FXUS63 KOAX 182053
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
253 PM CST THU NOV 18 2010
.SHORT TERM...TONIGHT THROUGH SUNDAY.
FORECAST CONCERN IN THE SHORT TERM REMAINS SHALLOW COLD AIR THAT
WILL BE SLIPPING SOUTH UNDER SWRLY UPPER FLOW LATE FRIDAY THROUGH SAT
...MAINLY WITH REGARDS TO MOISTENING LOW LVLS ON SATURDAY WITH PROBABLE
LOW CLOUD DEVELOPMENT THEN WHETHER OR NOT SOME LIGHT PCPN GETS
SQUEEZED OUT OF THESE CLOUDS SAT NGT/EARLY SUNDAY.
STLT IMAGERY THIS AFTN SHOWED ENERGY PUNCHING ACROSS SRN CANADA
AIDING IN A WARM FRONT DVLPG FM CNTRL SD TOWARD SERN NEBR. APPEARS
THERE WILL BE ENOUGH WIND TNGT AS SFC LOW TRACKS TWD NRN MN TO
KEEP READINGS NEAR 30 OR A BIT WARMER...LTL CHANGES MADE. FRONT
DROPPING SOUTH BEHIND LOW SHOULD BE NEAR AN OMA-LNK LINE BY 18Z
FRI AND PUSH THRU CWA BEFORE 00Z. ALTHOUGH COOLING WILL START
FILTERING IN BEHIND FRONT...IT MAY NOT ARRIVE QUICKLY ENOUGH TO
KEEP READINGS FROM REACHING NEAR NAM/GFS SOUNDING SUGGESTED MID
40S AT OFK TO LOW/MID 50S FM LNK SEWD. HOWEVER...AIRMASS BEHIND
FRONT IS QUITE COOL...EVIDENT TEENS/LOWER 20S SPILLING INTO CNTRL
MT AND CURRENT READINGS IN SRN CANADA. THIS COOLER AIR WILL FILTER
SOUTH ACROSS CWA FRI NGT EVEN THOUGH FRONT STILL FORECAST TO
STALL JUST S OF THE CWA AS IT ENCOUNTERS SWRLY UPPER FLOW. WITH
LOW LVL ISENTROPIC UPGLIDE DVLPG SAT...LOW CLOUDS SHOULD QUICKLY
DVLP WHICH COULD TRAP THIS COLD AIR IN AND COULD CONCEIVABLY KEEP
SOME READINGS BELOW FREEZING SAT AFTN...SPCLY N. DID NOT LOWER
TEMPS THAT MUCH JUST YET...BUT OVERALL DID LOWER TWD GFS MOS
GUIDANCE. STILL LEFT FORECAST DRY UNTIL BETTER LIFT IS FCST IN
MOIST LAYER SAT NGT AS A WAVE ATTEMPTS TO LIFT FRONT NWD INTO CWA.
THIS COULD GENERATE DRIZZLE S AND SOME FZDZ IS POSSIBLE N WHERE
TEMPS MAY DROP BELOW FREEZING...IF THEY EVEN RECOVER ABOVE IT.
MOIST LAYER FAIRLY SHALLOW SO DID NOT CARRY POPS ATTM. PCPN AND
LOW CLOUDS ATTEMPT TO CLEAR OUT ON SUNDAY...ALTHOUGH NAM SOUNDINGS
HOLD ON TO THEM THE LONGEST EAST. SOME POTENTIAL FOR WARMING ON
SUNDAY IF SW SFC WINDS MANAGE TO DVLP BY MIDDAY...PER NAM/GFS...BEFORE
REINFORCING FRONT PUSHES S. ATTM MADE NO CHANGES TO MAX TEMPS
WHICH WERE SUPPORTED BY FORECAST SOUNDINGS FROM 12Z GFS BUT EITHER
LOW CLOUDS LINGERING OR COLD FRONT PUSHING S FASTER WOULD KEEP
THEM BELOW THESE VALUES.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY.
THE MAIN QUESTION IN THE LONG TERM WILL BE HOW QUICKLY THE VERY COLD
AIR WILL EXPAND FROM CANADA AND THE NRN U.S. INTO THE CENTRAL PLAINS
AND PRECIPITATION ASSOCIATED WITH THIS LONGWAVE TROF. THE 00Z AND
12Z ECMWF ARE NOW MUCH COLDER THAN WHAT WE HAD YESTERDAY TO WORK
WITH.
SUNDAY NIGHT...THERE IS A BROAD TROF EXTENDING FROM CANADA INTO THE
NRN AND WRN U.S. A COLD FRONT IS PUSHING THRU THE STATE WITH -10 DEG
H85 AIR HEADING TOWARD NRN NEB BY 7AM MONDAY. THERE MAY BE SOME
LIGHT SNOW NORTH WITH THE FIRST BIT OF CAA...HOWEVER A STRONGER TROF
IS LAGGING BEHIND. ANOTHER EMBEDDED WAVE MOVING THRU THE TROF TUES
MAY GENERATE LIGHT SNOW AND CAA WITH THE MAIN TROF WILL MOVE THROUGH
TUESDAY NIGHT AND WED. THE LATEST ECMWF IS A LITTLE SLOWER AND
BRINGS THE TROF THRU WED AND WED NIGHT. AT THIS TIME ANY SNOW
AMOUNTS LOOK TO BE ON THE LIGHT SIDE. THE TIMING WILL NEED TO BE
REFINED...BUT GENERALLY TRENDED TEMPERATURES MUCH COLDER. THE COLD
AIR MOVES INTO THE NORTH MONDAY WITH HIGHS IN THE 30S. TUES-THUR
HIGHS LOOKS TO HOLD IN THE 20S AND 30S WITH TEENS AND 20S FOR LOWS.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
VFR CONDITIONS EXPECTED THRU THE FCST PD. ALL TERMINALS WILL SEE
SIGNIFICANT LLWS FL020 AGL DEVELOP AROUND 19/03Z AND CONTINUE TILL
ABOUT 19/12Z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
CHERMOK/ZAPOTOCNY/DEE