816  
FXUS61 KCLE 212247 CCA  
AFDCLE  
 
AREA FORECAST DISCUSSION...CORRECTED  
NATIONAL WEATHER SERVICE CLEVELAND OH  
647 PM EDT SAT OCT 21 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE OVER THE EAST COAST WILL START TO MOVE EAST BY MONDAY  
TO ALLOW A SERIES OF COLD FRONTS TO PUSH EAST ACROSS THE REGION  
MONDAY NIGHT INTO WEDNESDAY. HIGH PRESSURE WILL BRIEFLY BE OVER THE  
AREA THURSDAY BEFORE A LOW TRACKS NORTHEAST INTO THE GREAT LAKES  
FRIDAY AND SATURDAY.  
 

 
   
NEAR TERM /THROUGH SUNDAY NIGHT/
 
 
MADE SOME MINOR CHANGES TO CLOUD COVER AND HOURLY TEMPERATURES  
THROUGH THE OVERNIGHT. MAIN CHANGE WAS TO NUDGE LOWS DOWN  
SLIGHTLY IN THE TYPICALLY COOLER LOCATIONS.  
 
PREVIOUS DISCUSSION...  
THE INFLUENCE OF HIGH PRESSURE TO THE EAST SHOULD KEEP THE  
LOWER LEVELS OF THE AIRMASS DRY ENOUGH TO PREVENT ANY RAIN THRU  
SUNDAY AND MAYBE EVEN SUNDAY NIGHT. AS THE UPPER TROUGH MOVES  
CLOSER SUN NIGHT AND LOWER LEVELS START TO MOISTEN, SCT SHRA  
SHOULD START TO PUSH OUT OF INDIANA INTO WESTERN OH BUT MAY NOT  
MAKE IT AS FAR EAST AS THE I75 CORRIDOR. A SSW FLOW AT UPPER  
LEVELS WILL CONTINUE TO SUPPLY ABUNDANT CIRRUS FOR THE AREA  
TONIGHT THRU SUN.  
 
TEMPS WILL STAY WELL ABOVE NORMAL SO ENJOY IT AS MAJOR CHANGES ARE  
ON THE WAY NEXT WEEK.  
 

 
   
SHORT TERM /MONDAY THROUGH WEDNESDAY/
 
 
UPPER LEVEL TROUGH OVER THE ROCKIES IS FORECAST TO CLOSE OFF  
OVER THE MID- MISSISSIPPI VALLEY BY MONDAY. AT THE SURFACE, LOW  
PRESSURE WILL UNDERGO CONSIDERABLE DEEPENING AS IT MOVES  
NORTHEAST ACROSS THE CENTRAL GREAT LAKES. MOISTURE FROM THE GULF  
OF MEXICO WILL BE TRANSPORTED NORTH AHEAD OF THE TROUGH. THE  
ARRIVAL OF THE DEEP MOISTURE COMBINED WITH STRONG DYNAMICS  
PROVIDES HIGH CONFIDENCE IN A WET FORECAST ON MONDAY AFTERNOON  
INTO MONDAY NIGHT. MODELS HAVE SPED UP THE TIMING OF THIS SYSTEM  
AND HAVE RAISED POPS IN MOST AREAS TO 90 OR 100 PERCENT  
SOMETIME IN THAT WINDOW. MOST AREAS WILL SEE OVER AN INCH OF  
RAIN AND CAN NOT RULE OUT SOME POCKETS OF 1.50 OR MORE. THIS  
SYSTEM WILL ALSO PULL A STRONG COLD FRONT EAST ACROSS THE AREA  
MONDAY NIGHT. THE 12Z GEM/ECMWF HAVE TRENDED TOWARDS A DEEPER  
LOW AND MORE CONSOLIDATED COLD FRONT WHILE THE NAM/GFS EXHIBIT  
MORE GRADUAL COLD ADVECTION THROUGH TUESDAY. LOWERED HIGHS ON  
MONDAY BY A COUPLE DEGREES GIVEN THE EARLIER ONSET OF THE RAIN.  
EASTERN AREAS WILL BE A FEW DEGREES WARMER ON TUESDAY AS THE  
COLDER AIR CONTINUES TO TRICKLE IN FROM THE WEST. ANOTHER PUSH  
OF COOLER AIR ARRIVES BY WEDNESDAY AS A STRONGER TROUGH DIGGING  
SOUTH OUT OF CANADA ARRIVES. HIGHS ON WEDNESDAY WILL STRUGGLE TO  
GET OUT OF THE 40S AS 850MB TEMPERATURES DROP TO BETWEEN 0 TO  
-2C.  
 
DRIER AIR ALOFT DOES GETS WRAPPED AROUND THE UPPER LEVEL TROUGH ON  
TUESDAY BUT SUSPECT ENOUGH LOW LEVEL MOISTURE WILL REMAIN FOR  
LIGHTER SHOWERS TO PERSIST TRIGGERED BY SHORTWAVE ENERGY AND OTHER  
VARIOUS TROUGHS MOVING THROUGH. ANOTHER PUSH OF DEEPER MOISTURE  
ACCOMPANIES THE PASSAGE OF THE UPPER LEVEL TROUGH AXIS ON WEDNESDAY  
AND SHOULD ENHANCE SHOWERS, WITH LIKELY POPS DOWNWIND OF LAKE ERIE.  
 

