FXUS63 KOAX 040259
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
959 PM CDT WED AUG 3 2011
.UPDATE...
SMALL CLUSTER OF THUNDERSTORMS THAT FORMED OVER SOUTH CENTRAL NE
THIS AFTERNOON DRIFTED INTO OUR CWA DURING THE EVENING AND
WEAKENED/DISSIPATED AS IT ENCOUNTERED THE RELATIVELY STABLE
AIRMASS ON THE SW PERIPHERY OF SFC RIDGE. THIS STABLE AIRMASS MAY
TEND TO DELAY THE ONSET OF THE NEXT ROUND OF CONVECTION WHICH
SHOULD WORK ITS WAY FROM THE CENTRAL PLAINS OVERNIGHT...AND HAVE
BACKED OFF ON POPS FOR AREAS ALONG AND N OF A COLUMBUS-OMAHA-RED
OAK LINE UNTIL THE PREDAWN HOURS. AFTERNOON MODEL RUNS AND A
QUICK LOOK AT SOME OF THE NEW 00Z RUNS SUGGESTS THAT MODELS ARE
STRUGGLING WITH THE DEVELOPMENT/LOCATION OF THISOVERNIGHT
CONVECTION...BUT MASS FIELDS WOULD SUGGEST THAT LIKELY POPS NEAR
KS/NE BORDER STILL APPROPRIATE FOR THE OVERNIGHT HOURS...AND
ESPECIALLY VERY LATE TONIGHT. ZONES COMING OUT SHORTLY.
&&
.PREV DISCUSSION... /ISSUED 330 PM CDT WED AUG 3 2011/
SHORT TERM...TONIGHT.
A SHORT WAVE CURRENTLY OVER EASTERN COLORADO....WILL RIDE OVER THE
BROAD MID LEVEL RIDGE AND ALONG THE NEBRASKA/KANSAS STATE LINE
THROUGH THE EVENING. SHORT TERM MODELS ARE IN GOOD AGREEMENT THAT
THE H50 VORT MAX TRIGGERS AN AREA OF SHOWERS AND THUNDERSTORMS THAT
MOVES INTO NORTH CENTRAL KANSAS AROUND 06Z...TRACKING INTO SE
NEBRASKA/NE KANSAS IN THE 09-12Z TIME FRAME. UNCERTAINTY REMAINS IN
THE TIMING AND SUSPECT MAY BE GOING A FEW HOURS FAST DUE TO THE DRY
AIR IN THE LOW LEVELS TO OVERCOME.
LONG TERM...THURSDAY THROUGH WEDNESDAY.
PASSING SHORT WAVE SHOULD PROVIDE LIKELY POPS FOR SOUTHERN
PORTIONS OF THE FORECAST AREA DURING THE DAY THURSDAY. INSTABILITY
IS MODERATE AT BEST SO THE RISK OF SEVERE THUNDERSTORMS REMAINS
LOW. DRIER AIR SPREADS IN BEHIND THE EXITING SHORT WAVE THURSDAY
NIGHT LOWERING RAIN CHANCES ONCE AGAIN.
FORECAST AREA REMAINS ON THE NORTHERN EDGE OF A LARGE UPPER RIDGE
THROUGH THE LONG TERM FORECAST PERIOD. AS WE HEAD INTO THE WEEKEND
THE UPPER RIDGE RETROGRADES AND BUILDS PUTTING THE REGION UNDER AN
INCREASINGLY NORTHWEST UPPER FLOW PATTERN...ALLOWING ANOTHER COLD
FRONT TO SLIP ACROSS THE AREA SATURDAY AND SATURDAY NIGHT. THE
UPPER SHORT WAVE ASSOCIATED WITH THIS FRONT IS WELL NORTH AND
NORTHEAST OF THE AREA AND THE ATMOSPHERE IS EXPECTED TO REMAIN
RELATIVELY DRY. FOR NOW I WILL KEEP CHANCE POPS SPREADING SOUTH
ACROSS THE FORECAST AREA FOR SATURDAY THROUGH SATURDAY NIGHT WITH
THIS SYSTEM SINCE CONFIDENCE IN WIDER-SPREAD COVERAGE IS STILL A
BIT LOW. FOR SUNDAY THROUGH WEDNESDAY...UPPER FLOW FLOW REMAINS
NORTHWESTERLY. THIS SHOULD HELP KEEP TEMPERATURES FAIRLY MILD FOR
AUGUST. ANOTHER FRONTAL SYSTEM IS POSSIBLE EARLY NEXT WEEK. THIS
ALONG WITH POTENTIAL WEAK SHORT WAVES IN THE NORTHWEST FLOW WILL
KEEP LOW POPS IN THE EXTENDED FORECAST...BUT CONFIDENCE IN TIMING
AND STRENGTH KEEP ME FROM BUMPING POPS UP PAST SLIGHT CHANCE FOR
NOW.
AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
VFR CONDITIONS WILL PREVAIL THROUGH 06Z...WITH DECREASING CEILINGS
FROM THE WEST THROUGH THURSDAY MORNING. SHOWERS AND THUNDERSTORMS
ARE EXPECTED INTO SE NEBRASKA IN THE 09-12Z TIME FRAME. INTRODUCED
VCSH AND CB TO ALL TAF SITES LATE TONIGHT...BRINGING IN A PROB30 FOR
RA AND MVFR CIGS TO KLNK AFTER 12Z WHERE CONFIDENCE IS HIGHEST.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...TRUETT