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FXUS64 KOUN 251118

Area Forecast Discussion
National Weather Service Norman OK
618 AM CDT Sun Aug 25 2019



For the 12z TAFs: 

Thunderstorms will impact PNC by 12z with the worst of the
conditions (strong winds, low ceiling/vis) occurring initially,
through about 14-15z, followed by continued rain/occasional 
lightning for at least a few hours after. Another period of
thunderstorms may reach OKC/OUN by 14z. At both sites, conditions
should improve during the afternoon. Further west, isolated
showers and storms could affect CSM, but unlikely at other TAF
sites, through about 15z. 


.PREV DISCUSSION... /issued 227 AM CDT Sun Aug 25 2019/ 

Initial focus is with ongoing convection and associated hazards 
early this morning. As of this writing, upscale growth and a 
maturing cold pool/RIJ was noted over south-central Kansas. This 
forward propagating MCS is coincident with cooler midlevel 
temperatures associated with a shortwave trough that continues to 
move southeast, and should enter north-central Oklahoma around 
4am. Damaging winds will be the primary threat given 
maturity/organization of the system in an unstable environment. 

Across northwest and north-central Oklahoma, convection has already 
been ongoing on the periphery of large scale ascent and augmented by 
strengthening low level jet. 40-50 knots of effective shear across 
this region has aided in organization of cells and they have been 
marginally severe at times. Over the last hour has expanded in 
coverage. Downstream longevity to near and south of the I-40 
corridor is somewhat in question given proximity of large scale 
ascent/cooler temperatures aloft and core of low-level jet, and will 
probably be dictated by how strong of a cold pool can form. 

Flash flooding is another concern. Given the progressive nature of 
the MCS moving out of Kansas, intense rainfall rates should be 
rather short in duration but portions of the area have seen 
saturating rains lately, particularly in Payne, Lincoln, and 
Harper counties per 7-day AHPS QPE and mesonet data. Also, FLASH 
CREST soil moisture really stands out in these areas. Another 
concern is that this complex is occurring at the nose of the low 
level jet and there may be a period of training along the western 
flank of convection which could yield some locally very high 
amounts. This behavior is already being noted in central Kansas.
We'll continue to monitor trends on the mesoscale and update the 
configuration of the Flood Watch accordingly. Western sections 
may be trimmed shortly if trends continue. 

Midlevel height rises as shortwave trough moves east should
preclude redevelopment this afternoon, even near residual
outflow boundary and surface convergence. 

A surge of hotter 850-mb temperatures Monday will translate to
surface temperatures 5-10 degrees above normal for late August.
The hottest temperatures will be across our southwest counties
where a few locations could approach 110F. Particularly low RH
values may develop in this area, and even with light breezes some
concern for intense fire growth/plume dominated type fires may
exist given the dry state of the fuels. We'll need to assess this
potential further as this time period nears. 

Hot temperatures along with high dew points will bring heat 
indices to 105-110F across most of the area with the exception 
being roughly the northwest two-thirds of the area which will be 
north of a synoptic surface boundary. The synoptic scale upper 
flow pattern by then will feature broad cyclonic flow to our north
and not much forcing for us. Any thunderstorms that do form will 
be diurnally driven and focused near convergence of aforementioned

A lower latitude track of the next shortwave embedded within the
westerlies and on the periphery of persistent mid-upper high may
enhance convective coverage into Tuesday, particularly across
southern Oklahoma and north Texas in the vicinity of remnant 
surface boundary. This may become a setup favorable for 
flooding/flash flooding given the boundary orientation to modest 
flow aloft and anomalous precipitable water values that are 
actually quite impressive. At least low convective chances
continue into late week, although no significant forcing for a
more widespread/significant event is indicated by medium range
guidance during that period. 



Oklahoma City OK  84  73  97  70 /  60   0   0  50 
Hobart OK         97  74 103  71 /  20   0   0  30 
Wichita Falls TX  98  76 104  75 /  20   0   0  20 
Gage OK           94  69  97  64 /  20   0   0  40 
Ponca City OK     80  70  90  66 /  90  10  10  40 
Durant OK         90  74  98  75 /  20   0   0  40 


OK...Flood Watch until 1 PM CDT this afternoon for OKZ004>013-015>020-


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