Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 132100 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 400 PM EST SAT FEB 13 2016 .SYNOPSIS... AS A LARGE UPPER TROUGH MOVES EAST OF THE REGION...ARCTIC HIGH PRESSURE WILL BUILD INTO THE AREA THIS EVENING. A WARM FRONT WILL START TO MOVE THROUGH THE REGION ON SUNDAY...BRINGING SNOW TO THE AREA THROUGH SUNDAY NIGHT. LOW PRESSURE WILL MOVE SOUTHEAST OF THE AREA ON MONDAY...WITH ADDITIONAL PRECIPITATION. ANOTHER AREA OF LOW PRESSURE WILL MOVE INTO THE AREA ON TUESDAY...WITH WARMER TEMPERATURES EXPECTED FOR THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... THE CURRENT SURFACE ANALYSIS INDICATES THAT AN AREA OF HIGH PRESSURE IS CENTERED OVER ILLINOIS. THE SOUTHERN GREAT LAKES AND NORTHERN OHIO VALLEY REMAIN IN A REGIME OF NORTHWESTERLY FLOW...WITH LOW PRESSURE (AND A LARGE UPPER TROUGH) STILL TO THE EAST OF THE AREA. ALTHOUGH THERE IS NO APPRECIABLE FORCING THIS AFTERNOON...STEEP LOW-LEVEL LAPSE RATES HAVE DEVELOPED (ESPECIALLY DOWNWIND OF THE LAKES)...LEADING TO SOME ENHANCED STRATOCUMULUS DEVELOPMENT. FLURRIES ARE EXPECTED ACROSS THE NORTHERN CWA ON OCCASION THROUGH EVENING...WITH JUST A SLIGHT CHANCE OF A LEGITIMATE SNOW SHOWER. THE DIURNAL CLOUDS ARE EXPECTED TO GRADUALLY DIMINISH HEADING INTO THE OVERNIGHT...AS THE DRY HIGH PRESSURE CENTER MOVES CLOSER TO THE AREA...WITH VERY LIGHT WINDS. HOWEVER...SOME HIGH AND MID LEVEL CLOUDS (POTENTIALLY THICK) WILL BE MOVING IN FROM THE WEST AND SOUTHWEST DURING THE OVERNIGHT HOURS AS WELL. THE TIMING OF THIS PROCESS WILL HAVE AN IMPACT ON THE MIN TEMPS TONIGHT...AS CONDITIONS ARE VERY FAVORABLE FOR SIGNIFICANT DROPS IN TEMPERATURE IF SKIES REMAIN CLEAR. THIS SHOULD HOLD TRUE FOR AT LEAST A WHILE IN ALL BUT THE FAR SOUTHWESTERN CWA...AND MIN TEMPS THROUGH THE CENTRAL PART OF THE FORECAST AREA ARE EXPECTED TO BE IN THE LOW SINGLE DIGITS. SOME OUTLYING LOCATIONS (AS WAS THE CASE LAST NIGHT) MAY END UP WITHIN A DEGREE OR TWO ON EITHER SIDE OF ZERO. THANKFULLY...SINCE WINDS WILL BE VERY LIGHT (AND PERHAPS EVEN COMPLETELY CALM)...WIND CHILLS WILL NOT BE AN ISSUE. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... DURING THE SHORT TERM FORECAST PERIOD...TWO SHORTWAVES WILL BE MOVING THROUGH THE OHIO VALLEY...PRESENTING AN ARRAY OF FORECASTING CONCERNS. IMPACTS FROM THE FIRST SHORTWAVE (SNOW ON SUNDAY / SUNDAY NIGHT) ARE COMING INTO VIEW WITH RESPECTABLE CLARITY...WITH DECENT AGREEMENT BETWEEN MODELS IN THE OVERALL SETUP. CONFIDENCE IS ALSO GROWING THAT IMPACTS FROM THE SECOND SHORTWAVE (LARGELY A RAIN EVENT FOR MONDAY) WILL BE MINOR...EVEN THOUGH THE DETAILS OF THE ACTUAL METEOROLOGICAL FACTORS REMAIN REMARKABLY DISCOMBOBULATED. ON SUNDAY