
Cloudiness will probably be persistent in south central and
southwest Nebraska until early afternoon. Low level wind from the
east to southeast will bring an increase in precipitable water later
this afternoon or early evening.
This evening...as the surface low makes its way out of Wyoming and
into Montana...a warm front re-forms in the Lee of The Rockies. Warm
advection will then lift air up over the front and bring showers to
central and western Nebraska...especially after midnight. There
should be enough instability for isolated thunderstorms to become
embedded in the showers.
Long term...(friday through wednesday)
issued at 345 am CDT Thursday may 23 2013
Large upper level low pressure system will remain nearly stationary
across the Pacific northwest Friday...with the Central Plains in
southwest flow aloft. The flow will be modest...with 500 mb speeds
around 35 kts. Appears elevated showers and thunderstorms will be possible
in warm air advection pattern through middle afternoon...then attention
turns to possible surface based convection along the Lee trough/dry line
during the late afternoon. Very steep low level lapse rates develop
eastward into northeast Colorado and the southern Nebraska Panhandle by
late Friday afternoon...with MLCAPE values around 2000 j/kg and
adequate shear. As a weak vorticity maxima moves northeast around
peak heating...at least isolated thunderstorm development seems possible.
These would most likely develop on the nose of the steeper low level
lapse rates across northeast Colorado into the southern Nebraska
Panhandle. A severe storm is possible...as shear and instability are
adequate enough to support the potential. It is unclear how far east
these storms will make it into southwest or western Nebraska...as
extensive low level moisture in the form of stratus clouds will
likely inhibit instability. Some chance that storms will develop
east during the evening aided by a southerly low level jet...and the GFS hints
at this...but uncertain of this scenario...and will keep probability of precipitation fairly
low Friday night.
Saturday afternoon and evening still expecting a round of thunderstorms.
Both the 23/00z runs of the GFS and European model (ecmwf) have a short wave trough
ejecting northeast across the area providing lift...the only
negative for convection is a well defined boundary to focus
initiation on. There does appear to be a weak inverted trough across
west central Nebraska...and a weak warm front across southern/central
Nebraska. Other subtle boundaries may exist from any prior convection.
If storms do indeed develop...atmosphere is quite unstable
and 0 to 6 km shear on the order of 30 to 40 kts would support some
severe storms.
With the large upper level low remaining west of the area Sunday
into next week...convective chances will remain. But timing and
location is uncertain...as previous bouts of convection will likely
have an impact on boundary placement et cetera.
Temperature wise...a fairly warm period expected Friday through the
Holiday weekend and into next week. It will be rather muggy as well
with the increased Gulf of Mexico moisture. Highs should make it
into at least the 70s each day...with 80s possible especially across
western/southwest Nebraska. Clouds and precipitation could have an impact at
times however...but overall pretty decent temperatures expected for
the Holiday weekend.
&&
Aviation...(for the 12z tafs through 12z Friday morning)
issued at 643 am CDT Thursday may 23 2013
Patchy fog in northern Nebraska this morning should clear rather
quickly since there are no low or middle clouds above it. The
stratus in south central and southwest Nebraska will be slow
clearing. East to southeast wind in the lowest 3000 feet will not be
much help clearing it out.
After 06z tonight...stratus is likely to return from the southwest
as a warm front makes its way onto the High Plains. In addition...
the return of moisture will result in isolated showers or even a
thunderstorm late tonight in western Nebraska. However...the
coverage will not be enough to warrant including it in the terminal
forecasts for vtn and lbf.
&&
Lbf watches/warnings/advisories...
none.
&&
$$
Synopsis...Springer
short term...Springer
long term...Taylor
aviation...Springer
