Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 300540

Area Forecast Discussion
National Weather Service Topeka KS
1240 AM CDT Sat Sep 30 2023

...Update to aviation forecast discussion...

Issued at 247 PM CDT Fri Sep 29 2023

No big changes to the forecast. Confidence in the forecast ahead
of the frontal passage is good through the weekend and have stayed
close to the NBM for the mid to lake week forecast next week.

19Z water vapor imagery showed a shortwave trough moving onshore
over the Pacific Northwest coast. This shortwave was within a
broader area of cyclonic flow across western Canada. For the central
plains, this left mainly westerly to southwesterly flow aloft with
only weak upper ridging along the LA gulf coast. At the surface, an
inverted trough of low pressure extended from southeastern CO into
the middle MO river valley. A south-southwesterly low level wind and
strong mixing had allowed dewpoints to mix out across north central
KS a little more than over eastern KS.

For tonight through Monday, the forecast is little changed from the
prev forecast. Southerly low level flow is progged to keep a warm
and relatively dry airmass over the central plains, and highs today
are looking like they`ll be between the 75 and 90 percentile of the
NBM. Models show some slight cooling at 925MB and 850MB over the
coming days. But with no significant moisture advection and good
insolation anticipated, have continued with well above normal highs
in the 90s and keeping them around the 75 percentile of the NBM. The
lone chance for precip looks to be limited to diurnally driven
elevated showers. Models keep a warm air advection pattern over the
area but the nose of the low level jet is likely to be well north of
the forecast area with little to no theta-e advection progged.
However there are indications of isentropic lift between 750MB and
600MB. The question is whether there will be enough saturation in
place for the lift to be sufficient to produce some showers. At this
point the bulk of guidance fails to develop and precip. Though there
is the GFS and NAMNest that have some QPF by 12Z Saturday. The
signal for some lift is consistent among the models, but with the
saturation uncertainty have left POPs around 10 percent through
sunrise tomorrow. Later shifts can monitor trends and adjust the
forecast accordingly. Isentropic lift looks less organized for
Saturday night and into Sunday morning.

A shortwave trough is still on track to move through the central
plains Tuesday night and Wednesday, bringing a frontal system
through the forecast area. The better chances for precip (50 to 70
percent) look to be Tuesday night and Wednesday morning as the front
passes through. Confidence in the POP forecast decrease by Wednesday
evening as the deterministic models show the trough axis passing to
the east with the surface front well passed the forecast area. Think
the small POPs into Thursday are a result of the model blends. There
is also greater spread in the models with the evolution of the upper
trough by Friday. The GFS remains progressive but the ECMWF and
Canadian want to dig additional energy south on the back side
keeping a more amplified pattern over the plains. Because of this
there is greater spread in temps and even some small POPs on Friday
with the potential for another frontal push to pass south. The POPs
on Friday look to be mainly driven by the Canadian which is the
strongest of the operational solutions so if the blend hadn`t
included POPs on Friday, I would not be adding them to the forecast
at this time. As for temps, more seasonal temperatures should move
in behind the front for the end of next week with highs in the 70s
and lows in the 40s by Friday. This forecast pretty close to the
mean of the possible solutions so there is room for both cooler and
warmer adjustments as we get closer.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1235 AM CDT Sat Sep 30 2023

VFR prevails this period. Surface winds stay around 10 kts through
the night with some gusts at KMHK. Another breezy day expected
Saturday with south winds gusting to around 25 kts.


Issued at 247 PM CDT Fri Sep 29 2023

Similar fire weather conditions as seen today are forecast each
afternoon through the weekend. Gusty south winds of 25 to 35 MPH
should develop by the late morning hours and persist through the
afternoon as RH values fall into the 25 to 35 percent range. Based
on fuels still showing some green and not completely dried out,
this should cause rangeland fire danger to be in the high category
across north central KS and the moderate category for northeast
and east central KS.


Updated at 247 PM CDT Fri Sep 29 2023

High Temperature Records

                  Forecast          Record (Year)
Today (9/29)
Topeka              95                 95 (1952)
Concordia           97                 96 (1994)

Saturday (9/30)
Topeka              94                 97 (1938)
Concordia           96                 95 (1994)

Sunday (10/01)
Topeka              92                 95 (1976)
Concordia           92                 94 (2002)

Monday (10/02)
Topeka              91                 95 (1963)
Concordia           91                 95 (1938)

Warm Low Temperature Records

                  Forecast          Record (Year)
Friday (9/29)
Concordia           71                 68 (1981)

Saturday (9/30)
Topeka              69                 76 (2019)
Concordia           72                 76 (2019)




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