FXUS63 KOAX 130253
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
853 PM CST FRI NOV 12 2010
.DISCUSSION...
OPTED TO ISSUE A QUICK WINTER WEATHER ADVISORY BASED ON REPORTS
COMING IN FROM THE OMAHA METRO AREA...ALONG WITH ANOTHER QUICK
SNOW BURST THAT WAS MOVING UP THE MISSOURI RIVER YET THIS
EVENING...AND WITH EXPECTED DEFORMATION BAND EXPECTED TO IMPACT
THE SAME AREA OVERNIGHT. SOMEWHAT OF A VERY UNIQUE SITUATION THAT
NOT EVERY LOCATION IN THE ADVISORY AREA WILL RECEIVE SIGNIFICANT
SNOW. BOTH THE WESTERN/EASTERN EDGES OF THE AREA IN QUESTION STILL
ARE RECEIVING A RAIN SNOW MIXTURE...BUT LOCATIONS IN BETWEEN HAVE
LIKELY PICKED UP AROUND 2 INCHES OF SNOW ALREADY. AND...A POSSIBLE
CLOUD TO CLOUD LIGHTNING FLASH WAS NOTED...AND THIS ISNT
SURPRISING GIVEN THE CONVECTIVE INSTABILITY IN THE MID MISSOURI
RIVER VALLEY...COUPLED WITH THE 50DBZ BAND OF BRIEF HEAVY SNOW
MOVING UP THE RIVER. PLUS...IT IS THE FIRST SIGNIFICANT SNOW OF
THE SEASON...AND THE IMPACT ON THE METRO AREA AND I29 WAS ENOUGH
TO ISSUE THE WINTER WEATHER ADVISORY.
&&
.PREV DISCUSSION... /ISSUED 702 PM CST FRI NOV 12 2010/
DISCUSSION...
DID A QUICK UPDATE TO INCREASE THE SNOW TOTALS FROM OMAHA
NORTHWARD...GENERALLY ADDING ANOTHER INCH OR SO AS REPORTS HAD
INDICATED THAT A CHANGEOVER HAD ALREADY OCCURRED IN SOME AREAS
WITH SOME ACCUMULATIONS ON GRASSY SURFACES. ITS WIDELY VARIABLE
THOUGH...AS BOTH VALLEY AND EPPLEY REMAIN A RAIN/SNOW MIX...BUT
AREAS IN BETWEEN WERE 100% SNOW. 00Z KOAX SOUNDING JUST POPPED
IN...WHICH INDICATED JUST THE LOWEST 50MB SLIGHTLY ABOVE FREEZING.
THIS IS SOMEWHAT ALARMING...WHICH WILL LIKELY RESULT IN MORE OF A
THREAT FOR ACCUMULATING SNOWFALL...WHICH WILL POSSIBLY OVERWHELM
WARMER GROUND TEMPERATURES NOW THAT THE SUN HAS GONE DOWN. 21Z RUC
WAS ALSO VERY ALARMING...INDICATING A DECENT TROWEL SETTING UP
ALONG THE MO RIVER OVERNIGHT AS WELL...WHICH WOULD LIKELY BE ALL
SNOW AS WELL. SO WHILE THE FORECAST WAS UPDATED TO INCREASE
SNOWFALL AMOUNTS...MAY HAVE TO CONSIDER INCREASING AMOUNTS EVEN
MORE AFTER A DETAILED UPPER AIR ANALYSIS...WHICH WOULD LIKELY PUSH
US INTO A WINTER WEATHER ADVISORY AS WELL.
PREV DISCUSSION... /ISSUED 316 PM CST FRI NOV 12 2010/
SHORT TERM...TONIGHT THROUGH MONDAY.
