000
FXUS63 KOAX 181850
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
150 PM CDT SAT MAY 18 2013

.UPDATE...
MORNING UPDATE TO ADD SOME SHOWERS AND ISOLATED THUNDERSTORMS IN
NORTHEAST NEBRASKA THIS AFTERNOON AND EARLY AFTERNOON UPDATE AS
THESE MAY GET INTO THE OTHER WESTERN PARTS OF THE CWA DURING THE
AFTERNOON. LOWERED HIGHS AND ADJUSTED THE CLOUDS.

&&
DEEPER MOISTURE AND CLOUDS HAVE INCREASED ACROSS THE FORECAST AREA
AND THIS SHOULD HOLD BACK HIGH TEMPERATURES SOMEWHAT WITH MOST
LOCATIONS TOPPING OUT IN THE LOWER TO MID 80S. A FEW ELEVATED
SHOWERS DEVELOPED AROUND ALBION AND NORFOLK...AND ANOTHER AREA IS
LIFTING NORTH THROUGH NORTH CENTRAL KANSAS INTO CENTRAL NEBRASKA.

DEEP MOISTURE WITH DEWPOINTS IN THE 70S WERE NOTED FROM KANSAS
INTO OKLAHOMA...AND H85 MOISTURE WAS POOLED FROM SOUTHWEST NEB
INTO NORTH CENTRAL KANSAS TO SOUTHEAST KANSAS. THE DRYLINE WAS IN
FAR SOUTHWEST KANSAS AND THE TEXAS PANHANDLE. AS HEATING
CONTINUES ALONG WITH LARGE SCALE LIFT AND A STRENGTHENING LOW
LEVEL JET...LOOK FOR CONVECTION TO INCREASE ACROSS OKLAHOMA AND
KANSAS INTO WESTERN AND CENTRAL NEBRASKA...SPREADING INTO
NORTHEAST NEBRASKA AND THE WESTERN PARTS OF THE FORECAST AREA LATE
THIS AFTERNOON/THIS EVENING AND THEN THE REST OF EASTERN NEBRASKA
AND WESTERN IOWA LATER THIS EVENING AND OVERNIGHT.

&&

.AVIATION...
18Z TAFS FOR KOFK...KOMA AND KLNK.

A FEW ELEVATED SHOWERS AROUND TODAY WITH THUNDERSTORMS INCREASING
IN PROBABILITY TONIGHT. VFR CIGS MOSTLY FL035-050...HOWEVER DID
MENTION MVFR CIGS AND VSBYS WITH PROB30 GROUPS AFTER 03Z.
SOUTHEAST SURFACE WINDS MOSTLY 10 TO 20KTS THIS AFTERNOON AND 8 TO
15KTS AFTER 01Z. LLWS MAY NEED TO BE ADDED LATER TONIGHT. SHORT
TERM GUIDANCE NOT CONSISTENT ON HOW THIS WILL EVOLVE.

EXTENDED PERIOD OF MID AND UPPER LEVEL LIFT AND WARM AIR ADVECTION
AS A STORM SYSTEM MOVING INTO THE ROCKIES PROGRESSES INTO THE
PLAINS SUNDAY.

&&

.PREV DISCUSSION... /ISSUED 339 AM CDT SAT MAY 18 2013/

SHORT TERM...TODAY THROUGH MONDAY NIGHT.

THE FOCUS FOR THIS PORTION OF THE FORECAST IS SEVERE WEATHER
POTENTIAL TONIGHT AND MORE SO INTO SUNDAY AND SUNDAY NIGHT.