MORNING...SURFACE HIGH PRESSURE WILL BE MOVING TO THE EAST OF THE ILN CWA. THE SHORTWAVE IN QUESTION WILL BE MOVING EASTWARD THROUGH IOWA AT AROUND 12Z. AHEAD OF THE WAVE...SURFACE TO 700MB FLOW WILL TAKE ON A SOUTHERLY COMPONENT...AND ELEVATED WARM FRONTAL PROCESSES WILL BEGIN (WITH NOTABLE CONVERGENCE AND ASCENT AT 850MB). A SWATH OF SNOW (WITH THE FRONT EDGE ORIENTED NW-TO-SE) IS EXPECTED TO DEVELOP AND MOVE INTO THE ILN FORECAST AREA DURING THE LATE MORNING TO EARLY AFTERNOON. IT MAY TAKE SOME TIME FOR THE COLUMN TO SATURATE...WITH QUITE A BIT OF DRY AIR (ESPECIALLY IN THE 5KFT-10KFT LAYER) TO WORK THROUGH. ONCE IT OCCURS...THE FORCING TYPE AND OVERALL SETUP FAVOR A WIDESPREAD LIGHT SNOW FOR THE ENTIRE FORECAST AREA...WITH SOME SLIGHTLY HEAVIER RATES IN THE SOUTHERN THIRD OF THE CWA. TEMPERATURES THROUGH THE LOWEST 10KFT APPEAR LIKELY TO WARM UP JUST ENOUGH TO NOT REALLY SUPPORT ANY SIGNIFICANT DENDRITE DEVELOPMENT...SO SNOW RATIOS MAY NOT END UP BEING AS HIGH AS THE INITIALLY FRIGID TEMPERATURES MIGHT OTHERWISE SUGGEST. NONETHELESS...THE PROLONGED NATURE OF THE SNOW (PERHAPS UP TO 6-8 HOURS OF STEADY LIGHT SNOW) WILL ALLOW FOR A GRADUAL ACCUMULATION...ESPECIALLY IN THE SOUTHERN CWA WHERE DEEP-LAYER MOISTURE WILL REMAIN IN PLACE FOR A LONGER PERIOD OF TIME. TOTAL ACCUMULATIONS OF 2-3 INCHES CAN BE EXPECTED FOR THE FAR SOUTHERN COUNTIES...WITH AROUND 2 INCHES NEAR THE CUTOFF OF THE WINTER WEATHER ADVISORY...AND LESSER AMOUNTS FURTHER TO THE NORTH. THE ADVISORY GOES INTO EFFECT IN TWO SEGMENTS TOMORROW BASED ON TIMING. HOWEVER...THE ENTIRE ADVISORY WILL REMAIN ACTIVE UNTIL MONDAY MORNING...ALLOWING TIME FOR SURFACE TEMPERATURES TO RISE ABOVE FREEZING. THOUGH NOT SPECIFICALLY MENTIONED IN THE WSW PRODUCT...THERE DOES APPEAR TO BE SOME POTENTIAL FOR LIGHT PRECIPITATION TO CONTINUE AFTER THE WAVE HAS MOVED THROUGH...BUT MOISTURE BECOMES EXTREMELY SHALLOW DURING THIS TIME FRAME (EARLY MONDAY MORNING). THUS...FREEZING DRIZZLE COULD BE A POSSIBILITY...WITH GROUND CONDITIONS THAT WILL BE VERY SUSCEPTIVE FOR ICING IF THAT SCENARIO WERE TO OCCUR. THE FORECAST FOR THE SECOND SYSTEM ON MONDAY REMAINS NOTABLY CONVOLUTED...WITH MAJOR DIFFERENCES BETWEEN MODELS IN THE EVOLUTION OF THE NEXT SHORTWAVE...AND THE SURFACE LOW IT HELPS TO DEVELOP. THIS WAVE (OR AT LEAST ITS GENESIS) CAN BE TRACED ALL THE WAY BACK TO THE SOUTHERN BRITISH COLUMBIA COAST THIS EVENING...AN INDICATION THAT IT HAS A LONG WAY TO TRAVEL BEFORE REACHING THE OHIO VALLEY ON MONDAY. THE VAST MAJORITY OF 12Z OPERATIONAL GUIDANCE ALLOWS FOR A SURFACE LOW TO DEVELOP...REMAIN SOMEWHAT WEAK...AND HEAD EAST-NORTHEAST INTO THE MID-ATLANTIC STATES. THE ECMWF HAS REMAINED THE FURTHEST WEST WITH REGARDS