Forecast Discussions mentioning "ACARS", "MDCRS", or "AIRCRAFT" received at FSL on 02/23/03

AVIATION DISCUSSION FOR 18Z TAFS

BASED ON LATEST RADAR TRENDS AND MODELS HAVE PULLED SN OUT OF DPA, ORD, MDW. WHILE MIGHT BE A FEW FLURRIES LATER NOT SIGNIFICANT. KEPT A LITTLE SN IN AT GYY AS WILL BE ON THE EDGE THERE. LOOKS LIKE STRONG NE WINDS TO CONT THIS AFTERNOON BECOME N TONIGHT AND NNW LATE TONIGHT AND DIE OFF. STILL A LITTLE IFR CIGS N OF ORD SO FOR ANOTHER HOUR OR 2 COULD DROP TO A HIGH IFR AT ORD MDW BUT AFTER THAT SHOULD BE MVFR WITH A SLOW CLIMB. LOOKING UPSTREAM OVER MN, WI LOTS OF MVFR CIGS SO DO NOT THINK WILL BREAK UNTIL MIDDAY SUNDAY.

AF

PUBLIC DISCUSSION FOR 11 AM ZONES UPDATE:

THE UPDATES ARE TO ADJUST THE WORDING IN THE FORECAST. WE HAVE REACHED THE HIGH TEMPERATURES FOR NORTHEAST ILLINOIS AND NORTHWEST INDIANA THIS MORNING. PRECIPITATION IS SEEN ON THE RADAR OVER FORD TO SOUTHEAST PORTER COUNTIES AND SOUTH. OBSERVATIONS AT KANKAKEE AND CHAMPAIGN ILLINOIS SHOW SNOW AT THE SURFACE. THE ACARS SOUNDING AT ORD AT 1709 UTC SHOW MOST OF THE LOW LEVELS OF THE ATMOSPHERE ARE BELOW FREEZING. PROFILER WINDS AT WOLCOTT INDIANA SHOW THE TURBULENT DEPTH OF THE CONTINENTAL POLAR AIR MASS INCREASING AT LOW LEVELS. WILL KEEP THE ADVISORY FOR SNOW IN FOR JASPER COUNTY INDIANA TO FORD COUNTY IN ILLINOIS. NORTH OF THAT AREA IS A PROBABILITY OF SNOW FROM LIKELY TO JUST A CHANCE AT THE WISCONSIN BORDER. WILL FORECAST 15 TO 25 MPH WINDS WITH GUSTS.

.CHI...SNOW ADVISORY FOR FORD...IROQUOIS...BENTON...JASPER AND NEWTON COUNTIES FOR AROUND 4 INCHES SNOW THIS AFTERNOON AND TONIGHT.

WHW



LAYER THAT WILL MIX TO MVFR AFTER SUNRISE. CWA CONTINUES TO BE ON THE NW EDGE OF THE PRECIP SHIELD...WITH KRFD UNLIKELY TO SEE ANY PRECIP AT ALL...AND THE OTHERS WITH JUST MINOR VSBY RESTRICTIONS THIS AFTERNOON. TIGHTENING GRADIENT MEANS GUSTY WINDS...AND THIS SHOULD CONTINUE WELL INTO THE OVERNIGHT HOURS BEFORE GRADUALLY SLACKENING.

JHV



LOTS OF LITTLE DETAILS TO IRON OUT ON THIS ONE. SFC ANALYSIS WAS SHOWING SFC RIDGE AXIS CONTINUING TO HOLD IN PLACE ACROSS EASTERN KS MUCH STRONGER THAN MODELS WERE PROJECTING FOR THE PREVIOUS RUN...DUE TO 3MB PRESSURE CHANGE STILL RISING OVER THAT AREA. ACARS/PROFILER DATA SEEMED TO BE INDICATING THAT UPPER LOW WOULD DIG FURTHER SOUTH AS WELL WITH JET ENERGY DIVING MORE SOUTH. THIS SHOULD SHIFT THINGS A BIT FURTHER SOUTH AND THIS WAS BEING CONFIRMED BY NEW MESOETA RUN WITH DATA NOW POURING IN. THIS WILL ALSO DELAY THE TIMING OF SNOW FALL ACROSS THE AREA. SO WILL NEED TO ADJUST TIMING ON THE WINTER STORM WARNING AND ADVISORIES FOR THE CWA...SUNDAY MORNING AND EARLY AFTERNOON. WILL GO AHEAD AND KEEP CURRENT WARNING/ADVISORY LOCATIONS IN PLACES BUT WILL BUMP SNOW TOTALS DOWN A BIT FOR SOME AREAS. HEAVIER SNOWFALL TOTALS LOOK TO AFFECT AREAS ALONG THE KS/OK BORDER. THIS ADJUSTMENT ON SNOW TOTALS WOULD PUT SOME OF THE NORTHERN COUNTIES BELOW WARNING CRITERIA ON AMOUNTS...HOWEVER STRONG NORTHERLY WINDS AND WIND CHILL READINGS ON THE LOW END OF THINGS STILL WARRANT KEEPING IT GOING AS THIS WILL CAUSE PROBLEMS WITH BLOWING SNOW.

