Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 241106
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
606 AM CDT Mon Jul 24 2017

...AVIATION UPDATE...

.SHORT TERM...(Today and tonight)
Issued at 259 AM CDT Mon Jul 24 2017

07Z water vapor imagery shows an upper ridge over the southwestern
U.S. There were several waves around this ridge with one shortwave
noted over WY moving into the Dakotas, another off the northern CA
coast and a shortwave moving across Alberta. At the surface, a
modest ridge of high pressure was centered over the upper Midwest
with the ridge axis extending through the mid MO river valley and
into north central KS.

For today and tonight, models keep all of the dynamics to the north
while surface ridging gradually moves east across the central
plains. So there does not appear to be much if any forcing for
storms. The only caveat may be from daytime heating. Models show
inhibition across central KS all but gone as surface temps approach
the convective temp. Although most of the models including the
convective allowing solutions fail to generate any storms. So will
keep a dry forecast in tact. Models do not show much change in
airmass or cold air advection with the surface ridge, so highs are
forecast to be in the lower and middle 90s once again. Dewpoints
should be a little cooler with the ridge passing, so there should be
more of a break from the afternoon heat indices. Lows tonight are
expected to be around 70 as light winds become a little more
southerly overnight.

.LONG TERM...(Tuesday through Sunday)
Issued at 259 AM CDT Mon Jul 24 2017

Low level southerly flow becomes established Tuesday for a warmer
day than today. Models are much less aggressive with moisture
influx around 800mb and any mid level warm air advection during
the day than they were 24 hours ago, keeping any mention of precip
out of this period. Confidence on specifics in dewpoints is not
high but at least some locations look to approach Heat Advisory
levels.

The 00Z NAM is the fast and strong outlier of the operational
guidance and nearly every GFS Ensemble member with the upper trough
and subsequent timing of the associated cold front passing through
the area. There is enough mid level moisture and isentropic upglide
around 315K for a mention of thunderstorms late Tuesday night
into midday Wednesday for northern areas, but better chances look
to be delayed until late afternoon Wednesday into Thursday along
and behind the front. This should keep Wednesday on the hot and
humid side with greater confidence in a widespread Advisory day,
though still too little for issuance at this range given
cloud/precip possibilities and variations on frontal timing.
Instability does ramp up with enough shear for minor potential for
some strong to severe storms Wednesday afternoon and evening.
Precip chances slowly diminish from north to south Thursday into
early Friday as the front sags into the Red River Valley with
cooler and drier conditions building in. Upper ridge builds over
the western states late in the week into the weekend for weak
north to northwest flow aloft. Could see a weak wave or two bring
at least isolated elevated convection in these periods but nothing
validating a mention yet.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 606 AM CDT Mon Jul 24 2017

The RAP and NAM are showing some weak isentropic upglide across
eastern KS which appears to be responsible for the CIGS around
4500 ft. This upglide weakens over the next few hours. So expect
VFR conditions to prevail with light winds.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Wolters
LONG TERM...65
AVIATION...Wolters



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