 
   
LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/
 
 
A HIGHLY AMPLIFIED PATTERN WILL BE IN PLACE ACROSS THE CONUS WITH A  
DEEP TROUGH CENTERED OVER THE OHIO VALLEY AT THE START OF THE LONG  
TERM. PRECIPITATION FROM EARLIER IN THE DAY WEDNESDAY WILL BE  
TAPERING OFF DURING THE OVERNIGHT HOURS WITH THE BEST CHANCES BEING  
CONFINED TO THE EASTERN HALF OF THE AREA. AS WINDS TURN ON SHORE  
WEDNESDAY NIGHT WE WILL SEE SOME LAKE EFFECT/ENHANCED SHOWERS ACROSS  
THE SNOWBELT. WITH TEMPERATURES EXPECTED TO FALL INTO THE MID-30S  
ACROSS INLAND AREAS OF NORTHEAST OHIO AND NORTHWEST PENNSYLVANIA  
WEDNESDAY NIGHT, A CHANCE OF A FEW SNOW SHOWERS MIXING IN WITH THE  
RAIN CAN'T BE RULED OUT.  
 
STRONG WARM AIR ADVECTION ARRIVES THURSDAY AS A SHORT WAVE RIDGE  
MOVES OVERHEAD. THIS SHOULD DRY OUT THE AREA BY THURSDAY AFTERNOON  
WITH HIGHS GENERALLY IN THE MIDDLE AND UPPER 50S. TEMPERATURES WILL  
CONTINUE TO WARM FRIDAY AS THE RIDGE IS SLOW TO MOVE OFF TO THE  
EAST. THE NEXT FRONT LOOKS TO ARRIVE SOMETIME NEXT WEEKEND, BUT THE  
MODELS ARE IN A SIGNIFICANT DISAGREEMENT WITH THE TIMING OF THE COLD  
FRONT. THE ECMWF IS AROUND 48 HOURS SLOWER THAN THE GFS. WITH SUCH A  
HIGHLY AMPLIFIED PATTERN IN PLACE IT IS MORE LIKELY THE LARGE TROUGH  
OUT WEST BECOMES A CLOSED LOW, WHICH IS THE SOLUTION THE ECMWF  
FAVORS COMPARED TO THE MUCH MORE PROGRESSIVE GFS. SO HAVE ONLY WENT  
WITH 20-30 PERCENT POPS AND WARMER TEMPERATURES (UPPER 50S/LOWER  
60S) FOR FRIDAY INTO SATURDAY.  
 

 
   
AVIATION /00Z SATURDAY THROUGH THURSDAY/
 
 
VARIABLE AMOUNTS OF MIDDLE AND HIGH LEVEL CLOUD COVER WILL DRIFT  
ACROSS THE REGION THROUGH THE NIGHT INTO SUNDAY. SOUTHERLY WINDS  
WILL BE UNDER 8 KNOTS THROUGH THE NIGHT. THE SOUTHERLY WINDS  
INCREASE ACROSS THE WEST ON SUNDAY WITH A FEW GUSTS AROUND 20  
KNOTS POSSIBLE.  
 
OUTLOOK...AREAS IF NON-VFR IN RAIN SHOWERS SUNDAY NIGHT THROUGH  
WEDNESDAY. SOME SNOW MAY OCCUR WEDNESDAY INTO WEDNESDAY NIGHT.  
 

 
   
MARINE
 
 
MARINE CONDITIONS WILL REMAIN RELATIVELY GOOD INTO MONDAY WITH SMALL  
CRAFT ADVISORY CONDITIONS DEVELOPING MONDAY NIGHT THROUGH MIDWEEK.  
SOUTHERLY FLOW OF 10-15 KNOTS THROUGH SUNDAY WILL INCREASE TO 20-30  
KNOTS BY MONDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS NORTH ACROSS  
THE LAKE. WINDS WILL SHIFT TO THE WEST WITH THE PASSAGE OF A COLD  
FRONT BEFORE BACKING TO SOUTHWEST AGAIN ON TUESDAY. MODELS ARE  
SHOWING SIGNS OF TRENDING TOWARDS A STRONGER COLD FRONT AND CAN NOT  
RULE OUT A WINDOW OF GALE CONDITIONS. BRISK CONDITIONS AND CONTINUED  
SMALL CRAFT ADVISORIES WILL CONTINUE THROUGH MID-WEEK AS A SERIES OF  
TROUGHS BRING MUCH COLDER AIR TO THE REGION. IMPROVING CONDITIONS  
EXPECTED BY THURSDAY AS A RIDGE BUILDS INTO THE GREAT LAKES BETWEEN  
SYSTEMS.  
 

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

 
 

 
SYNOPSIS...ADAMS  
NEAR TERM...ADAMS/MULLEN  
SHORT TERM...KEC  
LONG TERM...MOTTICE  
AVIATION...MULLEN  
MARINE...KEC  
 
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