Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 200436
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1136 PM CDT Tue Aug 19 2014

...AVIATION UPDATE...

.SHORT TERM...(This Evening through Wednesday)
Issued at 342 PM CDT TUE AUG 19 2014

An upper level trough was moving east across the upper Midwest and
mid MS river valley late this afternoon. An upper level ridge across
NM and CO will build east across the plains tonight and east into
the lower and mid MS river valley by late Wednesday afternoon.

Any convective complexes that form across the central and northern
high plains this evening should move well north of the CWA tonight.
Isentropic lift will cause elevated storms to form across southeast
SD and eastern NE but these storms will move east into IA.

Wednesday will be mostly sunny and warm as the upper level ridge
axis moves east across the state of KS. Highs will reach the mid to
upper 90s, with highs of 100 degrees possible across the southwest
counties of the CWA. Deeper mixing across the western counties
should cause dewpoints to drop into the mid 60s during the afternoon
hours. The northeast counties may keep lower 70 dewpoints through
the afternoon hours but high temperatures will be slightly cooler in
the mid 90s. Heat indices will range from 100 to 104 degrees across
the CWA during the afternoon hours.

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 342 PM CDT TUE AUG 19 2014

The GFS is the only model hinting at clipping the far northwest
county warning area with convection Wednesday night despite forecast
soundings showing inhibition aloft through the night. Will therefore
maintain a dry forecast through Thursday morning as the shortwave
helping to develop precip should pass well north and west of the
CWA. Another shortwave trough over the southern Rockies will move
northeast and bring a chance for thunderstorms to the northwest
third of the CWA Thursday night...although again the better chances
will remain well north and west of the CWA.

Following this wave...the ridging with the upper level high will
undergo amplification as the stronger shortwave trough begins to
rotate out of the case of the western trough and into the
central/southern Rockies. Although this should keep the CWA dry and
hot on Friday...it may allow for some of the high plains convection
that forms late in the day to spread east and northeastward and
briefly clip the CWA Friday night. Highs Thursday through Saturday
will generally be in the middle to upper 90s.

Models differ some with the overall timing/speed of the final
shortwave to rotate out through the western trough and into the
central plains next week. However they are similar in bringing the
western trough slowly eastward into the ridge and gradually
flattening it with time. This will result in one front moving into
the CWA by Monday with a second arriving by Wednesday. This will
keep the chances for showers and thunderstorms across most of the
area Sunday thru Tuesday. With more clouds...precip chances and
initial front...cooled high temperatures slightly for now into the
80s and lower 90s. At the same time...cooled lows in the middle 70s
Thursday and Friday into the 60s by Monday and Tuesday.

&&

.AVIATION...(For the 06Z TAFs through 06Z Wednesday Night)
Issued at 1136 PM CDT TUE AUG 19 2014

Models continue to depict the best convergence on the nose of the
low level jet to stay just north and east of the forecast area.
Therefore will maintain a VFR forecast. RAP and NAM forecast
soundings continue to support the possibility for some LLWS and
profiler data is starting to show the winds at 925MB strengthen.
So will maintain the mention of wind shear. Additionally the RAP
and NAM show a decent pressure gradient developing by Wednesday
afternoon with dry adiabatic low level lapse rates and good
mixing. Because of thin think south winds will become gusty by the
afternoon.

&&

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

&&

$$

SHORT TERM...Gargan
LONG TERM...63
AVIATION...Wolters





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