FXUS63 KOAX 150231
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
931 PM CDT SUN AUG 14 2011
.UPDATE...
UPDATED TO INCREASE POPS/QPF IN A GOOD PART OF EASTERN NEB AND
DECREASE WINDS.
&&
.DISCUSSION...
EVENING UPPER AIR ANALYSIS INDICATED A MOISTURE AXIS OF +15 C 850
MB DEWPOINTS FROM THE SOUTHERN PLAINS TO CENTRAL AND WESTERN NEB.
AS THE THE LOW LEVEL JET CONTINUES TO INCREASE FROM KS INTO
CENTRAL NEB THIS EVENING...WE EXPECT THE SHOWERS AND THUNDERSTORMS
OVER NORTH CENTRAL NEB TO CONT TO EXPAND IN COVERAGE INTO
NORTHEAST NEB OVERNIGHT. LAPSE RATES ABOVE THIS MOISTURE WAS ONLY
MARGINAL...BUT CERTAINLY SUPPORT OF WEAK INSTABILITY...SUFFICIENT
FOR CONTINUED CONVECTION. ALTHOUGH THE 00Z NAM WOULD INDICATE THIS
ACTIVITY WEAKENS AND DISSIPATES...THIS SEEMS UNLIKELY GIVE CURRENT
OBSERVATION AND SHORT RANGE GUIDANCE TRENDS. THUS HAVE INCREASED
POPS AND QPF FOR NORTHEAST NEB...AND WE WOULDN'T BE SURPRISED TO
SEE SOME 2 INCH AMOUNTS IN THIS AREA. OTHER WESTERN HIGH PLAINS
CONVECTION IS STILL EXPECTED TO MAKE THE TRACK ACROSS CNTRL NEB
AND INTO EASTERN NEB AFTER MIDNIGHT. OTHER ELEMENTS OF THE
FORECAST APPEAR TO BE ON TRACK ATTM...BUT DID LOWER WIND SPEEDS
OVERNIGHT. NEW ZFP AND GRIDS WILL BE OUT BY 945 PM.
BOUSTEAD
&&
.PREV DISCUSSION... /ISSUED 347 PM CDT SUN AUG 14 2011/
SHORT TERM...TONIGHT THROUGH MONDAY
SURFACE HIGH PRESSURE CONTINUES TO PUSH EASTWARD...WITH RETURN
SOUTHERLY FLOW INCREASING MOISTURE AND SOUTHERLY WINDS OVER THE
AREA. ACTIVE PATTERN SETTING UP WITH NUMEROUS WAVES/FRONTS TO
PUSH ACROSS THE CENTRAL/NORTHERN PLAINS THIS WEEK. FIRST WEAK
WAVE OVER N CENTRAL NEB THIS AFTERNOON WITH A FEW RADAR RETURNS
DEVELOPING NEAR KVTN. SHORT RANGE MODELS DIMINISH THIS IN THE
NEXT FEW HOURS AS IT MOVES INTO A LOWER MOISTURE REGION. WILL
NEED TO MONITOR THIS AREA CLOSELY AS IT MAY CONTINUE INTO NE
NEBRASKA. A MORE SUBSTANTIAL WAVE IS MOVING ACROSS THE ROCKIES
AND WILL BRING A HIGH CHANCE FOR RAIN OVERNIGHT. STRONG
ISENTROPIC LIFT ALONG WITH A 30KT LL JET SHOULD SUSTAIN THE
STORMS AS THE TREK ACROSS THE STATE.
LINGER STORMS MONDAY MORNING WILL CONTINUE TO PUSH EAST SOUTHEAST.
MODELS IN AGREEMENT WITH ACTIVITY BEFORE 18Z...HOWEVER HIGH
VARIABILITY DURING THE AFTERNOON. FEELING ACTIVITY WILL BECOME
ISOLATED IF NOT END WITH A FEW BREAKS IN THE CLOUDS DEVELOPING FOR
THE AFTERNOON. HIGHS WILL BE DEPENDENT ON THE CLOUDS...AND
FORECAST SPLITS THE COOLER/WETTER GFS GUIDANCE TO THE MUCH WARMER
AND DRY NAM.
LONG TERM...MONDAY NIGHT THROUGH SUNDAY
MONDAY NIGHT ANOTHER WAVE/WARM FRONT LIFTS ACROSS THE AREA.
DYNAMICS FOCUS MORE INTO KANSAS AND SOUTHERN NEBRASKA. WILL
CONTINUE POPS OVER THE SOUTHERN CWA BASED ON THE GFS/18Z
NAM...HOWEVER COULD EASILY SEE A NEED TO PUSH FURTHER NORTH IN
ASSOCIATION WITH WAA.
BY TUESDAY WARMER AIR ARRIVES WITH HIGHS IN THE MID TO UPPER 80S.
BY TUESDAY NIGHT THE NEXT COLD FRONT WILL BEGIN TO PUSH EAST
ACROSS THE CENTRAL PLAINS. EXPECT A LINE OF STORMS ALONG THE
FRONT...WITH MORE INSTABILITY...HIGHER CAPE VALUES...FURTHER
NORTH AND COINCIDES WITH SPC DAY 3 SLIGHT RISK. ISOLATED SEVERE
THUNDERSTORMS ARE POSSIBLE OVER THE CWA...ESPECIALLY OVER
NORTHEAST NEBRASKA LATE IN THE DAY.
COOLER HIGH PRESSURE AND MAINLY DRY CONDITIONS BUILD INTO THE
REGION FOR WEDNESDAY. HIGHS IN THE LOWER TO MID 80S. FRONT STALLS
TO NEAR THE NEB/KS BORDER AND WILL KEEP LOW POPS OVER THE SOUTHERN
CWA.
ACTIVE PATTERN RETURNS BY THE END OF THE WEEK WITH YET ANOTHER
COUPLE OF WAVES EXPECTED FRIDAY AND SATURDAY. SEASONAL CONDITIONS
WITH HIGHS IN THE LOWER TO MID 80S. WILL CONTINUE TO MENTION
POPS...HOWEVER NOT EXPECTING IT TO RAIN ALL DAY...BUT TO FAR OUT
TO PINPOINT TIMING.
AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z ISSUANCE.
VFR CONDITIONS ARE EXPECTED THROUGH MUCH OF THE FORECAST PERIOD. AN
UPPER LEVEL DISTURBANCE IS EXPECTED TO CREATE A CHANCE OF
THUNDERSTORMS AFTER 06Z AT KOFK AND AFTER 10Z KLNK. THERE IS ALSO A
SLIGHT CHANCE OF FOG AFTER 09Z AT ALL LOCATIONS.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$