FXUS63 KOAX 172045
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
345 PM CDT WED AUG 17 2011
.SHORT TERM...TONIGHT
AFTER EARLY MORNING FOG AND STRATUS...CLOUDS DECREASED DURING THE
AFTERNOON...WITH SOME CU ACROSS THE SOUTHERN COUNTIES. AFTERNOON
HIGHS CLIMBED INTO THE LOWER TO MID 90S.
HIGH PRESSURE WILL CONTINUE TO MOVE EAST TONIGHT...WITH RETURN FLOW
BRINGING UPSLOPE CONDITIONS ACROSS WESTERN AND CENTRAL NEBRASKA.
LATER TONIGHT...A 40 KNOT JET ACROSS CENTRAL NEBRAKSA WILL BRING
PLENTY OF MOISTURE TO THE REGION...AND INTERACT WITH A DISTURBANCE
MOVING ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE. THINK THAT
DUE TO THESE FACTORS...AN MCS WILL DEVELOP ACROSS CENTRAL NEBRASKA
OVERNIGHT AND MOVE INTO EASTERN NEBRASKA AROUND 12Z. HAVE KEPT TREND
OF SCATTERED THUNDERSTORMS AFTER MIDNIGHT...WITH HIGHEST POPS ACROSS
THE WEST AND SOUTHWEST ZONES.
.LONG TERM...THURSDAY THROUGH WEDNESDAY
SHORT WAVE EMBEDDED IN WEST NORTHWEST FLOW AND ASSOCIATE SURFACE
TROUGH WILL APPROACH ERN NEBRASKA/WRN IOWA LATE IN THE DAY ON
THURSDAY. LOW LEVEL JET STRENGTHENS OVER KANSAS WITH THE NOSE
REACHING SERN NEBRASKA BY THURSDAY EVENING. INCREASING DEEP LAYER
SHEAR AND MIXED LAYER CAPE (WITH THE 12Z GFS SHOWING VALUES
APPROACHING 5000 J/KG) COMBINED WITH ASCENT FROM APPROACHING SHORT
WAVE WILL RESULT IN STRONG TO SEVERE THUNDERSTORMS FOR THE FORECAST
AREA LATE THURSDAY AFTERNOON THROUGH THE EVENING. CONVECTION WILL
DIMINISH THURSDAY NIGHT AS SHORT WAVE MOVES DOWNSTREAM AND SURFACE
FRONT SAGS SOUTHEAST ACROSS THE FORECAST AREA.
FRIDAY INTO SATURDAY...WITH THE POSSIBLE EXCEPTION OF THE FAR
SOUTHEAST CORNER EARLY IN THE DAY...THE FORECAST AREA BECOMES
STABLE. THIS WILL BE SHORT LIVED AS THE NEXT EMBEDDED SHORT WAVE
STREAMS ACROSS NEBRASKA WITH SCATTERED CONVECTIVE DEVELOPING FRIDAY
AFTERNOON OVER WRN NEBRASKA AND SPREADING EASTWARD LATE IN THE
AFTERNOON AND CONTINUING INTO SATURDAY WITH THE POTENTIAL OF MORE
HEAVY RAINS AND POSSIBLE SEVERE STORMS. THINGS START TO SETTLE DOWN
LATE SATURDAY NIGHT AS DRIER AIR FILTERS FROM THE NORTHWEST AS SHORT
WAVE ENERGY MOVES DOWNSTREAM.
SUNDAY THROUGH WEDNESDAY...
DECIDED TO KEEP LOW PRECIPITATION CHANCES GOING FOR SUNDAY AND
SUNDAY NIGHT...THEN KEPT POPS AT 14 OR LESS MONDAY THROUGH
WEDNESDAY. 500 MB RIDGE WILL INITIALLY BE OVER THE SOUTHERN PART OF
THE UNITED STATES...THEN IT WILL RETROGRADE BACK TO THE FOUR CORNERS
REGION. MID TROPOSPHERIC FLOW WILL TURN FROM WEST/NORTHWEST SUNDAY
TO MORE NORTH/NORTHWEST BY MID WEEK. BOTH THE 12Z ECMWF AND 12Z GFS
ONLY SLIGHTLY INCREASE 500 MB HEIGHTS (30-60 METERS) BUT 700 MB
TEMPERATURES SHOULD INCREASE ENOUGH TO PUT A MODEST CAP ON MUCH OF
THE FORECAST AREA BY 12Z TUESDAY (GFS SHOWED WARMER VALUES THAN THE
ECMWF). EXPECT HIGHS MOSTLY IN THE 80S WITH LOWS IN THE 60S.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z ISSUANCE.
PRIMARY FORECAST CONCERN WILL BE THUNDERSTORM CHANCES DURING THE
OVERNIGHT HOURS.
SCATTERED CU DEVELOPED ACROSS THE REGION THIS AFTERNOON...AND WITH
MOISTURE REMAINING IN PLACE...HAVE INCLUDED MVFR CONDITIONS AFTER
18/09Z.
TIMING OF CONVECTION REMAINS A CONCERN AFTER 18/06Z...AND INCLUDED A
PROB30 GROUP UNTIL THUNDERSTORMS DEVELOP TONIGHT.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
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