500  
FXUS61 KILN 171505  
AFDILN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON OH  
1005 AM EST SUN DEC 17 2017  
   
SYNOPSIS
 
 
WEAK WEATHER DISTURBANCES CROSSING THE OHIO VALLEY TODAY AND  
TOMORROW WILL BRING CLOUDS AND A LITTLE RAIN OR DRIZZLE TO MUCH  
OF THE AREA AS TEMPERATURES REMAIN MILD IN THE 40S. WHILE CLOUDS  
WILL LIKELY HANG ON INTO TUESDAY, TEMPERATURES WILL WARM INTO  
THE 50S AHEAD OF THE NEXT WEAK COLD FRONT WHICH WILL SLIP  
THROUGH THE AREA RATHER QUIETLY ON TUESDAY EVENING. THIS FRONT  
WILL BRING COOLER TEMPERATURES AND A LITTLE SUNSHINE FOR  
WEDNESDAY.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
WATER VAPOR SATELLITE IMAGERY SHOWS SHORTWAVE OVER MID MS VLY  
THIS MORNING. THIS S/W WILL EJECT NORTHEAST AND RUN INTO THE  
MEAN RIDGE POSITION OVER THE REGION AND DEAMPLIFY AND SHEAR OUT.  
FORCING WILL BE WEAK AND AIRMASS IS STARTING OUT RATHER DRY.  
EXPECT TO SEE A GOOD DEAL OF VIRGA ON THE RADAR WITH A LIGHT  
RAIN EVENT DEVELOPING THIS AFTERNOON. WILL CONTINUE TO HAVE POPS  
RAMP UP TO LIKELY WHERE BAND OF LIGHT RAIN IS EXPECTED TO  
DEVELOP GENERALLY ALONG AND SOUTH OF THE I-70, ONCE THE COLUMN  
SATURATES LATER THIS AFTERNOON. HAVE USED A BLENDED APPROACH FOR  
TEMPERATURES WITH MAV GUIDANCE APPEARING TOO HIGH GIVEN LIGHT  
RAIN AND CLOUDS. GENERALLY EXPECT HIGHS OF 40 TO 45 DEGREES  
TODAY.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/
 
 
WAVE DEPARTS THIS EVENING WITH SCATTERED LIGHT RAIN QUICKLY  
ENDING BUT CLOUDS CONTINUING TO THICKEN/LOWER AS WEAK WARM  
ADVECTION ON SWLY BOUNDARY LAYER FLOW CONTINUES IN THE WAKE OF  
THE WAVE. IN FACT, FORECAST SOUNDINGS SUGGEST LOW LEVEL MOISTURE  
WILL CONTINUE TO DEEPEN PAST 2KM THIS EVENING AS NEXT SUBTLE  
RIPPLE IN MIDLEVEL HEIGHT FIELD APPROACHES. COMBINATION OF WEAK  
VERTICAL MOTION IN/ABOVE THIS DEEPER LOW LEVEL MOISTURE FIELD  
WILL INDUCE PATCHES/AREAS OF DRIZZLE AND FOG, PARTICULARLY LATER  
TONIGHT INTO MUCH OF MONDAY. INTRODUCED A POP FOR MEASURABLE  
DRIZZLE OR EVEN VERY FINE/LIGHT RAIN GIVEN MAINTENANCE OF LOW  
LEVEL MOISTURE FIELD IN EXCESS OF 1.5KM INTO MONDAY EVENING.  
WITH SATURATED SURFACE TEMP/DEWPOINT TRACES, THINK THE TEMP  
CURVES WILL BE MUTED ON BOTH MONDAY AFTERNOON AND MONDAY NIGHT,  
SO TIGHTENED THOSE UP CONSIDERABLY. MONDAY NIGHT MAY NOT SEE ANY  
FALL, AND DESPITE CURRENT FORECAST INDICATING STEADY TEMPS  
OVERNIGHT OR PERHAPS DROPPING A DEGREE, WOULD NOT BE AT ALL  
SURPRISED IF TEMPS MONDAY NIGHT ACTUALLY WENT UP A DEGREE OR TWO  
GIVEN MOST RECENT DATA TRENDS. BOTTOM LINE - THE MONDAY AND  
MONDAY NIGHT PERIODS WILL SEE PLENTY OF STRATUS, LIGHT FOG, AND  
PATCHES/AREAS OF DRIZZLE - MOST OF WHICH WILL DIMINISH WITH TIME  
THROUGH MONDAY NIGHT.  
 
