Area Forecast Discussion
Issued by NWS Tulsa, OK

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FXUS64 KTSA 230128

Area Forecast Discussion
National Weather Service Tulsa OK
828 PM CDT Mon May 22 2017


Showers continue to move eastward into parts of eastern Oklahoma
and far western Arkansas as an upper level vorticity max swings
through the region. Thunderstorms have so far been confined to the
western half of Oklahoma, with diminishing lightning upon
approaching the lower instability east of Interstate 35.
Mesoanalysis indicates that some increase in instability has
occurred across the area in the past 3 hours, which could
eventually lead to some isolated thunder potential this far east
later in the evening and overnight. The main change to the going
forecast has been to increase POPs some, especially along and
north of Interstate 40. Other elements appear on track. Updates
already out.


.PREV DISCUSSION... /Issued 552 PM CDT Mon May 22 2017/



Showers and isolated thunderstorms will begin to affect the
terminals this evening, waning after midnight, with another round
likely to develop early to mid afternoon tomorrow. With regards to
the ongoing activity, will cover the potential with VCSH in the
prevailing group, with tempo groups containing thunder during the
most likely time frame at each site, except BVO, this evening. The
expected thunderstorms tomorrow afternoon will be most likely at
the AR terminals, where tempo groups have been included, with the
E OK sites covered with a PROB30. In between the two rounds of
showers/thunderstorms, MVFR visibilities and ceilings will develop
early tomorrow morning and persist through late morning.

PREV DISCUSSION... /Issued 335 PM CDT Mon May 22 2017/

Broad upper trough centered over southern Canada continues to
result in cyclonic northwest upper flow over the plains states
with trey warm sector air suppressed well to our south at present.
Lead shortwave has resulted in widespread showers across western
into central OK this afternoon and this precip will continue to
spread into eastern OK this evening. Limited instability will
keep the chance of thunder isolated through tonight as well.

Stronger shortwave in northwest flow currently near Black Hills
region will drive a cold front through the area Tuesday, offering
additional chances for showers and isolated thunderstorms, again
with very limited potential for severe weather, though small hail
and strong wind gusts may occur with a few storms Tuesday
afternoon as colder mid level temps accompany wave passage. Front
will bring an atypical airmass for late May over the region mid-
week with temperatures remaining several degrees below normal
through Wed night.

The warm and humid air we more often experience this time of year
should return late this week with upper flow trending more west
or southwesterly with time and low level flow from the Gulf.
Models continue to show differences with shortwave energy moving
through the plains and driving another front south over Memorial
Day weekend. At this time it appears the best chance of
thunderstorms and attendant severe weather/heavy rainfall threat
will be early in the weekend, with front bringing cooler and
drier airmass south for the end of the holiday.




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