Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 ktop 212323 

Area forecast discussion
National Weather Service Topeka Kansas
623 PM CDT Mon Oct 21 2019

..update to aviation forecast discussion...

Short term...(this evening through tuesday)
issued at 230 PM CDT Mon Oct 21 2019

A deep upper low was located across northeast NE/northwest Iowa this
afternoon, with an upper level trough axis extending southward
across far eastern Kansas into east central Texas. Wrap around moisture has
caused stratus to develop across much of the County Warning Area. The cloud cover
has limited the deeper mixing of the pbl, and thus winds have
remained just below advisory criteria across north central Kansas. There
are some breaks in the overcast beginning to develop across north
central KS, which may lead to deeper mixing and better momentum
Transfer to the surface for winds to increase to or just above
advisory levels. Some gusts across the southwest counties of the County Warning Area
may approach 50 miles per hour through the remainder of the this afternoon.
Therefore, i'll keep the Wind Advisory going through 7 PM.

Tonight, the stronger winds will gradually diminish through the
evening hours. The winds will remain around 10 to 15 miles per hour through the
night, thus given clear skies and lower dewpoints, temperatures will
only drop into the upper 30s to lower 40s.

Tuesday the upper low will shift northeast into the upper Great
Lakes states as the upper trough axis moves east across the
eastern US. The central and Southern Plains will remain in
northwesterly aloft. A broad ridge of surface high pressure will
build southeast from the Central High plains into OK and eastern
Texas. Surface winds will veer more to the west as the center of the
surface ridge passes well south of the County Warning Area. Highs will warm
slightly into the upper 50s to mid 60s.

Long term...(tuesday night through monday)
issued at 230 PM CDT Mon Oct 21 2019

Tuesday night through Thursday night, an upper trough will dig
southeast out of western Canada and across the central rockies, then
shear apart as it moves across the plains. The southern section of
the 500 mb trough will become a closed upper low across western Texas and
become cut off from the northern branch of the upper jet according
the European model (ecmwf) and Canadian models. The GFS keeps the southern stream
trough as an open wave. A cold front will move south across the County Warning Area
on Wednesday, as low-level cold air advection across the northern plains
develops as the northern branch of the 500 mb trough shifts east
across the northern plains into the upper Midwest. Northwest of
the front there may be enough weak isentropic lift along with
larger scale ascent, from the DCVA ahead of the positive tilt 500 mb
trough axis, for light rain showers to develop Wednesday night
into Thursday. The best rain chances will be across the southeast
counties of the County Warning Area. As the surface cold front pushes southward
across central and eastern TX, the better area of isentropic lift
and mid-level ascent will shift southeast of the County Warning Area and the rain
showers will end Thursday evening. Highs on Wednesday, ahead of
the surface cold front will warm into the mid to upper 60s. As the
front passes southeast across north central and northeast Kansas
Wednesday afternoon, temperatures may begin to fall back into the
50s by the late afternoon hours. North winds, cloud cover and
scattered rainshowers will only allow highs on Thursday to reach
the upper 40s to lower 50s. Skies may clear late Thursday night,
allowing overnight lows to drop into the upper 20s to lower 30s.

Friday through Friday night, the European model (ecmwf) and Canadian model solution
show the closed upper low over West Texas only drifting east across
west central Texas through the day. The GFS solution shows a southern
stream upper trough moving east across central and eastern Texas.
The stronger ascent will remain well south of the cwa, so we
should remain dry. Given more insolation, high temperatures will
warm slightly into the upper 50s to lower 60s.

Saturday through Saturday night, the European model (ecmwf) and Canadian models lift
the upper low northeast into OK and southern MO. The European model (ecmwf) is more
amplified and shows an area of stronger ascent ahead of the 500 mb
trough moving across east central and northeast Kansas Saturday into
Saturday night. If the European model (ecmwf) verifies, then there will be a
chance for light rain Saturday into Saturday night. The Canadian
is less amplified and tracks the upper low a bit farther south of
the cwa, which would keep any precip across far southeast Kansas on
Saturday. The GFS has an open southern stream 500 mb trough which is
more progressive and shifts east across the southern US. If the
GFS were to verify, then Saturday will remain dry and warmer with
highs in the mid to upper 60s. All models show another upper
trough digging into the western US.

Sunday through Monday, the upper trough across the western US will
move east across the plains. The GFS and Canadian are more
progressive than the European model (ecmwf). The GFS moves the surface front across
the County Warning Area Sunday morning with the stronger ascent ahead of the 500 mb
trough remaining north and northeast of the County Warning Area. While the European model (ecmwf)
solution amplifies the upper trough across the southwestern US and
does not bring the front southward across the County Warning Area until Monday
afternoon. Both model solutions show dry conditions for most of the
area Sunday and Monday. Highs will be dependent on frontal passage but expect
60s on Sunday and may be a cool down on Monday with mid to upper 50s.


Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 622 PM CDT Mon Oct 21 2019

VFR cigs with stratus will continue through 03z, then skies will
become sky clear. Forecast soundings Show Low level wind shear developing around 1500 ft
above ground level at mhk around 03z and at top and foe around 07z. Low level wind shear will
last until 13z at all sites. Winds remain west northwest around 14
to 16 kts with gusts to 23 kts through the period.


Top watches/warnings/advisories...
Wind Advisory until 7 PM CDT this evening for ksz008-009-020>022-



National Weather Service Glossary of Abbreviations