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000
FXUS63 KSGF 181143
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
643 AM CDT SAT MAY 18 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 232 AM CDT SAT MAY 18 2013

UPPER LEVEL RIDGING WAS IN THE PROCESS OF MOVING OVER THE REGION
THIS MORNING. THIS HAS RESULTED IN GENERALLY CLEAR SKIES AND LOW
TEMPERATURES IN THE 60S ACROSS THE OZARKS. PERSISTENT SOUTHERLY
WINDS WERE TRANSPORTING GULF MOISTURE INTO THE THE REGION WHICH
HAS AIDED IN THE DEVELOPMENT OF DENSE FOG ACROSS PORTIONS OF SOUTH
CENTRAL MISSOURI. VISIBILITIES WERE REPORTED AROUND A QUARTER OF A
MILE IN THE WEST PLAINS AREA AND THE FOG IS EXPECTED TO CONTINUE
THROUGH SUNRISE THIS MORNING BEFORE IT BURNS OFF.

WARM AIR AND MOISTURE ADVECTION WILL CONTINUE THROUGH THE DAY
TODAY AND INTO TONIGHT AS THE UPPER LEVEL RIDGE TRAVERSES THE
REGION AND A STRONG UPPER LEVEL TROUGH DIGS AND MOVES EAST ACROSS
THE ROCKIES AND INTO THE PLAINS. THIS WILL ALLOW AN UNSTABLE
AIRMASS TO DEVELOP ACROSS THE REGION THIS EVENING INTO THE
OVERNIGHT HOURS...HOWEVER A STRONG ELEVATED MIXED LAYER WILL
PROVIDE A RATHER STRONG CAP OVER MUCH OF THE AREA. DESPITE THE
CAP...A FEW ELEVATED STORMS MAY BE POSSIBLE ESPECIALLY IN THE
VICINITY OF A STRONG LOW LEVEL JET THAT WILL BEGIN TO IMPACT
SOUTHEASTERN KANSAS AND PORTIONS OF THE MISSOURI OZARKS DURING THE
OVERNIGHT HOURS TONIGHT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 232 AM CDT SAT MAY 18 2013

POTENTIAL SIGNIFICANT SEVERE WEATHER EVENTS ARE TAKING SHAPE FOR
LATE SUNDAY AFTERNOON THROUGH TUESDAY. THIS PERIOD REMAINS THE
FOCUS OF THE CURRENT FORECAST WITH THE POTENTIAL FOR SEVERE
THUNDERSTORMS PRODUCING LARGE HAIL...DAMAGING WINDS...FLOODING
RAINS AND TORNADOES.

BY SUNDAY MORNING AND INTO THE AFTERNOON HOURS THE UPPER LEVEL
TROUGH OVER THE PLAINS WILL HAVE TAKEN ON A NEGATIVE TILT.
SURFACE LOW PRESSURE OVER WESTERN KANSAS WILL BEGIN TO MOVE TO THE
NORTHEAST TOWARDS SOUTHEASTERN NEBRASKA WITH A TRAILING COLD
FRONT PUSHING INTO EASTERN KANSAS AND NORTHEASTERN OKLAHOMA
BETWEEN 18Z SUNDAY AND 00Z MONDAY. PLENTY OF MOISTURE WILL BE
IN PLACE ACROSS THE CWA THANKS TO THE SOUTHERLY WINDS THROUGH THE
WEEKEND. AROUND THE 21Z TIME FRAME STORMS ARE EXPECTED TO DEVELOP
ALONG THE COLD FRONT AND BEGIN TO MOVE EAST. MODEL INSTABILITY
ACROSS THE AREA IS EXPECTED TO BE IN THE 2500 TO 3500 J/KG RANGE
ALONG WITH AN ERODING CAP THANKS TO A STRONG LOW LEVEL JET AND
UPPER LEVEL JET STREAK. THE 0-6KM BULK SHEAR VALUES ARE EXPECTED
TO BE FROM 40 TO 50 KNOTS WITH HELICITIES BETWEEN 300 AND 400
M2/S2. MID LEVEL LAPSE RATES IN EXCESS OF 7 C/KM WILL ALSO BE IN
PLACE IN RESPONSE TO THE MID AND UPPER LEVEL JET INTERACTIONS...
UPPER LEVEL DIFFLUENCE...AND THE REMNANTS OF THE ELEVATED MIXED
LAYER. AS A RESULT OF THE INGREDIENTS THAT ARE EXPECTED TO BE IN
PLACE ACROSS THE REGION...SUPERCELLS ARE THE MORE LIKELY STORM
MODE ANTICIPATED AS THE COLD FRONT MOVES TOWARDS THE REGION. SHEAR
VECTORS WOULD SUPPORT STORMS MOVING OFF THE FRONT. THE GOOD UPPER
LEVEL DYNAMICS WITH THIS SYSTEM WOULD SUPPORT STORMS CAPABLE OF
PRODUCING VERY LARGE HAIL...DAMAGING WINDS AND TORNADOES. A
PRIMARY CONCERN WITH THIS SYSTEM IS THAT IT APPEARS AS THOUGH IT
WILL MOVE THROUGH THE OZARKS DURING THE OVERNIGHT HOURS.

