Area Forecast Discussion
Issued by NWS Wilmington, OH

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KILN 220211 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 911 PM EST SUN DEC 21 2014 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE MOVING EAST OF THE REGION TONIGHT...AS A TROUGH OF LOW PRESSURE BEGINS TO MOVE INTO THE MISSISSIPPI VALLEY. WITH SOUTHERLY WINDS BEGINNING TO INCREASE...WARMER CONDITIONS ARE EXPECTED THROUGH WEDNESDAY. AS THE TROUGH AND A COLD FRONT MOVE THROUGH THE REGION...CHANCES OF PRECIPITATION WILL INCREASE FOR TUESDAY AND WEDNESDAY...WITH COOLER CONDITIONS FOR THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
-- Changed Discussion --
UPDATES THIS EVENING HAVE CENTERED AROUND LOCALIZED CLEARING AND QUICK POST-SUNSET TEMP DROP WHICH HAVE SOME LOCATIONS ALREADY IN THE MID 20S. THIS WAS WELL DOCUMENTED BY PVS SHIFT IN DISCUSSION BELOW. HAVE CONTINUED TO PLAY FOR TEMPS TO LARGELY STABILIZE THROUGH LATE EVENING ACROSS THE NRN KY/SRN OH BUT CONTINUE TO SLOWLY FALL IN CNTL OHIO. 22.00Z KILN SOUNDING SHOWS WEAK WAA CENTERED AROUND 900MB WHERE WINDS BEGIN TO TURN MORE SOUTHERLY. SATELLITE LOOPS THIS EVENING CAPTURE AN EXPANDING AREA OF STRATUS OVER TN/KY SURGING NWRD. RECENT RAP/HRRR/NAM RUNS EXPAND THIS STRATUS /USING 925MB RH AS PROXY/ NORTH TO THE OHIO RIVER AND INTO SRN OHIO BY SUNRISE ON MONDAY. BUFR SOUNDINGS AT CVG FROM VARIOUS HRRR/RAP/NAM RUNS HAVE SHOWN A PROPENSITY TO SATURATE AMIDST WEAK VERTICAL MOTION...WITH POTENTIAL FOR A PATCH OR TWO OF LIGHT FREEZING RAIN OR RAIN DEPENDING ON BOUNDARY LAYER TEMPS AS THE MOISTURE ARRIVES. INTERESTINGLY...RECENT HRRR SIMULATED REFLECTIVITIES ARE QUITE ROBUST BUT ACCUMULATED PRECIPITATION /QPF/ IS VERY SPARSE IN THE MODEL...SUGGESTING NEAR SFC DRY LAYER /SOUTHEASTERLY FLOW/ MAY BE ENOUGH TO KEEP MUCH FROM HITTING THE GROUND. VERY LOW CONFIDENCE HERE...AND NOT ENOUGH FEEL FOR A HAZ WX THREAT TO PUT IN HAZ WX OUTLOOK RIGHT NOW...BUT DID UPDATE FORECAST TO MENTION SMALL THREAT OF LIGHT FREEZING RAIN IN NRN KY/SERN IND/FAR SRN OH BETWEEN 08Z AND 13Z. GIVEN THE WEAK VERTICAL MOTION...THE MARGINAL SATURATION...AND VERY LIGHT/SCATTERED QPF FOOTPRINT ON RECENT RAP/HRRR/NAM RUNS...DON/T HAVE ENOUGH CONFIDENCE TO HIGHLIGHT IN EITHER AN HWO OR SPECIAL WX STATEMENT. GOING FORECAST ONLY NEEDED MINOR TEMPORAL/SPATIAL TWEAKS TO LATE NIGHT RA/FZRA CHANCES. PREVIOUS DISCUSSION... IT TOOK SOME TIME...BUT THE LOW CLOUDS HAVE ALL ERODED FROM THE ILN FORECAST AREA...UNDER THE INFLUENCE OF WARMING TEMPERATURES (ESPECIALLY AT AROUND 900MB). THE WEATHER PATTERN IS GRADUALLY EVOLVING INTO ONE THAT IS FAVORABLE FOR DEEP SOUTHERLY FLOW...BUT IT WILL STILL BE ANOTHER FORECAST PERIOD OR TWO BEFORE THIS ALIGNMENT IS MAXIMIZED. FOR NOW...THE RIDGING OVER THE MID- ATLANTIC IS RATHER FLAT...AND THE SURFACE HIGH IS STILL CLOSE ENOUGH TO PROVIDE AN EASTERLY COMPONENT TO THE LOW-LEVEL FLOW. AS THE 925MB/850MB GRADIENT BEGINS TO TIGHTEN OVERNIGHT...MOISTURE WILL BEGIN TO BE TRANSPORTED NORTH...EVENTUALLY REACHING THE OHIO VALLEY BEFORE MORNING. UNTIL THEN...IT APPEARS THAT SKIES WILL BE COVERED ONLY IN CIRRUS...LEADING TO SOME FAIRLY FAVORABLE RADIATIONAL COOLING CONDITIONS (AT LEAST DURING THE FIRST HALF OF THE OVERNIGHT PERIOD). TEMPERATURES MAY BEGIN TO WARM SOMEWHAT BEFORE 12Z...ESPECIALLY ONCE THE LOW CLOUDS MOVE IN. RAW MODEL TEMPERATURES ALL INDICATED A SHARP DROP IN TEMPERATURES BETWEEN 21Z AND 03Z...FOLLOWED BY LITTLE CHANGE AFTER THAT.
