Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service North Platte NE
1146 PM CDT Friday Oct 9 2015
issued at 258 PM am CDT Friday Oct 9 2015
At 19z...surface high pressure extends from eastern Nebraska into
western Kansas. A leeside trough of low pressure extends from central
Montana into eastern Wyoming and central Colorado. Light south to southwest winds across
western Nebraska with scattered cirrus. Temperatures have warmed
into the upper 60s most areas.
Short term...(this evening through saturday)
issued at 258 PM CDT Friday Oct 9 2015
A surface trough will develop eastward into western Nebraska tonight
with light southwest winds to continue. Cirrus cloudiness should
clear out overnight. Lows tonight will be coolest across the eastern
Panhandle into southwest nebr in the middle 40s...to the lower 50s northestern
On Saturday...a significant warmup to occur. A strong thermal ridge
already in place across the Central High plains will get mixed down
to the surface into the afternoon as a downsloping west to southwest
wind occurs. 850 mb temperatures near 24c at lbf and vtn supportive of
forecast highs near 90. These highs would fall short or record highs
as the record at vtn is 95 and 93 at lbf. Anomalously high
temperatures none the less.
Fire weather concerns will also increase. Surface dewpoints will
fall after 17z and should bottom out in the upper 30s to near 40
west of vtn through iml. When combined with maximum temperatures in the upper
80s to near 90...minimum rhs will fall to 17-20 percent. So while
critical conditions are not forecast due to light winds...near
critical relative humidity values are already forecast and could end up lower if
dewpoints fall lower than forecast.
Long term...(saturday night through friday)
issued at 258 PM CDT Friday Oct 9 2015
Saturday night through Monday...some of the guidance suggests the
potential for record monthly highs Sunday. The forecast blends some of
this data to capture the spirit of the weather expected Sunday afternoon.
Highs in the 80s to middle 90s should be expected ahead of a very
strong Pacific cold front which will move into northern Nebraska during the
afternoon. The models are a bit faster with the frontal timing which will
send a surge of hot dry air into central Nebraska during the afternoon.
The NAM and GFS show mixing heights approaching or reaching 700 mb.
Temperatures at that level are 10c-12c with the ecm showing the
No Fire Weather Watch this forecast but conditions appear to
trending toward a 3 to 5 hour window of near or critical fire danger
Sunday afternoon. The wind forecast now shows west winds increasing to
around 25 miles per hour across the Panhandle and 15 to 20 miles per hour elsewhere. Gusts
to 25 to 35 miles per hour are quite possible.
The cold front Sunday night will move south at around 50 miles per hour
suggesting a gust potential to the same speed. The front could be in
Kansas before midnight. Highs Monday rise into the middle 60s to around
70 which is close to but a bit warmer than the bias corrected mex
and ece data.
The forecast is dry. In fact...clear or mostly clear skies should
prevail Saturday night through Monday with just high cirrus.
Monday night through Friday...the upper level flow will gradually
amplify as and upper level low forms across Hudson Bay. Weak ridging
is indicated across The Rockies in the model ensemble. Northwest
flow aloft will predominate featuring fast moving weather systems
and dry conditions. No rain is forecast.
The models are in good agreement that a second weaker surge of warm
air will move through Nebraska Tuesday. This is in response to
another low pressure system moving through southern Canada. H850 mb
temperatures are near 20c for this surge vs 25c Sunday. Thus highs
in the upper 70s to around 80 should result. Mixing heights in the
GFS reach 750 mb...not nearly as deep as Sunday. The mex guidance
suggested lower 80s south. A cold front may be moving through the
forecast area during the day taking an edge of the temperatures.
This front would be followed by a stronger push of Pacific and
Canadian air Thursday. Highs Wednesday in the 70s fall to near
normal Thursday and Friday...60s. The bias corrected European model (ecmwf) model and
ece guidance suggested lows next Friday below freezing in many
areas. If this cool high pressure verifies...and the latest models
are in good agreement...then the first widespread freeze will occur
next Thursday night and Friday.
Aviation...(for the 06z tafs through 06z Saturday night)
issued at 1145 PM CDT Friday Oct 9 2015
Visual flight rules with clear skies and southerly winds under