Area Forecast Discussion
Issued by NWS Topeka, KS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

590
FXUS63 KTOP 191737
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1237 PM CDT Sun Mar 19 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 255 AM CDT Sun Mar 19 2017

Surface high pressure is gradually retreating eastward this
morning allowing the return flow to become further established. A
strengthening low level jet is supporting moisture return aloft
under modest mid level lapse rates. This is yielding elevated cape
on the order of 1500 j/kg. Soundings show that parcels within the
moist warm nose are basically unstable and just need some
forcing. The vertical wind profiles show a low level jet that is
fairly unidirectional, but there is some speed convergence over
eastern KS. There is also isentropic lift on the 300-305 K
surfaces, which could support isolated to scattered storms in the
few hours centered around sunrise as advertised by the models. The
latest trends have been to develop these storms further east over
MO, which is where the forcing may end up migrating by sunrise.
Given the instability in place if a storm is able to develop small
hail may be possible. The highest chances for storms appear to be
along and southeast of the KS turnpike. By late morning the storm
threat will move east into MO therefore have decreased pops.

The 850 mb temperatures will approach 18 C today, which should
mix down into the 80s today. The high res models are introducing a
complex low level moisture scenario today. The 50 and 60 dew
points in OK will move into the area late morning ahead of a cold
front driven by a shortwave progressing over the northern plains.
A dry punch associated with the EML will stretch from southwest to
central KS during the afternoon. Also an area of deep mixing and
gusty winds will stretch from south central into northeast KS.
This will cause the RH values to drop into the 20-30 percent
range. Wind gusts in the deep mixing will be around 30 to 35 mph
late morning and afternoon. This dew point and wind gusts forecast
is close to the HRRR, which is usually the most extreme guidance
and leads to the worst case scenario regarding these parameters.
The conditions today will cause extreme fire danger in the
southwest portion of the forecast area. Most of the remaining area
will reach very high fire danger with the exception of far
northeast KS. The cold front pushes through the area from the
northwest this evening tonight. Any instability should be capped
as the front moves through.

.LONG TERM...(Monday through Saturday)
Issued at 255 AM CDT Sun Mar 19 2017

Incoming front on Monday moves southward slowly, leaving the far
southern counties under the thermal ridge and with the potential
to hit the 80s for a second day. Farther north toward the Nebraska
border highs hold generally in the 60s. Chances for some light
precip return generally after midnight Monday night through
Tuesday afternoon as shortwave energy moves over the front, but
resulting amounts are light. Could actually see a bit of a break
Tuesday night into early Wednesday with less coverage as the
front pushes southward through the Texas panhandle. Highs Monday
and Tuesday behind the front hold in the 50s with lows in the 30s
to 40s Tuesday night and Wednesday night.

Thursday still looks to be a transitional day as upper ridge
shifts over eastern Kansas, followed by a quick return to
southwesterly flow aloft and southerly winds at the surface
bringing moisture and instability back into the area. GFS is
weaker with the return before the cold front sweeps through the
are Friday morning. The ECMWF is about 18 hours slower with the
frontal passage, and rain chances that linger into Saturday are a
probabilistic reflection of those differences. System could still
bring strong to severe storms to the area anytime from late
Thursday afternoon through Friday, but uncertainty on timing and
strength still remains.

Some consistency with guidance for highs in the 60s over the
weekend, before the next system approaches for early next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1235 PM CDT Sun Mar 19 2017

VFR conditions are expected through today and the first part of
tonight with southerly winds gusting up to 25 to 30 kts this
afternoon. LLWS may develop between 00-08Z before a frontal
boundary moves through and shifts winds to the north late in the
night. Patchy fog may develop out ahead of this front tonight, but
should dissipate once the front moves through.

&&

.FIRE WEATHER...
Issued at 255 AM CDT Sun Mar 19 2017

The winds will be out of the southeast this morning, but gradually
veer to the south by noon and perhaps southwest especially in the
afternoon and evening. Winds speeds will be about 15 to 25 mph with
gusts up to 35 mph. The minimum RH values will generally drop into
the 30 percent range with some locations dropping into the 20s. This
low RH be caused by a dry punch across central KS and an axis of
deep mixing that will stretch from Wichita to Topeka. This axis will
also be where the highest wind speeds occur this afternoon.
Therefore a red flag has been issued to highlight the extreme fire
danger. Given the dry and windy conditions across the entire area
the remaining locations should experience very high fire danger with
the exception of far northeast KS.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 8 PM CDT this evening for KSZ021-022-
034>038-054.

&&

$$

SHORT TERM...Sanders
LONG TERM...67
AVIATION...Skow
FIRE WEATHER...Sanders



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.