959  
FXUS63 KPAH 210730  
AFDPAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PADUCAH KY  
230 AM CDT SAT OCT 21 2017  
   
SHORT TERM
 
(TODAY THROUGH MONDAY NIGHT)  
ISSUED AT 230 AM CDT SAT OCT 21 2017  
 
TODAY WILL BE OUR TRANSITION DAY, AS WE WAIT FOR THE ARRIVAL OF OUR  
NEXT COLD FRONT. THIS MORNING, WE WILL CONTINUE TO SEE MOISTURE  
INCREASE ESPECIALLY OUT IN OUR SOUTHEAST MISSOURI COUNTIES, AND  
THAT IS WHERE WE MIGHT ENCOUNTER SOME SPRINKLES BUT NOTHING TOO  
MAJOR.  
 
BY 18Z, THE COLD FRONT WILL BE SITUATED FROM WESTERN MINNESOTA TO  
EASTERN NEBRASKA TO THE OK/TX PANHANDLES. DURING THE AFTERNOON HOURS  
THE FRONT WILL SLIDE EASTWARD. MID TO HIGH CLOUDS COULD KNOCK A FEW  
DEGREES OFF TEMPERATURES FROM WHAT THEY HAVE BEEN THE LAST FEW DAYS,  
BUT STILL EXPECT HIGHS IN THE UPPER 70S TODAY. AGAIN A FEW SPRINKLES  
OR A FEW LIGHT SHOWERS ARE NOT OUT OF THE QUESTION IN SEMO DURING  
THE AFTERNOON TODAY. BUT MOST AREAS SHOULD REMAIN DRY.  
 
WE SHOULD SEE A MARKED INCREASE IN RAIN CHANCES DURING THE EVENING  
HOURS BUT ESPECIALLY OVERNIGHT TONIGHT, AS THE FRONTAL BOUNDARY  
INCHES EVEN CLOSER THE CWA. PRIOR TO 12Z SUNDAY, THE BEST RAIN  
CHANCES WILL BE SOUTHEAST MO, SOUTHWEST IL AND POSSIBLY FAR WEST KY.  
STILL APPEARS TO BE A DECENT CHANCE FOR RAIN AND EMBEDDED STORMS  
DURING THE DAY ON SUNDAY. THE PROBLEM LIES IN JUST HOW FAR EAST THE  
PRECIPITATION WILL MAKE IT PRIOR TO 00Z MONDAY. DURING THE DAY ON  
SUNDAY, AN UPPER LEVEL LOW DEVELOPS NEAR THE ARKLATEX REGION.  
MODELS DIFFER ON WHERE EXACTLY THIS UPPER LOW TRAVELS THROUGH THE  
REST OF THE DAY ON SUNDAY. THIS HAS SOME PRETTY SUBSTANTIAL  
IMPLICATIONS ON WHERE ANY PRECIPITATION BANDS SET UP. THEREFORE,  
WE CONTINUE TO SEE POP CHALLENGES FOR THE SUNDAY-SUNDAY NIGHT  
PERIOD. WE WILL KEEP THE CATEGORICAL WORDING FOR AREAS FURTHER  
WEST AND EARLY ON IN THE PERIOD, BUT BACK OFF TO CHANCE TO LIKELY  
WORDING FURTHER EAST AS WE HEAD THROUGH THE SUNDAY EVENING PERIOD.  
HIGH TEMPERATURES ON SUNDAY WILL BACK OFF INTO THE LOWER TO MID  
70S, ALTHOUGH WE COULD REACH THE UPPER 70S FAR EASTERN SECTIONS.  
 
HEADING INTO MONDAY, THE FORECAST CONTINUES TO HINGE ON THE MOVEMENT  
OF THE AFOREMENTIONED UPPER LOW. IT DOES MOVE EAST DURING THE DAY ON  
MONDAY AND WE SHOULD SEE RAIN OVER A DECENT PART OF THE AREA ON THE  
NORTHERN SIDE OF THIS LOW. BUT AGAIN, PLACEMENT OF WHERE THE HIGHEST  
POPS SHOULD BE AS WELL AS QPF IS STILL QUESTIONABLE BECAUSE MODELS  
DIFFER ON THE DEVELOPMENT OF A NEW SFC LOW ALONG THE FRONT AS  
WELL. ANOTHER FLY IN THE OINTMENT HEADING INTO MONDAY NIGHT IS  
THAT A NORTHERN STREAM UPPER TROUGH WILL BE HEADING SOUTHEAST INTO  
THE AREA. DEPENDING ON HOW FAST AND DEEP THIS TROUGH ENDS UP  
BEING, WILL DICTATE HOW QUICKLY WE SHOVE THIS PRECIPITATION EAST  
OF OUR AREA. RIGHT NOW, WE WILL CONTINUE TO SHOW AN EASTWARD  
PROGRESSION OF THE PRECIP PROBABILITIES DURING MONDAY EVENING AND  
OVERNIGHT.  
 