STORMS WILL LIKELY BE ONGOING MONDAY MORNING THOUGH THERE MAY BE A
LULL PERIOD DURING THE LATE MORNING INTO THE AFTERNOON AS ANOTHER
SURFACE LOW BEGINS TO MOVE EAST OUT OF NORTHERN TEXAS AS THE
UPPER LEVEL TROUGH BECOMES MORE OF A STACKED LOW PRESSURE CENTER.
ANOTHER COLD FRONT WILL THEN MOVES ACROSS THE REGION ORIENTED
NEARLY ALONG THE INTERSTATE 44 CORRIDOR. THE OVERALL ORIENTATION
OF THE FRONT COMPARED WITH THE SHEAR VECTORS WOULD SUPPORT THE
POTENTIAL FOR ADDITIONAL SEVERE THUNDERSTORMS AND TRAINING STORMS
DURING THE OVERNIGHT HOURS...MONDAY NIGHT INTO TUESDAY. COMBINING
THIS WITH CONTINUING SOUTHERLY FLOW AT THE SURFACE AND
PRECIPITABLE WATER VALUES NEARING 1.75 INCHES WOULD ALLOW FOR VERY
EFFICIENT RAIN PRODUCING THUNDERSTORMS. THIS POTENTIAL HEAVY
RAINFALL WOULD LIKELY LEAD TO FLOODING ACROSS THE REGION AFTER THE
RAINS FROM STORMS SUNDAY NIGHT INTO EARLY MONDAY.

MODELS DO DIFFER ON THE SPEED OF THE SYSTEM DURING THE DAY TUESDAY
WITH THE PRECIPITATION FIELD SLIGHTLY BUT WOULD EXPECT THE SYSTEM
TO MAKE STEADY PROGRESS THROUGH THE DAY...FINALLY MOVING EAST OF
THE OZARKS BY EARLY WEDNESDAY MORNING.

THE UPPER LEVEL TROUGH/LOW THEN IS EXPECTED TO LINGER OVER THE
GREAT LAKES REGION AND PROVIDE A LITTLE COOLER WEATHER...HIGHS IN
THE 70S...FOR WEDNESDAY INTO THURSDAY WITH A FEW ISOLATED CHANCES
FOR LIGHT SHOWERS ACROSS THE REGION. THIS WILL LINGER INTO THE END
OF THE WEEK AS ANOTHER UPPER LEVEL RIDGE MAKES ITS WAY ACROSS THE
PLAINS INTO THE WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 635 AM CDT SAT MAY 18 2013

SURFACE DEW POINTS IN TEH 60S AND SOUTHERLY WINDS HAVE ALLOW THE
DEVELOPMENT OF DENSE FOG TO OCCUR THIS MORNING. RESTRICTIONS TO
VISIBILITIES AT BRANSON THIS MORNING WILL KEEP A BRIEF PERIOD OF
IFR FOR THAT TERMINAL. SLOWLY IMPROVING CONDITIONS THROUGH THE
MORNING HOURS WILL SEE MVFR CEILINGS LINGER ACROSS THE REGIONS
AERODROME THROUGH EARLY AFTERNOON. CEILINGS WILL THEN LIFT TO VFR
LEVELS WITH THE CHANCE OF ISOLATED THUNDERSTORMS LATE THIS EVENING
AND OVERNIGHT.

LOW LEVEL WIND SHEAR WILL BE A CONCERN AFTER 3-4AM AS A STRONG LOW
LEVEL JET MAKES ITS WAY INTO THE REGION.

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MOZ058-070-
     071-082-083-092-096>098-105-106.

KS...NONE.
&&

$$

SHORT TERM...HATCH
LONG TERM...HATCH
AVIATION...HATCH