Area forecast discussion
National Weather Service North Platte NE
104 PM CDT Wednesday may 22 2013
Update...
issued at 949 am CDT Wednesday may 22 2013
Updated the forecast for trends in cloud cover and precipitation.
The surface low which has the moisture rotating around it is now
over northeast Iowa as of 14z...while high pressure builds into
the Panhandle and western Nebraska. The cloud cover was starting
to break up this morning...mainly over the southwest parts of the
forecast area. There is a narrow band from approximately koga to
kcdr that may persist a bit longer...but expecting this area to
mix out and dissipate by the noon hour. Going further east...the
clouds will likely persist through much of the day...or at least
through middle afternoon as a thicker layer of moisture will remain.
The showers have decreased in area and intensity by late this
morning...with the stronger echoes now over eastern Nebraska and
eastern South Dakota...closer to the surface low. Will keep
mention of showers and sprinkles across north central and central
Nebraska through the morning...then dry conditions expected for
the afternoon.
&&
Short term...(today and tonight)
issued at 345 am CDT Wednesday may 22 2013
Wrap around cloudiness will continue today across northern Nebraska. The light
rain should end by noon. There is one more impulse across eastern South Dakota
which will drop south before the surface low drifts east into the
Midwest this afternoon. This leaves much of the southern half of the forecast
area in partly cloudy skies with highs in the 60s while overcast
skies keep the north in the 50s.
Tonight...an inverted surface low pressure trough will sharpen up across
the northern and cntl rockies. This will set up a broad belt of
easterlies across the forecast area which could trap low level moisture
and produce upslope fog and stratus across western Nebraska. Presumably...dry
air could move into ncntl Nebraska clearing skies there. Given the poor
model performance of the NAM in these types of situations...the rap
model might be the best handle for tonights sky forecast.
Long term...(thursday through tuesday)
issued at 345 am CDT Wednesday may 22 2013
Surface high pressure will move east of the region Thursday...with east
to southeast winds keeping conditions rather cool...with highs in
the 60s to perhaps 70 in a few locals. Increasing low level moisture
could lead to some stratus development...especially across southwest
Nebraska and the Panhandle...which could hold highs down further. A
southerly low level jet cracks up to around 45 kts...advecting more moisture
and better chances for stratus clouds into the area. Will maintain a
slight chance for showers/thunderstorms across southwest Nebraska...where
warm air advection will be maximized.
Friday through Tuesday appears to be quite active in terms of
convective potential. A large upper level low pressure system will
become anchored across the Pacific northwest...providing a southwest
flow aloft across the central Continental U.S.. this flow doesn/T appear overly
strong...but adequate enough to support some severe thunderstorm potential
from time to time. Meanwhile...plenty of low level moisture and
steep middle level lapse rates...will result in strong instability
during the afternoon and evening hours. It appears that a leeward
trough/dry line will be established each afternoon across western
neb/KS...and could serve as a focus for convective initiation as
shortwave troughs eject eastward from the western upper low. Of
course timing of these troughs will be a factor...and later
forecasts will refine the timing and intensity of any thunderstorms.
Temperatures through the period could be a challenge...especially
high temperatures...as potential exists for quite a bit in the way
of stratus clouds due to increased Gulf of Mexico moisture...and any
convective debris cloudiness. For now will go with highs mainly in
the lower 70s to lower 80s...with the warmest readings across the
western portions of the area. Lows will be mild...middle 50s to lower
60s.
&&
Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 103 PM CDT Wednesday may 22 2013
Forecast through Thursday is plagued by cloud cover with passage
of backdoor cold front tonight. Should get stratus in the vicinity
of the front...which would occur across all of western and north
central Nebraska. Models would suggest the stratus moving out of
north central Nebraska by 12z...but with inversion set up...kept
the stratus in through middle morning at kvtn and klbf. Winds will
switch over to the east by Thursday morning...and could get some
gusts to 20 miles per hour by late morning. Should the stratus not develop as
anticipated...forecast will improve greatly.
&&
Lbf watches/warnings/advisories...
none.
&&
$$
Update...Brooks
short term...cdc
long term...Taylor
aviation...Brooks