IMPRESSIVE DYNAMIC FORCING PER MODELS ASSOCIATED WITH VORT ENERGY
ROUNDING BASE OF CENTRAL CONUS SHORTWAVE TROF RESULTING IN AREA OF
INTENSE PCPN EXTENDING FROM CNTRL KS TO SCNTRL OK. ACTIVITY WAS
TRACKING NEWD AND WILL BE THE FOCUS FOR PCPN LATER TONIGHT...AND ON
THE WHOLE FCST SEEMS FAIRLY STRAIGHT FORWARD. THE DIFFICULTY WILL BE
DELINEATING PTYPE. AT THIS POINT MODELS IN PRETTY GOOD AGREEMENT
BEST DYNAMIC SUPPORT WILL TRACK ALONG THE SRN CWA THRU 06Z TONIGHT
THEN BECOME MORE FOCUSED IN WRN IA INTO EARLY SAT MORNING. INCREASING
DPVA WILL INDUCE SFC CYCLONIC MOTION ALONG A STATIONARY FRONT
CURRENTLY SITUATED FROM ABOUT THE GREAT LAKES TO NRN OK. EXPECT SFC
LOW TO DEVELOP INVOF WRN MO AND QUICKLY DEEPEN WITH APPROACH OF VORT
MAX LIFTING INTO THE MID MS VLY. CAA WRAPPING AROUND STRENGTHEN SFC
LOW WILL RESULT IN RASN MIX TWD 06Z THEN MAINLY SN OVER MOST
OF THE CWA. LIFT WILL EVENTUALLY BE FOCUSED OVER WRN IA GENERALLY
BTWN 06Z-09Z WHERE PTYPE WOULD PREDOMINATELY BE SNOW...BUT SNOW
ACCUMULATIONS WITHIN THE IA CWA MAY BE HINDERED DUE TO SHORT PERIOD
OF RELATIVELY WEAK DENDRITIC OMEGA AS WELL AS WARM GROUND. GIVEN
SITUATION...ANTICIPATE SN AMOUNTS BY SAT MORNING GENERALLY 1-2 INCHES
INVOF ONAWA TO MISSOURI VLY TO HARLAN...AND AROUND AN INCH FROM ABOUT
WAYNE TO FREMONT TO JUST NORTH OF THE OMAHA METRO. PCPN ACTIVITY
SHOULD QUICKLY DIMINISH BY LATE MORNING AS THE SYSTEM LIFTS TO THE
UPPER MIDWEST. OTHERWISE REMAINDER OF FCST DRY. GOOD AGREEMENT
FROM MODELS THAT LARGE SCALE FLOW WILL REMAIN STAGNANT WITH
LONGWAVE TROF THE DOMINATE FEATURE OVER THE CONUS.
LONG TERM...MONDAY NIGHT THROUGH FRIDAY.
THE GENERAL PATTERN IN THE EXTENDED IS FOR THE CENTRAL PART OF THE
COUNTRY TO INITIALLY HAVE A MID TROPOSPHERIC TROF OVER THE
AREA...THEN RIPPLES IN THE FLOW BROADEN THE TROF...FOLLOWED BY
RIDGING AND THEN FLATTENING IT DOWN AGAIN. THIS LEADS TO SOME CHC
OF RAIN OR RAIN/SNOW TUES NIGHT-WED WITH ADJUSTMENTS TO TIMING AS
THESE WAVES CAN BE TIMED BETTER. WEDNESDAY AND THU MORNING LOOK TO
BE THE COLDEST TIME PERIODS. OVERALL TEMPERATURES ARE EXPECTED TO
BE BELOW NORMAL WITH NEAR NORMAL TEMPS TUESDAY AND FRIDAY.
AVIATION...
18Z TAFS
KOMA AND KLNK TAF SITES WILL EXPERIENCE A PROLONGED PERIOD OF IFR
CONDITIONS IN RAIN...WITH SOME SNOW...THROUGH THE EARLY SATURDAY
MORNING HOURS. EXPECT JUST RAIN THROUGH AROUND 06Z...THEN EITHER A
MIX OF RAIN AND SNOW OR SWITCHING TO ALL SNOW AFTER 06Z. THE
PRECIPITATION SHOULD COME TO AN END AT KLNK BY 09Z AND AT KOMA BY
12Z. SNOWFALL ACCUMULATIONS ON THE PAVEMENT AT THE AIRPORTS SHOULD
BE UNDER ONE INCH DUE TO WARM GROUND...BUT SOME SLUSHY ACCUMULATIONS
WILL BE POSSIBLE. CIGS EXPECTED TO MOSTLY BE BELOW 1000 FEET
THROUGH ABOUT 15Z AT KOMA AND 12Z AT KLNK...THEN GRADUALLY LIFTING
THROUGH THE MORNING ON SATURDAY.
KOFK IS FAR ENOUGH NORTH THAT MOST OF THE PRECIPITATION SHOULD BE
SOUTH THE TAF SITE WITH THE EXCEPTION OF OCCASIONAL LIGHT RAIN MIXED
WITH LIGHT SNOW. CIGS WILL BE SLOWER TO DROP BELOW 1000 FEET GIVEN
DRIER AIR IN THAT AREA.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL 6 AM CST SATURDAY FOR NEZ034-045-
052-053-067-068.
IA...WINTER WEATHER ADVISORY UNTIL 6 AM CST SATURDAY FOR IAZ043-055-
056-069-079-090.
&&
$$
DEWALD