-- End Changed Discussion --
&& .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... THE CHANGES IN THE WEATHER PATTERN OVER THE OHIO VALLEY WILL BECOME MORE PRONOUNCED ON MONDAY. A SURFACE PRESSURE GRADIENT WILL BEGIN TO INCREASE...BETWEEN A DEVELOPING SURFACE LOW IN WESTERN IOWA AND A DEPARTING SURFACE HIGH OVER THE CANADIAN MARITIME PROVINCES. A LARGE MID-LEVEL TROUGH OVER THE CENTRAL STATES WILL DEVELOP INTO A CLOSED LOW...AND WITH RIDGING OFF THE ATLANTIC COAST...A REGIME OF DEEP SOUTHWESTERLY FLOW WILL SET UP OVER THE OHIO VALLEY. MOISTURE TRANSPORT FROM THE GULF WILL REACH THE ILN FORECAST AREA EARLY MONDAY MORNING...WITH PRECIPITABLE WATER VALUES GRADUALLY INCREASING THROUGH TUESDAY...LEADING THROUGH THE FIRST OF TWO MAIN WAVES OF PRECIPITATION. THE SECOND WAVE ON WEDNESDAY WILL BE COVERED IN THE LONG TERM SECTION OF THE FORECAST DISCUSSION. A WEAK LEAD SHORTWAVE IS FORECAST TO ROTATE NORTHEAST THROUGH THE OHIO VALLEY ON MONDAY MORNING...COMBINING WITH THE FRONT EDGE OF THE NORTHWARD-MOVING MOISTURE. THERE APPEARS TO BE JUST ENOUGH ISENTROPIC LIFT TO SUPPORT SOME WEAK SHOWERS...MAINLY IN THE SOUTHERN AND SOUTHEASTERN PORTIONS OF THE FORECAST AREA...WHERE A 20-POP HAS BEEN USED IN THE FORECAST. HOWEVER...THIS SHORTWAVE WILL BE WEAKENING WITH TIME...AND WIDESPREAD PRECIPITATION IS NOT LIKELY TO OCCUR. AS THIS LIGHT PRECIPITATION MOVES IN...THE REGION WILL BE COMING OUT OF ANOTHER CHILLY MORNING...WITH TEMPERATURES ONLY EXPECTED TO RISE ABOVE FREEZING JUST BEFORE THE PRECIPITATION ARRIVES. A WORST-CASE SCENARIO COULD SUPPORT SOME LIGHT FZRA NEAR THE OHIO RIVER AT AROUND 12Z...BUT IT APPEARS THAT THE PRECIPITATION WILL BE LIGHT/SPARSE ENOUGH (AND TEMPERATURES WARMING JUST SOON ENOUGH) TO MAKE THIS A LOW-PROBABILITY SCENARIO. TEMPERATURES ON MONDAY WILL WARM SIGNIFICANTLY BEYOND VALUES ON SUNDAY...THANKS TO WARM ADVECTION...AND EVEN IN THE ABSENCE OF MUCH INSOLATION. TEMPERATURES ACROSS THE ILN FORECAST AREA SHOULD RANGE FROM THE LOWER-TO- MID 40S IN THE NORTH TO THE LOWER 50S IN THE SOUTH. THESE WARMING TEMPERATURES WILL BE AIDED BY A LACK OF PRECIPITATION...AS THE FORWARD PROGRESSION OF THE DEVELOPING LOW PRESSURE IS NOT PARTICULARLY FAST. CHANCES FOR PRECIPITATION WILL INCREASE AHEAD OF THE PROGRESSION OF THE MID-LEVEL LOW...WHICH WILL BE MOVING NORTHEAST INTO THE GREAT LAKES ON TUESDAY MORNING. AS MOISTURE CONVERGENCE INCREASES OVER THE LOWER OHIO VALLEY...A SWATH OF SHOWERY PRECIPITATION IS EXPECTED TO TRANSLATE NORTHEASTWARD AS WELL. THIS ACTIVITY WILL EVENTUALLY OUTRUN THE SLOWING COLD FRONT...BUT WILL BE AIDED BY FAVORABLE DIFFLUENT FLOW AHEAD OF THE APPROACHING