Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 172325
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
625 PM CDT Tue Apr 17 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Wednesday)
Issued at 326 PM CDT Tue Apr 17 2018

Some cirrus overhead today as upper winds tap into the subtropical
plume, but drier air aloft was working into the area as a deep
upper trough works its way over the central Rockies. Local winds
remain east to southeast with surface low in northeast Colorado
with a nearly 20-degree temperature gradient across the CWA as
warmer air pushes north in warm-air advection over the boundary
layer.

Models are in good large-scale agreement with the upper trough push
quickly east across Nebraska tonight and surface low moving through
northern Kansas. Continued south winds ahead of these features
allows some decent moisture return, but under a stout EML. 500mb
heights will fall around 60m this evening in northern areas and help
weaken the cap, but may not be enough to allow convection. Will keep
a small pop in northern areas in the 02Z-08Z window, with any
convection bringing small hail potential in elevated CAPE near 1000
J/kg. Strong pressure gradient force behind the surface low brings
brief potential for winds near Advisory levels, but a more
persistent wind threat comes Wednesday as mixing increases before
the synoptic system exits Iowa. Could see a few hours of sustained
speeds reach Advisory speeds in the far southwest, but not confident
enough in this apparently marginal episode for any headlines yet.
Low cloud is expected to rotate southwest around the low tonight
into midday Wednesday, and will likely keep temps a bit cooler than
earlier expected.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 326 PM CDT Tue Apr 17 2018

Thursday remains quiet with upper ridge in place and modest north to
east winds but temps should still reach near seasonal normals. Next
upper trough approaches the area as the weekend approaches but
continues to track southeast of the area, keeping precip light,
though at least small chances persist through Sunday morning.
Another wave moving east across southern Canada helps keep column
temps from supporting any wintry precip.

Split flow continues into early next week for little of concern and
mild temps.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 618 PM CDT Tue Apr 17 2018

VFR prevails to start the forecast period with the main focus
being an incoming cold front bringing strong winds to the
terminals in the 03Z-09Z time frame from the west. As gusty sfc
winds from the east veer towards the northwest, low level speed
and directional shear is expected through 2 kft aft 02Z at KMHK
and 03Z at KFOE and KTOP. Mid and high clouds increase thereafter
with short term guidance coming into better agreement with an MVFR
stratus deck developing southward aft 12Z. Forecast soundings
have the depth of the stratus being shallow around 500 feet, so I
would expect it to dissipate back to VFR for tomorrow afternoon.
The strong northwest winds above 20 kts sustained will persist
through the period.

&&



.FIRE WEATHER...
Issued at 326 PM CDT Tue Apr 17 2018

Conditions Wednesday continue to support elevated fire weather
levels. Main change with this forecast was to lower temps a bit in
the northeast where low cloud looks to hang on longer. This limits
minimum RH values there somewhat. Very High fire danger is likely
for all of north central and east central Kansas on gusty northwest
winds. Winds will shift significantly tonight as a surface low and
cold front pass, shifting to the west to northwest late this evening
into the pre-dawn hours.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...65
LONG TERM...65
AVIATION...Prieto
FIRE WEATHER...65



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