Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 300554

National Weather Service Topeka KS
1154 PM CST SUN NOV 29 2015

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Monday)
Issued at 243 PM CST SUN NOV 29 2015

20Z water vapor imagery shows an upper low over UT cut off from the
mean westerlies with a vort max rotating around the southwest quad
of the upper low. A fetch of mid level moisture continues to feed
into the central plains within southwest flow, although it is
shifted a little further east. At the surface, a broad area of high
pressure remains over the region. Current trends show the surface
high weakening this morning. Temps have effectively been steady with
overcast skies an neutral temperature advection.

The weather will get worse for north central and parts of northeast
KS before getting better. Models continue to show large scale
forcing overspreading the forecast area as the vort max over Las
Vegas lifts through the central plains late tonight. Large scale
assent is progged to overspread the area leading to widespread
precip overnight and Monday morning. Unfortunately the cold air at
the surface is likely to remain right about where it is. Models seem
to gradually be coming into agreement with the thermal profiles,
although the GFS continues to be the warmer solution while the HRRR
and RAP tend to keep the freezing line about where it is now. From a
big picture view, temps will be steady through the night. However
from a perspective of the precip type forecast, where the freezing
line sets up will have a major impact. The forecast tends to regard
the GFS as a slightly warm outlier which has verified to warm
recently. With this in mind think an axis of freezing rain from
Abilene through Marysville is probable. Models are generating
between a third and a half inch of QPF with the system overnight.
With temps expected to be right at or a degree or two colder than
freezing, think significant ice accumulations are possible and I
have a quarter to a third of an inch within that corridor. The model
forecast soundings also show a small window across north central KS
where there is ice in the cloud and a thermal profile hovering
around freezing. This could allow for some minor accumulations of
snow from Concordia to Washington and northwest. At this point it
looks like there could be around an inch of snow just west of the
axis if ice accumulations. From Emporia to Topeka and areas east,
temperatures are expected to remain just above freezing through the
night with precip remaining all rain. I am relatively confident in
this scenario happening, but there is a higher than normal risk in
being off on the location depending on where freezing temps set up.
Will issue a warning for the areas most likely to see the damaging
ice accumulations and have an advisory in the remaining north
central counties for a mix of freezing rain and snow.

Models are still on track in lifting the forcing north of the area
during the afternoon. Therefore precip should taper off during the
day. As the surface low lifts north, a Pacific cold front sweeps
through shifting winds to the west with weak cold air advection
occurring. Since there should not be a lot of insolation, afternoon
highs Monday are not anticipated to be much more than 5 or 10
degrees warmer than the morning temps.

.LONG TERM...(Monday Night through Sunday)
Issued at 243 PM CST SUN NOV 29 2015

Tomorrow night the mid/upper level low pressure center is forecast
to lift northeastward over the upper Midwest. There is the potential
for a shortwave rotating around the main mid level low to pass
over northeast KS during the day Tuesday. Models are indicating
fairly light precip is possible near the NE state line in the form
of rain or snow. After that there is a trend of quiet weather going
through next weekend. This current system will push the moisture well
into the gulf for several days as a reinforcing trough drops down
from western Canada. Surface high pressure gradually migrates
across the central US with temperatures warming into the 40s and
50s by the end of the week. Towards the end of the weekend a mid
level low pressure digs over the southern Rockies and eventually
the plains. This system will have some return flow ahead of it
although the moisture appears limited for now. This system has a
better chance of producing mostly rain.


.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1141 PM CST SUN NOV 29 2015

Developing light rain and drizzle are advancing toward the
terminals with KMHK already seeing -RA. High confidence that a
prolonged period of low GIGS/VIS will hinder operations at all
terminals probably through most of the TAF period. Lower
confidence exists in exactly how low GIG/VIS conditions go down
to. Some guidance suggests that the sites may all go into the
VLIFR category at some point overnight into the early morning
hours as additional lift moves into the region. Have not taken
conditions quite that low at this time. Planners should monitor
TAFs closely if conditions actually do go into the lowest
category. However, if this is the case, would only expect it to be
for a short periods of time. Also, the biggest hazard to aviation
will likely exist at the KMHK site with the possibility of -FZRA
near the 12z time frame.


.TOP Watches/Warnings/Advisories...
Winter Storm Warning until noon CST Monday for KSZ009>011-

Winter Weather Advisory until noon CST Monday for KSZ008-020.



SHORT TERM...Wolters
LONG TERM...Sanders
AVIATION...Drake is the U.S. government's official web portal to all federal, state and local government web resources and services.