Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 210815
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
315 AM CDT Sun May 21 2017

.SHORT TERM...(Today and tonight)
Issued at 251 AM CDT Sun May 21 2017

As of 08z, an upper low was centered over central Minnesota. At the
surface, a center of high pressure was over western Kansas, while a
low pressure center was over southern Minnesota. Low level stratus
has exited the area as the surface low continues to progress
northeast. Clear skies with dew points in the upper 30s and lower
40s has allowed temperatures to plummet into mainly the 40s across
the area. Areas across far north central Kansas low temperatures may
reach the upper 30s by dawn. Given the recent rainfall, patchy fog
is possible in low lying areas. Winds near 10 MPH should preclude
any widespread fog formation this morning. Plentiful sunshine today
will allow temperatures to surge near 70 this afternoon!
Precipitation will begin to increase after midnight tonight. A vort
max within the upper flow is expected to traverse the area after 06Z
coupled with increasing isentropic lift within the 300-305K should
provide enough ascent for scattered showers. Mid level lapse rates
remain modest near 6 C/KG through 12Z, resulting in MUcape of
upwards of 200 J/KG. Therefore, have a mention of thunder mention as
well. QPF amounts will remain light through 12Z with less than a
tenth of an inch expected.

.LONG TERM...(Monday through Saturday)
Issued at 251 AM CDT Sun May 21 2017

Monday through Monday night, residual gulf moisture return and
isentropic lift at the 300K level will cause scattered elevated
showers and thunderstorms through the morning. There will probably
be a break in the rain chances during most of the afternoon hours.
An upper trough will be digging southeast across the central high
plains into the central southern plains by Monday evening. A surface
cold front will move into the northwest counties late Monday
afternoon. Most numerical models forecast only 1000 to 1500 J/KG of
ML CAPE developing ahead of the surface front across north central
KS, and given 0-6 KM effective shear of 20 to 30 KTS there may be a
brief window in the late afternoon and early evening hours where a
few storms may become strong or marginally severe with hail to the
size of quarters and perhaps some isolated damaging wind gusts.
After 02Z the MLCAPE will drop to less than 500 J/KG and the line
of storms will weaken as they move southeast across northeast and
east central KS, ahead of the surface front through the overnight
hours.

Tuesday, The upper level trough moving east across the central and
southern plains will phase with an upper low across the upper
midwest. If we some insolation during the late morning and early
afternoon hours isolated showers and thunderstorms may develop under
the trough axis. The deeper gulf moisture will be well southeast of
the CWA, but there may be enough residual moisture under the cold
core trough for a few thunderstorms. MLCAPES will be less than 500
J/kg, thus lightning would be the only hazard.

Tuesday night through Thursday. The amplified full latitude trough
across the Midwest and eastern plains will move east across the
eastern US. An upper ridge axis will shift east across the plains on
Thursday. A surface ridge over eastern KS Tuesday night and
Wednesday will shift southeast into the mid and lower MS river
valley. Expect dry conditions with warmer weather by Thursday. Highs
wednesday will continue to be cool with mid to upper 60s. Highs on
Thursday will warm into the mid to upper 70s.

Thursday night through Sunday, A broad upper trough will develop
across the western US. A stronger mid-level subtropical jet will
extend from the northern Mexico, northeast into the southern plains.
Minor H5 troughs will be embedded with the subtropical jet stream,
which may provide chances of for thunderstorms as the deeper gulf
moisture returns northward Friday and Saturday. The upper trough in
the western US will begin to fill late Saturday into Sunday and a
surface front will move southward across eastern KS Saturday night,
which may push the better chance for showers and thunderstorms south
of the CWA for Sunday. Highs will be in the upper 70s to lower 80s
through the period.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1145 PM CDT Sat May 20 2017

VFR conditions prevail the next 24hrs. Winds remain westerly and
increase to above 10kts sustained after 13Z time frame.


&&

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

$$

SHORT TERM...Baerg
LONG TERM...Gargan
AVIATION...Drake



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