ON TUESDAY, HEIGHT FALLS DROPPING THROUGH THE NORTHERN GREAT  
LAKES WILL ALLOW A WEAK COLD FRONT TO SLIP TOWARD THE AREA.  
CONTINUED SOUTHWESTERLY LOW LEVEL FLOW WILL ALLOW TEMPERATURES  
TO RESPOND INTO THE 50S, PARTICULARLY WITH A FEW BREAKS OF  
SUNSHINE POSSIBLE ON TUESDAY AFTERNOON, THOUGH STILL EXPECT  
MOSTLY CLOUDY SKIES WITH ANY BREAKS CONFINED TO THE LATER PART  
OF THE AFTERNOON. FRONT SLIPS THROUGH QUIETLY /DRY/ ON TUESDAY  
EVENING WITH MODEST LOW-LEVEL COLD ADVECTION SIGNAL AND TEMPS  
BACK BELOW FREEZING TUESDAY NIGHT.  
 
WEDNESDAY WILL FEATURE HIGH PRESSURE MOVING DIRECTLY OVER THE  
AREA WITH GOOD SUBSIDENCE/DRYING WHICH SHOULD ALLOW FOR MORE  
SUNSHINE ALTHOUGH IT WILL BE COOLER, WITH HIGHS BACK IN THE  
LOWER 40S.  
 
WILL NEED TO WATCH SOUTHERN STREAM SHORTWAVE TROUGH/SURFACE LOW  
COMING OUT OF THE SOUTHERN BRANCH OF THE WESTERN CONUS SPLIT  
FLOW REGIME. BULK OF DETERMINISTIC/ENSEMBLE DATA HAS TAKEN THIS  
SYSTEM AND ITS RAIN SHIELD SOUTH OF THE AREA, THOUGH ENOUGH  
MEMBERS GRAZING NRN KY WITH A BIT OF LIGHT RAIN TO KEEP AN EYE  
ON THIS SYSTEM INTO MID-WEEK.  
 

 
   
LONG TERM /THURSDAY THROUGH SATURDAY/
 
 
WHILE THURSDAY IS A RELATIVELY HIGH CONFIDENCE DRY FORECAST AS  
HIGH PRESSURE PULLS AWAY INTO NEW ENGLAND AND A LARGE UPPER  
TROUGH ADVANCES EASTWARD FROM THE CENTRAL PLAINS, CONFIDENCE IN  
THIS PORTION OF THE FORECAST DEGRADES VERY QUICKLY. GEFS/EPS  
PLUMES CONTINUE TO INDICATE A TREMENDOUS AMOUNT OF SPREAD IN THE  
DETAILS DESPITE A SLOWLY INCREASING SIGNAL OF A COLD FRONT/LOW  
PRESSURE SHIFTING THROUGH THE GREAT LAKES FRIDAY AFTERNOON  
THROUGH SATURDAY MORNING.  
 
THERE'S A GREAT DEAL OF VARIETY IN THE TIMING OF THE FRONT,  
ORIENTATION OF THE BOUNDARY, AND WHETHER A FRONTAL WAVE WILL  
FORM ON THE BOUNDARY OR A DOMINANT SURFACE LOW WILL DEEPEN  
THROUGH THE GREAT LAKES AND SWING THE COLD FRONT THROUGH WITH  
MUCH MORE BRUTE FORCE. THERE'S SOLUTIONS RANGING FROM A VERY  
POTENT SURFACE LOW DEVELOPING THROUGH WI/MI WHICH ALLOWS HIGHS  
ON FRIDAY WELL INTO THE 50S WITH NEARLY SIMILAR DEWPOINTS, AND  
THEN A STRONG FRONTAL SURGE WITH HINTS OF CAPE AND NEED FOR  
THUNDER CONSIDERATION. OTHER SOLUTIONS CONTINUE TO BE SEEN OF A  
MUCH SLOWER/STRUNG OUT FRONTAL PASSING THAT TAKES FAR LONGER AND  
ENTRAINS VERY DEEP MOISTURE FROM THE GULF OF MEXICO, AND HINTS  
AT A HEAVY RAIN/FLOODING THREAT FRIDAY NIGHT INTO SATURDAY.  
STILL FURTHER, THERE HAVE BEEN MEMBERS/RUNS SHOWING A RAIN-TO-  
WET SNOW SCENARIO FOR FRIDAY NIGHT/SATURDAY MORNING, OR A BAND  
OF RAIN PASSING QUIETLY THROUGH AND THEN THE FRONT CLEARING FOR  
A QUIET/DRY SATURDAY. JUST NOT SEEING ANY ENSEMBLE MOVEMENT TO  
A PREFERRED SOLUTION, SO WILL HIT RAIN CHANCES HIGHEST ON FRIDAY  
NIGHT, WITH A TREND TO COOLER TEMPERATURES FOR SATURDAY AND  
PERHAPS SOME RAIN/SNOW MIX OR BRIEF WET SNOW. GIVEN ENSEMBLE  
SPREAD THAT EXCEEDS THE NATURAL VARIABILITY, CONTINUE TO EXPECT  
A VERY LOW CONFIDENCE FORECAST IN THIS TIME PERIOD FOR A FEW  
MORE DAYS.  
 

