Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 211126

Area Forecast Discussion
National Weather Service Topeka KS
526 AM CST Tue Nov 21 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 316 AM CST Tue Nov 21 2017

Eastern Kansas in an area of transition early this morning as weak
surface trof bisects the area, with the next surface front on
approach from the Dakotas into Nebraska.  Stronger gradient and
associated wind speeds are anticipated to move southward into the
state later this morning and through the afternoon hours, before
diminishing this evening. Center of the surface high also moves into
our area toward early morning on Wednesday, bringing a shot of light
winds and cold air as it does so.  Sensible weather impacts for
today are increasing winds from the north northwest, then
diminishing into the evening and overnight.  Daytime highs hold
nearly steady to current temperatures with highs in the 40s, and
overnight lows fall considerably as the cold advection and light
wind settle in with lows forecast from the teens near the Nebraska
border to the lower 20s along and south of I-35.

.LONG TERM...(Wednesday through Monday)
Issued at 316 AM CST Tue Nov 21 2017

Through the upcoming weekend, persistent northwesterly flow
aloft between mean midlevel ridging over the central Great Basin and
southwest states, and troughing over the East, should maintain dry
conditions across the region. A couple of surface fronts are
expected to cross the region for the mid/late week timeframe, in
association with speed maxima traversing the flow aloft and cyclonic
perturbations reinforcing the eastern states troughing. Moisture
return ahead of these boundaries will be minimal, and the primary
impacts associated with the boundaries will be locally gusty
gradient winds and wind shifts. This will especially be the case on
Friday, when temperatures are forecast to rise to well-above-normal
readings ahead of a cold front, and locally elevated fire-weather
conditions could occur if frontal passage is delayed until late day.
Medium-range guidance suggests that the aforementioned midlevel
ridge could break down and progress eastward by early next week, as
a deep trough spreads across the northern states with preceding
ascent encouraging cyclogenesis over the northern and central Great
Plains. While confidence in the evolution of this pattern is
limited, the primary impact would be enhanced gradient winds
accompanying frontal passage amidst limited return moisture.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 526 AM CST Tue Nov 21 2017

A cold front will continue to move southward across the region
this morning. LLWS is expected at the TAF sites from around 12Z
to 15Z, before surface winds strengthen behind the front during
the mid-morning hours and become gusty. The top of the LLWS layer
is expected to generally be around 1300 ft. Thereafter, NW to N
winds around 15 kt gusting to around 25 kt should prevail through
the afternoon before diminishing this evening. VFR conditions are
expected through the period.


Issued at 356 AM CST Tue Nov 21 2017

An incoming front mid morning through the afternoon will bring
breezy northwest winds of 20-25mph with higher gusts, and the
drier air behind the front will drop RH values into the 25-30%
range. Combined with dry cured fuels, this brings the rangeland
fire danger index up into the very high category - and outdoor
burning is not recommended today.




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