Area Forecast Discussion
Issued by NWS Tulsa, OK

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000
FXUS64 KTSA 210437
AFDTSA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
1137 PM CDT SAT SEP 20 2014

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
SURFACE COLD FRONT TO MOVE THROUGH THE AREA FROM NORTH TO SOUTH
AROUND 12Z ACROSS FAR NE OK AND THROUGH THE MORNING HOURS FOR
SITES TO THE SOUTH AND EAST. WARM AND MOIST AIRMASS COMBINED WITH
LIGHT WINDS AHEAD OF THE FRONT WILL LIKELY AID IN FOG POTENTIAL
ACROSS NE OK AND NW AR FOR PORTIONS OF THE OVERNIGHT...RESULTING IN A
PERIOD OF MVFR/IFR VSBYS PRIOR TO FRONTAL PASSAGE. LOW CHANCES FOR
TSRA WILL BE HANDLED WITH VCTS ACROSS NE OK AND NW AR JUST AHEAD
OF FRONT. OTHERWISE VFR CONDITIONS WILL PREVAIL OUTSIDE OF FOG AND
ISOLATED THUNDER...AND FOR THE REMAINING PORTION OF THE TAF AS
DRIER AIR SETTLES IN BEHIND THE FRONT.

&&

.PREV DISCUSSION... /ISSUED 701 PM CDT SAT SEP 20 2014/

DISCUSSION...

A BAND OF STORMS IS ONGOING OVER EAST CENTRAL KANSAS ALONG A PRE-
FRONTAL TROUGH/WIND SHIFT. THE SYNOPTIC COLD FRONT LAGS BEHIND AND
IS NEAR THE NEBRASKA-KANSAS BORDER ATTM. THE LATEST LOCAL WRF AND
HRRR RUNS SHOW POTENTIAL FOR CONVECTION OVER NORTHEAST OK AND
POSSIBLY NORTHWEST AR AFTER MIDNIGHT TONIGHT. IT IS UNCLEAR
WHETHER THIS WILL BE NEW DEVELOPMENT...OR A CONTINUATION OF WHAT
IS CURRENTLY GOING ON. THE HRRR SEEMS TO THINK THE FORMER RATHER
THAN THE LATTER. A THETA-E RIDGE AXIS LIES ACROSS SOUTHEAST OK
DOWN INTO NORTHEAST OK...SO EITHER SCENARIO IS POSSIBLE ONCE THE
FOCUSING BOUNDARY GETS DOWN HERE. REGARDLESS...WITH THE NAM/LOCAL
WRF/HRRR ALL SHOWING SOMETHING OVER NE OK LATER TONIGHT...I HAVE
RAISED POPS SOME IN THIS AREA. TEXT/WEB PRODUCTS HAVE BEEN UPDATED.

LACY

PREV DISCUSSION... /ISSUED 608 PM CDT SAT SEP 20 2014/

AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
SURFACE COLD FRONT TO MOVE THROUGH THE AREA FROM NORTH TO SOUTH
AFTER 12Z. WARM AND MOIST AIRMASS COMBINED WITH LIGHT WINDS AHEAD
OF THE FRONT WILL AID IN FOG POTENTIAL ACROSS NE OK AND NW AR
OVERNIGHT...RESULTING IN A PERIOD OF MVFR/IFR VSBYS. LOW CHANCES
FOR TSRA WILL BE HANDLED WITH VCTS ACROSS NE OK AND NW AR JUST
AHEAD OF FRONT. OTHERWISE VFR CONDITIONS WILL PREVAIL OUTSIDE OF
FOG AND ISOLATED THUNDER...AND FOR THE REMAINING PORTION OF THE
TAF ONCE THE BOUNDARY MOVES THROUGH.

PREV DISCUSSION... /ISSUED 329 PM CDT SAT SEP 20 2014/

DISCUSSION...
SFC ANALYSIS AT 3 PM SHOWED PRE-FRONTAL TROUGH EXTENDING FROM
ROUGHLY KSTJ-KLBL WITH ACTUAL COLD FRONT LAGGING FROM EXTREME NW
MISSOURI INTO SE COLORADO. FRONT WILL GRADUALLY DROP SOUTH THIS
EVENING AND WILL LIKELY BE APPROACHING OK/KS BORDER BY MIDNIGHT OR
EVEN LATER. GIVEN WEAK CONVERGENCE ALONG BOUNDARY...WEAK LAPSE
RATES AHEAD OF THE FRONT AND UPPER LEVEL SUPPORT WELL TO THE
NORTHEAST...NOT EXPECTING MUCH MORE THAN SCATTERED CONVECTION
LATE TONIGHT. THUNDERSTORM CHANCES WILL TREND SOUTH DURING THE DAY
SUNDAY...ALTHOUGH THERE WILL LIKELY BE A LULL IN THE ACTIVITY
DURING THE MORNING OR EARLY AFTERNOON BEFORE REDEVELOPMENT
COMMENCES SOUTH OF I-40 IN THE AFTERNOON...AGAIN WITH SCATTERED
COVERAGE AT BEST.

FRONT WILL USHER IN MUCH LOWER DEW POINTS LEADING TO STRETCH OF
PLEASANT TEMPS AND MAINLY DRY WEATHER. WEAK UPPER LOW PASSING TO OUR
NORTHWEST TUE/WED MAY INCH CLOSE ENOUGH TO BRING A CHANCE OF
SHOWERS TO FAR NORTHWEST AREAS. HOWEVER WITH THE SFC PATTERN
FEATURING A BROAD AREA OF HIGH PRESSURE EXTENDING ALL THE WAY FROM
NEW ENGLAND TO OK/AR...DRY AND STABLE REGIME WILL PERSIST THROUGH
THE REMAINDER OF THE EXTENDED PERIOD.

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&

$$

AVIATION...23




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