Heat in Missouri, July 25, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
1240 PM CDT SAT JUL 25 2015

.MESOSCALE DISCUSSION...
ISSUED AT 1240 PM CDT SAT JUL 25 2015

DESPITE THE APPROACH OF AN APPARENT MCV TO OUR NNW...ATMOSPHERE IS
ESSENTIALLY CAPPED EVERYWHERE SAVE FOR SEMO...WHERE ML CAPES HAVE
JUMPED TO 3000+. SOME MID LEVEL COOLING WORKING IN FROM THE NW
SHOULD STEEPEN LAPSE RATES AND ALLOW FOR SOME CONVECTIVE POTENTIAL
IN THIS AREA. EXTENDING NW FROM SEMO TOWARD I-64...MAY BE A SPOT
SHOWER OR THUNDERSHOWER...BUT OVERALL UNIMPRESSIVE AND ONLY SLIGHT
CHANCE AT THAT...PER WEAK INSTABILITY...AND WITHOUT ANY LOWER TROP
CONVERGENCE. HI RES MODELS NOT TOO EXCITED ABOUT CONVECTIVE
POTENTIAL EITHER. SPC REMOVED SLIGHT RISK AREA...LIKELY OVERDONE
TO BEGIN WITH...THAT PREVIOUSLY COVERED THE WEST 1/3 OF THE AREA.

&&

.UPDATE...
ISSUED AT 1214 PM CDT SAT JUL 25 2015

AVIATION SECTION FOR 18Z TAFS.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 341 AM CDT SAT JUL 25 2015

MAIN NEAR TERM CONCERNS INCLUDE: (1.) THE POTENTIAL FOR SHOWERS
AND THUNDERSTORMS; AND (2.) THE BUILDING HEAT AND HUMIDITY THROUGH
MONDAY. GIVEN THE UNCERTAINTY OVER CONVECTIVE POTENTIAL AND ITS
IMPACT ON TEMPERATURES...CONFIDENCE IS AVERAGE TO BELOW AVERAGE IN
THE NEAR TERM.

THE UPPER LEVEL HIGH WILL REMAIN IN PLACE ACROSS THE SOUTHERN
STATES THROUGH EARLY IN THE NEW WEEK. IMPULSES OF ENERGY STREAMING
SOUTHEASTWARD ALONG THE NORTHERN PERIPHERY OF THIS HIGH WILL YIELD
THE POTENTIAL FOR CONVECTIVE COMPLEXES AS OBSERVED IN MISSOURI
OVERNIGHT. THE 00Z NAM AND HI-RES ARW-WRF APPEAR TO HAVE THE BEST
HANDLE ON THIS CONVECTION. BOTH MODELS BRING THE THUNDERSTORM
COMPLEX INTO SOUTHEAST MISSOURI EARLY THIS MORNING BEFORE ITS
EVENTUAL DEMISE. ADDITIONAL BOUNDARY-DRIVEN DIURNAL DEVELOPMENT
ALSO CANNOT BE RULED OUT THIS AFTERNOON...ESPECIALLY OVER
SOUTHEAST MISSOURI WHERE HUMIDITY WILL BE SUBSTANTIALLY HIGHER.

THE CONVECTIVE DEBRIS CLOUDS MAY IMPACT TEMPERATURES...ESPECIALLY
WEST OF THE MISSISSIPPI RIVER THIS MORNING. HOWEVER...A TREND
TOWARDS MORE CLEARING IS EXPECTED BY AFTERNOON. THIS SHOULD ALLOW
TEMPERATURES TO REACH THE LOWER 90S ACROSS MOST OF THE AREA. GIVEN
THE PERSISTENCE OF A SHARP WEST-EAST DEW POINT GRADIENT...HEAT
INDEX VALUES SHOULD REMAIN BELOW 105 OVER ALL BUT A HANDFUL OF OUR
MISSOURI COUNTIES THIS AFTERNOON. WILL ISSUE A HEAT ADVISORY FOR
LOCATIONS GENERALLY ALONG AND WEST OF A GREENVILLE TO NEW MADRID
MISSOURI LINE.

