817  
FXUS61 KCLE 171711  
AFDCLE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CLEVELAND OH  
1211 PM EST SUN DEC 17 2017  
   
SYNOPSIS
 
 
A WEAK LOW MOVING NORTHEAST INTO LOWER MICHIGAN TONIGHT WILL PULL A  
WARM FRONT NEAR THE SOUTH SHORE OF LAKE ERIE NORTH INTO CANADA. A  
COLD FRONT WILL MOVE EAST ACROSS THE REGION TUESDAY THEN HIGH  
PRESSURE WILL SPREAD SOUTHEAST FROM CENTRAL CANADA INTO THE AREA BY  
LATE WEDNESDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
NO SIGNIFICANT CHANGES TO FORECAST FOR 1230 UPDATE. TWEAKED  
TEMPS UP ANOTHER COUPLE OF DEGREES SOUTH OF WARM FRONT.  
 
ORIGINAL DISCUSSION...  
AREAS OF STRATUS AND FOG WILL BE PRESENT FOR A WHILE THIS  
MORNING UNTIL DAYTIME HEATING AND INCREASED WINDS DISSIPATE THE  
FOG BY LATE MORNING. SOME OF THE FOG MAY BE LOCALLY DENSE.  
FREEZING TEMPS EARLY WILL ALLOW FOR ICY SPOTS ON ROADWAYS THAT  
ARE WET.  
 
A SERIES OF WEAK UPPER AND SURFACE LOWS WILL QUICKLY MOVE EAST  
ACROSS THE REGION LATER TODAY/EARLY TONIGHT AND ON MONDAY. MOISTURE  
WITH THESE SYSTEMS IS MARGINAL SO ONLY EXPECTING AREAS OF LIGHT  
PRECIP AND THE MODELS CONTINUE TO DIFFER ON WHERE THE BETTER CHC FOR  
THE PRECIP WILL BE.  
 
TEMPS ARE EXPECTED TO WARM JUST ENOUGH FOR MOST OF THE PRECIP TO BE  
RAIN BUT A LITTLE WET SNOW COULD MIX IN, ESPECIALLY AROUND THE  
HIGHER TERRAIN OF NW PA. MOST OF THE AREA SHOULD SEE LOWS TONIGHT  
STAY ABOVE FREEZING BUT SOME OF THE NORMALLY COLDER LOCATIONS SUCH  
AS BJJ AND INLAND NW PA COULD SEE 32 OR 31 WHICH MAY PRODUCE SOME  
ICY SPOTS BY THE END OF THE NIGHT. HIGHS TODAY SHOULD MAINLY BE 35  
TO 40 THEN A COUPLE DEGREES WARMER ON MONDAY.  
 

 
   
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
 
 
THE SHORT TERM FORECAST BEGINS ON MONDAY NIGHT WITH MOSTLY ZONAL  
FLOW IN PLACE, AS THE FORECAST AREA FINDS ITSELF BETWEEN TWO SYSTEMS  
WITH LOW PRESSURE OFF TO THE NORTH AND HIGH PRESSURE OFF TO THE  
SOUTH. THE FORECAST FOR THIS PERIOD HAS CONSISTENTLY HAD A SLIGHT  
CHANCE TO LOW CHANCE POP, AS THE GUIDANCE SHOWS A PIECE OF ENERGY  
STREAMING THROUGH THE REGION. IN ADDITION, THERE IS AMPLE MOISTURE  
AS LOW-LEVEL WINDS FROM THE SOUTH WILL POOL SOME MOISTURE IN WITH  
DEW POINTS IN THE UPPER 30S. HOWEVER, CONFIDENCE IN WIDESPREAD  
PRECIPITATION OCCURRING DURING THIS PERIOD IS NOT VERY HIGH WITH THE  
ZONAL FLOW ALOFT AND LACK OF A FORCING MECHANISM SO WILL LEAVE MUCH  
OF MONDAY NIGHT INTO EARLY TUESDAY UNCHANGED FOR NOW. TEMPERATURES  
WILL BE WELL ABOVE NORMAL FOR MONDAY NIGHT AND TUESDAY  
 
FOR TUESDAY AFTERNOON AND BEYOND, THE AFOREMENTIONED LOW PRESSURE TO  
THE NORTH WILL EXTEND A COLD FRONT ACROSS THE AREA DURING THE LATTER  
HALF OF TUESDAY. RAIN WILL CHANGE OVER TO SNOW AS TEMPERATURES DROP  
BACK DOWN BELOW FREEZING ON TUESDAY NIGHT. THE WINDS WILL SHIFT  
AROUND TO THE WEST AND ALLOW FOR LAKE-EFFECT CONDITIONS IN THE SNOW  
BELT REGION. THE CONDITIONS FOR SOME LAKE-EFFECT LOOK A BIT BETTER  
FOR TUESDAY NIGHT THAN THEY DID DURING THE FORECAST PACKAGE  
YESTERDAY MORNING. HOWEVER, DRY AIR WILL QUICKLY MOVE INTO THE AREA  
ON WEDNESDAY AND SHUT DOWN THE LAKE-EFFECT BEFORE ANYTHING HEADLINE  
WORTHY OCCURS. HIGH PRESSURE WILL MOVE IN AT THE SURFACE FOR  
WEDNESDAY AND WILL ALLOW FOR SEASONABLE DRY DAY ACROSS THE REGION.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SATURDAY/
 
