FXUS63 KOAX 202116
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
316 PM CST THU JAN 20 2011
.SHORT TERM...TONIGHT THROUGH SUNDAY.
THERE ARE SEVERAL CONCERNS IN THE SHORT TERM. THE MAIN ONES INCLUDE
LOWS TNGT...LIGHT SNOW EVENT FRIDAY AND POTENTIAL FOR 3 TO 6 INCHES
OF SNOW FROM SATURDAY AFTN INTO EARLY SUNDAY AFTN.
SFC CHART EARLY THIS AFTN SHOWED HIGH PRES EXTENDING SWD THROUGH THE
PLAINS. A CDFNT WILL CONT TO DROP SWD...THEN STALL THIS EVENING.
AS THE SFC RIDGE AXIS MOVES EWD...FRONT WILL LIFT BACK NWD AS A
WRMFNT. EXPECT LOWS TNGT TO DROP BELOW ZERO IN THE ERN HALF OF THE
FCST AREA BUT PROBABLY REMAIN ABOVE ZERO WEST. LIGHT WINDS AND FRESH
SNOW ON THE GROUND WILL ALLOW FOR EXCELLENT RADIATIONAL COOLING
CONDITIONS EARLY TNGT IN LOCATIONS WHERE SKIES WILL BE MOSTLY CLEAR.
SOUTH OR SOUTHEAST WINDS WILL INCREASE OVERNIGHT AND CLOUDS SHOULD
THICKEN AS ISENTROPIC LIFT INCREASES IN THE 280-290K LAYER. THE
12Z GFS SEEMED TO HAVE A DECENT HANDLE ON THINGS...IN REGARDS TO
THE ALBERTA CLIPPER FRIDAY AND THE SYSTEM OVER THE WEEKEND. LIGHT
SNOW IS EXPECTED TO DEVELOP IN OUR NRN ZONES LATER TNGT...THEN
MOVE ACROSS THE AREA FRIDAY MORNING AND INTO EARLY FRIDAY AFTN.
AMOUNTS AT THIS TIME APPEAR LIGHT...GENERALLY AN INCH OR LESS.
A SYSTEM THAT LOOKS STRONGER AND WILL HAVE MORE POTENTIAL FOR SOME
SIGNIFICANT SNOW STARTS TO DROP TOWARD THE AREA FROM THE NORTHWEST
BY SATURDAY AFTN. BUMPED POPS UPWARD INTO THE LIKELY CATEGORY FOR
MOST AREAS FOR SATURDAY NIGHT. THIS SYSTEM SHOULD TRACK OFF TO THE
SOUTHEAST SUNDAY WITH POPS DECREASING DURING THE DAY. RIGHT NOW...
THINK THAT TOTALS FROM THE SATURDAY/SUNDAY SYSTEM COULD REACH 3 TO
6 INCHES OR MORE. THE GFS HAS BEEN FAIRLY CONSISTENT...AND THE
12Z ECMWF QPF HAS INCREASED FOR OUR AREA COMPARED TO PREVIOUS RUN
(NOW IS 0.10-0.45 WATER EQUIVALENT). 12Z GFS SHOWED ABOUT 0.40 TO
0.65 WATER EQUIVALENT. ONE OF THE MAIN THINGS THAT LEADS ME TO
BELIEVE THERE IS AT LEAST SOME POTENTIAL FOR A MODERATE TO HEAVY
SNOW EVENT IS THAT BOTH THE ECMWF AND GFS SHOW OR AT LEAST HINT AT
A LOW CLOSING OFF AT 500 MB AS THE SHORTWAVE MOVES ACROSS OUR AREA.
MID LEVEL MIXING RATIOS ARE MODEST...MAINLY 2-3 G/KG BUT THERE IS
A PERIOD WITH IMPRESSIVE VERTICAL MOTION. THE STRONGEST VERTICAL
MOTION AT 700 MB IS BETWEEN 00Z SUNDAY AND 12Z SUNDAY...WITH
VALUES MAXING OUT NEAR 15 MICROBARS/SECOND OVER SERN NE AT 06Z
SUNDAY. CONSIDERED ISSUING A WINTER STORM WATCH...BUT CONFIDENCE
IS JUST BELOW WHAT I WOULD LIKE IT TO BE TO ISSUE A WATCH AT THIS
POINT. WILL BEEF UP THE WORDING IN THE HWO (HAZARDOUS WEATHER
OTLK). SYSTEM SATURDAY AND SUNDAY DOES LOOK LIKE IT WOULD HAVE
MORE WIND THAN THE EVENT FROM YESTERDAY (WEDNESDAY) DUE TO A
STRONGER SFC PRES GRADIENT.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY.
ON THE WHOLE MED RANGE DETERMINISTIC MODELS AND ENSEMBLES MAINTAIN
LARGE SCALE FEATURE OF TROF TO THE EAST AND RIDGING OVER THE WRN
CONUS WITH SEVERAL PIECES OF ENERGY RIDING DOWN FRONT SIDE OF WRN
RIDGE AND INTO THE GREAT PLAINS. AS USUAL...TIMING/PLACEMENT DETAILS
CONCERNING SHORTWAVE TROFS AND RESULTING SFC FEATURES OUT OF SYNC.
HOWEVER...CONFIDENCE IS PRETTY HIGH WE WILL NOT SEE MUCH OF A TEMP
RECOVERY WITH NW FLOW PREVAILING ALOFT THRU THE FCST PD. DETAIL
DIFFERENCES THOUGH ARE MAKING SNOW FCSTING PROBLEMATIC AT BEST. AT
ANY RATE SEEMS THAT BEST CHANCE FOR GETTING ANYTHING...PER
ECM/CMC...WILL COME ON MONDAY WHEN CLIPPER TYPE LOW DROPS INTO THE
DAKOTAS/MN EARLY MORNING AND DRAGS ATTENDANT COLD FRONT INTO THE
CNTRL PLAINS. GOING FCST ALREADY HAS SMALL POPS IN PLACE AND LEAVE
AS IS. SEEMS TO BE SOME POTENTIAL FOR SNOW TUESDAY ALSO GIVEN
ECM/GFS ADVERTISING UPPER SUPPORT VIA DPVA. MOISTURE THOUGH IS IN
QUESTION AT THIS POINT. WILL OPT FOR DRY FCST THEN WITH THE REST OF
THE PD DRY AS WELL.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
AN ARCTIC FRONT PASSING THRU ERN NEBRASKA WILL RESULT IN A FEW HOURS
OF GUSTY NORTHWEST WINDS AND PATCHY MVFR CIGS AND FLURRIES. THE
BAND OF MID CLDS AROUND 4-6KFT HAS SOME PATCHY 1500FT CIGS...AND
THESE MAY PASS OVER THE TAF SITES. THESE SHOULD NOT LAST LONG...SO
HAVE PREVAILING VFR CONDITIONS. NORTHWEST BREEZES AT 10 TO 20KTS
WILL GIVE WAY TO LIGHT SOUTHEAST WINDS OVERNIGHT. THESE SOUTHEAST
WINDS WILL INCREASE TO 8 TO 12KTS AFT 08Z. THE NEXT STORM SYSTEM
WILL BRING INCREASING MID CLOUDS OVERNIGHT WITH LIGHT SNOW
DEVELOPING. INCLUDED MVFR CIGS/VSBYS AT KOFK AFTER 12Z WITH SNOW...
AND MENTIONED MVFR CONDITIONS AND SNOW AFTER 14-15Z AT KOMA AND KLNK.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...MILLER
LONG TERM....DEE
AVIATION...ZAPOTOCNY