ANOTHER THUNDERSTORM COMPLEX IS FORECAST TO DEVELOP UPSTREAM OVER
THE MISSOURI VALLEY TONIGHT...THEN HEAD SOUTHEAST INTO NORTHERN
PORTIONS OF THE QUAD STATE REGION LATE TONIGHT AND SUNDAY MORNING.
THE ACTIVITY WILL LIKELY DISSIPATE THROUGH THE MORNING AS IT LOSES
SUPPORT. IT IS LIKELY THAT DEBRIS CLOUDS WILL HAVE AN IMPACT ON
TEMPERATURES ON SUNDAY AS WELL. SO BELIEVE THE BEST APPROACH IS TO
TAKE THE HEAT HEADLINES ONE DAY AT A TIME FOR NOW.

BY MONDAY...THE INFLUENCE OF THE UPPER LEVEL HIGH WILL BECOME MORE
NOTICEABLE AS PRECIPITATION CHANCES BEGIN TO SHIFT NORTHEAST AND
DWINDLE. HEAT AND HUMIDITY WILL TAKE HOLD WITH HIGHS IN THE LOWER
90S AND HEAT INDEX READINGS OF AT LEAST 100 TO 105 ACROSS MOST OF
THE AREA.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 341 AM CDT SAT JUL 25 2015

AVERAGE TO BELOW CONFIDENCE IN THE LONG TERM AS MODELS NOT IN GOOD
AGREEMENT ON PLACEMENT AND STRENGTH OF SYNOPTIC FEATURES.

THE LONG TERM PERIOD STARTS OFF WITH AN H5 RIDGE STRETCHING
NORTHEAST ACROSS OUR CWA. ALTHOUGH MODELS NOT IN GOOD AGREEMENT ON
THE STRENGTH OF THE RIDGE AND THE PLACEMENT OF ITS AXIS...THE
PRESENCE OF THE RIDGE AND WARM MID LEVEL AIR (AOA 10C) COINCIDENT
WITH IT SHOULD PRECLUDE THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS
OVER ALL EXCEPT THE FAR NORTHEAST SECTIONS OF OUR CWA MONDAY NIGHT
AND TUESDAY.

MODELS SHOW THE RIDGE BUILDING A BIT TUESDAY NIGHT SO NO ACTIVITY
EXPECTED IN THAT PERIOD. PRECIPITATION CHANCES MAKE THEIR WAY BACK
INTO THE FORECAST ON WEDNESDAY AS UPPER LEVEL ENERGY ATTEMPTS TO
PUSH A FRONTAL BOUNDARY OUT OF THE PLAINS TOWARD OUR AREA. THIS
SHOULD SUPPRESS THE RIDGE AND WARM AIR ALOFT ENOUGH TO ALLOW THE
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS AREA WIDE. AGAIN MODELS NOT
IN AGREEMENT ON TIMING AND PLACEMENT OF QPF...SO JUST WENT WITH SCHC
POPS FOR NOW.

THE AFOREMENTIONED BOUNDARY IS FORECAST TO CROSS OUR CWA WEDNESDAY
NIGHT. THEORETICALLY SPEAKING THIS SHOULD WARRANT POPS ACROSS OUR
ENTIRE CWA LIKE THE GFS INDICATES BUT FOR SOME REASON THE ECMWF JUST
SHOWS PRECIPITATION CHANCES OVER THE NORTHEAST HALF OF OUR CWA.
DECIDED TO GO WITH HIGHER POPS (CHC) OVER THE NORTHEAST HALF AND THE
LOWEST POSSIBLE POPS (15) TO GENERATE PRECIPITATION WORDING OVER THE
SOUTHWEST HALF JUST IN CASE THE GFS VERIFIES.

MODELS NOT IN GOOD AGREEMENT AT ALL ON THURSDAY. IN THE WAKE OF THE
FRONTAL PASSAGE THE ECMWF HAS ALL PRECIPITATION SOUTHEAST AND EAST
OF OUR CWA WHILE THE GFS HANGS UP LIGHT PRECIPITATION OVER OUR CWA
ALL DAY. THIS MAKES NO SENSE SYNOPTICALLY BECAUSE EVEN WITH WEAK
WEST NORTHWEST FLOW ALOFT IT SHOULD BE ENOUGH TO PUSH THE DEEPER
MOISTURE TO OUR SOUTH AND EAST. FOR POPS DECIDED TO SPLIT THE
DIFFERENCE (HIGHER POPS SOUTHEAST...LOWER POPS NORTHEAST) TO IMPLY
AT LEAST LOWERING POPS AND FOR BETTER COLLABORATION.

