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000
FXUS63 KOAX 150446
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1146 PM CDT TUE MAY 14 2013

.AVIATION...
06Z TAFS FOR KOMA...KLNK...KOFK.

VFR CONDITIONS EXPECTED TO CONTINUE THROUGH THE FORECAST PERIOD
AS SURFACE FRONT DROPS SOUTH THROUGH 15Z THEN STALLS NEAR THE
KANSAS NEBRASKA BORDER INTO NORTHERN MISSOURI.

&&

.PREV DISCUSSION... /ISSUED 330 PM CDT TUE MAY 14 2013/

DISCUSSION...
RECORD WARM TEMPERATURES...CLOSE TO OR ABOVE 100 DEGREES...ARE
OCCURRING ACROSS THE AREA THIS AFTERNOON...THIS JUST 2 DAYS AFTER
RECORD LOWS AND NEAR RECORD LATEST FREEZES WERE SET. SUBJECTIVE
12Z UPPER AIR ANALYSIS INDICATES BONE-DRY AIRMASS OVER MOST OF THE
US...WITH 850MB 8C+ DEWPOINTS IN FAR SOUTH TX AND THE SOUTHERN TIP
OF FL. 850MB TEMPS AT 12Z WERE ABOVE 25C AT KLBF...WITH A BROAD
SWATH OF THE CENTRAL PLAINS ABOVE 20C. UPPER-LEVEL FLOW WAS
FLATTENING...WITH 500MB HEIGHTS DECREASING ACROSS THE ROCKIES TO
HIGH PLAINS...AND INCREASING IN THE EASTERN US. SURFACE FRONT AT
20Z EXTENDED FROM NEAR KMKT TO KSUX TO KLXN TO KGLD...WITH VERY
HIGH-BASED CU ALONG THE FRONT AT AROUND 15000 FT.

MAIN FORECAST CONCERNS ARE INTERMITTENT THUNDERSTORM CHANCES
THROUGHOUT THE FORECAST.  STARTING THIS EVENING...WITH TEMPERATURES
MOST CERTAINLY EXCEEDING CONVECTIVE TEMPS...MAY GET A STRAY CU TO
DEVELOP ENOUGH VERTICAL EXTENT TO PRODUCE LIGHTNING AND PERHAPS A
BRIEF SHOWER THAT CAN REACH THE GROUND.  SHEAR IS WEAK AND
CONVERGENCE IS ALSO NOT THAT STRONG...AND INSTABILITY IS LIMITED BY
SEVERE LACK IN MOISTURE. OVERALL...THINK COVERAGE OF ANY MEASURABLE
PRECIP WOULD BE SCANT...AND THINK ANY DEVELOPMENT WILL FADE LATER
THIS EVENING. THAT SAID...WITH SUCH STRONG INVERTED-V
SOUNDINGS...WOULD HAVE TO BE KEEP AN EYE ON WIND GUSTS IF ANY
STORMS CAN GET GOING.

FRONT SETTLES TO NEAR THE KS/NEB AND IA/MO BORDERS TOMORROW.
TEMPS ALONG AND SOUTH OF THAT FRONT SHOULD BE ABLE TO GET QUITE
WARM...BUT MORE SEASONABLE HIGH TEMPERATURES WILL PREVAIL NORTH OF
THAT BOUNDARY. THINK THE AREA WILL STAY DRY THROUGH THE DAY...WITH
SHOWERS/THUNDERSTORMS DEVELOPING ALONG AND SOUTH OF THE BOUNDARY
BY LATE AFTERNOON/EARLY EVENING AS AN UPPER WAVE MOVES ACROSS THE
SOUTHERN PLAINS AND AFTER DESTABILIZATION. SOUTHERN CWA WILL BE ON
NORTHERN FRINGE OF THIS ACTIVITY...AND HAVE IT MOVING IN AFTER 00Z
THURSDAY AND LIFTING NORTHWARD THROUGH THE CWA OVERNIGHT AS THE
850MB BOUNDARY LIFTS NORTHWARD.

