Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

FXUS63 KTOP 162322

Area Forecast Discussion
National Weather Service Topeka KS
622 PM CDT Wed Oct 16 2019

Issued at 315 PM CDT Wed Oct 16 2019

19Z water vapor imagery shows an upper ridge over the Rockies 
with an upper trough just off the west coast. This kept northwest 
flow across the central plains. At the surface, ridging was 
centered over central OK with an off shore wind along the TX gulf 


...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Thursday)
Issued at 315 PM CDT Wed Oct 16 2019

Quiet weather is expected for tonight and Thursday as upper 
ridging keeps a dry northwest flow pattern over the forecast area.
Other than the occasional high cloud passing by, skies should 
remain mostly clear. The surface ridge is progged to move east 
through Thursday. This should allow winds to become more southerly
overnight and then begin to increase through the day Thursday. 
With this in mind, lows tonight should be slightly warmer with 
readings in the upper 30s and lower 40s. Highs Thursday are 
expected to warm into the lower 70s thanks to good insolation and 
increasing low level warm air advection. 

.LONG TERM...(Thursday night through Wednesday)
Issued at 315 PM CDT Wed Oct 16 2019

Low level moisture return is forecast to begin Friday ahead of an
approaching upper shortwave. Although moisture return does not 
look all that impressive since the deeper gulf moisture gets 
shifted south with the current cold front. Additionally lapse 
rates are not all that steep. Nevertheless there is a chance for 
some shower and storms Friday evening as a pacific cold front 
passes with the upper wave. If the precip is not over by 12Z 
Saturday, is should come to an end in a few hours after 12Z as 
models show dry air advecting back in along with increasing mid 
level subsidence. Goo southerly winds and warm air advection is 
expected to push highs on Friday into the mid and upper 70s. 
Modest cold air advection behind the pacific cold front should 
limit high temps to around 70 for Saturday. 

The second upper level shortwave is progged to move across the 
central plains Sunday night. As it does, the system is forecast to 
strengthen as surface cyclogenesis occurs along the SD/NB state 
line. Increasing southerly low level flow is expected to bring some 
higher dewpoints north into eastern KS on Sunday and the potential 
for some thunderstorms along an advancing cold front Sunday 
afternoon and evening. However there is a question as to the quality 
of the moisture return and GFS progs only develop around 1000 J/kg 
of CAPE ahead of the boundary. Wind profiles look favorable for 
rotating updrafts with 0-6km bulk shear values of 60KT or more. So 
while chances for storms developing are only around 30 to 40 
percent, the strong wind profiles and severe potential is enough to 
keep an eye to the forecast for Sunday if you have plans in the 
afternoon or early evening. The better chances for precip may end up 
being with the front as increasing dry air advection is progged. The 
blend of models that is used to initialize the forecast has chance 
POPs Sunday night and through the day Monday. Am not sure why the 
blend is doing this as all of the deterministic solutions have the 
front well east of the forecast area by Monday morning with 
increasing subsidence. Have opted to maintain the chances for now 
since it is unclear where the blend is coming up with the potential. 
But if later runs of the operations models continue to show dry air 
advection with the surface low lifting into WI on Monday the POPs 
will be way overdone with dry weather more likely. The more 
confident impacts of the storm system will be the winds. There are 
differences in the strength of the surface low, but all solutions 
deepen it as the system moves into the Upper Midwest. So a 
strengthening pressure gradient is expected to bring breezy 
conditions on Sunday and Monday. Highs Sunday should see a bump up 
into the lower 70s and this may be on the cool side if there is a 
lot of sunshine. With renewed cold air advection for Monday, temps 
may struggle to reach the lower 60s. 

Northwest flow is expected to redevelop for Tuesday and Wednesday 
with limited moisture return. So the forecast calls for dry weather 
with temps moderating. 


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 621 PM CDT Wed Oct 16 2019

VFR conditions are expected through the period with light and
variable winds tonight increasing out of the south at 10 to 20 
kts late Thursday morning.




National Weather Service Glossary of Abbreviations