Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 182335

Area Forecast Discussion
National Weather Service Topeka KS
635 PM CDT Sat Mar 18 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday)
Issued at 338 PM CDT Sat Mar 18 2017

The 20Z afternoon surface analysis showed a high pressure axis
extending down the central Missouri River basin, bisecting the
eastern half of the CWA. Upper level ridging encompassed much of the
western CONUS with high orographically-generated cirrus spilling
southeastward across the Central Plains. As the high slides east
tonight, return flow is expected to bring an increase in low-level
moisture northward from the Southern Plains. Low level stratus
should be the visual manifestation of this moisture, working its way
northward this evening and persisting through the overnight. This
H850 saturated nose in combination with a modest EML will create an
unstable profile with MUCAPE values ranging from 1000-2000 by
12Z Sunday (though some of the NAM profiles look somewhat
unrealistic with an exaggerated warm nose). With a 30 to 40 kt LLJ
anchored just under this unstable layer, it would not take much of a
perturbation to launch a parcel. However, given the weak effective
shear profiles, little in the way of organized or long-lived
convection is expected, with small hail being the only real threat
from these elevated storms. The best threat for initiation based on
the latest CAM consensus would be over the southern and eastern
CWA, moving out of the area around 15Z. Kept POPs at slight chance
to chance wording given the uncertainty in coverage and timing.

Attention then turns to Sunday`s near record to record high
temperatures as H850 temps surge to +15 to +20 C. How quickly the
lingering stratus can clear will dictate the eastward extent of the
80+ degree readings tomorrow. Early indications from the RAP point
toward the stratus being thin in nature and will burn off quickly as
solar insolation increases during the early to mid morning hours.
Thus leaned towards the more aggressively warm solutions for highs
tomorrow, with highs in the 80s CWA-wide with upper 80s in the south
and west. This would easily set record highs at Topeka (record high
for tomorrow being 82 set in 1907) and Concordia (record high: 81
set in 1921). Also increased winds above 20 kts sustained in the
south on Sunday with a modest pressure gradient in place, likewise
increasing the fire danger over these same areas.

.LONG TERM...(Sunday night through Saturday)
Issued at 338 PM CDT Sat Mar 18 2017

Sunday night a shortwave moving east through the upper zonal flow
across the Northern Plains will bring a frontal boundary southward
into northeast Kansas by Monday morning. The front is forecast to
gradually move to the southeast through the day as high pressure
builds southward into the Central Plains. This present a challenge
for high temperatures with areas behind the front in the 60s with
mid to upper 70s ahead of the front. The next chance for
precipitation looks to be Tuesday into Wednesday as a series of
small waves move eastward across the area in the zonal to slightly
northwest flow. Moisture will begin to return northward over the
frontal boundary to the south Tuesday night into Wednesday. Thermal
profiles suggest that parts north of I-70 may see a mix of rain and
snow with parts of north central Kansas seeing some light west snow.

The main focus for the forecast shifts to the main upper trough
moving into the Plains for the end of the week. The medium range
models continue to differ with the speed and depth of the upper low.
That said have retained continuity for the end of the week leaning
toward and ensemble mean solution. A warm front moving northward
from southern Kansas Wednesday night along with an increasing low
level jet will lead to elevated thunderstorms into Thursday morning.
A rather dynamic upper low is expected to move out into the Plains
by Friday. Given the differences in the models confidence in the
placement of the surface synoptic features remains low at this time.
Shear and instability along with moisture should be sufficient for
strong to severe storms from Thursday through Friday evening.
Temperatures will be cooler in the 50s Tuesday and Wednesday before
warming back into the 60s Thursday.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 623 PM CDT Sat Mar 18 2017

VFR conditions are likely through the TAF period. Primary aviation
impacts are potential for scattered TS between 09-13Z at TOP/FOE.
Also expect winds around 35 kts at 1300 feet, and have not
included LLWS at this point but conditions will be borderline for
inclusion between 08-13Z.




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