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FXUS63 KDDC 192341

Area Forecast Discussion
National Weather Service Dodge City KS
641 PM CDT Thu Sep 19 2019

...Updated Aviation Section...

.SHORT TERM...(This afternoon through Friday night)
Issued at 1130 AM CDT Thu Sep 19 2019

Full sunshine in progress across SW KS at midday, sending
temperatures well above normal once again this afternoon. There
has been a few degrees of cooling at 850 mb compared to previous
days, so most locations will hold in the lower 90s, compared to
the mid 90s. S/SE winds gusting near 30 mph will maintain boundary
layer dewpoints in the 60s all afternoon, with CAPE increasing to
2000-3000 J/kg. All models, CAMs and otherwise, agree on scattered
thunderstorm development after 3 pm, beginning across the
western/SW zones first, and then subsequently spreading
northeastward. A subtle wave in the SW flow should easily
encourage convective development, especially given the full
insolation, and the 5% marginal wind/hail probabilities from SPC
are justified. CAPE and limited shear will support mainly strong 
multicells, with wind gusts to 50-60 mph and up to quarter size 
hail. Model consensus continues to favor coverage across the 
western 1/2 of the CWA (west of US 283) through this evening. 
Activity should wane before reaching much of the eastern/NE zones. 

The persistently warm overnight/morning temperatures continue
tonight, holding in the mid/upper 60s at sunrise Friday. MOS
guidance is several degrees too cool and was ignored. Increasing
mid level clouds are expected overnight. Another wave embedded in
the SW flow aloft will approach near sunrise, spreading rain
showers (perhaps embedded thunder) into the western zones early

Welcomed cooler temperatures are expected on Friday, courtesy of
cloud cover and showers. Models are changing their tune on
Friday's weather, with 12z NAM and 4km NAM now keeping thick
clouds and persistent showers across SW KS through at least
midday Friday. 12z GFS also shows notable cooling at 850 mb
Friday, down to the 18C range. NAM-based guidance suggests areas
that stay under clouds/showers all day will hold in the 70s. Will
trim max temp grids on Friday, but any cloud breaks will send
temperatures into the 80s in only a few minutes, so remained 
above the coolest guidance. Temperature forecasts directly linked
to sunshine availability are difficult to say the least. Obviously
a cooler boundary layer in SW KS would force any trough/dryline 
stronger storm development westward to near the CO/KS border 
(perhaps SE CO) as several CAMs suggest. Another risk of severe 
storms will exist Friday afternoon/evening, focusing on the 
western zones (west of US 83) where the atmosphere has the most 
opportunity to recover from morning activity and overturning. 
Primary risk from any supercell storms across the western zones 
Friday afternoon/evening will be large hail. 

.LONG TERM...(Saturday through Thursday)
Issued at 203 PM CDT Thu Sep 19 2019

Strong to severe thunderstorms are becoming increasingly probable
Saturday afternoon/evening as a frontal boundary sags southward
across Kansas and interacts with a highly moist atmosphere. High
moisture will create plentiful CAPE, and kinematics/dynamic lift 
will also be substantial with trough axis still west of SW KS. 
12z ECMWF focuses initiation along/east of US 283, aligning well
with 5-15% severe probabilities from SPC. Large hail and damaging
winds are possible from the strongest storms, with the threat 
highest east of Dodge City. With S/SW flow ahead of the frontal 
boundary, temperatures will remain warm and above normal, in the 
upper 80s to lower 90s. 

12z ECMWF projects a large MCS to develop along the front across
central/eastern Kansas Saturday night, which will help propel the
frontal boundary southward during the cooler nocturnal hours. Will
need to monitor eastern zones for convective/flooding impacts
Saturday night. Models are now slightly stronger with cooler 
surface high pressure ridging on Sunday, delivering a light north 
wind, and forcing temperatures close to normal for a change. Now
forecasting highs in the 78-82 range Sunday, with lows well down 
into the 50s Monday morning. All convective potential will end 
Sunday afternoon as frontal forcing exits southward and heights 
rise strongly. 

Next week, the forecast will be an exercise involving tracking a 
cutoff low. There will clearly be one, as all models develop one, 
but the very nature of cutoff lows (separated from primary jet 
stream flow) makes their tracks notoriously difficult to predict. 
12z ECMWF drops its cutoff into Arizona Monday night, with warm
air advection well ahead of it spreading showers and thunderstorms
into Kansas. According to the 12z ECMWF, the cutoff is not east of
SW KS until Friday Sep 27th. Point being, we may be talking about
this system for many days. 12z GFS appears way too progressive 
with this system, resulting in wildly divergent model solutions 
for next week. Continue to lean toward the ECMWF solutions, but 
forecast clarity for next week will be fuzzy for a while. 


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 635 PM CDT Thu Sep 19 2019

South winds will continue through this TAF period with overnight
speeds 8 to 12 knots and late morning through late afternoon
Friday speeds 15 to 18 knots sustained (strongest around GCK
terminal). Some stratus clouds are expected to develop to the
south of southwest KS late tonight/early Friday morning, but 
there is some question as to how far north these will reach before
scattering out after sunrise. For now, given the degree of
uncertainty in IFR/MVFR ceiling, we will keep out of the TAF. This
will need to be assessed further for the next TAF cycle, though.
Evening thunderstorms at the onset of this TAF period are expected
to remain far enough from any from the terminals (GCK, DDC, HYS, 
LBL), so no mention of convection is warranted at issuance time.
Showers and and isolated thunderstorm or two may develop in the
12-18Z time frame Friday, however again, the uncertainty is quite
high regarding coverage and intensity of any of this activity so
this TAF set will not include any showers or thunderstorms during
the morning/midday time frame Friday. This will also need to be
further scrutinized on the next TAF update at 20/06Z.


DDC  65  84  67  89 /  20  30  20  40 
GCK  64  84  65  88 /  30  30  30  20 
EHA  62  86  63  89 /  40  20  10  10 
LBL  62  85  65  90 /  40  40  20  10 
HYS  68  85  68  85 /  20  30  20  30 
P28  67  85  69  88 /  10  20  20  50 



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