FXUS63 KOAX 242107
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
307 PM CST THU FEB 24 2011
.SHORT TERM...TONIGHT THROUGH SUNDAY.
MAIN FORECAST ISSUES IN THE SHORT TERM INCLUDE SNOW AMOUNTS THROUGH
THIS EVENING...POTENTIAL FOR LIGHT SNOW FRIDAY THROUGH SATURDAY AND
CHANCE FOR PRECIPITATION ON SUNDAY.
WATER VAPOR AND INFRARED SATELLITE IMAGERY EARLY THIS AFTN SHOWED A
VIGOROUS SHORTWAVE TROUGH THAT WILL MOVE ACROSS NORTHEAST KANSAS AND
SOUTHEAST NEBRASKA INTO PARTS OF IOWA AND MISSOURI. 20Z SURFACE
ANALYSIS SHOWED COLD HIGH PRESSURE OVER THE NRN PLAINS WITH
TEMPERATURES IN THE SINGLE DIGITS ABOVE AND BELOW ZERO IN ND. TO
THE SOUTH...READINGS IN THE 40S WERE NOTED AS FAR NORTH AS
SOUTHEAST KANSAS. MAIN SURFACE LOW WAS WELL TO THE SOUTH IN ERN
OKLAHOMA. THERE WAS SOME SLEET IN PARTS OF SERN NEBRASKA THIS
MORNING BUT THE PRECIPITATION TYPE FROM TONIGHT THROUGH SATURDAY
IN OUR AREA SHOULD BE SNOW OR MOSTLY SNOW. NUMERICAL MODELS HAVE
NOT BEEN IN VERY GOOD AGREEMENT WITH THE SYSTEM TODAY INTO
TONIGHT.
REGIONAL RADAR SHOWED SNOW OVER PARTS OF THE REGION ALONG WITH AN
ENHANCED BAND STRETCHING FROM PARTS OF SCNTRL NEBRASKA INTO SWRN
IOWA. SNOW AMOUNTS WILL NOT BE EASY TO NAIL DOWN DUE TO MESOSCALE
ENHANCEMENT. 12Z RUN OF THE 12 KM NAM MAY HAVE DONE A DECENT JOB
WITH THIS BAND...WHICH WAS CAUSING MODERATE TO HEAVY SNOW JUST
NORTH OF THE 700 MB LOW. CROSS SECTIONS SHOW THAT MID LEVEL
FRONTOGENESIS WEAKENS IN OUR AREA BY AROUND 00Z AND THEN ENDS THIS
EVENING. STILL EXPECT 2 TO 5 INCHES OF SNOW IN PARTS OF SOUTHEAST
NEBRASKA AND SOUTHWEST IOWA. LOCALLY HEAVIER AMOUNTS POSSIBLE BUT
DIFFICULT TO SAY EXACTLY WHERE. LIGHT SNOW WILL ALSO OCCUR TO THE
NORTH. DECIDED TO EXPAND THE WINTER WEATHER ADVISORY FARTHER TO
THE NORTH...INTO BUTLER...SAUNDERS...DOUGLAS...SARPY AND
POTTAWATTAMIE COUNTIES.
SEVERAL DISTURBANCES WILL MOVE THROUGH FRIDAY THROUGH SATURDAY...
BUT POTENTIAL FOR OVER 2 INCHES OF SNOW IS LOW. THE AFWA ENSEMBLE
PROBABILITY PLOTS SUPPORT THAT THINKING.
A LOW PRESSURE SYSTEM WILL ORGANIZE OVER EASTERN COLORADAO SATURDAY
INTO SATURDAY NIGHT...WITH PRECIPITATION DEVELOPING WITH ISENTROPIC
LIFT NORTH OF A WARM FRONT. A STRONG CLOSED LOW AT 500 MB SHOULD BE
OVER NORTHERN ARIZONA AT 12Z SUNDAY...THEN IT WILL OPEN UP AND MOVE
QUICKLY NORTHEAST TOWARD KANSAS CITY BY SUNDAY NIGHT. WENT WITH A
CHANCE FOR MIXED PRECIPITATION IN SOUTHEAST NEBRASKA AND SOUTHWEST
IOWA WITH THAT SYSTEM WITH SNOW FARTHER NORTH. THERE COULD BE SOME
EMBEDDED THUNDERSTORMS WITH THAT...BUT LEFT OUT FOR NOW SINCE THE
CHANCE WAS HIGHER FARTHER SOUTH.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY.
MAIN ISSUE IN THE EXTENDED PDS IS POTENT VORT LOBE EXITING THE
ROCKIES AND MIGRATING ACROSS THE CNTRL PLAINS NIGHT. IMPRESSIVE 12HR
500MB HGT FALLS AROUND 20 DAM OVER KS/OK SHOWING JUST HOW STRONG
THIS SYSTEM IS ADVERTISED TO BE. AXIS OF MAX OMEGA/BEST 500-300MB
QVECT CONVG PER GFS/ECM PRETTY MUCH EXTENDING FROM THE CWA INTO KS
AND OK WITH THE SYSTEM EVENTUALLY INDUCING LEESIDE CYCLOGENESIS IN
WRN KS. SFC REFLECTION PROGGED TO QUICKLY LIFT OUT OF KS SUNDAY
NIGHT AND REACH THE WRN GREAT LAKES BY MON 12Z. STRONG UPPER
DYNAMICS COUPLED WITH TIMING/PLACEMENT OF BEST LLVL MOIST CONVG AND
MID LYR AGEOSTROPHIC LIFT SUGGESTING FOCUS FOR SNOW ACTIVITY FAVORED
FOR AREAS ALONG AND SOUTH OF I-80. GIVEN SPEEDY NATURE OF THE
SYSTEM...ANTICIPATE ANY ACCUMULATION WOULD BE ON THE LIGHT SIDE.
THEREAFTER DETERMINISTIC MODELS AND ENSEMBLE SOLUTIONS IN QUITE GOOD
AGREEMENT LARGE SCALE FLOW WILL TRANSITION TO ZONAL WITH A NORTHERN
AND SOUTHERN BRANCH JET SITUATED OVER THE CONUS. THUS PATTERN SHOULD
FAVOR HINDERING ANY SIGNIFICANT CAA ATTEMPTING TO PENETRATE SWD INTO
THE CNTRL PLAINS DAYS 5-7.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
TWO STORM SYSTEMS WILL AFFECT THE TAF SITES DURING THE PERIOD. THE
FIRST SYSTEM WILL CONTINUE TO BRING SNOW...HEAVY AT TIMES INTO THIS
EVENING...WITH MVFR CIGS VSBYS AND LOCAL IFR/LIFR CIGS/VSBYS IN THE
SNOW. INCLUDED VSBSY RESTRICTIONS AT KOFK ENDING 00Z AND AT
KOMA/KLNK 04-06Z. NORTH WINDS AT 10 TO 20KTS WILL CONTRIBUTE TO THE
REDUCED VISIBILITIES. EXPECT LOCAL IFR VSBYS AT KOFK AND KOMA AND
LIFR CIGS/VSBYS AT KLNK. MVFR CIGS ARE EXPECTED OVERNIGHT WITH MORE
SNOW MOVING INTO KOFK AFT 14Z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL 11 PM CST THIS EVENING FOR
NEZ051>053-066>068-089>093.
WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR NEZ065-
078-088.
IA...WINTER WEATHER ADVISORY UNTIL 11 PM CST THIS EVENING FOR IAZ069-
079-080-090-091.
&&
$$
SHORT TERM...MILLER
LONG TERM....DEE
AVIATION...ZAPOTOCNY