FXUS63 KOAX 060908
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
408 AM CDT SAT AUG 6 2011
.DISCUSSION...
DENSE FOG HAS FORMED OVER MUCH OF E NE DURING THE PREDAWN HOURS.
OUTFLOW WITH APPROACHING CONVECTION SHOULD END THE DENSE FOG
THREAT OVER KNOX COUNTY SHORTLY...BUT THE FOG SHOULD CONTINUE TO
BE A PROBLEM ELSEWHERE INTO THE EARLY MORNING. HAVE OPTED TO
ISSUE A DENSE FOG ADVISORY FOR MOST OF THE CWA WITH THE
AFOREMENTIONED EXCEPTION OF KNOX COUNTY...AND OUR EXTREME E IA
COUNTIES AS STRATUS IS LIMITING VSBY DROP THERE.
OTHERWISE...PRIMARY FORECAST CONCERN CONTINUES TO BE PINNING DOWN
THUNDERSTORM CHANCES OVER THE NEXT FEW DAYS IN THE INCREASINGLY
ACTIVE QUASI-ZONAL MID LEVEL FLOW. FOR TODAY...EARLY MORNING
ELEVATED STORMS SHOULD CLIP N COUNTIES THEN AMS SHOULD RESET FOR
SURFACE-BASED CONVECTION LATER THIS AFTERNOON AND INTO THE EVENING
AS COLD FRONT AND MID LEVEL SHORTWAVE INTERACTS WITH UNSTABLE
AIRMASS FUELED BY SFC DEWPOINTS IN THE MID 70S. MUCAPES 3000-4000
J/KG AND 30-40KTS OF 0-6KM SHEAR SHOULD BE MORE THAN ENOUGH TO
SUPPORT A FEW SEVERE STORMS DURING THE LATE AFTERNOON AND EARLY
EVENING HOURS. HAVE CONTINUED WITH SCATTERED-TYPE POPS FOR
NOW...BUT ONCE STORMS SHOW THEIR HAND POPS MAY NEED TO BE
INCREASED ESPECIALLY FOR THE EVENING.
COLD FRONT WILL SWEEP THROUGH THE AREA...TEMPORARILY ENDING STORM
THREAT LATE TONIGHT AND INTO SUNDAY MORNING. HOWEVER...THE NEXT
WAVE IN THE FAST MOVING MID LEVEL FLOW WILL APPROACH THE CENTRAL
PLAINS SUNDAY AFTERNOON...ALLOWING THE FAIRLY RAPID DEVELOPMENT OF
RETURN LOW LEVEL FLOW. I HAVE ADDED SOME LOW POPS FOR MUCH OF THE
AREA ON SUNDAY AFTERNOON...BUT THE PRIMARY STORM THREAT SHOULD BE
SUNDAY NIGHT AS LOW LEVEL FLOW INTENSIFIES AND BEGINS TRANSPORTING
EXTREMELY MOIST AND UNSTABLE AIRMASS BACK INTO THE STALLED
BAROCLINIC ZONE. ALL MODELS ARE IN AGREEMENT WITH THIS
SCENARIO...BUT THEYE DO DIFFER IN TIMING AND LOCATION OF THIS NEXT
ROUND OF CONVECTION. BELIEVE NAM IS TOO FAR N WITH SUNDAY NIGHTS
QPF AND HAVE TRENDED FORECAST TO A MORE S SOLUTION ALA GFS AND
SREF. CERTAINLY...PARTS OF THE AREA COULD SEE A SEVERE WEATHER
THREAT FROM STRONG ELEVATED STORMS ALONG WITH HEAVY RAIN.
THIS COMPLEX SHOULD PUSH OUT OF THE AREA EITHER LATE SUNDAY NIGHT
OR EARLY MONDAY MORNING...AND THUNDERSTORM TRENDS BECOME A LITTLE
LESS CLEAR AFTER THIS TIME. BEST INSTABILITY APPEARS TO BE SHUNTED
SOUTH BY THE SUNDAY NIGHT COMPLEX AND DYNAMICS PROGGED INTO AREA
APPEAR TO BE A BIT LESS ROBUST. HOWEVER APPROACH OF THE NEXT COLD
FRONT SHOULD MEAN A CONTINUED THUNDERSTORM THREAT...ESPECIALLY
MONDAY NIGHT AS COLD FRONT PASSES ACROSS AREA.
NO CHANGES MADE TO REMAINDER OF FORECAST...WITH SHORTWAVES
EMBEDDED IN THE WESTERLY FLOW PRODUCING PERIODIC THUNDERSTORM
THREATS.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
DENSE FOG HAS FORMED ACROSS MUCH OF EASTERN NEB EARLY THIS MORNING.
STRATUS DECK IS ALSO FILLING IN. EXPECTING TAF SITES TO BE IMPACTED
BY THE FOG EARLY THIS MORNING...PROBABLY THROUGH AT LEAST 14Z.
CEILINGS SHOULD LIFT SHORTLY AFTER 15Z AS SOUTHWEST WINDS INCREASE
TO 5 TO 10 KTS AHEAD OF AN APPROACHING COLD FRONT. THIS COLD FRONT
WILL BE THE FOCUS FOR TSTMS...FIRST IN THE KOFK AREA AROUND 00Z
SUNDAY...THEN SPREADING SOUTHEAST TOWARD KOMA AND KLNK BETWEEN 03Z
AND 06Z SUNDAY.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR NEZ012-
015>018-030>034-042>045-050>053-065>068-078-088>093.
IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ043-055-
069-079-090.
&&
$$
AVIATION/SHORT TERM...TAYLOR
LONG TERM...TRUETT