Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 171145
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
645 AM CDT Mon Apr 17 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 237 AM CDT Mon Apr 17 2017

A weak upper level trough was moving east across OK and central TX.
This upper trough will remain well south of the CWA. A frontal
boundary will remain stationary across norther OK Today. Weak
isentropic lift across the southeast counties of the CWA may provide
a slight chance for showers through the mid morning hours. The
better MUCAPE will remain just north of the KS border where
scattered thunderstorms will continue to track east-southeast across
southeast KS and northeast OK during the morning hours.

Skies will remain partly cloudy across northeast and north central
KS, with mid and high clouds continuing into the afternoon hours
across east central KS. The warmest highs Today will occur across
the northern counties, with lower to mid 70s due to increase
insolation. the cooler highs in the upper 60s will be across the
southeast counties where skies will remain mostly cloudy through
most of the afternoon hours.

Tonight as zonal flow increases across the central Rockies a lee
trough will deepen across the high plains. 850mb winds will increase
from the south and begin to transport deeper moisture northward
across western and central KS. The increasing isentropic lift across
the western counties will provide a chance for showers and
thunderstorms to develop late Tonight across north central KS.

.LONG TERM...(Tuesday through Sunday)
Issued at 237 AM CDT Mon Apr 17 2017

Residual overnight convection may approach north central areas by
Tuesday morning, before dissipating in the early afternoon period.
Instability increases along and south of a frontal boundary entering
the cwa from the northwest by Tuesday afternoon. In addition, models
are similar in a upper shortwave trough passing through, providing
decent midlevel lapse rates at this time. While ample instability
exists aloft, believe the best convergence and subsequent
thunderstorms are expected to form along the boundary where sfc CAPE
exceeds 2000 J/KG underneath eroding inhibition layer. Initial
updrafts may be strong enough for large hail and damaging winds. As
the boundary orients more perpendicular to the effective shear, more
widespread convection may result in localized flooding once again.
Latest GFS for example, produces over an inch of rainfall over areas
north of Interstate 70. This may change however, depending on where
the boundary stalls.

The boundary is expected to lift northward into Nebraska Wednesday
afternoon, increasing temps once again back into the upper 70s and
lower 80s. The next progressive, however stronger upper trough
passes the northern plains Wednesday evening, surging the boundary
once again through northeast Kansas. Additional round for possible
strong to severe thunderstorms is forecast in the late Wednesday
afternoon to evening time frame. Ample instability, weak inhibition,
and stronger bulk shear up to 45 kts focuses mainly over east
central Kansas.

As this system clears the region on Thursday, skies become mostly
sunny with strong cool advection, holding highs to the low 60s
through Saturday. In addition to the cooler temps, a closed upper
low consistently centers over Kansas Friday and Saturday. Models
also keep the track of the system further south, leaving the cwa on
the stable, northeast periphery. Showers remain likely for this
period, with perhaps isolated thunder initially on Friday. By
Sunday, upper ridge builds into the region, providing a relief from
the precipitation chances and the return of southerly flow and
warming temperatures.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 642 AM CDT Mon Apr 17 2017

Expect VFR conditions for most of the next 24 hours. Some model
guidance shows stratus with MVFR ceilings moving northward across
the terminals after 9Z TUE. Moderate low-level vertical windshear
will develop as the low-level jet 1200 feet above the ground
increases to 30 KTS after 6Z TUE.

&&

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

$$

SHORT TERM...Gargan
LONG TERM...Prieto
AVIATION...Gargan



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