TO THE LOW TRACK...AND THE STRONGEST WITH REGARDS TO THE LOW STRENGTH. LOOKING AT ENSEMBLES (GFS/SREF)...EVEN THROUGH AN ARRAY OF PERTURBATIONS...THERE APPEARS TO BE LITTLE SUPPORT FOR THE ECMWF SOLUTION. THE EXPECTED WEAKER LOW TRACK DOES STILL ALLOW FOR ANOTHER INCREASE IN PRECIPITATION CHANCES FOR THE SOUTHEASTERN ILN CWA...AND PERHAPS A SIGNIFICANT INCREASE FOR MONDAY AFTERNOON AND EVENING...WITH GOOD FORCING TO THE NORTH OF THE LOW AND PLENTY OF MOISTURE TO WORK WITH. HOWEVER...THERE IS A HUGE CAVEAT TO ALL OF THE ABOVE...AND THAT IS THE CONTINUED TREND TOWARD A WARMER SOLUTION ACROSS ALL AVAILABLE MODELS SANS THE NAM. THIS MEANS THAT MUCH OF THE PRECIPITATION ON MONDAY...AND IN PARTICULAR ANY POTENTIAL FOR HEAVIER PRECIPITATION...WILL FALL AS A COLD RAIN. SO...DESPITE THE CONTINUED BEFUDDLING MODEL DIFFERENCES IN THE SETUP...A SOMEWHAT-REASONABLE LEVEL OF CONFIDENCE IN THE TEMPERATURE SITUATION DOES PROVIDE FOR A SLIGHTLY BETTER IDEA THAT THIS SECOND SYSTEM WILL PRODUCE LITTLE ADDITIONAL HAZARDOUS WINTER WEATHER IMPACT. THERE REMAINS A POSSIBILITY THAT COOLING TEMPERATURES MONDAY EVENING COULD ALLOW FOR SOME LIGHT SNOW ON THE BACK SIDE OF THE SYSTEM...BUT GIVEN ALL THE OTHER UNCERTAINTIES MENTIONED...IT WOULD BE FOOLISH TO TRY TO MAKE AN ACCUMULATION FORECAST (IF ANY SNOW OCCURS AT ALL) AT THIS POINT IN THE FORECAST PROCESS. TEMPERATURES WERE HAND-EDITED NON-DIURNALLY THROUGH THE ENTIRE FORECAST PERIOD. ALTHOUGH CONDITIONS AT THE SURFACE ON SUNDAY WILL ONLY WARM A LITTLE FROM SATURDAY (DESPITE THE START TO A WARM ADVECTION PATTERN)...A MORE SIGNIFICANT BOUNDARY LAYER WARMING WILL BEGIN ON SUNDAY NIGHT. TEMPERATURES WILL LIKELY BE RISING GOING INTO MONDAY MORNING...AND WILL THEN GO ABOVE FREEZING FOR THE ENTIRE CWA BY EARLY MONDAY AFTERNOON. && .LONG TERM /TUESDAY THROUGH FRIDAY/... A FAST MOVING S/WV IN A NORTHWEST FLOW ALOFT WILL BE RIGHT ON THE HEELS OF DEPARTING SYSTEM MONDAY NIGHT. THIS DISTURBANCE WILL BE ASSOCIATED WITH AN AREA OF SFC LOW PRESSURE. MODELS HAVE THE ENERGY IN DIFFERENT SPOTS WITH THE NAM THE FARTHEST NORTH AND THE ECMWF THE FARTHEST SOUTH. HAVE GONE WITH THE MIDDLE OF THE ROAD GFS. REGARDLESS...ALL SOLUTIONS SUGGEST THAT WAA AHEAD OF THIS SYSTEM SHOULD KEEP PCPN IN THE FORM OF RAIN AS IT MOVES IN ON TUESDAY. HAVE USED LIKELY POPS. TEMPERATURES WILL WARM INTO THE UPPER 30S TO THE LOWER 40S. FOR TUESDAY NIGHT INTO WEDNESDAY...AS THE SYSTEM QUICKLY MOVES EAST...COLDER AIR WILL FILTER INTO THE REGION ON THE BACK SIDE...SO SOME MIX WITH OR A BRIEF CHANGE OVER TO SNOW IS EXPECTED BEFORE TAPERING OFF TOWARD WEDNESDAY MORNING. ANY SNOW ACCUMULATIONS SHOULD BE ACROSS THE FAR NORTH AND MINOR IN NATURE...LESS THAN AN INCH. ON