UPPER JET STREAK. WHILE THE GREATEST CHANCES FOR PRECIPITATION (AND GREATEST MODEL OUTPUT QPF) APPEAR TO BE IN THE NORTHWESTERN CWA...THE FOCUS FOR ANY POTENTIAL FOR THUNDER WILL BE IN THE NORTHERN KENTUCKY AND SOUTH CENTRAL OHIO. SURFACE-BASED INSTABILITY WILL BE VERY UNLIKELY...WITH SOME LEVEL OF INVERSION STILL REMAINING IN PLACE...AS ALSO EVIDENCED BY THE SLIGHTLY DECOUPLED WIND DIRECTIONS BETWEEN THE SURFACE AND 850MB. HOWEVER...850MB PARCELS WILL HAVE A ROUGHLY MOIST-ADIABATIC PROFILE ABOVE THEM...WITH 15Z SPC SREF PARAMETERS INDICATING AT LEAST A CHANCE OF EQUILIBRIUM LEVELS COLD ENOUGH TO SUPPORT SOME WEAK CONVECTION. THUS...A BRIEF PERIOD WITH A SLIGHT CHANCE OF THUNDER WAS INCLUDED THURSDAY MORNING AND AFTERNOON IN THE SOUTHERN/SOUTHEASTERN PORTIONS OF THE FORECAST AREA. POPS WILL DECREASE ON TUESDAY EVENING AS THE MID-LEVEL WAVE MOVES OFF...AND UPPER SUPPORT IS LOST. CHANCES WILL INCREASE AGAIN EARLY WEDNESDAY MORNING...AS LOW-LEVEL FORCING AND CONVERGENCE BEGINS TO INCREASE AHEAD OF A DEVELOPING SURFACE LOW. THROUGHOUT THIS PERIOD...TEMPERATURES WILL BE DOMINATED BY ADVECTION...WITH NON-DIURNAL CURVES REQUIRED FOR THE FORECAST GRIDS. HIGHS ON TUESDAY SHOULD RANGE FROM THE LOWER 50S TO UPPER 50S FROM NORTH TO SOUTH...WITH LITTLE CHANGE IN TEMPERATURE EXPECTED TUESDAY NIGHT. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... LOW PRESSURE WILL DEEPEN ALONG A COLD FRONT AT THE BEGINNING OF THE LONG TERM PERIOD. GFS/CMC ARE SIMILAR IN THE INTENSIFYING PROCESS AS THE LOW MOVES NORTHEAST FROM THE MIDDLE OHIO VALLEY TO SOUTHEAST ONTARIO INTO WEDNESDAY NIGHT. THE ECMWF IS A LITTLE STRONGER AND THE NAM IS A WEAK OUTLIER. HAVE TAKEN A BLEND OF THE GFS/CMC. AS THE DEEPENING PROCESS OCCURS...WIDESPREAD SHOWERS ARE EXPECTED WEDNESDAY MORNING. BY WEDNESDAY AFTERNOON...THE COLD FRONT WILL PUSH NORTHEAST THROUGH THE REGION. THE COVERAGE OF PCPN WILL DECREASE BEHIND FRONTAL PASSAGE AS DRIER SLOT OF AIR ALOFT MOVES IN BRIEFLY. BY WEDNESDAY NIGHT...SOME WRAP AROUND MOISTURE WILL OCCUR...BUT COVERAGE LOOKS TO BE CHANCE AT BEST. IT WILL BE WARM AHEAD OF THE FRONT WITH TEMPERATURES DROPPING WEDNESDAY AFTERNOON INTO THE NIGHT. HIGHS ON WEDNESDAY WILL RANGE FROM THE 50S TO NEAR 60 WITH LOWS BOTTOMING OUT INTO THE LOWER AND MID 30S BY CHRISTMAS MORNING. IT SHOULD BECOME COLD ENOUGH FOR A CHANCE OF RAIN/SNOW SHOWERS AND THEN A CHANCE OF SNOW SHOWERS CHRISTMAS EVE NIGHT. HOWEVER...LITTLE IS EXPECTED IN THE WAY OF ACCUMULATIONS GIVEN RECENT WARM TEMPERATURES AND NO REAL FOCUS/FORCING FOR APPRECIABLE SNOWFALL RATES. IT WILL BECOME BRISK TO LOCALLY WINDY DURING THE PERIOD...BUT WINDS ARE EXPECTED