Area Forecast Discussion
Issued by NWS Topeka, KS

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469
FXUS63 KTOP 290434
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1134 PM CDT TUE JUN 28 2016

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Wednesday)
Issued at 320 PM CDT TUE JUN 28 2016

19Z water vapor shows a broad upper ridge over the four corners
region and an upper trough moving east of the great lakes region.
This sets up northwest flow from the northern Rockies through the
central plains. At the surface, weak ridging stretches from the
upper Midwest into northeast KS, but there is not a strong gradient
in temps or dewpoints denoting a synoptic frontal boundary. Surface
obs suggest the better low level convergence is over eastern CO with
the easterly upslope winds. Think the festering convection over
south central KS is a result of a weak MCV from the morning
convection.

The forecast for tonight and Wednesday is focused on convection
currently ongoing over eastern WY. The NAM and GFS indicate a
convectively induced vort max for this evening`s convection over the
high plains should propagate across the forecast area by Wednesday
morning. However the ECMWF and GEM are much less obvious with any
MCV. Additionally the high resolution models that do a better job of
simulating convection seem to be mixed on coverage of possible
storms overnight. The overall expectation is for the convection over
WY to move towards northern KS late tonight. Models indicate that
mid level lapse rates should still be steep enough for some elevated
instability mainly across central KS. The low level jet is also
progged to gradually veer to the southwest by 12Z which could air in
an MCS holding together. Based on storms from this morning, think
there could be a damaging wind risk if a decent cold pool forms with
the MCS. Because of the uncertainty in storm coverage, the forecast
has POPs increasing to 50 percent by the early morning hours
Wednesday. But it appears the north central KS counties stand the
better chance for precip as the instability axis and nose of the low
level jet appear to be set up across central KS. If indeed an MCS
forms, showers and storms could persist over part of the forecast
area through the morning and into the early afternoon. Again the
main uncertainty is where the possible MCS will track so POPs
through the day Wednesday have been held in the chance category.
Lows tonight are forecast to be in the mid 60s. Highs Wednesday are
expected to be in the lower and middle 80s due to the weak surface
ridging and possible cloud cover.

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 320 PM CDT TUE JUN 28 2016

Moderate precipitation chances continue to inhabit these periods.
Northwest flow aloft continues into the end of the week. Isentropic
lift is depicted on GFS and NAM on the 305 to 310K surfaces
Wednesday night and may produce convection into Thursday, mainly in
southern areas. This is where the greater lift is progged, as lower
level winds increase ahead of a cold front pushing south into the
area. Front looks to hold up not far to the south for continued
thunderstorm chances Thursday night into Friday night as flow
becomes more zonal aloft for continued isentropic lift setup. Upper
wave is fairly well agreed upon to move east across the region
Saturday night into Sunday. Still appears a general drying trend
into the early week with ridging increasing aloft.

Convergence along the Thursday front looks weak, and with
some convection potentially lingering into the day, questions
on instability remain, but at least a small risk for pulse severe
weather exists. Next best chance for severe weather looks to be
Saturday and Saturday night with potential for the boundary to
lift back in. Perhaps the bigger impacts could come from heavy
rain with several periods of rain potential, good moisture in
place, and front nearly parallel to upper flow.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1130 PM CDT TUE JUN 28 2016

There is a complex of storms in central NE that is moving
southeastward. There is a chance they hold together and make it to
the taf sites. Isolated showers and storms out ahead of this line
are also possible. A few models are developing another round
tomorrow afternoon although confidence is low at this point.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

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



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