Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 141728
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1228 PM CDT Tue Apr 14 2015
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 257 AM CDT TUE APR 14 2015
Surface high pressure will continue to retreat eastward today as a
mid/upper level low currently over NW TX tracks over the eastern KS.
High level clouds have already spread across the area and should
keep temperatures from completely dropping out with lows in the mid
40s. Clouds will hang around today, which may keep temps slightly
cooler with highs in the mid to upper 60s. As the mid/upper level
low approaches isentropic lift and moisture advection will support
scattered showers. Initially this moisture and lift will be in the
mid levels and gradually lower through out the day. It is currently
spreading into SE KS this morning and will continue to slowly move
northward. There is a rather deep layer of dry air in the lower
levels that it will have to overcome before precip reaches the
ground. Sprinkles could therefore be possible later this morning and
afternoon across east central KS. After sunset tonight isentropic
lift moves more over eastern KS where there is a chance for more
widespread showers. The instability seems almost non existent during
this time frame due to the lapse rates aloft. Although an isolated
lightning strike could not be ruled out in association with the
mid/upper level that the models may not be capturing. The area of
showers will spread into NE KS during the overnight hours as the
mid/upper level low begins to get absorbed into the flow ahead of a
stronger western shortwave.
.LONG TERM...(Wednesday through Monday)
Issued at 257 AM CDT TUE APR 14 2015
Wednesday through Wednesday Night, an upper level trough across the
Pacific northwest will dig and amplify as it moves into the four
corners area Thursday Night. The more amplified H5 trough will act
as an upstream kicker and lift the filling trough over OK northeast into
the Midwest. The lead H5 trough will fill and I don`t expect much
ascent ahead of this trough as it tracks northeast across
southeast KS into northern MO on Wednesday. I kept a few showers
possible in the eastern counties but most of the deeper gulf
moisture will be well south of the CWA across southern TX.
Thursday through Friday Night, the closed upper level low will
remain near stationary across the four corners region into early
Saturday morning. The deeper gulf moisture advection will occur from
west central TX into western KS. The CWA will be on the eastern
edge of the deeper moisture and relatively weak isentropic lift.
Minor shortwave troughs may be ejected around the closed upper low
to provide for small chances of rain showers through the period.
Skies will be mostly cloudy with highs only reaching the mid 60s
to lower 70s.
Saturday through Sunday, the closed upper low over the four
corners region will slowly lift northeast into the southern and central
high plains due to a northern stream upper trough digging
southeast into the northern high plains from western Canada
(upstream kicker). Rain chances will probably increase as the
ascent ahead of the lifting H5 trough increases across eastern KS.
There will be a lot of thunderstorm activity across central and
southern TX Saturday. This will limit the quality of deeper gulf
moisture that may get advected northward across the southern and
central plains. Showers and thunderstorms may be more widespread
as the H5 trough lifts northeast into the the southern and central
high plains, but thunderstorm intensity and the amount of QPF may be
limited due to the lack of true gulf parcels. Cloud cover and rain
chances may keep highs in the mid to upper 60s.
Sunday night through Monday, The H5 low will become an open trough
as it lifts northeast across KS and will phase with the northern
stream trough moving into the the upper Midwest. A cold front will
move southeast across the CWA Sunday evening. Post frontal rain
showers will be possible Sunday night into Monday morning then skies
should clear through the afternoon hours of Monday. Highs on Monday will
only reach the lower to mid 60s behind the cold front.
.AVIATION...(For the 18Z TAFs through 18Z Wednesday Afternoon)
Issued at 1223 PM CDT TUE APR 14 2015
VFR prevails for much of the terminals as high clouds stream
northward and increase during the afternoon. As the next system
approaches, stratus deck lowers to low end VFR as scattered
showers develop near terminals. Spotty nature of the activity lead to a
mention of VCSH aft 05Z. MVFR ceilings remains possible however delayed
the timing until after 14Z.