Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 021744

1244 PM CDT Sat May 2 2015

Issued at 911 AM CDT SAT MAY 2 2015

Updated the forecast to keep a mention of scattered showers over
eastern KS into the early afternoon. The RAP has analyzed a weak
vort max drifting over the area which can be seen in the 500MB
profiler data. Think the HRRR may have a reasonable grasp on the
showers through the morning. Also there appears to be little or no
instability. Mid level lapse rates are not that steep and models
prog little change to them into the early afternoon. With there
being little lightning activity now, do not think it will
intensify over the next several hours so have removed the mention
of thunder from the forecast.

UPDATE Issued at 649 AM CDT SAT MAY 2 2015

More light showers are developing across central and south central
KS this morning and have upped POPs for southern portions of
forecast area this morning because of that. Precip falling from
mid-level deck and considerable low-level dry air to overcome, so expect
sprinkles to a few hundredths at most with this activity. Short
range models weaken this area this morning as it moves east.
Otherwise no changes to going forecast.


...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 351 AM CDT SAT MAY 2 2015

Showers/isolated thunderstorms across southeast Nebraska and far
northeast KS are occurring in elevated warm advection zone near
convergence at nose of low-level jet.  This activity has been
confined to far northeastern part of forecast area and should remain
there this morning.  Bigger question what else gets going in
central/north central KS in the next few hours and that could move
across a far greater portion of northeast KS this morning.  Poorly
defined shortwave trough seen best in RAP analysis and also somewhat
apparent in water vapor loop moving toward north central KS at the
current time.  HRRR, RAP and 06Z NAM all have a larger area of
precip developing in the next few hours apparently associated with
this feature.  If it develops as forecast, it will affect a wider
part of northeast KS this morning than previously thought.  Have
expanded area of 20-30 percent POPs this morning due to trends in
short range models, but difficult to go too high with virtually
nothing showing up on radar over central KS at this time.

Whatever precip develops should be moving out of far northeast KS
early this afternoon and expect dry conditions for the rest of this
afternoon through tonight as weak ridging aloft is over the area.
Temps today will depend on cloud cover with far eastern KS most
likely to see the most persistent clouds and temps only in the upper
70s while some clearing this afternoon in central KS should lead to
lower 80s.

.LONG TERM...(Sunday through Friday)
Issued at 351 AM CDT SAT MAY 2 2015

By Sunday, models show a broad mid-level ridge stretched across the
southern CONUS with surface low pressure extending from the High
Plains into the Northern Plains.  With this low pressure just west
of the forecast area, a decent pressure gradient is expected to set
up over the area, resulting in breezy southerly winds supporting
good warm-air advection across the entire forecast area. With these
conditions in place, have continued to trend on the warmer side of
model guidance with highs in the low/mid 80s.

Models continue to hold off on the front moving into north
central Kansas until Sunday evening, so have a dry forecast for
the daytime hours with chance to likely PoPs Sunday night through
Monday as the cold front advances into the CWA and then stalls out
over the area. By Monday the mid-level ridge will be focused
across the southeastern U.S. and should start building northward
Monday night into Tuesday, causing the stalled cold front to lift
northward as a warm front. There are still some model
discrepancies with how far north the warm front will lift (near
the KS/NE border or into southern NE), but have lowered or even
removed PoPs from far east central Kansas Monday night with likely
PoPs still near the KS/NE border. The best chance for dry
conditions looks to be on Tuesday with the front likely to the
north, so have continued to drop PoPs to only slight chances or
even dry for some locations. However, shower and thunderstorm
chances return Tuesday night as a mid-level trough over the
southwestern U.S. lifts northeastward toward the area,
strengthening the surface low pressure system and pushing it into
the High Plains. Models seem to be coming into slightly better
agreement with the tracking of the mid-level trough and surface
low, with the trough lifting into the Central Plains Wed/Wed night
and into the Northern Plains by Thursday. At the surface, the
surface low and associated cold front look to be stalled out along
the High Plains Tuesday night through Wednesday before shifting a
bit further east. With this steady southerly flow into the region,
should see some modest moisture advection into the area by mid-
week as we should be able to tap into moisture from the Gulf of
Mexico. This moisture advection along with some mid-level forcing
will bring increasing chances for scattered showers and
thunderstorms Tuesday night through Wednesday night with
diminishing chances for the remainder of the week as we lose the
mid-level forcing. With low confidence in whether or not scattered
precipitation will be lingering by the end of the week, have
dropped PoPs to low-end chances for Thursday night and Friday. The
persistent southerly flow and moisture advection also will lead to
mild conditions with highs in the 70s and lows in the 50s/60s as
well as humid conditions with dewpoints steadily in the 50s/60s.


.AVIATION...(For the 18Z TAFs through 18Z Sunday Afternoon)
Issued at 1224 PM CDT SAT MAY 2 2015

Improving conditions will be the trend for the rest of today
outside of the increase in winds. Gusts are likely as clouds
dissipate and mixing takes place. Wind shear conditions could be
present tomorrow morning with the LLJ increasing over the region,
but did leave mention out of the TAFs for now. There is the
possibility also for a round of showers or elevated convection late
in the TAF period associated with a vorticity max moving out of
the Central Rockies affecting all the terminals. Timing on this
would be uncertain at this point but will be something to pay
attention to for longer term planning.




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