FXUS63 KOAX 200943
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
343 AM CST SUN FEB 20 2011
.DISCUSSION...
EARLY SPRING-LIKE STORM BRINGING A MULTITUDE OF WEATHER ISSUES TO
FORECAST AREA FROM FREEZING RAIN/WINTRY MIX WITH THUNDER FAR NW TO
MARGINALLY SEVERE TSTMS NW OF OMA METRO TO A WIDE RANGE IN
TEMPERATURES BY MIDDAY FOLLOWED BY SHARPLY FALLING TEMPERATURES
THIS AFTERNOON.
LEAD PIECE OF ENERGY PUNCHING UP TOWARD NCNTRL NEBRASKA AT 09Z PER
MORNING SATELLITE IMAGERY WAS SPREADING BULK OF PRECIPITATION
TOWARD NCNTRL/NERN NEBRASKA WITH THE NEAR-SEVERE CONVECTIVE LINE
EXTENDING EWD INTO WRN IA AT 09Z...PROBABLY NEAR 850 MB BOUNDARY.
AT THE SURFACE AN INVERTED TROUGH HAS BEEN NEARLY STATIONARY LAST
SEVERAL HOURS FROM NEAR NELIGH TOWARD YKN. HOWEVER...EITHER SOME
SORT OF LATENT HEAT RELEASE/WARMER PRECIP LOADING OR WEAK SURFACE
WARM ADVECTION HAS CAUSED TEMPERATURES TO CREEP UP NW OF BOUNDARY
LAST FEW HOURS WHICH COULD LIMIT ICING THIS MORNING. ALSO WITH
LEAD SHORTWAVE ENERGY POSSIBLY SHIFTING BULK OF PCPN N OF FORECAST
AREA BY 15Z...PER HIGH RESOLUTION RUC...EXACTLY HOW MUCH
ADDITIONAL ICING WILL OCCUR THIS MORNING IS IN DOUBT. PLUS WITH
STRONG AND DEEP COLD ADVECTION RAPIDLY SPREADING SEWD THIS AFTN
ANY LINGERING PRECIP SHOULD CHANGE TO SNOW AND BE WHIPPED AROUND
BY WINDS THAT COULD APPROACH 40KTS...IN GUSTS ANYWAY. EVEN THEN
PRECIP AMOUNTS LATE THIS MORNING/THIS AFTERNOON COULD BE QUITE
LIGHT OR EVEN END. BECAUSE OF THE STRONG WINDS/PRECIP
QUESTION/POSSIBLE SNOW/BLOWING SNOW...ESPECIALLY NEAR SD
BORDER...CHANGED ICE STORM WARNING TO WINTER STORM WARNING KNOX
COUNTY AND WINTER WEATHER ADVISORY OTHER COUNTIES TAKE IN MORE
MULTIPLE THREATS WITH DECREASED CHANCE OF SIGNIFICANT ICING/SNOW S
AND E OF KNOX COUNTY. ISSUED A WIND ADVISORY SE OF WINTER HEADLINES
TO KANSAS BORDER W OF OMAHA TO ACCOUNT FOR THE STRONG AFTERNOON
MIXING/COLD ADVECTION WEST AND COMBO OF GUSTY SW WINDS AHEAD OF
LOW LIFTING OUT EARLY SE FOLLOWED BY COLD ADVECTION LATER THIS
AFTN. TEMPERATURES...ESPECIALLY IN CNTRL/SERN ZONES...ARE VERY
DEPENDENT ON TRACK OF SFC LOW. 00Z GFS HAS SHIFTED TRACK NORTH OF
00Z RUN OF YDA...ALTHOUGH SIMILAR TO ITS 12Z RUN...AND WAS NOW THE
FARTHEST N BETWEEN THE NAM/GFS/ECMWF. THIS HELPS EXPLAIN THE 25
DEGREE DIFFERENCE IN GUIDANCE FOR HIGHS TODAY BETWEEN NAM AND GFS
AT LNK. USING A QUICK BLEND OF GFS/ECMWF BROUGHT TEMPS BACK UP
INTO UPPER 50S FM LNK TO OMAHA AND RAISED THEM FARTHER NW AS WELL.
WITH ENERGY CLOSING OFF UPPER LOW SD/MN VCNTY MONDAY...SOME LIGHT
SNOW WILL LIKELY LINGER NRN ZONES TILL SYSTEM DEPARTS LATE MONDAY.
KEPT MODEST SNOW CHANCES IN TONIGHT NORTH WITH A SLIGHT DECREASE
MONDAY MORNING. LTL/NO CHANGES TO REST OF FORECAST. TURNING MUCH
COLDER TONIGHT/MONDAY/MONDAY NIGHT THEN RECOVERING TUE/WEDNESDAY.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
COMPLEX TAF FORECAST AS STRONG STORM SYSTEM CONTINUES TO MOVE ACROSS
THE REGION. SCATTERED TSTMS ARE POSSIBLE THRU THE FIRST HALF OF THE
TAF PD AT ALL THREE SITES WITH MVFR CIGS. SFC LOW WILL MOVE FROM
NERN CO THIS MORNING TO SERN NEB BY 18Z. PCPN COULD END EARLY ACROSS
KLNK AND KOMA. KOFK WILL BE THE TRICKY SPOT WHERE TEMPS DROP BELOW
FREEZING BEHIND THE SYSTEM. KOFK MAY SEE A MIX OF WINTERY PCPN
BEFORE CHANGING OVER TO ALL SNOW AND BLOWING SNOW. ONLY LIGHT
ACCUMULATIONS OF SNOW ARE EXPECTED AT KOFK. GUSTY NORTHWEST SFC
WINDS OF 20-30KTS ARE POSSIBLE BY LATE AFTN AND WILL CONTINUE THRU
THE EVENING.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY FROM 9 AM THIS MORNING TO 9 PM CST THIS EVENING
FOR NEZ066-078-088-089.
WIND ADVISORY FROM NOON TODAY TO 9 PM CST THIS EVENING FOR
NEZ030-031-042-043-050-065.
WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR NEZ012-
016-017.
WINTER STORM WARNING UNTIL 9 PM CST THIS EVENING FOR NEZ011.
IA...NONE.
&&
$$
CHERMOK/KERN