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Area Forecast Discussion (AFD)

Issued by Topeka, KS (TOP)

                            
000
FXUS63 KTOP 230448
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1148 PM CDT Sat Jun 22 2019

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday)
Issued at 329 PM CDT Sat Jun 22 2019

Main concern this afternoon and evening will be convection rapidly 
developing across the area. Latest satellite trends show building 
cumulus along a frontal boundary across central Kansas as well as a 
northward moving warm front across east central Kansas. These were 
developing in areas of deep moisture convergence, especially just 
north of the surface low in south central Kansas. Good deep moisture 
advection was occurring across eastern Kansas at 19Z and surface dew 
points have risen into the mid and upper 70s across east central 
Kansas. The atmosphere was becoming increasingly unstable with 
SBCAPE exceeding 4000 J/kg across much of the CWA at 19Z. Effective 
shear of 30 to 45 kts was observed with the highest across north 
central Kansas. Some backing of the low level winds in central and 
north central Kansas will locally enhance low level helicity so 
cannot rule out an isolated tornado. 

Also along with the severe threat of winds and hail will be locally 
heavy rainfall potential. As stated above good deep moisture flux 
into eastern Kansas will make for efficient precipitation potential 
where storms could quickly produce 1 to 2 inches of rainfall. 
precipitable water values look to rise to near 1.8 inches across the 
area. Expect one round this evening and then a second toward sunrise 
from an MCS from western Kansas. Given the amount of moisture 
expected have decided to issue a flash flood watch for much of the 
area through 1 PM Sunday. May need to possibly extend parts of east 
central Kansas longer depending on where the frontal boundary is 
located. Overall severe threat could be minimized if morning 
convective debris limits destabilization in the afternoon hours. 

.LONG TERM...(Sunday night through Saturday)
Issued at 329 PM CDT Sat Jun 22 2019

Majority of the active convection should be well east and southeast 
of the area by Sunday evening.  Axis of short-wave trough still 
upstream by 00Z Monday with strengthening upper-level jet rotating 
northeastward toward eastern Nebraska by 06z Monday.  Significant 
westerly component to low-level winds Sunday evening, but appears 
enough lingering modest instability could be in place for some 
scattered evening convection, primarily across northeast and east-
central Kansas.

Seasonably cool and dry day for Monday.  Increasingly moist and 
conditionally unstable air begins to return Monday night.  Despite 
decent low-level theta-e advection, soundings look generally 
unsupportive of convection until later Tuesday.  By that time, 
typical summer airmass in place with abundant CAPE and only limited 
convective inhibition, but also not much in the way of any 
substantial source of initiation.  GFS does kick out some modest QPF 
late Tuesday. There may be a very weak boundary near KS/NE border 
then, and going forecast has this well-covered with low-chance PoPs.

Wed-Fri look more like summer with slowly rising mid-level heights 
and weakening flow. Could be some isolated late-afternoon/early-
evening thunderstorm activity as mid-level temps don't become 
prohibitively warm through the forecast period.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1142 PM CDT Sat Jun 22 2019

VFR with stratiform rain showers with embedded thunder expected to
continue throughout the overnight period at KTOP/KFOE as
additionalTSRA develops to the southwest through 15Z. Lesser 
confidence in prevailing TSRA at KMHK aft 07Z so have only 
mentioned VCTS. Ceilings may fall to MVFR towards sunrise, but 
should lift by mid morning as activity clears eastward. Scattered 
TSRA is possible again towards late afternoon, however confidence 
remains low on coverage so have only a VCTS mention at this time.

&&


.TOP WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Sunday afternoon for KSZ010>012-
022>024-026-035>040-054>056-058-059.

&&

$$

SHORT TERM...53
LONG TERM...Manion
AVIATION...Prieto