 
THE LONG TERM BEGINS ON THURSDAY WITH HIGH PRESSURE SLIDING OFF TO  
THE EAST. COMPARED TO YESTERDAY'S MODEL RUNS, THE NEXT SYSTEM THAT  
WILL APPROACH THE AREA FOR THE END OF THE WEEK HAS SLOWED  
SIGNIFICANTLY. THE SYSTEM LIKELY WON'T REACH THE AREA UNTIL THE  
SECOND HALF OF FRIDAY WITH THE REGION IN THE WARM SECTOR FOR THE  
ENTIRETY OF THURSDAY AND THE FIRST HALF OF FRIDAY. THEREFORE, HAVE  
BUMPED UP TEMPERATURES FOR THE FIRST HALF OF THE LONG TERM AND HELD  
OFF PRECIPITATION UNTIL AFTER 12Z FRIDAY.  
 
LOW PRESSURE WILL MOVE THROUGH FRIDAY NIGHT AND SATURDAY WITH THE  
COLD FRONT CLEARING THE AREA SOMETIME SATURDAY EARLY AFTERNOON.  
WHILE THERE IS SOME UNCERTAINTY ON THE ONSET OF THE PRECIPITATION  
FOR THE END OF THE WEEK, THERE HAS BEEN MUCH CONSISTENCY IN FRIDAY  
NIGHT AND SATURDAY BEING A WET PERIOD SO HAVE LIKELY POPS THROUGH  
THOSE TIME PERIODS. PRECIPITATION WILL BEGIN AS RAIN AND THEN CHANCE  
OVER TO SNOW HAS THE LOW AND COLD FRONT MOVE THROUGH AND  
TEMPERATURES DROP BELOW FREEZING. WESTERLY FLOW OVER LAKE ERIE WILL  
THEN ALLOW FOR LAKE-EFFECT TO SET UP OVER THE SNOW BELT FOR SATURDAY  
NIGHT.  
 

 
   
AVIATION /18Z SUNDAY THROUGH FRIDAY/
 
 
SOME LIGHT RAIN MOVING UP FROM THE OHIO VALLEY AS LOW PRESSURE  
OVER IOWA DRIFT NORTH. EXPECT IFR CIGS/VIS TO DEVELOP LATE  
TONIGHT AS BOUNDARY SAGS OVER THE FORECAST AREA.  
 
OUTLOOK...NON-VFR EXPECTED MONDAY IN -RA/DZ. NON-VFR ALSO  
POSSIBLE NORTHEAST OH AND NORTHWEST PA LATER TUESDAY INTO  
WEDNESDAY.  
 

 
   
MARINE
 
 
HIGH PRESSURE OFF TO THE NORTH ARE ALLOWING FOR MOSTLY LIGHT  
EASTERLY WINDS FOR TODAY. WINDS WILL REMAIN RATHER LIGHT BUT WILL  
FLIP AROUND TO THE SOUTH SUNDAY NIGHT INTO MONDAY AS LOW PRESSURE  
MOVES NORTHWEST OF THE AREA FOR MONDAY. THE LOW WILL INCREASE THE  
PRESSURE GRADIENT OVER THE LAKE AND WINDS WILL INCREASE TO 10 TO 20  
KNOTS. ON MONDAY NIGHT, THE LOW MOVES OFF TO THE NORTHEAST AND A  
COLD FRONT APPROACHES THE AREA. WINDS WILL INCREASE TO 25 KNOTS AND  
WINDS WILL SHIFT SLIGHTLY TO THE WEST AS THE FRONT APPROACHES CLOSER  
FOR TUESDAY. A SMALL CRAFT ADVISORY WILL BE LIKELY FROM MONDAY NIGHT  
THROUGH WEDNESDAY WITH STRONG SOUTHWEST WINDS AND WAVES BUILDING TO  
3 TO 6 FEET OR HIGHER THROUGH THAT PERIOD. HIGH PRESSURE BUILDING TO  
THE SOUTH ON THURSDAY WILL EASE THE WINDS OVER THE LAKE AND SHIFT  
WINDS AROUND TO THE SOUTH FOR THE END OF THE WEEK.  
 

 
   
CLE WATCHES/WARNINGS/ADVISORIES
 
 
OH...NONE.  
PA...NONE.  
MARINE...NONE.  
 

 
 

 
SYNOPSIS...ADAMS/DJB  
NEAR TERM...ADAMS  
SHORT TERM...SEFCOVIC  
LONG TERM...SEFCOVIC  
AVIATION...DJB  
MARINE...SEFCOVIC  
 
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