FCSTID = 15/JAKUB

------------------------------------------------------------------- 305 PM CST SAT FEB 22 2003

TWO SIGNIFICANT WINTER WEATHER SYSTEMS TO CONTEND WITH OVER NEXT SEVERAL DAYS.

FIRST SYSTEM NOW SEEN ON WATER VAPOR IMAGERY HEADING OUR WAY FROM CTRL ROCKIES. MODELS HAVE BEEN IN IMPRESSIVE AGREEMENT LAST DAY OR SO...THOUGH THIS MORNING...ETA TRENDING A LITTLE SOUTH OF OTHER MODELS. DESPITE EXITING SYSTEM TO OUR EAST...SATELLITE...SOUNDINGS AND MODELS SHOW RESIDUAL LOW-LEVEL MOISTURE ACROSS REGION. VERY IMPRESSIVE LIFT WITH SYSTEM...AS SHOWN IN FRONTOGENETIC FORCING PLOTS AND ISENTROPIC PLOTS (SURFACES RISING, COMBINED WITH AIR PARCELS RISING ON SURFACE).

SYSTEM WILL BE FAST MOVER...CUTTING DOWN SOMEWHAT ON PRECIPITATION AMOUNTS. REGARDLESS...CLOUDS TO BE ON THE INCREASE THIS EVENING... WITH SNOW DEVELOPING ACROSS CTRL AND PORTIONS OF SOUTHCENTRAL KS WELL AFTER MIDNIGHT. HEAVY SNOW SHOULD DEVELOP OVER CTRL KS BEFORE DAWN...SHIFTING TO SOUTHCENTRAL KS AROUND DAWN...AND FAR SOUTHERN AND SOUTHEASTERN COUNTIES LATER IN THE MORNING. BUFKIT SHOWING MODEL SNOWFALLS OF 1-2 INCHES PER HOUR FOR A FEW HOURS. MODEL SOUNDINGS SUGGEST SUFFICIENT INSTABILITY FOR CONVECTIVE SNOW. SNOW SHOULD START WINDING DOWN FROM WEST TO EAST DURING THE AFTERNOON...BUT EXPECT WIDESPREAD 5-8 INCHES OF SNOW ACROSS SOUTCENTRAL AND SOUTHEAST KS. ACROSS CENTRAL KANSAS...ANTICIPATING SLIGHTLY LESS ACCUMULATION AS BETTER LIFT QUICKLY SHIFTS SOUTH AND EAST...BUT STILL COULD GET 3-6 INCHES.

MY PLAN IS TO ISSUE ADVISORY FOR CENTRAL KANSAS (BARTON TO CHASE COUNTIES NORTHWARD)...AND WARNING FOR SOUTHCENTRAL AND SOUTHEAST KANSAS. MOST OF THE SNOW WILL FALL IN THE 2ND PERIOD (SUNDAY) ACROSS SOUTHEAST KANSAS...BUT WILL GO AHEAD WITH WARNING THERE TOO. IN ADDITION TO ACCUMULATING SNOW...15-25 MPH WINDS SHOULD YIELD SOME BLOWING SNOW TOO. THANK GOODNESS ITS NOT DURING THE NORMAL WORKWEEK.