TO STAY BELOW ADVISORY CRITERIA ATTM. ON CHRISTMAS DAY...DEEPENING LOW PRESSURE WILL CONTINUE TO MOVE NORTHEAST AWAY FROM THE REGION. ANY THREAT FOR SNOW SHOWERS WILL QUICKLY COME TO AN END DURING CHRISTMAS MORNING. BY AFTERNOON...SKIES SHOULD BECOME PARTLY CLOUDY AS SURFACE RIDGING QUICKLY BUILDS INTO THE AREA BEHIND DEPARTING SYSTEM. HIGHS ON CHRISTMAS WILL RANGE FROM THE UPPER 30S TO THE LOWER 40S...NEAR SEASONAL NORMALS. FOR THURSDAY NIGHT...SURFACE RIDGE WILL MOVE EAST WITH RETURN SOUTHWEST FLOW ENSUING ALONG WITH INCREASING CLOUDS AHEAD OF THE NEXT SYSTEM. FOR FRIDAY INTO SATURDAY...LOW PRESSURE AND A COLD FRONT WILL MOVE ACROSS THE GREAT LAKES AND OHIO VALLEY. SYSTEM APPEARS TO BE MOISTURE STARVED SO WILL CONTINUE WITH LOW CHANCE POPS. WE SHOULD SEE A WARM UP ON FRIDAY FOLLOWED BY A COOL DOWN SATURDAY IN THE WAKE OF THE SYSTEM. BY SUNDAY...HIGH PRESSURE AND MUCH COLDER TEMPERATURES ARE EXPECTED. HIGHS BY THEN WILL RANGE FROM THE UPPER 20S TO THE LOWER 30S. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... THE EVENING KILN RAOB CONFIRMS SOME DRIER AIR IN THE LOW LEVELS OF THE ATMOSPHERE. OUR AREA WILL REMAIN UNDER BROKEN CIRRUS FOR THE BULK OF THE OVERNIGHT HOURS. AS SURFACE HIGH PRESSURE DRIFTS FURTHER EAST OF THE AREA...SOUTHERLY LOW LEVEL FLOW WILL DRAW INCREASING MOISTURE UP FROM THE SOUTH LATE TONIGHT INTO MONDAY MORNING. LATEST SATELLITE IMAGERY REVEALS LOW LEVEL CLOUDS ALREADY WORKING THEIR WAY FROM TENNESSEE INTO SOUTHERN KENTUCKY. EXPECT AN MVFR CLOUD DECK TO MOVE IN FROM SOUTH TO NORTH OVER THE TERMINALS AROUND 10Z TO 13Z MONDAY. ALONG WITH THIS INCREASE IN LOW LEVEL MOISTURE AND A WEAK UPPER DISTURBANCE WILL COME THE CHANCE FOR PERHAPS SOME ISOLATED RAIN SHOWERS IN THE MORNING. LATEST HI-RES MODELS ARE NOT OVERLY EXCITED ABOUT THIS POSSIBILITY BUT THEY DO HINT AT IT. THUS...WENT WITH VCSH FOR NOW. IF THE RAIN DOES MATERIALIZE...CANNOT RULE OUT PERHAPS A BRIEF PERIOD OF VERY LIGHT FZRA AT THE CINCINNATI TERMINALS BEFORE 12Z WITH SURFACE TEMPERATURES EXPECTED TO BE RIGHT AROUND FREEZING. THE MVFR CLOUD DECK SHOULD MIX OUT A BIT IN THE AFTERNOON...THEN REDEVELOP BY THE END OF THE KCVG TAF PERIOD WITH A CHANCE OF SHOWERS AS THE NEXT STORM SYSTEM APPROACHES FROM THE WEST. WINDS WILL REMAIN LIGHT OUT OF THE SOUTHEAST TONIGHT...PICKING UP TOWARDS THE END OF THE TAF PERIOD. OUTLOOK...MVFR TO IFR CIGS AND VSBYS ARE POSSIBLE MONDAY NIGHT INTO THURSDAY. WINDS WILL PICK UP SIGNIFICANTLY STARTING WEDNESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...BINAU SHORT TERM...HATZOS LONG TERM...HICKMAN AVIATION...KURZ

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.