Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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000
FXUS64 KOUN 271803
AFDOUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
103 PM CDT WED MAY 27 2015

.DISCUSSION...
SEE THE 18Z AVIATION DISCUSSION BELOW.

&&

.AVIATION...
LOW CONFIDENCE FORECAST THROUGH THE TAF PERIOD.

ONGOING SHOWERS AND THUNDERSTORMS IN CENTRAL OKLAHOMA ARE EXPECTED
TO CONTINUE THOUGH THE EARLY AFTERNOON. THEREFORE...INCLUDED TEMPO
FOR TSRA AT BOTH OKC AND OUN.

LATER THIS AFTERNOON...THUNDERSTORMS ARE EXPECTED TO DEVELOP
ACROSS WESTERN OKLAHOMA. INCLUDED TEMPO FOR TSRA AT
KGAG/KWWR/KCSM/KHBR/KLAW THROUGH THE EVENING. THESE THUNDERSTORMS
ARE EXPECTED TO MOVE FROM WEST TO EAST. THE HRRR SUGGESTS THESE
STORMS WILL DISSIPATE AS THEY APPROACH CENTRAL OKLAHOMA.
HOWEVER...THE 4KM NAM AND OPERATIONAL NAM INDICATE THE STORMS WILL
AFFECT KSPS/KOKC/KOUN/KPNC. OPTED NOT TO MENTION TSRA AT THESE
SITES FOR NOW DUE TO LOW CONFIDENCE.

LATE TONIGHT...WIDESPREAD LOW CLOUDS ARE EXPECTED...WITH MVFR TO
BRIEF PERIODS OF IFR CONDITIONS. SOME FOG IS ALSO POSSIBLE...BUT
DID NOT TO MENTION DUE TO LOW CONFIDENCE.

MAHALE

&&

.PREV DISCUSSION... /ISSUED 639 AM CDT WED MAY 27 2015/

DISCUSSION...
THE 12Z AVIATION DISCUSSION FOLLOWS....

AVIATION...
A SMALL AREA OF DENSE FG HAS FORMED ONCE AGAIN ALONG THE W EDGE OF
DEPARTING MID-LEVEL CLOUDS. THIS FG APPEARS TO BE VERY
SHALLOW...SO SHOULD BE GONE WITHIN AN HOUR OR TWO. A FEW SHRA AND
TSRA HAVE DEVELOPED IN PARTS OF W OK...AND A FEW MAY AFFECT TAF
SITES. IN PARTICULAR...A RATHER STRONG TSRA WILL PROBABLY PASS
OVER OR NEAR KLAW AROUND 12Z. THESE ELEVATED STORMS SHOULD
DISSIPATE AROUND MID- TO LATE-MORNING. NEW TSRA DEVELOPMENT IS
EXPECTED TO BEGIN AROUND 19Z IN SW OK. THESE TSRA WILL LIKELY
SPREAD OUT AND ADVANCE NE DURING THE AFTERNOON AND
EVENING...AFFECTING MAINLY W AND N OK AND THE KSPS AREA...BUT A
FEW MAY REACH KOKC/KOUN THIS EVENING OR OVERNIGHT. BR/FG MAY FORM
AGAIN TOMORROW MORNING...BUT UNTIL WE HAVE A BETTER IDEA OF WHERE
POST-THUNDERSTORM CLOUDS WILL BE...ANY FORECAST OF BR/FG WOULD BE
LITTLE MORE THAN A GUESS.

CMS

PREV DISCUSSION... /ISSUED 419 AM CDT WED MAY 27 2015/

DISCUSSION...
DEPARTING CONVECTIVE SYSTEMS HAVE LEFT A SITUATION SIMILAR TO THIS
TIME YESTERDAY...WITH CLEARING SKIES OVER VERY HIGH RELATIVE
HUMIDITIES AT THE SURFACE. THIS RESULTED IN AN AREA OF DENSE FOG
YESTERDAY MORNING. SO FAR TODAY...HOWEVER...THERE ARE NO
SIGNIFICANT VISIBILITY RESTRICTIONS...AND WITH LOW CONFIDENCE THAT
ANY FOG WILL DEVELOP...HAVE OPTED NOT TO INCLUDE IT IN THE
FORECAST FOR THIS MORNING.

THE 00Z AND 06Z NAM GENERATES A CONVECTIVE SYSTEM OVER EASTERN
OKLAHOMA THIS MORNING...THEN DRIVES IT WEST-SOUTHWEST ACROSS OUR
FORECAST AREA DURING THE DAY TODAY. THERE APPEARS TO BE NO REAL
JUSTIFICATION FOR THIS SCENARIO...SO HAVE IGNORED THE NAM FOR THE
FIRST 12 TO 24 HOURS OF THE FORECAST.

THE NEXT COUPLE OF DAYS WILL FEATURE WEAK FLOW ALOFT AND NEAR THE
SURFACE...MODERATE TO STRONG INSTABILITY...AND LITTLE IN THE WAY
OF FOCUSING MECHANISMS. SO...EXPECT SHOWERS/THUNDERSTORMS WITH
RELATIVELY LITTLE GEOGRAPHIC OR TIMING COHERENCE. THIS CHANGES
THURSDAY NIGHT INTO SATURDAY...AS AN UPPER-LEVEL SYSTEM...FOLLOWED
BY A SURFACE COLD FRONT...MOVE INTO OKLAHOMA AND NORTH TEXAS. RAIN
WILL BE MORE LIKELY...AND RAINFALL AMOUNTS WILL INCREASE OVERALL.

BEGINNING SUNDAY OR MONDAY...UPPER-LEVEL RIDGING STARTS TO TAKE
HOLD...WHICH SHOULD PROVIDE SUMMER-LIKE WEATHER ACROSS OKLAHOMA
AND NORTH TEXAS. ASSUMING THIS HAPPENS...IT WILL FINALLY SHUT
DOWN THE ALMOST DAILY BARRAGES OF STORMS AND FLOODING
RAIN...LEAVING ONLY ISOLATED SHOWERS AND STORMS IN THE AFTERNOONS.
WITH THE VERY WET GROUND...THESE AFTERNOON SHOWERS/STORMS WILL BE
MORE COMMON THAN IN A NORMAL SUMMER PATTERN. SIMILARLY...AFTERNOON
TEMPERATURES WILL REMAIN SOMEWHAT COOLER THAN WHAT WOULD OTHERWISE
BE EXPECTED...AS THE HEAT IS USED TO EVAPORATE WATER RATHER THAN
HEAT THE GROUND AND ADJACENT AIR.

&&

.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK  80  65  80  66 /  40  40  50  60
HOBART OK         84  64  78  63 /  40  50  50  60
WICHITA FALLS TX  86  65  82  66 /  50  40  40  70
GAGE OK           83  62  80  61 /  40  50  50  50
PONCA CITY OK     82  65  80  66 /  30  40  40  50
DURANT OK         82  66  82  67 /  60  40  40  60

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&

$$

06/84/10



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