WELL...NOT THAT SYSTEM ANYWAY. AN EVEN STRONGER SYSTEM IS ON TAP FOR TUE-THU TIMEFRAME. AGREE WITH NCEP THAT ECMWF MAY BE WAY TO GO RIGHT NOW...STRONGER AND SLOWER COMPARED TO GFS. OF MORE IMPORTANCE... ECMWF SHOWS PERSISTENT CONFLUENT ZONE ALOFT OVER NRN PLAINS...WHICH TRIES TO KEEP HIGH PRESSURE RIDGE AND COLD AIR IN PLACE OVER CENTRAL PLAINS. SNOW COVER FROM 1ST SYSTEM MAY HELP KEEP SHALLOW COLD AIR IN PLACE AS SWRLY FLOW DEVELOPS ALOFT.

THIS SYSTEM HAS THE POTENTIAL TO BRING SIGNIFICANT ICE ACCUMS TO SOUTHCENTRAL KANSAS...AND PERHAPS HEAVY SNOW FURTHER NORTH... OCCURRING DURING THE WORKWEEK. STILL A LONG WAY AWAY...AND MODELS CAN CHANGE...WILL NEED TO MONITOR THIS CLOSELY.

AS FOR TEMPS...GOING COLDER THAN NGM MOS GIVEN ANTICIPATED SNOWCOVER. SHOULD SEE STEADY/FALLING TEMPERATURES DURING THE DAY TOMORROW... WITH SINGLE DIGITS TOMORROW NIGHT. IF SKIES END UP CLEAR...COULD SEE TEMPS AROUND 0 OR LOWER...WON'T GO THAT COLD JUST YET. TEMPERATURES WILL BE ON SLOW RISE TUESDAY INTO WEDNESDAY.

THANKS FOR COORD EFFORT TOP/SGF. GRIDS SENT.

WOLF FCSTID = 19 ICT 22 25 7 17 / 70 90 10 10 HUT 21 24 6 16 / 70 80 5 10 EWK 22 24 7 17 / 60 80 10 10 EQA 22 25 7 17 / 50 90 10 10 WLD 25 27 9 20 / 50 90 10 10 RSL 19 21 5 13 / 80 70 5 10 GBD 20 22 6 14 / 80 70 5 10 SLN 19 21 5 13 / 70 80 5 10 MPR 22 24 7 17 / 60 80 10 10 CFV 25 28 9 20 / 30 90 20 10 CNU 23 26 8 18 / 30 90 20 10 K88 22 26 8 18 / 30 90 20 10

.ICT... KS...WINTER STORM WARNING FOR LATE TONIGHT THROUGH SUNDAY AFTERNOON FOR ZONES KSZ067>069...KSZ082>083...KSZ091>093.

WINTER STORM WARNING FOR SUNDAY FOR ZONES KSZ070>072...KSZ094>096... KSZ098>100.

WINTER WEATHER ADVISORY FOR LATE TONIGHT THROUGH SUNDAY AFTERNOON FOR ZONES KSZ032>033...KSZ047>053.



...SNOW TONIGHT/SUNDAY MORNING AND ASSOCIATED WINTER WX HEADLINES FOR PORTIONS OF THE CWA ARE MAIN CONCERN...

12Z UPPER AIR DIAGNOSTICS AND WATER VAPOR IMAGERY FEATURING STRONG VORTEX THROUGH THE LOWER/MIDDLE MISSISSIPPI RIVER VALLEY...WHILE A MID TO UPPER SHORTWAVE TROUGH -- THE MAIN PLAYER IN THE LOCAL FORECAST TONIGHT/SUNDAY -- AND ACCOMPANYING HEIGHT FALLS QUICKLY MOVES THROUGH THE INTERMOUNTAIN WEST/NORTHERN ROCKIES. LATTER FEATURE ASSOCIATED WITH 300MB/ACARS INDICATED 100KT-120KT JET CORE FROM THE PACIFIC NORTHWEST INTO THE CENTRAL GREAT BASIN AREA.

LATEST SURFACE ANALYSIS SHOWING QUASI-STATIONARY FRONTAL BOUNDARY EXTENDING FROM SOUTHERN MONTANA INTO NORTHEAST WYOMING AND THE NEBRASKA PANHANDLE...WHILE LEADING EDGE OF ARCTIC FRONT PLUNGES THROUGH SOUTHWEST KANSAS...CENTRAL OKLAHOMA...AND NORTHERN ARKANSAS.