FORECAST FOR THURSDAY HAS BECOME COMPLEX AND IS TRENDING WETTER.
AFTER MODIFYING FORECAST SOUNDINGS TO CORRECT FOR GFS/NAM DEWPOINT
HIGH BIAS...SOUNDINGS ARE CAPPED AND MUCH LESS STABLE THAN THE
MODELS THINK.  STILL BELIEVE GFS/NAM ARE OVERDONE ON PRECIP EXTENT
DURING THE DAY ON THURSDAY.  THAT SAID...WITH THE NORTHERN UPPER-
LEVEL WAVE MOVING ACROSS NEB DURING THE DAY...AND RESULTING Q-VECTOR
CONVERGENCE...IT MAY BE ENOUGH TO OVERCOME THE LACKING INSTABILITY
TO PRODUCE SHOWERS AND THUNDERSTORMS.  HAVE INCREASED POPS A LITTLE
IN THE MORNING...AND TO CHANCES IN THE WESTERN CWA THROUGH THE
AFTERNOON.  OTHER ACTIVITY MAY DEVELOP ON THE HIGH PLAINS IN THE
LATE AFTERNOON...WITH THE REMNANTS POSSIBLY REACHING EASTERN NEB
BEFORE IT DISSIPATES. HAVE TRENDED POPS DOWNWARD ON THURSDAY NIGHT
THOUGH...AS THE AREA WILL BE BEHIND THE UPPER WAVE WITH A
SHORTWAVE RIDGE MOVING IN.

THUNDERSTORMS SHOULD DEVELOP ON FRIDAY LATER AFTERNOON WEST OF THE
AREA...LIKELY FROM EAST CENTRAL SD THROUGH CENTRAL NEB AND INTO
NORTHWEST KS...THOUGH LOCATION STILL DEPENDS ON SPEED OF MAIN LOW
MOVING THROUGH THE AREA.  THESE STORMS SHOULD REACH THE CWA IN THE
EVENING...THOUGH DID INCLUDE A CHANCE UP IN THE NORTHWEST IN THE
LATE AFTERNOON TO ACCOUNT FOR POTENTIAL TIMING ERRORS.  BULK OF
ACTIVITY WOULD BE IN THE EVENING...WITH STORMS DIMINISHING AND
MOVING AWAY IN THE LATER EVENING AND OVERNIGHT.

OVERALL...SYSTEM SEEMS TO BE SLOWING...WITH MAIN FRONTAL PASSAGE NOW
DRAGGING THROUGH SATURDAY AND INTO SUNDAY.  IT IS IN THIS PERIOD
WHEN THE AREA WOULD HAVE THE BETTER SHOT FOR ANY SEVERE
WEATHER...WITH PROXIMITY TO CONVECTIVE INITIATION AND IMPROVING DEEP-
LAYER SHEAR.  TOUGH TO NAIL DOWN ANY SPECIFIC PERIODS THAT ARE MORE
LIKELY TO SEE STORMS...BUT FOR NOW...THE RISK EXISTS THROUGHOUT THE
WEEKEND.  ONCE THE FRONT MOVES THROUGH...THE AIRMASS STABILIZES AND
COOLS...AND PRECIP SHOULD SHUT DOWN.  HAVE EXTENDED POPS A LITTLE
INTO MONDAY WITH THE REMNANTS OF THE LOW...BUT KEPT MONDAY NIGHT AND
TUESDAY DRY.

MAYES

CLIMATE... OMAHA: HIGH SO FAR IS 100. THIS IS A RECORD DAILY
MAXIMUM...PREVIOUS RECORD 96 SET IN 1915. THIS IS ALSO THE
EARLIEST 100+ DEGREE READING ON RECORD...PREVIOUS RECORD 5/29/1934
AT 102 DEGREES.

LINCOLN:  HIGH SO FAR IS 99.  THIS IS A RECORD DAILY
MAXIMUM...PREVIOUS RECORD 96 SET IN 1915.  THIS IS ALSO THE EARLIEST
99+ DEGREE READING ON RECORD...PREVIOUS RECORD 5/24/1967 AT 100
DEGREES.

NORFOLK:  HIGH SO FAR IS 102.  THIS IS A RECORD DAILY
MAXIMUM...PREVIOUS RECORD 96 SET IN 1915 AND 1941. THIS IS THE
SECOND EARLIEST 102+ DEGREE READING ON RECORD...WITH THE RECORD
STANDING ON 4/28/1910 AT 102 DEGREES. THIS IS ALSO THE THIRD
EARLIEST 100+ DEGREE READING ON RECORD...WITH THE SECOND EARILEST
ON 5/6/1934 AT 101 DEGREES.

MAYES

&&

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

$$

FOBERT