TODAY AND TONIGHT...THIS PERIOD BEGINS WITH UPPER LEVEL RIDGING
IN PLACE. A SUBSIDENCE INVERSION IN PLACE FROM THIS RIDGE WILL
ACT TO SUPRESS CONVECTION FOR MUCH OF THE DAY. THE TRIGGER FOR
ANY CONVECTION WILL BE A SHORTWAVE DIGGING INTO THE BACKSIDE OF
THE RIDGE THIS EVENING INTO TONIGHT. GIVEN THE LACK OF SIGNIFICANT
FORCING AND ENOUGH HEATING (CONVECTIVE TEMP IS AROUND 91 F) ITS
QUITE LIKELY THE ATMOSPHERE WILL REMAIN CAPPED INTO THE EARLY
EVENING HOURS.

THE BETTER OPPORTUNITY FOR WIDESPREAD CONVECTION IS ACROSS
PORTIONS OF WESTERN NEBRASKA/KANSAS AND OKLAHOMA WHERE DRY LINE
INFLUENCES AND STRONG DAY TIME HEATING WILL ACT TO ERODE ANY
EXISTING CAP. THIS WILL BE THE ACTIVITY WE END UP SEEING TONIGHT.
DECIDED TO MAINTAIN GOING FORECAST AND KEEP EASTERN NEBRASKA AND
SOUTHWEST IOWA DRY THROUGH THE DAY...THEN STEADILY PUSH
THUNDERSTORMS CHANCES EAST THROUGH THE EVENING AND OVERNIGHT
HOURS. THE MAIN SEVERE WEATHER THREATS WILL BE HAIL AND WIND AS
OUTLINED BY THE SLIGHT RISK AREA FROM THE STORM PREDICTION CENTER.

SUNDAY THROUGH MONDAY NIGHT...ONCE AGAIN OUR AREA IS OUTLINED IN
THE SLIGHT RISK AREA. THIS PERIOD BRINGS WITH A MUCH BETTER
OPPORTUNITY FOR SEVERE WEATHER. THE MAIN FOCUS IS A NEGATIVELY
TILTED UPPER LEVEL TROUGH MOVING EAST THROUGH THE REGION. UNLIKE
TODAY AND TONIGHT THERE ISN`T A CAPPING INVERSION TO OVERCOME AND
CONVECTION WILL LIKELY INITIATE EARLY IN THE AFTERNOON ON SUNDAY.
MODIFIED FORECAST SOUNDINGS INDICATE MODEST INSTABILITY AVAILABLE
AND DEEP LAYER SHEAR AROUND 35 KNOTS. AS THE UPPER LEVEL TROUGH
AND ITS SURFACE REFLECTION TRANSLATE THROUGH THE AREA...STRONG
THUNDERSTORMS AND EVEN SUPERCELLS ARE EXPECTED TO FORM. THE
SPECIFIC SEVERE WEATHER THREATS ARE LARGE HAIL...POSSIBLY GREATER
THAN 2 INCHES...STRONG WINDS AND EVEN A FEW TORNADOES CAN`T BE
RULED OUT.

UNSETTLED WEATHER WILL CONTINUE THROUGH MONDAY NIGHT AS THE UPPER
LEVEL TROUGH TRANSFORMS INTO A CLOSED LOW AND SLOWLY MEANDERS NORTH
AND EAST. THIS WARRANTS A CONTINUED MENTION OF SHOWERS AND
THUNDERSTORMS AS WELL AS COOLER TEMPERATURES FOR MONDAY.

DP

LONG TERM...TUESDAY THROUGH SATURDAY.

CLOSED UPPER LOW LINGERS OVER THE AREA AT THE BEGINNING OF THE
PERIOD FOR A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS BEFORE
MOVING EAST OF THE AREA ON THURSDAY. SHORT WAVE RIDGE THEN DEVELOPS
THURSDAY NIGHT INTO FRIDAY AS UPPER SYSTEM DIGS OVER THE WESTERN
CONUS WITH INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY
NIGHT INTO SATURDAY AS UPPER ENERGY EJECTS OUT OF THE WESTERN
TROUGH. TEMPERATURES LOOK TO REMAIN SEASONAL THROUGH THE PERIOD.

FOBERT
&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$

ZAPOTOCNY