Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 221057 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 657 AM EDT WED APR 22 2015 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION THIS MORNING...WITH RAIN EXPECTED TO END BY EARLY AFTERNOON. BEHIND THE FRONT...DRIER AND COOLER CONDITIONS ARE EXPECTED THROUGH THE REST OF THE WEEK. ANOTHER AREA OF RAIN WILL MOVE INTO THE OHIO VALLEY FOR SATURDAY...IN ADVANCE OF A LOW PRESSURE SYSTEM MOVING JUST SOUTH OF THE AREA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... TWO ROUGHLY PARALLEL (THOUGH WIDE AND ILL-DEFINED) BANDS OF PRECIPITATION HAVE DEVELOPED DURING THE OVERNIGHT HOURS...BOTH WITH SIGNS OF DIFFERENT TYPES OF FORCING AND DIFFERENT ENVIRONMENTS. ONE BAND SET UP ACROSS THE CENTER OF THE FORECAST AREA...WITH CONVECTIVE UPDRAFTS THAT PRODUCED LIGHTNING. THIS BAND APPEARED TO DEVELOP IMMEDIATELY ON THE WARM SIDE OF THE SLOWLY-PROGRESSING COLD FRONT...WITH SOME WEAK ISENTROPIC ASCENT...AND CONVERGENCE AHEAD OF THE FRONT. HOWEVER...ATTENTION IS NOW TURNING TO A WIDER AREA OF LIGHT RAIN...WHICH IS EXPECTED TO MOVE ACROSS THE NORTHERN TWO-THIRDS OF THE CWA THIS MORNING. THIS AREA APPEARS TO BE FORCED WELL BEHIND THE SURFACE FRONT...WITH SOME DEFORMATION IN THE 700MB-500MB LAYER. POPS ARE HIGHEST IN THE FIRST SIX HOURS OF THE FORECAST...DIMINISHING SIGNIFICANTLY BY AFTERNOON. COLD ADVECTION SHOWERS APPEAR LIKELY TO REMAIN NORTH OF THE FORECAST AREA THIS AFTERNOON...AND CLOUDS WILL LIKELY CLEAR OUT SIGNIFICANTLY IN THE SOUTHWESTERN TWO-THIRDS OF THE CWA IN THE EVENING. WINDS WILL BE GUSTY TODAY...THOUGH NOT NEARLY AS STRONG AS YESTERDAY. THE 00Z KILN SOUNDING FROM LAST EVENING MIXED TO SOMEWHERE AROUND 650MB-600MB...A RARE FEAT THAT WILL NOT BE DUPLICATED TODAY. EVEN STILL...MIXING TO AROUND 800MB WILL PROVIDE OCCASIONAL GUSTS OF UP TO 30 KNOTS. EVEN WITH MIXING EXPECTED TO OCCUR...THE COLD ADVECTION BEHIND THE FRONT WILL LIMIT THE POTENTIAL FOR TEMPERATURE GAINS TODAY...AND A 4-8 DEGREE DROP FROM YESTERDAY IS EXPECTED. THE COLDEST 850MB AIR WILL REMAIN OVER THE GREAT LAKES...WITH A STRONG GRADIENT ACROSS OHIO AND KENTUCKY...RANGING FROM -6C IN THE NORTH TO +2C IN THE SOUTHEAST. MIXING EASILY THROUGH 850MB...THIS SHOULD SUPPORT MAX TEMPS IN THE UPPER 40S TO UPPER 50S. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... A NARROW WEDGE OF SURFACE HIGH PRESSURE WILL EXTEND INTO THE OHIO VALLEY FROM THE NORTHERN MISSISSIPPI VALLEY THROUGH THE NEXT SEVERAL DAYS. THIS WILL KEEP THE ILN FORECAST AREA COMFORTABLY BETWEEN THE DISORGANIZED SOUTHERN STREAM ENERGY TO THE SOUTH...AND THE CLOUDS AND RAIN ASSOCIATED WITH THE LARGE UPPER LOW TO THE NORTHEAST. THUS...THE WEATHER THROUGH THE END OF THE WEEK IS EXPECTED TO BE FAIRLY SUNNY AND DRY (IN TERMS OF BOTH DEWPOINTS AND THE LACK OF PRECIPITATION). WITH THE FROST/FREEZE PROGRAM NOW IN EFFECT FOR OUR ENTIRE FORECAST AREA...THIS WILL PRESENT THE FIRST OPPORTUNITIES TO EXAMINE POSSIBLE HEADLINES FOR THURSDAY MORNING AND FRIDAY MORNING. THURSDAY MORNING DOES NOT LOOK ESPECIALLY FAVORABLE FOR WIDESPREAD FROST. THE COOLEST CONDITIONS ARE EXPECTED IN THE NORTHERN PART OF THE FORECAST AREA...WHERE CLOUDS WILL STILL BE DEPARTING THROUGH THE OVERNIGHT HOURS...AND WINDS ARE