Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 182316

Area Forecast Discussion
National Weather Service Topeka KS
616 PM CDT Sun Jun 18 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Monday)
Issued at 256 PM CDT Sun Jun 18 2017

Upper level ridging will build across the Desert Southwest on the
backside of our departing Northern Plains trough that helped fuel an
active weather pattern over the last few days. This will keep NE
Kansas under a dry and seasonal weather pattern for the beginning
of the work week. Surface high pressure over eastern Kansas will
meander over NE Oklahoma/SE Kansas through the day tomorrow, keeping
a light westerly flow over much of the area. We will see highs in
the mid 80s tomorrow, with increasing return flow possibly pushing
temps a few degrees higher west of Manhattan.

A mid-level cloud shield over western SD and SE Montana will slide
southeast into NE Kansas with the H500 flow tonight and tomorrow.
The RAP and HRRR in particular develop precip with this elevated
feature overnight. Synoptic support is marginal at best with rising
heights aloft and Td depressions near 20 C in the BL beneath the
thin moisture plume. Thus am expecting most if not all of the precip
to fall from this band as virga. As the cloud shield mixes out
during the day, steepening mid-level lapse rates may yield a few
spotty mid-afternoon showers, though the CAPE profiles are quite
short and barely reach the freezing level before encountering a
500mb cap. Did not raise POPs to mentionable levels quite yet given
the lack of CAM consistency in these showers developing (the NAM is
the most bullish).

.LONG TERM...(Monday night through Sunday)
Issued at 256 PM CDT Sun Jun 18 2017

The Monday night and Tuesday periods appear to be the most likely to
be dry at this point. Northwest flow continues aloft with one area
of weak surface high pressure moving off Monday night and a weak
boundary sinking toward the area as an upper wave rotates around the
eastern Canadian upper low. Increasing westerlies over the northern
Plains keeps this boundary from making too much progress into the
state with little if any instability or convergence to keep daytime
precip in check. West to southwest low-level flow allows for a
warmer day with highs around 90.

Models are similar in shallow mid-level isentropic upglide
developing Tuesday night into early Wednesday ahead of the next
shortwave in the northern Plains but differ on moisture
availability. Will keep precip chances low at this point but some
scattered storms seem possible in the overnight. This wave brings a
weak cold front into south central Nebraska in the late afternoon
Wednesday with continued low-level theta advection ahead of it to
create a narrow band of ML CAPE values above 1000 J/kg with CIN less
than 60 J/kg ahead of it. Could see convection fire there in late
afternoon and translate east and south in the nighttime as 850mb
winds increase to around 45 knots. Afternoon temps bump up a bit
more especially in the west with gusty south-southwest winds

The Thursday into Saturday periods look to bring a few more waves
across the northern states, with intensity increasing with time as
the upper flow amplifies downstream of West Coast ridging. This
brings several opportunities for convection, though timing of the
best chances is very difficult at this range. There is good
agreement with the final trough bringing cooler and drier conditions
by Sunday. The highest temps into the weekend should occur Wednesday
and Thursday with heat indices again nearing 100 degrees.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 616 PM CDT Sun Jun 18 2017

VFR conditions are expected throughout the period. Winds will be
light and variable overnight prevailing from the WSW after 16Z.
There is a chance for some light showers to move across far
northeast Kansas in the very early morning, but it looks like any
precipitation will stay north and east of the terminals.




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