Area Forecast Discussion
Issued by NWS Topeka, KS

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448
FXUS63 KTOP 282332
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
532 PM CST Mon Nov 28 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Tuesday)
Issued at 303 PM CST Mon Nov 28 2016

Main upper low centered over North Dakota while minor perturbations
within the mean flow are dipping south and east over the desert
southwest into the southern plains. A few high clouds were passing
through Kansas this afternoon but otherwise two areas of sfc low
pressure were observed. One is centered over Iowa while a secondary
low pressure is over southern Colorado. In between across northeast
Kansas, winds are west to slightly northwest between 10 and 15 mph.
As the sun sets, winds calm as the two pressure centers lift
north and east. With the light winds and strong radiational
cooling, lows tonight are seasonable with readings in the lower to
middle 30s.

Sfc winds veer to the northwest tomorrow as the sfc low stacks
underneath the upper trough shift further east, with wrap around
precipitation developing southward over Nebraska Tuesday afternoon.
While the CWA is not expected to see any precipitation, cloud cover
and stronger northerly winds will impact northern Kansas by late
afternoon, cooling highs by a few degrees to near 50. Elsewhere,
improved sunshine warms highs to the middle 50s with wind speeds
near 10 mph.

.LONG TERM...(Tuesday night through Monday)
Issued at 303 PM CST Mon Nov 28 2016

Tuesday night into Wednesday a mid-level trough will be skimming
eastward across the Northern Plains toward the Great Lakes region.
Any precipitation associated with this system will remain north of
the area. Decent northwesterly flow aloft and at the surface will
result in colder air being ushered into the area, which will drop
temperatures to near or slightly below the seasonal normals. With
this northerly/northwesterly flow remaining in place through the
remainder of the week, expect high temperatures in the 40s and low
temperatures in the 20s.

Thursday into Friday the models show a mid-level trough beginning to
develop across the northern Rockies and deepening toward the Baja
peninsula by Friday/Friday night.  Models start diverging in their
solutions over the weekend and into early next week with how they
handle the evolution of this system.  The GFS/Canadian models
develop a closed mid-level low over the Baja peninsula while the
ECMWF keeps the system an open wave, which results in a faster onset
of precipitation across the area on Saturday compared to the
GFS/Canadian. By Monday, the ECMWF shows the open wave shifting east
of the area and developing a closed low. In contrast, the GFS shows
the stalled closed-low just moving into Texas.  As a result,
confidence is very low with regards to precipitation chances,
temperatures, and, thus, precipitation type for this weekend.  The
ECMWF produces more precipitation across the CWA with the open-wave
solution and is also generally cooler than the GFS. With
temperatures near or below freezing in the evenings over the weekend
into Monday, there is the potential for some mixed precipitation.
Due to the uncertainty in the forecast, have predominantly gone with
a rain/snow mix wording for precipitation type.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 531 PM CST Mon Nov 28 2016

VFR conditions are expected through the period. Winds west
southwest under 10kts becoming northwest after 15Z Tuesday.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Prieto
LONG TERM...Hennecke
AVIATION...53



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