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Area forecast discussion...updated 
National Weather Service North Platte NE
723 PM CDT Tuesday Sep 30 2014

issued at 327 PM CDT Tuesday Sep 30 2014

There are signs in the models of a gradual transition to a winter
pattern with the development of deep low pressure over Hudson Bay
later this week and high pressure moving through Alaska and down
the High Plains of Canada and the U.S. This signals cooler weather
to western and ncntl Nebraska and perhaps the first frost of the season in
some areas Friday morning. Rain is still expected Wednesday
night...mainly across southern Nebraska.


issued at 723 PM CDT Tuesday Sep 30 2014

Updated forecast to drop Wind Advisory. Minor tweaks to going
forecast with winds and cloud cover. Remainder of forecast on


Short term...(this evening through wednesday)
issued at 327 PM CDT Tuesday Sep 30 2014

Winds will diminish this evening as the surface low that was
situated across northwest Nebraska is now located in South
Dakota...and continues to move north away from the area. Clouds will
diminish across the area giving way to clear skies...this combined
with drier air that has moved into the area should allow for lows in
the middle 40s to lower 50s...with some lower 40s possible in the
typical colder spots like river valleys.

Next chance for rain arrives Wednesday afternoon and evening...will
continue to mention the possibility of thunder. 0 to 3 km lapse rates
will be quite steep and marginal moisture in place should yield a
few hundred joules of cape. Any severe threat should remain east and
southeast of the County Warning Area where better instability and shear will reside.
Highs tomorrow will be in the low to middle 60s across northwest
Nebraska where cloud cover will be in place much of the day...should
remain mostly sunny across southwest and north central Nebraska so
have left highs in the low to middle 70s.

Long term...(wednesday night through tuesday)
issued at 327 PM CDT Tuesday Sep 30 2014

Wednesday night through Friday...rain appears likely along and south
of Nebraska Highway 2 Wednesday night. The 700 mb trough is nearly upright
and almost closed as it tracks across southern Nebraska. The NAM 750mb cape is
less than 500 j/kg but greater than 0 supporting isolated thunderstorms
during the evening. This instability moves south of the forecast area
after midnight. Model blended quantitative precipitation forecast produces 1/4 to 1/2 inch of rain
in this area and probability of precipitation are set at the likely category for this
forecast...a slight increase from the previous forecast. Although
the models are in good agreement with this system the risk of a
lower level dry air intrusion cutting off the moisture supply will
continue to haunt the forecast.

Pacific high pressure invades the forecast area Thursday with 850-700mb
temperatures in the single digits. This should produce highs in the
60s Thursday. A second stronger push of high pressure moves through
Thursday night sending temperatures in this layer well below
freezing by Friday morning. The air is very dry and despite strong
winds in the 850-700mb layer Thursday night...there is reasonable
agreement in the NAM model...met and mav guidance that low
temperatures Friday morning would fall to the lower 30s across the
northwest with patchy frost in sheltered areas.

Highs Friday rise into the 50s and 60s Friday with cool air
continuing across the forecast area.

Friday night through Tuesday...warmer air invades the forecast area
Friday night as high pressure moves south of the forecast area. This
would likely preclude freeze conditions Saturday morning as h850mb
temperatures rise to near 10c. Still...the best guess on lows is low to middle
30s which would produce frost in some areas.

A weak cold front will move through the forecast area Sunday. The
forecast is dry Saturday through Tuesday. The newly formed Hudson
Bay low will modulate the weather by shunting the colder air north
and east of the forecast area. Highs are expected in the upper 60s to
upper 70s with generally clear skies and low humidity.


Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 645 PM CDT Tuesday Sep 30 2014

Strong winds will subside over western Nebraska this evening and
become light and variable through the early morning hours. Middle and
high clouds over night...visual flight rules.


Lbf watches/warnings/advisories...


short term...Gomez
long term...cdc

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