FXUS63 KOAX 041953
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
253 PM CDT MON JUL 4 2011
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT. THUNDERSTORM CHANCES
/TIMING MAIN FORECAST CONCERN IN THE SHORTER TERM AS SHORTWAVE
ENERGY DRIVING ACROSS ND/SRN CANADA WILL PUSH A COLD FRONT INTO
AND PROBABLY THROUGH ERN NEBRASKA TUESDAY/TUESDAY EVENING.
HOWEVER...ANY POSSIBLE WAVE AT THIS LATITUDE RIDING OVER UPPER
RIDGE LATE TUESDAY WHICH COULD AID NEW DEVELOPMENT IS FORECAST TO
BE PRETTY WEAK. THUS UPPER HEIGHTS ACROSS THE FORECAST AREA REMAIN
ON HIGH SIDE MAKING COVERAGE A BIT UNCERTAIN AS CAPPING ISSUES
POSSIBLE. BEFORE THEN...MODEL QPF FM 12Z GFS SUGGESTS MCS
THAT DEVELOPS THIS EVENING ALONG/BEHIND FRONT FM WY INTO DAKOTAS
WOULD BEGIN TO MOVE INTO FAR NERN ZONES LATE TNGT AND THEN MOVE
ACROSS NERN ZONES THRU 18Z TUE. 12Z NAM/00Z ECMWF WERE 6-12HRS
SLOWER WITH THIS SCENARIO AS WAS SREF. SINCE 4KM WRF BROUGHT PCPN
INTO NERN NEBR BY MORNING FELT GFS MAY INITIALLY HAVE CORRECT IDEA
IN MCS SPREADING ACROSS FAR NERN NEBRASKA IN MORNING AND THUS
RESTRICTED LIKELY POPS TO THAT AREA AT THAT TIME. OTHERWISE...KEPT
POPS IN HIGH CHC CATEGORY WITH THIS FORECAST SINCE FRONT COULD
APPARENTLY BE WEAKLY PUSHING THROUGH AREA. HOWEVER...DID RAISE
POPS W-N OF OMAHA TUESDAY AFTERNOON A BIT AND THEN AROUND AND SW
THROUGH NE OF OMAHA IN THE EVENING JUST BEHIND EXPECTED FRONTAL
LOCATION. AFTER 06Z HIGHER POPS WOULD PROBABLY SHIFT TO SW ZONES
AS THAT AREA COULD CATCH POSSIBLE MCS ACTIVITY THAT COULD DVLP SW
NEBR/NW KS VCNTY. INCREASED SKY COVER TNGT A BIT WCNTRL THROUGH
NORTH DUE TO EITHER BLOW-OFF FM UPSTREAM CONVECTION OR REFORMATION
OF STRATUS DECK. TEMPERATURES ON TUESDAY COULD BE HELD DOWN IN
LOWER 80S NRN ZONES DUE TO DEBRIS/SCT PCPN...BUT SHOULD RECOVER
STRONGLY AHEAD OF FRONT IF ACTIVITY REMAINS N OR HOLDS OFF TILL
LATE AFTN. THUS MADE LTL CHANGES TO SRN ZONES...CLOSE TO OR A BIT
ABOVE HIGHER READINGS FROM MAV.
WED THROUGH THURSDAY...FELT DRIER NAM/00Z ECMWF COULD HAVE A
LITTLE BETTER HANDLE ON TRENDS AS FRONT SHOULD BE SHOVED SW OF
AREA. HOWEVER...LEFT IN SLGT CHC POPS ON WEDNESDAY AND THURSDAY SWRN
ZONES SINCE GFS CONTINUED TO DEVELOP PCPN MUCH OF THE AREA THOSE
PERIODS. QUICK GLANCE AT NEW 12Z ECMWF SHOWED THAT MODEL FLIPPING
OVER TOWARD BULLISH GFS REDUCING CONFIDENCE FACTOR. HIGH PLAINS
CONVECTION ROLLING DOWN UPPER RIDGE COULD AGAIN CATCH SWRN ZONES
WED NGT...THUS THE HIGHER POPS THAT REGION THEN. LTL CHANGES TO
TEMPERATURES TUE NGT THROUGH WED WHICH FIT CLOSELY TO MAV/MET
BLEND. DID TRIM TEMPS A BIT ON THU AS SLIGHT COOL ADVECTION WAS
SUGGESTED BY 00Z ECMWF/12Z NAM AT H85 AS HIGH PRESSURE DROPPED
DOWN E OF MS VALLEY.
REST OF EXTENDED...WOULD EXPECT A DRIER AND WARMER SOLUTION FOR FORECAST
AREA FRI/SAT AND POSSIBLY THRU WEEKEND AS UPPER RIDGE BUILDS EWD
BRINGING A MORE W/SW UPPER FLOW TO PLAINS. RESTRICTED ANY POPS TO
MAINLY FAR N FRI NGT/SATURDAY. NEXT FRONT ATTEMPTS TO MOVE INTO
ERN NEBRASKA VCNTY SUNDAY OR MONDAY ALLOWING PCPN CHCS TO DEVELOP
FARTHER S. AGAIN UPPER HEIGHTS REMAIN ON HIGH SIDE SO UPPER
SUPPORT COULD BE MEAGER AND HOW FAR SOUTH FRONT MOVES IS QUESTIONABLE.
BUT ALSO BY THAT TIME SUBTROPICAL MOISTURE MAY BE MORE LIKELY
WRAPPING AROUND UPPER RIDGE SO ANY WEAK WAVE RIDING OVER RIDGE AND
FRONT IN VCNTY COULD EASILY OVERCOME HIGHER HGTS. SO MANY ILL-
DEFINED MOVING PARTS ENTERING PICTURE BY THEN.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
VFR CONDITIONS EXPECTED TO CONTINUE FOR FIRST HALF OF THE TAF
PERIOD...ALTHOUGH EXPECTING MVFR FOG TO DEVELOP OVERNIGHT AT ALL
THREE TAF SITES...AND POSSIBLY IFR CEILINGS AT KOFK. A COLD FRONT
APPROACHING THE AREA COULD TRIGGER SOME CONVECTION LATE TONIGHT IN
NORTHEAST NEBRASKA...BUT BOTH NAM/SREF WERE A LITTLE SLOWER...THUS
HELD OFF ADDING ANY PRECIP TO THE KOFK TAF...ALTHOUGH DID ADD A CB
CLOUD GROUP BY ABOUT 05/15Z. MOST LIKELY WILL NEED TO ADD SOME
PROB30 GROUPS AT THE VERY LEAST ON THE NEXT TAF ISSUANCE.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
CHERMOK/DEWALD