 
   
AVIATION /15Z SUNDAY THROUGH THURSDAY/
 
 
WARM FRONTAL PROCESSES NORTH OF THE AREA WILL HELP USHER IN  
MORE MOIST AIR ON SOUTHERLY WINDS TODAY. A MID LEVEL SHORTWAVE  
WILL ENTER THIS AFTERNOON AND FLATTEN OUT THE WEAK H5 RIDGE THAT  
IS CURRENTLY IN PLACE OVER THE OHIO VALLEY. AS IT SHEARS OUT  
CROSSING OHIO, A FEW SHOWERS OR AREA OF LIGHT RAIN IS EXPECTED  
TO AFFECT THE REGION. MODELS CONTINUE TO INDICATE A WSW-ENE  
ORIENTATION OF THE BAND OF RAIN, WHICH WOULD HIT DAYTON AND THEN  
COLUMBUS AREAS WITH A HIGHER POTENTIAL FOR RAIN FOR A FEW HOURS  
THIS AFTERNOON. HRRR AND NAM12 ARE SHOWING ANOTHER SOUTHERN  
MAXIMA TO THE RAIN TODAY, SO HAVE INCLUDED SOME SHOWERS WITH  
MVFR CIGS AND VFR VSBYS AT JUST ABOUT EVERYWHERE WITH A SLIGHTLY  
PESSIMISTIC FORECAST WITH LOWER VSBYS FROM DAY TO CMH  
 
THIS H5 SHORTWAVE MOVES EAST OF THE REGION TONIGHT AND WITH IT  
THE THREAT FOR RAIN IS REMOVED. INCREASING MOISTURE IN THE LOWER  
LEVELS WILL BE FOUND IN THE REGION OVERNIGHT, AND AN AREA OF  
ENHANCED UPWARD MOTION MAY INITIATE SOME PATCHY DRIZZLE OR A FEW  
SPRINKLES LATE OVERNIGHT OR EARLY MONDAY MORNING. THE SPRINKLES  
AND/OR DRIZZLE DOES NOT HAVE A FEATURE TO KEY OFF OF, AND THE  
H7 UPWARD MOTION FIELDS ARE AS SPLOTCHY IN COVERAGE AS THE QPF  
FIELDS BEING GENERATED BY THE NAM12. THE BETTER THREAT OF ANY  
DRIZZLE OR SPRINKLES WILL OCCUR TOWARDS 12Z MONDAY.  
 
MODELS CONTINUE TO SHOW SATURATION OF THE LOW LEVELS OVERNIGHT  
SO CEILINGS SHOULD LOWER OVERNIGHT AND TREND TOWARD IFR CATEGORY.  
HAVE KEPT VSBYS VFR FOR THE OVERNIGHT HOURS GIVEN THE LATEST  
GUIDANCE IS HOLDING THE ONSET OF ANY PRECIP UNTIL AFTER 12Z.  
 
OUTLOOK...IFR/LIFR CEILINGS AND MVFR/IFR VISIBILITIES CONTINUING  
INTO MONDAY. MVFR/IFR CEILINGS AND MVFR VISIBILITIES POSSIBLE  
MONDAY NIGHT INTO TUESDAY MORNING.  
 

 
   
ILN WATCHES/WARNINGS/ADVISORIES
 
 
OH...NONE.  
KY...NONE.  
IN...NONE.  
 

 
 

 
SYNOPSIS...BINAU  
NEAR TERM...BINAU/AR  
SHORT TERM...BINAU  
LONG TERM...BINAU  
AVIATION...FRANKS  
 
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