000
FXUS63 KOAX 190454
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1154 PM CDT TUE JUN 18 2013

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

VFR CONDITIONS EXPECTED THROUGH THE PERIOD WITH HIGH LEVEL CIGS
ACROSS THE AREA MUCH OF THE TIME. SOME CHANCE OF ISOLATED THUNDER
AFTER 18Z BUT NOT INCLUDED AT THIS TIME.

&&

.PREV DISCUSSION... /ISSUED 251 PM CDT TUE JUN 18 2013/

DISCUSSION...
MORNING SHOWERS/THUNDER HAVE GIVEN WAY TO A FAIR WEATHER DAY ACROSS
THE AREA.  SUBJECTIVE 12Z UPPER AIR ANALYSIS INDICATES UPPER-LEVEL
RIDGING CONTINUING TO BUILD OVER THE ROCKIES/HIGH PLAINS...WITH
SHORTWAVE ACROSS WI/IA THAT HELPED GENERATE MORNING ACTIVITY...AS
WELL AS ANOTHER EMBEDDED SHORTWAVE IN WESTERN NEB/EASTERN CO...AND
WITH A DEEPENING TROUGH CREATING 500MB HEIGHT FALLS UP TO 60M ALONG
THE PACIFIC COAST.  UPPER-LEVEL JET STREAK EXTENDED FROM EASTERN IA
INTO NEW ENGLAND...WITH JET SEGMENTS COMING ASHORE IN OR AND IN
SOUTHERN CA.  HIGHER 700-500MB LAPSE RATES WERE LOCATED FROM CO/WY
WESTWARD INTO THE ROCKIES.  HIGH PRESSURE AT 850MB WAS CENTERED IN
KS...WITH TEMPS WARMING INTO THE 20S C AS FAR EAST AS KLBF...AND
WITH 8C+ MOISTURE RETURNING UP TO SOUTHERN NEB/SOUTHERN IA.  SURFACE
HIGH AT 18Z WAS CENTERED IN SOUTHEAST NEB/SOUTWHEST IA...WITH RETURN
FLOW ACROSS CENTRAL/WESTERN NEB.  AREA OF SHRA/TSRA WAS STILL
FESTERING JUST SOUTH OF THE KS/NEB BORDER.

MAIN FORECAST CONCERN IS CONVECTIVE POTENTIAL ON WEDNESDAY/WEDNESDAY
NIGHT/THURSDAY MORNING...FOLLOWED BY WARMING TEMPERATURES THROUGH
THE WEEKEND AND INTO NEXT WEEK ALONG WITH WHACK-A-MOLE THUNDERSTORM
CHANCES.  MODELS STILL DIFFER SUBSTANTIALLY ON TIMING AND EXTENT OF
THUNDERSTORMS ON WEDNESDAY THROUGH THURSDAY.  NAM/4KM WRF KEEP THE
AREA DRY TONIGHT AND MUCH OF WEDNESDAY...WITH JUST SCATTERED
CONVECTION AFTER 00Z THURSDAY THAT GROWS UPSCALE IN CENTRAL IA.  GFS
HAS SOME SCATTERED CONVECTION ON WEDNESDAY AFTERNOON...WITH BROADER
SWATH TO THE WEST IN THE EVENING AND TO THE EAST AND SOUTH
OVERNIGHT.  ECMWF ALSO DEVELOPS CONVECTION ALONG THE RIVER IN THE
AFTERNOON...WHICH DIES QUICKLY IN THE EVENING...FOLLOWED BY
CONVECTION ALONG THE RIVER AGAIN ON THURSDAY MORNING.  SREF ENSEMBLE
MEMBERS ARE ALL OVER THE MAP...RANGING FROM THE DRIER SIDE TO WETTER
WEDNESDAY AFTERNOON/EVENING TO WETTER WEDNESDAY NIGHT/THURSDAY
MORNING.  OVERALL...CONFIDENCE IS LOW...BUT LEANED CLOSER TO NAM/GFS
COMPROMISE. KEPT TUESDAY NIGHT AND WEDNESDAY MORNING DRY AS HEIGHT
RISES MOVE OUT OF THE AREA...WITH SHORTWAVE APPROACHING BY WEDNESDAY
AFTERNOON.  WENT WITH A SLIGHT CHANCE IN THE AFTERNOON AS WAVE
APPROACHES AND CHANCES IN THE EVENING FOR POSSIBLE UPSCALE
GROWTH...TAPERING TO SLIGHT CHANCE NORTH/CHANCE SOUTH AFTER
MIDNIGHT.  INCLUDED A SLIGHT CHANCE MENTION ON THURSDAY MORNING EAST
OF THE RIVER. AGAIN...CONFIDENCE WOULD BE ON THE LOW SIDE...BUT
THINK THURSDAY WILL REMAIN DRY ACROSS THE AREA MUCH OF THURSDAY AND
THURSDAY EVENING ONCE THAT ACTIVITY MOVES OUT.  COULD SEE THE
POTENTIAL FOR AN MCS MOVING SOUTHEAST OUT OF SD TO SKIRT THE
NORTHEAST CWA THURSDAY EVENING/NIGHT...AND HAVE KEPT SLIGHT CHANCE
POPS UP THERE.

FOR FRIDAY THROUGH MONDAY...HAVE PLAYED CLOSER TO THE ECMWF
SCENARIO...WHICH KEEPS THE CWA CAPPED DURING THE DAY WITH THE
POTENTIAL FOR NIGHTTIME CONVECTION.  THINK THE BIGGEST THREAT WOULD
BE ON SUNDAY EVENING/SUNDAY NIGHT...AS A WEAK FRONT SLIPS ACROSS THE
CWA AND PROVIDES SOME CONVERGENCE...WHILE A SHORTWAVE SEEMS LIKELY
TO EJECT ACROSS THE CWA.  BY MONDAY...RISK IS TOO LOW FOR STORMS
WITH ANY KIND OF DIAGNOSABLE COVERAGE TO PUT IN POPS AT THIS TIME.
HAVE INCREASED TEMPS A DEGREE OR TWO THROUGH THE EXTENDED TO GET
AWAY FROM THE TENDENCY FOR GUIDANCE TO STEER TOWARD CLIMATOLOGY...AS
MEX GUIDANCE REMAINS IN THE 90S IN MOST PLACES...AND GFS/ECMWF
INDICATE 850MB TEMPERATURES CONSISTENTLY IN THE 20S AND WARMING
TO THE MID 20S C LATE IN THE PERIOD.

MAYES

&&

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

$$

FOBERT