Area Forecast Discussion
Issued by NWS Tulsa, OK

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000
FXUS64 KTSA 201057
AFDTSA

Area Forecast Discussion
National Weather Service Tulsa OK
557 AM CDT Thu Apr 20 2017

...UPDATE...

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.

MVFR ceilings will prevail through much of the day at all
terminals except FSM, which should see VFR ceilings during the
afternoon and early evening before decreasing to MVFR once again
overnight. BVO/TUL/RVS should see at least one period of TSRA
this morning before a lull during the afternoon and a portion of
the evening, with XNA/FYV/ROG most likely to see scattered SHRA
and possible TSRA this afternoon. More widespread thunderstorms
will develop late evening and into early Friday morning, with
prevailing IFR/MVFR conditions in TSRA for the last 4 to 6 hours
of the valid TAF period at the NE OK and NW AR terminals. These
thunderstorms may also affect MLC and FSM, and will cover with a
PROB30 at both sites.

&&

.PREV DISCUSSION... /Issued 321 AM CDT Thu Apr 20 2017/

DISCUSSION...
Very little has changed since yesterday regarding the upcoming
forecast. A frontal boundary will sag south into the area early
this morning, with convection likely to increase along this
boundary towards and just after sunrise. Organized severe weather
is not expected with the storms along the boundary today.

The main event begins to unfold this evening as isentropic lift
increases to the north of the front, which will be stalling out
near or a bit south of Interstate 40. Widespread showers and
thunderstorms will develop north of the boundary this evening and
continue into Friday. Elevated instability does support the rish
of hail with the stronger storms, but the main threat will be
heavy rainfall. Widespread rainfall amounts of 2-4 inches are
likely within the flash flood watch area, with local amounts over
5 inches likely. The front may try to lift slightly north during
the day Friday, but any northward progress will be hindered by
widespread precipitation to its north.

By late Friday, the front will begin to surge southeast, and
convection may attempt to fire on the advancing boundary. If
updrafts can become sustained on the warm side of the boundary, a
greater severe weather risk will ensue, but this appears rather
unlikely at this time.

A few wraparound showers may linger into Saturday across parts of
northest Oklahoma and northwest Arkansas, and it will be a chilly,
raw day, with afternoon temperatures remaining in the 50s in most
places.

A quick warmup ensues Sunday and continues into early next week.
Considerable model differences exist by the middle to latter part
of next week, so will keep pops during this time frame on the low
side for now.

Stayed close to guidance temperatures today and tonight, with the
colder side of guidance preferred for areas north of the frontal
boundary Friday.

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Flood Watch from late tonight through Friday evening for
     OKZ054>070.

AR...Flood Watch from late tonight through Friday evening for ARZ001-
     002-010-011.

&&

$$

AVIATION...22


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