Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 291145
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
645 AM CDT FRI APR 29 2016
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 317 AM CDT FRI APR 29 2016
An upper level trough was located across the four corners region
early this morning and will lift northeast into northwest KS by late
Showers this morning were due to weak isentropic lift and a minor
short-wave trough lifting northeast across central KS. These showers
should diminish as they lift northeast across the CWA through the
early morning hours.
This afternoon deeper gulf moisture at 850mb will begin to advect
northward from OK into southern KS. The resulting isentropic lift
will cause showers and isolated elevated thunderstorms to develop
from southwest to northeast across the CWA.
Highs Today will be cool with cloudy skies and a chance for rain
showers. Highs across north central KS may only reach the lower to
mid 50s with highs across the southeast counties reaching the mid
Tonight...The main H5 trough axis will lift northeast across the TX
PNHDL into northwest OK and then into KS, there will be stronger
ascent combined with isentropic lift for widespread showers and
thunderstorms to develop across the CWA. If the instability
increases sufficiently through the evening hours, then there could
be some strong to marginally severe elevated thunderstorms,
generally along and south of I-70. The primary hazard would be penny
to quarter size hail. The NAM model show only 400 to 800 J/KG of
MUCAPE developing across the CWA during the night along with 30 to
40 KTS of effective shear from the LFC up to 6 KM. The synoptic warm
front will lift from southern OK, northward into southeast KS by 9Z
SAT, thus the thunderstorms Friday night will remain elevated.
Total QPF today through tonight will range from near an inch
across north central KS to 0.6" across northeast KS. Most of the
QPF will occur over a 12 hour period, therefore I did not issue a
flood watch. River rises will probably occur and a few rivers may
approach or go over flood stage. However, if the instability is
forecast to increase and we see more elevated thunderstorms
through the night, then a flood watch may need to be issued, since
we could see more QPF and the potential of 1 inch of rainfall
within a three hour period with more numerous elevated
.LONG TERM...(Saturday through Thursday)
Issued at 317 AM CDT FRI APR 29 2016
On Saturday, the elongated upper level low pressure located over
western Kansas will move east through the afternoon. At the
surface, a low pressure center is expected to lift northeast across
the area that afternoon. The GFS and NAM continue to show just
enough CAPE and shear to allow for strong to severe storms to form
on Saturday. Some shorter range guidance suggest that storms will
be north of the best instability in the afternoon as a dry slow
works into northeast Kansas, making the severe weather threat
conditional for that afternoon. After sundown, any instability would
move east of the area allowing for any mention of thunderstorms to
be removed from this time frame. Chances for rain decrease Sunday
and Sunday night as the upper low moves northeast of the area.
Surface winds shift out of the north Sunday aiding in cold air
advection and highs topping out in the upper 50s and low 60s. On
Sunday night and Monday, a shortwave in the southern stream flow
across the CONUS could allow for a small chance for showers. From
here, the forecast is mainly quiet and dry with a warm up trend
through the end of the period. Temperatures should be back up to the
upper 70s by Friday.
.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 635 AM CDT FRI APR 29 2016
VFR conditions are expected for remainder of the morning hours and
early afternoon. Brief periods of MVFR cigs are possible at the
Topeka terminals this morning. An area of showers and
thunderstorms across central KS will slowly push toward MHK by 15Z.
A strong upper level wave will eject later this afternoon and
evening, creating widespread shower and thunderstorm activity.
Activity will end near the end of the TAF period.