FXUS63 KOAX 050102
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
253 PM CDT MON JUL 4 2011
.DISCUSSION...
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