MODELS IN BETTER AGREEMENT THURSDAY NIGHT AND FRIDAY IN THAT DRIER
HIGH PRESSURE OVERSPREADING THE REGION IN THE WAKE OF THE FRONT
SHOULD BRING PRECIPITATION CHANCES TO END AS WELL AS LOWERING
TEMPERATURES AND DEWPOINTS TO MORE TOLERABLE LEVELS.&&

&&

.AVIATION...
ISSUED AT 1214 PM CDT SAT JUL 25 2015

MAINLY VFR NEXT 24 HOURS. CANNOT RULE OUT CONVECTION COMPLETELY
BUT PROBS TOO LOW TO INCLUDE IN TERMINALS. LIGHT WINDS AND
VARIABLE CLOUD COVER.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR
MOZ100-107>110-114.
IN...NONE.
KY...NONE.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PADUCAH KY
454 AM CDT SAT JUL 25 2015

ILZ075>078-080>094-INZ081-082-085>088-KYZ001>022-MOZ076-086-087-
100-107>112-114-261000-
JEFFERSON-WAYNE IL-EDWARDS-WABASH-PERRY IL-FRANKLIN-HAMILTON-
WHITE-JACKSON-WILLIAMSON-SALINE-GALLATIN-UNION IL-JOHNSON-POPE-
HARDIN-ALEXANDER-PULASKI-MASSAC-GIBSON-PIKE-POSEY-VANDERBURGH-
WARRICK-SPENCER-FULTON-HICKMAN-CARLISLE-BALLARD-MCCRACKEN-GRAVES-
LIVINGSTON-MARSHALL-CALLOWAY-CRITTENDEN-LYON-TRIGG-CALDWELL-
UNION KY-WEBSTER-HOPKINS-CHRISTIAN-HENDERSON-DAVIESS-MCLEAN-
MUHLENBERG-TODD-PERRY MO-BOLLINGER-CAPE GIRARDEAU-WAYNE MO-CARTER-
RIPLEY-BUTLER-STODDARD-SCOTT-MISSISSIPPI-NEW MADRID-
454 AM CDT SAT JUL 25 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHERN
ILLINOIS...SOUTHWEST INDIANA...WESTERN KENTUCKY AND SOUTHEAST
MISSOURI.

.DAY ONE...TODAY AND TONIGHT

A FEW THUNDERSTORMS ARE POSSIBLE TODAY AND AGAIN LATE TONIGHT...
MAINLY ACROSS NORTHERN AND WESTERN PORTIONS OF SOUTHERN ILLINOIS
AND SOUTHEAST MISSOURI. PRIMARY IMPACTS WILL BE LIGHTNING AND
LOCALLY HEAVY RAIN.

THE COMBINATION OF HEAT AND HUMIDITY WILL MAKE FOR OPPRESSIVE
CONDITIONS THIS AFTERNOON ACROSS THE WESTERN HALF OF THE REGION.
PLEASE REFER TO THE HEAT ADVISORY AND SPECIAL WEATHER STATEMENT
FOR MORE DETAILS.

FLOODING CONTINUES ON THE MISSISSIPPI...WABASH...AND OHIO RIVERS.
PLEASE REFER TO THE LATEST RIVER FLOOD STATEMENTS FOR DETAILS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

SMALL CHANCES OF THUNDERSTORMS ARE FORECAST ACROSS MUCH OF
SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...AND SOUTHWEST INDIANA ON
SUNDAY...THEN OVER THE EVANSVILLE TRI-STATE AREA ON MONDAY. THE
CHANCE OF THUNDERSTORMS RETURNS TO THE ENTIRE REGION WEDNESDAY
INTO THURSDAY AS A WEAK COLD FRONT APPROACHES. LIGHTNING AND
LOCALLY HEAVY RAIN WILL BE THE PRIMARY IMPACTS.

THE EXPANDING HEAT AND HUMIDITY WILL MAKE FOR EVEN MORE OPPRESSIVE
CONDITIONS THROUGH THE MIDDLE OF THE NEW WEEK. MOST AREAS WILL SEE
MAXIMUM HEAT INDEX VALUES AROUND THE 105 DEGREE MARK...IF NOT
HIGHER IN SOME LOCATIONS.

REFER TO THE LATEST RIVER FLOOD WARNINGS AND STATEMENTS FOR
INFORMATION ON RIVER FLOODING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

RJP