Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 140458
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1158 PM CDT Thu Oct 13 2016
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Friday)
Issued at 313 PM CDT Thu Oct 13 2016
Return flow has developed across the area as high pressure retreats
eastward. Isentropic lift has increased ahead of a wave located over
the front range. Radar is showing light elevated returns therefore
sprinkles may be possible mainly in north central KS this afternoon.
Later tonight this weak shortwave will track over eastern KS. Out
ahead of the wave low level moisture will spread northward. Stratus
and possibly fog will work into the forecast area overnight. Not
sure how widespread or dense the fog will be since the models tend
to overestimate surface moisture. Also, the winds are not forecasted
to decouple, which may inhibit development of dense fog. An elevated
warm nose may become saturated high enough to allow elevated
instability mainly across east central KS. This instability if
present along with weak lift associated with the wave may support
isolated to scattered showers and storms. If this moisture is
overdone then the instability will be capped. A majority of the
models are highlighting light QPF in east central KS during the 10
pm to 7 am time frame. The highest chances will be for locations
along and south of interstate 35. Otherwise low temperatures tonight
should be in the mid to upper 40s moderated by cloud cover and light
winds. Tomorrow the southerly flow will usher in warmer temperatures
and skies should be mostly clear with the exception of east central
KS. Some of these clouds may linger in these areas through the
daytime. High temperatures will be in the lower to mid 70s.
.LONG TERM...(Friday night through Thursday)
Issued at 313 PM CDT Thu Oct 13 2016
An upper level trough will amplify across the western US through
next Monday and will lift northeast across the northern plains into
the upper Midwest next Monday and Tuesday.
Friday night through Monday, a down stream upper ridge across the
southern plains will amplify as the upper trough across the western
US amplifies. The stronger southwesterly flow at mid levels across
the central Rockies will cause a surface lee trough to deepen. The
southerly low-level flow Friday night into Saturday morning will
transport deeper moisture northward, thus patchy drizzle may be
possible across the northern half of the CWA late Friday night into
Saturday high temperatures will be dependent on cloud cover. At this
time it looks as if the stratus during the morning hours should
scatter out from west to east across the CWA during the afternoon
hours. Thus highs should reach the lower to mid 80s with deeper
mixing. However, if the stratus cloud cover holds through the
afternoon hours across the eastern counties of the CWA, then highs
may be 5 to 7 degrees cooler than forecasted.
South-southwest winds of 15 to 25 MPH with gusts during the
afternoon hours will warm highs into the mid 80s Sunday and Monday
with warm overnight lows in the upper 50s to mid 60s.
Monday night through Wednesday, as the upper trough across the
western US lifts northeast into the northern plains, a surface cold
front will move southeast across the CWA Monday night. Both the GFS
and ECMWF show the front moving through dry, as the stronger ascent
remains well north of KS. A surface ridge of high pressure will
build southward across the plains through mid week. Highs will be
cooler with mid to upper 70s on Tuesday and upper 60s to lower 70s on
Wednesday night and Thursday, an upper trough will dig southeast
across the CWA wednesday night bringing a chance for rain showers.
There will be a secondary surge of colder air which will drop
thursday night down into the lower to mid 60s.
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1142 PM CDT Thu Oct 13 2016
Kept a similar forecast as previous but tried to tighten up
windows of MVFR and IFR conditions at the terminals. MVFR cigs
come in over the next few hours with IFR still indicated by enough
guidance to carry for part of the morning hours. Does look to lift
to VFR by late morning.