EXPECTED TO REMAIN AT ABOUT 5-10 KNOTS. HOWEVER...TEMPERATURES WILL BE QUITE COLD...APPROACHING FREEZING IN THE NORTHERN HALF OF THE FORECAST AREA. NEITHER THE FROST OR FREEZE THREATS ARE YET AT A HIGH ENOUGH CONFIDENCE LEVEL FOR HEADLINE ISSUANCE (AGREED IN COLLABORATION WITH SURROUNDING OFFICES)...BUT FROST WILL BE MENTIONED IN THE HWO AND THE PUBLIC FORECAST. A SIMILAR SCENARIO APPEARS LIKELY FOR FRIDAY MORNING...BUT WITH LIGHTER WINDS THE POTENTIAL MAY END UP BEING SLIGHTLY HIGHER. OTHERWISE...VERY LITTLE IS EXPECTED TO OCCUR THROUGH LATE FRIDAY NIGHT. WITH THE COOLEST 850MB TEMPS OVERHEAD AT 12Z THURSDAY MORNING...THERE A WARMING TREND IS EXPECTED THROUGH THE END OF THE WEEK...WITH DAILY TEMPERATURE GAINS OF A FEW DEGREES ON THURSDAY AND AGAIN ON FRIDAY. ON FRIDAY NIGHT AND INTO SATURDAY...SURFACE LOW PRESSURE WILL BE MOVING EAST OUT OF THE MIDDLE MISSISSIPPI VALLEY...CROSSING THE SOUTHERN OHIO VALLEY AND NORTHERN TENNESSEE VALLEY BY SATURDAY EVENING. AS THIS OCCURS...A WEAKENING / SHEARING SHORTWAVE IN THE WNW 500MB FLOW WILL ALSO BE PASSING INTO THE OHIO VALLEY. ALL OF THIS ADDS UP TO SUPPORT A CHANCE OF RAIN...AND COOLER / WETTER CONDITIONS ON SATURDAY ACROSS THE ILN FORECAST AREA. POPS WERE INCREASED A LITTLE BIT...THANKS TO SOME IMPROVED MODEL AGREEMENT ON TIMING AND PLACEMENT OF THIS SYSTEM. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... ANOTHER DRY PERIOD IS SHAPING UP FOR SUNDAY AND MONDAY WITH THE RETURN OF HIGH PRESSURE. SHOWERS MAY RETURN ON TUESDAY WITH A TROUGH OF LOW PRESSURE...BUT MODEL SOLUTIONS ARE NOT IN GOOD AGREEMENT AND CONFIDENCE IS LOW FOR THIS EVENT. TEMPERATURES MAY STAY BELOW NORMAL THROUGH THE PERIOD. HIGHS ARE FORECAST TO BE IN THE 50S MOST LOCATIONS THURSDAY THROUGH SATURDAY. FROST MAY OCCUR THURSDAY NIGHT WHEN LOWS IN THE 30S ARE EXPECTED. HIGHS IN THE LOW TO MID 60S MAY BE ATTAINED SUNDAY THROUGH TUESDAY. NORMAL HIGHS FOR THIS PERIOD ARE IN THE MID AND UPPER 60S. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... LARGE SCALE UPPER LEVEL LOW CENTERED JUST NORTH OF THE GREAT LAKES THIS MORNING WILL MEANDER SLOWLY SOUTHEAST TOWARD THE ST. LAWRENCE RIVER VALLEY BY THURSDAY MORNING. EMBEDDED DISTURBANCES WILL CONTINUE TO ROTATE AROUND THE SOUTHERN PERIPHERY OF THIS LOW INTO OUR REGION. ONE SUCH DISTURBANCE WILL MOVE THROUGH THIS MORNING. WIDESPREAD RAIN HAS DEVELOPED OVER THE REGION IN RESPONSE TO THIS DISTURBANCE. SATURATION HAS RESULT IN MVFR CEILINGS AND VISIBILITIES. FOR LATER THIS MORNING INTO THIS AFTERNOON...A WEAK SURFACE TROF WILL PASS THROUGH ALONG WITH POST FRONTAL CAA TO BRING CONSIDERABLE POST FRONTAL CUMULUS/STRATOCUMULUS CLOUDS. BASES ARE EXPECTED TO RISE TO VFR AND RANGE BETWEEN 4000 AND 5000 FEET. IT WILL BE GUSTY WITH WEST TO NORTHWEST WINDS GUSTING UP TO 30 KNOTS. FOR TONIGHT...WINDS WILL SUBSIDE WITH DIURNAL COOLING. SURFACE HIGH PRESSURE WILL BEGIN TO WEDGE INTO THE LOWER OHIO VALLEY FROM THE WEST. WE SHOULD SEE A DECREASE IN CLOUD OVER WITH MAINLY RESIDUAL SCT STRATOCUMULUS CLOUDS EXPECTED. OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE SATURDAY INTO SATURDAY NIGHT. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...CONIGLIO AVIATION...HICKMAN

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