Scientific Forecaster Discussion
fxus63 klbf 230550
Area forecast discussion
National Weather Service North Platte NE
1250 am CDT Mon Oct 23 2017
Short term...(this evening through monday)
issued at 313 PM CDT sun Oct 22 2017
Wind and the subsequent threat of large fire growth headline the
weather concerns in the short term. Tonight, a cold front will
advance southeast across west central Nebraska. Enhanced mixing
with the frontal boundary will keep overnight lows mild with the
latest guidance indicating lows in the upper 30s to lower 40s.
Solid mixing on Monday will promote the Transfer of possibly as
much as 40kts of momentum to the surface. It will be very windy.
High temperatures tomorrow will cool in the Post frontal
atmosphere, but still enough heating and dry air in place to push
relative humidity values to near critical thresholds. So the debate is whether or
not to issue a fire related headline. Our latest fuel status
suggests the 1 hours are marginally supportive of large fire
growth expect for our far western zone (204) which is primed to
actively carry fire. We typically only will issue a watch or rfw
when confidence is high. At this point, wind is a no brainer, but
relative humidity and fuels are uncertain. So will hit the fire potential hard in
the fwf and severe weather potential statement and re-evaluate tonight. In the event conditions
are drier or after coordination with our local partners for the
fuel status, a short fused rfw may be issued. Somewhat concerning
is that relative humidity recovery overnight tonight will be moderate for most
locations. Numerous studies have shown a strong correlation of
large fire potential with previous poor overnight recovery. Again
something further to consider. Lastly, several near term solutions
indicate enough mid/upper level moisture and system generated
lift for a sprinkle across northwest/northern Nebraska overnight.
Due to the dry air in place, this was discounted, but should be
Long term...(monday night through sunday)
issued at 313 PM CDT sun Oct 22 2017
The stronger winds aloft (850-700mb) shift into eastern neb Tuesday.
A blend of guidance plus bias correction suggests northwest winds at
15 to 30 mph with the higher speeds east of Highway 83 across ncntl
Thermal ridging takes hold Wednesday with h850mb temperatures rising
to 15-20c and nearly full sun. A check on the high cloud procedure
indicated no significant moisture available for high clouds off The
Rockies. The blended model data plus bias correction suggested highs
in the 70s.
The season's first taste of Arctic air arrives Thursday and lasts
through Saturday. The models came in few degrees cooler at the
h850mb level, -5c to -10c. The frontal timing suggests morning highs
Thursday in the 40s. Friday is the coolest day as the high pressure
moves overhead (upper 30s to lower 40s). Strong winds (15 to 30 mph)
are expected both days but Thursday would the windier of the two. A
blend of model output statistics plus bias correction was the basis
for the wind forecast. The temperature forecast and stronger winds
suggest wind chill values in the teens and single digits Friday and
High pressure moves south of Saturday producing light winds. Note
the rain/snow chances have vanished with this forecast. The moisture
and forcing appear to be too limited.
The temperature forecast Thursday through Saturday is the model
blend plus bias corrected guidance and the models showed about a 5
degree f spread in temperatures during this time. The ecm was warmer
than the GFS. Sunday Marks a warming trend as sfc low pressure is
expected to track through srn Canada and draw milder air off The
Rockies into the cntl plains.
Aviation...(for the 06z tafs through 06z Monday night)
issued at 1250 am CDT Mon Oct 23 2017
Main aviation concerns tonight will be low level wind shear
developing over southwest Nebraska through the early morning hours.
Strong northerly flow associated with a strong upper level jet will
create low level wind shear as the surface winds decouple.
Mid and high clouds expected. Skies to become partly cloudy Monday
with strong northwest winds developing through the morning and
gusting to 35kts through the afternoon.