Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 281120
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
620 AM CDT THU JUL 28 2016
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 337 AM CDT THU JUL 28 2016
Water vapor loop shows a shortwave moving across southeast Nebraska
at 0730Z while another upstream wave was located over Wyoming.
Thunderstorms continue across parts of western Kansas in upslope
flow and within the moisture and instability axis. This activity
will remain to the west of the forecast area. The shortwave moving
across southeast Nebraska will move southeast into Missouri by 12Z.
May see an isolated shower with the passage of the wave before
sunrise. A surface frontal boundary was located across the southern
CWA in east central Kansas and will gradually move south into
southern Kansas this morning and then become stationary along the
Oklahoma border. Highs today will still be around seasonal values
with readings in the mid 80s to lower 90s.
Focus then turns to the upstream wave over Wyoming as it
moves southeast through the day and into northwest and north central
Kansas late this afternoon. Convection is expected to develop across
western Nebraska then move southeast across north central and
northeast Kansas this evening and tonight. Cluster of storms should
form a forward propagating QLCS this evening, then move southeast.
Shear increases to 40 to 50 kts by early evening across central
Kansas. Models continue to show the storms mainly affecting the
North central and central Kansas counties this evening with some
development further east as the shortwave moves through. Main QLCS
may just clip the western and southwestern counties of the forecast
area and will keep the higher precipitation chances focused there.
Main hazards with the storms will be damaging winds and hail. Low
temperatures tonight will cool into the mid and upper 60s.
.LONG TERM...(Friday through Wednesday)
Issued at 337 AM CDT THU JUL 28 2016
By Friday, the mid-level trough will still be in place across the
eastern U.S., resulting in northwesterly flow aloft across the
central U.S. Models continue to show several embedded waves
developing within this northwesterly flow through the weekend, which
will bring periods of off and on showers and thunderstorms. For
Friday, there are still model discrepancies with the strength of the
passing shortwave over northeast KS and whether or not it may
support scattered or more isolated precipitation. A stationary
boundary will be stretched across far southern Kansas Friday into
Saturday, so this nearby boundary may support some scattered storms
across southeast Kansas that may extend northward into portions of
central and east central Kansas Friday night into Saturday. But,
once again, there are model discrepancies on whether there is enough
available moisture to support these scattered storms. Precipitation
chances should increase again late Saturday night into Sunday
morning as the stationary boundary should lift northward into the
area as a warm front. This lifting boundary in combination with
another embedded shortwave should support a better chance for
scattered storms across the outlook area. With the region remaining
in the cool sector Friday and Saturday, expect slightly cooler than
normal temperatures with highs in the 80s.
This unsettled weather pattern should end by the start of next week
as a mid-level ridge builds in across the central U.S., pushing the
mid-level trough well east of the area. The 00z model runs show the
ridge not building quite as far north as in previous runs and, as a
result, some models are now showing the potential for some embedded
shortwaves to skim across far northern Kansas. With this trend in
mind, have some slight chance PoPs for Tuesday/Tuesday night. If any
shortwaves and associated scattered storms impact the forecast area
next week, that would have an impact on temperatures. But with such
a strong ridge in place and with persistent southerly surface winds,
have continued to trend warmer than the consensus blend for
temperatures. Highs for Monday through Wednesday will likely be in
the mid/upper 90s. These temperatures combined with dewpoints in the
upper 60s to low 70s will lead to heat indices reaching into the low
to mid 100s.
.AVIATION...(For the 12Z TAFS through 12Z Friday Morning)
Issued at 620 AM CDT THU JUL 28 2016
VFR conditions are expected through the period outside of
convection. Models continue to show that a complex of storms will
move through the area after 00Z. Confidence on track is medium for
the MHK terminal and have added VCTS for now. Further east to TOP
and FOE timing is more uncertain and will leave out for now.
Winds remain light from the north and northeast though the