WEDNESDAY...WILL GO WITH A DRY FORECAST...ALTHOUGH CONSIDERABLE CAA STRATOCUMULUS IS EXPECTED. FOR WEDNESDAY NIGHT INTO THURSDAY...HIGH PRESSURE WILL BUILD SOUTH INTO THE OHIO VALLEY. SKIES ARE EXPECTED TO BECOME PARTLY CLOUDY. MODELS DIFFERENT ON THE EXTENT OF COLD AIR FILTERING IN THE REGION...SO HAVE SIDED WITH A WPC BLENDED APPROACH. AS THE HIGH MOVES EAST THURSDAY NIGHT...A WARM FRONT IS FORECAST TO APPROACH FROM THE WEST. WE SHOULD SEE AN INCREASE IN WAA INDUCED CLOUDS. AS OF NOW...ANY PCPN GENERATED WITH THE WARM FRONT IS EXPECTED TO STAY NORTHWEST OF THE AREA. OVERNIGHT LOWS WILL BE EARLY FOLLOWED BY SLOWLY RISING TEMPERATURES AS WINDS INCREASE FROM THE SOUTH. FOR FRIDAY INTO FRIDAY NIGHT...LOW PRESSURE WILL TRAVERSE THE GREAT LAKES AS A COLD FRONT PUSHES IN FROM THE NORTHWEST. MODELS VARY ON HOW MUCH MOISTURE WILL BE PULLED NORTHWARD ALONG AND AHEAD OF THE FRONT SYSTEM...ALONG WITH THE TIMING...SO HAVE GONE WITH A CHANCE OF RAIN. FRIDAY CERTAINLY LOOKS TO BE THE WARMEST DAY OF THE EXTENDED WITH TEMPERATURES RISING INTO THE 50S AREA WIDE. ON SATURDAY...FRONT EXITS TO THE EAST...BUT CAA STRATOCUMULUS MOVES INTO THE REGION. PCPN WILL MOVE EAST AS WELL. TEMPERATURES WILL COOL INTO THE MID 40S TO LOWER 50S FOR HIGHS. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... CU FIELD IS THICKENING OVER THE REGION THIS AFTERNOON BUT WILL REMAIN VFR EVEN IF A BKN DECK PRESENTS ITSELF. WINDS SHIFTING WEST WILL PUSH RELATIVELY WARMER AIR INTO THE OHVLY AND ERODE THE WESTERN EDGE OF THE CU THIS AFTERNOON. BY THE LATE DAY...THE REST OF THE REGION WILL SEE ANY CU DISSIPATE BY NIGHTFALL WITH THE EXCEPTION OF CENTRAL OHIO WHERE KCMH/KLCK MAY HANG ON TO A VFR DECK THROUGH ABOUT 2Z. HIGH CLOUDS WILL STREAM IN OVERNIGHT AS THE SURFACE HIGH MAKES WINDS LIGHT AND VARIABLE AND EVENTUALLY TURN THEM SOUTHEAST BY MORNING. SOUTHEAST WINDS WILL INHIBIT CU FORMATION ON SUNDAY BUT HIGH CLOUDS WILL THICKEN AND LOWER THROUGH THE DAY. KCVG MAY SEE A BEGINNING MVFR SNOW SHOWER FLY BEFORE THE 36 HOUR TAF ENDS. OUTLOOK...MVFR/IFR CONDITIONS ARE POSSIBLE WITH PRECIPITATION FROM SUNDAY THROUGH TUESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...WINTER WEATHER ADVISORY FROM NOON SUNDAY TO 10 AM EST MONDAY FOR OHZ077-078. WINTER WEATHER ADVISORY FROM 5 PM SUNDAY TO 10 AM EST MONDAY FOR OHZ079>082-088. KY...WINTER WEATHER ADVISORY FROM NOON SUNDAY TO 10 AM EST MONDAY FOR KYZ089>098. WINTER WEATHER ADVISORY FROM 5 PM SUNDAY TO 10 AM EST MONDAY FOR KYZ099-100. IN...WINTER WEATHER ADVISORY FROM NOON SUNDAY TO 10 AM EST MONDAY FOR INZ073>075-080. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...HICKMAN AVIATION...FRANKS

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