Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 240757

Area Forecast Discussion
National Weather Service Topeka KS
257 AM CDT Tue Oct 24 2017

.SHORT TERM...(Today and tonight)
Issued at 257 AM CDT Tue Oct 24 2017

The region will remain along the downstream flank of a broad upper
tropospheric western CONUS ridge axis for today and tomorrow, with
weak shortwave ridging building eastward later today and tonight. To
the east, a seasonably strong cutoff low/pv lobe will slowly migrate
from the Midwest to the Mid-Atlantic states between now and
Wednesday evening. The overall effect of this pattern shift will be
a decrease in winds today and an increase in temperatures for

The main dilemma for today revolves around strong wind potential.
The window for any advisory level winds will be confined to the mid
morning to midday timeframe before the surface pressure gradient
begins to relax ahead of the approaching ridge axis. The lack of any
additional lower tropospheric CAA after 15Z and only weak surface
pressure rises in the wake of this passing system essentially mean
that an increasing component of strong winds by the afternoon will
have to be the result of momentum transport to the surface within
the BL. That being said, winds in the 850-900 mb layer will be in
the 35 to 40 kt range for much of the day (the 07Z VAD from KTWX
shows 40kts 2kft above the surface) and forecast soundings show the
BL mixing out to 850 mb by this afternoon. The question becomes if
this mixing alone could push winds to advisory levels. Given the
short-lived window for sustained winds to be aided by daytime mixing
and that winds yesterday barely touched advisory criteria during
peak heating at most sites, have opted along with neighboring
offices to withhold issuing a wind advisory for now. Would not be
surprised to see a few sites briefly clip advisory levels around mid
to late morning, but sustained winds will steadily decline through
the afternoon. Wind gusts will likely remain above 30 kts through
the day given the ample BL mixing and unidirectional flow through
the layer.

A downslope-modified airmass will overspread the region early
Wednesday morning as the decaying H850 ridge axis swings
southeastward. H850 temps will spike to +14 to +15 C by 21Z
Wednesday afternoon--bringing surface temps into the low to mid 70s.
Skies look to remain clear both today and Wednesday with the current
mid clouds clearing early this morning. Some upper level cirrus may
appear on the horizon late in the day on Wednesday ahead of our next
weather system.

.LONG TERM...(Wednesday through Monday)
Issued at 257 AM CDT Tue Oct 24 2017

Wednesday is shaping up to be the warmest day of the medium range
forecast. Rising heights in the low to mid levels occurs over
central and eastern Kansas with westerly downslope winds at 850mb
through the day along with southwest winds at the surface. Soundings
suggest mixing down from around 875 mb yielding highs in the 70s.
The warm temperatures will be short lived as another cold front
moves through on Thursday with gusty winds expected for the
afternoon hours behind the front. Atmosphere remains dry through the
column so the front will move through dry. Very high fire danger is
expected across north central and northeast Kansas Thursday
afternoon. Highs on Thursday will be in the 60s. An upper level
trough will deepen Friday from the Great Lakes to the southern
Plains. Cold advection along with a southward moving surface high
will bring colder temperatures to the area. Friday morning lows
cloud see north central and parts of northeast Kansas with lows near
30. By Saturday morning 529dm thickness is expected along with 850
mb temperatures in the -3C to -7C range settling over eastern
Kansas. This will bring the coldest readings of the fall with
morning lows in the mid to upper 20s Saturday morning. Freeze
headlines will likely be need Friday morning and Saturday morning.
High temperatures Friday drop into the 40s with 50s expected on
Saturday after the cold start. Temperatures moderate on Sunday ahead
of the next frontal boundary which is forecast to move through next
Monday. Lack of moisture will keep the extended forecast dry through
next Monday.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1149 PM CDT Mon Oct 23 2017

With surface winds recently backing and weakening, will continue
LLWS. Overnight cold air advection leads to gusts returning
quickly after sunrise and gusts in the 25-35KT range through
around 23Z.


Issued at 257 AM CDT Tue Oct 24 2017

The combination of strong and gusty winds, a dry airmass, and curing
fuels mean that a very high fire danger will exist today throughout
all of northeast and north central Kansas. Northwesterly winds will
rapidly increase early this morning with sustained values around 25
mph with gusts of 30 to 35 mph. Daytime RH values will fall to 25-30
percent in the mid-afternoon.

On Thursday, another cold front will sweep through the area with
gusty northwest winds of 20 to 30 mph with gusts around 40 mph
ushering in dry air once again. Afternoon RH will drop to around
30 percent and will yeild very high fire danger mainly across
north central Kansas.




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