AS FAR AS SEVERE POTENTIAL...MODELS SEEMED TO HAVE AMPED UP THE  
INSTABILITY OVERNIGHT SATURDAY NIGHT INTO SUNDAY, ESPECIALLY OVER  
SEMO. DECENT SHEAR WILL BE IN PLACE THERE TOO ALONG WITH GOOD MID  
LEVEL LAPSE RATES. THESE PARAMETERS WANE AFTER 12Z SUNDAY. SPC IS STILL  
NOT OVERLY EXCITED ABOUT SEVERE WEATHER PROSPECTS HOWEVER, SO  
CHANCES WILL REMAIN LOW FOR NOW. HOWEVER, PWS STILL LOOK RATHER  
HIGH SO THE THREAT FOR HEAVY RAIN DOES REMAIN.  
   
LONG TERM
 
(TUESDAY THROUGH FRIDAY)  
ISSUED AT 230 AM CDT SAT OCT 21 2017  
 
MEDIUM CONFIDENCE IN THE EXTENDED...HIGH CONFIDENCE IN AN UNSETTLED  
WEATHER PATTERN WITH SEVERAL FRONTS POISED TO MOVE THROUGH THE  
REGION.  
 
THERE ARE SOME SIGNIFICANT DISCREPANCIES AMONG THE MODELS FOR THE  
EXTENDED. AS USUAL THE GFS IS FASTER AND MUCH CLEANER WITH THE START  
AND STOP OF THE PRECIP CHANCES. THE GFS CREATES A CLOSED OFF LOW  
THAT TRAVELS ACROSS THE GULF STATES WHILE THE ECMWF KEEPS AN OPEN  
LOW TRAVELING THROUGH THE GREAT LAKES REGION. THE NAM HOWEVER KEEPS  
HAS A CLOSED LOW MOVING THROUGH THE GULF STATES BUT OPENS IT UP BY  
12Z TUE. THE CANADIAN IS SOMEWHERE IN THE MIDDLE OF THESE SOLUTIONS.  
THE ECMWF IS THE SLOWEST TO MOVE POPS OUT OF THE AREA AND THE BLEND  
IS STARTING TO DIMINISH PRECIP CHANCES INTO TUESDAY. HOWEVER ONE  
THING THEY DO AGREE ON IS THAT TUESDAY WILL BE A BREEZY DAY. WINDS  
ON TUESDAY WILL BE NORTHWEST WITH GUSTS APPROACHING 30 MPH. THIS  
WILL USHER IN MUCH DRIER AND COLDER AIR. IN FACT HAVE INTRODUCED AT  
LEAST PATCHY FROST WEDNESDAY MORNING. ALTHOUGH MOS DIFFERS A GREAT  
DEAL FOR HIGHS TUESDAY THEY COME INTO AGREEMENT WITH OVERNIGHT LOWS  
IN THE 30S. THINK STRONGLY SCATTERED FROST WILL OCCUR UNLESS THE  
WINDS STAY UP. LI'S REMAIN POSITIVE WITH CAPES IN BELOW A 100 J/KG2  
AND THE K INDEX BRIEFLY REACHES 30. SO FOR NOW WILL NOT INTRODUCE  
THUNDER BUT WILL MONITOR FOR POSSIBLE INTRODUCTION AT A LATER TIME.  
AS FOR TEMPS THE BLEND CAME IN A BIT COOLER THAN THE MEX WHICH WE  
THINK THIS IS THE RIGHT DIRECTION TO GO WITH SUCH STRONG CAA AND LOW  
SUN ANGLE FOR THIS TIME OF YEAR.  
 

 
   
AVIATION
 
 
ISSUED AT 230 AM CDT SAT OCT 21 2017  
 
VFR CONDITIONS WILL PERSIST ACROSS THE REGION THROUGH THE 24 HOUR  
TAF PERIOD AS RIDGING IS GRADUALLY REPLACED BY SOUTHWESTERLY FLOW  
ALOFT. WINDS AND MOISTURE WILL BE ON THE INCREASE AS SOUTHERLY FLOW  
STRENGTHENS IN RESPONSE TO A COLD FRONT APPROACHING FROM THE PLAINS.  
THIS WILL RESULT IN AN INCREASE IN HIGH CLOUDS TONIGHT AND SOME MID  
CLOUDS ON SATURDAY. IN ADDITION, LIGHT WINDS TONIGHT WILL PICK UP  
FROM THE SOUTH AROUND 10 KNOTS WITH SOME GUSTS TO 15 TO 20 KNOTS BY  
SATURDAY AFTERNOON. THE COMBINATION OF CLOUDINESS AND LOW LEVEL  
WINDS SHOULD BY AND LARGE PRECLUDE FOG FORMATION OVERNIGHT.  
 

 
   
PAH WATCHES/WARNINGS/ADVISORIES
 
 
IL...NONE.  
MO...NONE.  
IN...NONE.  
KY...NONE.  

 
 

 
 
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