Area Forecast Discussion
Issued by NWS Topeka, KS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

000
FXUS63 KTOP 201707
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1207 PM CDT TUE SEP 20 2016

.SHORT TERM...(Today and tonight)
Issued at 301 AM CDT Tue Sep 20 2016

A weak frontal boundary currently bisects the forecast area from
west to east as the mid level trough that drove it southward tracks
over the Great Lakes region. Winds are relatively light and or calm
near this boundary. Moisture has somewhat pooled just south of the
boundary keeping dew points in the lower 70s, while slightly drier
air resides across northern KS with dew points in the mid to upper
60s. The combination of clear skies and light winds will support the
development of haze and or ground fog especially in low lying areas
early this morning. Through out the day the boundary will lift
northward as a warm front allowing the winds to become southerly.
This will also allow the higher dew points to spread northward
across the area. By the afternoon temperatures will be in the lower
90s with dew points in the upper 60s to lower 70s. This will cause
heat indices to range from the upper 90s to lower 100s with the
highest values occurring in east central KS. Weather will continue
to be dry tonight with no overall change to the pattern. Low
temperatures tonight will be in the lower 70s with partly cloudy
skies.

.LONG TERM...(Wednesday through Monday)
Issued at 301 AM CDT Tue Sep 20 2016

Wednesday through Friday Night, an upper level trough will move on
shore across the Pacific Northwest and amplify as it digs south-
southeast across the western US. A downstream upper level ridge will
amplify across the eastern plains and central US. The extra-tropical
leftovers of tropical storm Paine will lift northeast across AZ into
eastern CO, western KS and eastern NE. The NAM and ECMWF models
forecast the better lift and moisture to remain across western KS
into NE Wednesday night into Thursday morning, with both models
showing no QPF forecast across the CWA Wednesday night into
Thursday. The GFS brings the minor H5 trough farther southeast
across central KS into southeast NE Wednesday night and forecast a
couple tenths of QPF across the western and northern counties of the
CWA. Therefore, I kept some low POPs in primarily for the western
and northern counties of the CWA Wednesday night into Thursday
morning. Thursday and Friday look dry as the upper ridge amplifies
across the lower and mid MS river valley and any minor H5 troughs
will track northeast across the central high plains into the
northern plains and midwest. Temperatures will continue to be warm
with mid 80s to lower 90s expected. Southerly low-level flow will
keep the deep gulf moisture in place, so afternoon heat indicies
will continue to range from the mid 90s to around 100 degrees.

Saturday through Monday, The upper level trough across the western
will move east across the plains. Both the GFS and ECMWF have
similar solutions with showers and thunderstorms developing across
central KS during the afternoon hours of Saturday and spreading east
across the CWA during the late afternoon and evening hours. The
stronger ascent ahead of the upper trough will move across eastern
KS late Saturday night through Sunday, and widespread showers and
thunderstorms will develop ahead of a surface cold front. Both the
ECMWF and GFS show the trough shearing apart across the plains with
the positive tilt trough axis moving across KS on Monday. The
showers and thunderstorms will move east of the CWA by Monday
afternoon and skies should clear from west to east behind the
surface cold front. Highs Saturday will probably continue to be warm
with mid to upper 80s expected. Sunday will be cooler due to cloud
cover and periods of showers and thunderstorms. Highs on Monday will
be cooler with mid to upper 70s expected.

There is a potential for heavy rainfall late Saturday night into
Sunday across the CWA. The ECMWF model is forecasting QPF of 2 to 4
inches of rain across the CWA. I suppose with meridional flow ahead
of the trough axis there could be a period of training
thunderstorms. Given the meridional flow pattern the 700mb-500mb
lapse rates may not be steep enough for stronger instability, so we
may not see much in the way of severe weather but there will be a
potential for heavy rainfall.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1206 PM CDT Tue Sep 20 2016

VFR prevails through forecast period with southerly winds below
10 kts.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.