FXUS63 KOAX 202047
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
347 PM CDT FRI MAY 20 2011
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT.
SURFACE HEATING CONTRIBUTING TO THUNDERSTORM DEVELOPMENT CNTRL
KS/CNTRL NEB WITHIN AXIS OF DESTABILIZATION AND DEEP LYR MOISTURE
CONVG. NARROW LINE OF ACTIVITY WAS MOVING NNE AND SHOULD BE OVER
CWA WRN PERIPHERY NEXT COUPLE HOURS. OVERALL FCST IN GOOD SHAPE.
EXPECT THUNDER ACTIVITY TO SPREAD EWD THRU THE CWA THIS EVENING.
HAVE BACKED OFF POPS AFTER MIDNIGHT TONIGHT GIVEN DRY SLOT WEDGE
COMING UP FROM THE SOUTH.
IMPULSES ROTATING AROUND UPPER CLOSED LOW SITUATED OVER THE
NRN/CNTRL PLAINS WILL CONTRIBUTE TO DESTABILIZATION SATURDAY AFTN
WITH MAIN INSTABILITY AXIS SETTING UP FROM THE CWA SWD THRU ERN
KS/WRN MO AHEAD OF AN APPROACHING COLD FRONT. DID NOTE THAT NAM A BIT
MORE ROBUST THAN GFS WITH MOISTURE ADVECTION INTO THE REGION. AS OF
NOW THINK THERE IS A DECENT CHANCE FOR SVR STORM DEVELOPMENT OVER
THE SRN CWA WHERE NRN EDGE OF BEST DEEP LYR SHEAR/MUCAPES PHASE.
COLD FRONT SHOULD CLEAR THE CWA QUICKLY SAT NIGHT...BUT LEAVE
SMALL TOKEN POPS IN PLACE ERN AREAS IN CASE OF LINGERING ACTIVITY.
ANOTHER COLDER AIRMASS SWEEPING IN SUNDAY NIGHT ASSOCIATED WITH
VORT MAX CROSSING THE DAKOTAS INTO THE UPPER MIDWEST...AND SEEMS
REASONABLE TO ADD SMALL POPS.
.LONG TERM...MONDAY THROUGH FRIDAY.
MODELS CONTINUE TO ADVERTISE SOMEWHAT COMPLICATED LARGE SCALE FLOW
REGIME IN THE EXTENDED PDS WITH 3 NEARLY STATIONARY UPPER LEVEL LOWS
SITUATED OVER...GULF OF AK/WRN CONUS/HUDSON BAY. HOWEVER FEATURE OF
CONCERN FOR US IS SHORT WAVE TROF EJECTING FROM THE WRN STATES AND
CROSSING THE CNTRL PLAINS. GFS/ECM SFC FEATURES IN POOR AGREEMENT
WITH RESPECT TO ATTENDANT SFC LOW...BUT APPEARS THOUGH HPC
GENERALLY PREFERRING ECM SOLUTION. POST-FRONTAL POPS TUESDAY THRU
WED NIGHT WILL BE FOCUSED OVER THE SRN CWA. MOIST BNDRY LYR
CONVG ZONE IS PROGGED TO EXTEND ACROSS KS/MO...BUT STOUT 305K
UPGLIDE/MOIST ADV SHOULD BE ENOUGH TO PRODUCE SCATTERED PCPN WITHIN
AXIS OF LOW CONDENSATION PRES DEFICITS. LIFT ENHANCED AS WELL WITH
PASSING IMPULSES/INCREASING DPVA ASSOCIATED WITH APPROACHING UPPER
TROF. DRY THEN THURSDAY AS LOW AMPLITUDE/SFC HIGH BUILD IN BEHIND
EXITING COLD FRONT. HAVE DECIDED TO INCLUDE THUNDER CHANCES
THURSDAY NIGHT/FRI WHEN COMBINATION OF STOUT UPPER DIVERGENCE/VORT
LOBE MOVES ACROSS THE NRN PLAINS. BNDRY LYR-250MB DIFFERENTIAL
DIVERGENCE IS QUITE STRONG....AND ECM QPF VALUES FROM DAKOTAS INTO
ERN NEB/WRN IA REFLECTING THIS. OTHERWISE STILL EXPECTING BELOW
NORM TEMPS THE END OF NEXT WEEK.
DEE
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
GENERALLY LOOKING AT A MIX OF MVFR AND IFR CONDITIONS AT ALL THREE
TAF SITES UNTIL AROUND 10Z TO 12Z. MORE GENERAL RAIN SHOWERS WILL
GIVE WAY TO THREAT OF THUNDERSTORM DEVELOPMENT BETWEEN 21Z AND 00Z
AS THUNDERSTORMS ONCE AGAIN DEVELOP ACROSS PARTS OF CENTRAL KANSAS
AND SOUTH CENTRAL NEBRASKA AND THEN MOVE NORTH NORTHEAST. EXPECT
IFR CONDITIONS IN VICINITY OF ALL THUNDERSTORMS THAT DEVELOP ALONG
WITH A THREAT OF LARGE HAIL. AFTER 12Z EXPECT CONDITIONS TO
IMPROVE...AT LEAST TREND TOWARD...VFR THOUGH SOME VICINITY SHOWER
ACTIVITY MAY REDEVELOP SATURDAY AFTERNOON.
MEYER
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$