QUESTION ULTIMATELY COMES DOWN TO HOW MUCH SNOW PORTIONS OF THE CWA WILL RECEIVE TONIGHT AND SUNDAY. NATURE OF COLD AIRMASS AND DENDRITIC CONSIDERATIONS WOULD SUGGEST A GOOD SNOW EFFICIENCY AS SNOW TO LIQUID WATER EQUIVALENTS MAY BE IN THE 15:1 TO 20:1 RANGE. BELIEVE THERE IS ALSO POTENTIAL FOR BANDING INTO PORTIONS OF THE SOUTHWEST CWA GIVEN ORIENTATION AND DEGREE OF LOW TO MID FRONTOGENETICAL FORCING... UPPER JET STREAK...AND OUTSIDE POSSIBILITIES FOR CONVECTIVE ENHANCEMENT. GIVEN THIS...SNOWFALL RATES AROUND/IN EXCESS OF 1 INCH/HOUR NOT OUT OF THE QUESTION OVERNIGHT AND EARLY SUNDAY MORNING IN THE SOUTHWEST CWA.

IN ALL...INCLINATIONS ARE STORM TOTAL 4 TO 6 INCHES (MAYBE LOCALLY TO 7 INCHES ALONG AND WEST OF HWY 183 IN NCNTRL KS?) ROUGHLY SOUTHWEST OF A LINE FROM BEAVER CITY...TO SMITH CENTER...TO BELOIT. COULD BE CLOSE CALL ON WARNING CRITERIA...BUT THINK MOST OF THE AREAS IN THE SOUTHWEST CWA WILL FALL SHORT OF WARNING THRESHOLD. FROM THERE... WOULD THEN EXPECT A NARROW CORRIDOR OF 3 TO 5 INCHES...TRAILING OFF TO 1 TO 3 INCHES OR SO FOR THE TRI-CITIES. NORTHEAST CWA STANDS TO SEE ONLY MINIMAL ACCUMULATIONS. SHORT RANGE ENSEMBLES /BASED AT 9Z/ AND LATEST RUC20/DEVELOPMENTAL RUC20 REAFFIRM THEORY OF MAX SNOW AMOUNTS BEING FAR ENOUGH SOUTH OUT OF THE CWA. SHOULD ALSO MENTION THAT GUSTY NE/N WINDS WILL BE AN ADDITIONAL NUISANCE FACTOR... ESPECIALLY IN THE SOUTHWEST CWA.

THE SNOW IS EXPECTED TO PERSIST THROUGH THE EARLY/MID MORNING HOURS OF SUNDAY...BEFORE TAPERING TO FLURRIES DURING THE AFTERNOON. WINDS WILL BEGIN TO DIE DOWN AS WELL THROUGH SUNDAY AFTERNOON/EARLY EVENING.

IN THE OUTER PERIODS...MEDIUM RANGE MODELS/ENSEMBLES IN REASONABLY GOOD AGREEMENT WITH COLD VORTEX SHIFTING EASTWARD THROUGH EASTERN CANADA BY THE MIDDLE OF THE WEEK...WHILE SPLIT FLOW/MEAN TROUGH THROUGH THE WESTERN CONUS. GOING SNOW CHANCES LATE TUE/WED/THU ARE STILL REASONABLE AND WILL BE MAINTAINED...BUT THINK ENTIRELY POSSIBLE THAT BULK OF PRECIP/BEST CHANCES COULD END UP BEING WELL SOUTH OF THE AREA GIVEN EXPECTED ORIENTATION OF SUBTROPICAL JET AND/OR CUT-OFF NATURE OF SOUTHWEST CONUS TROUGH.

COORDINATED WITH LBF...DDC AND ICT.

.GID...WINTER WEATHER ADVISORY OVERNIGHT AND SUNDAY MORNING FOR DAWSON...GOSPER...PHELPS...KEARNEY...FURNAS...HARLAN... FRANKLIN...AND WEBSTER COUNTIES IN SOUTH CENTRAL NEBRASKA.

WINTER WEATHER ADVISORY OVERNIGHT AND SUNDAY MORNING FOR PHILLIPS...SMITH...JEWELL...ROOKS...OSBORNE...AND MITCHELL COUNTIES IN NORTH CENTRAL KANSAS.

GUYER