Severe Thunderstorm Warning 48, NWS Paducah, KY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
658 AM CDT SUN APR 5 2009

.UPDATE...
UPDATED AVIATION SECTION FOR 12Z TAF ISSUANCE...

&&

.DISCUSSION.../ISSUED 314 AM CDT SUN APR 5 2009/
LATEST MODEL OUTPUT SUGGESTS A DECENT POTENTIAL FOR SEVERE WEATHER
TODAY...ESPECIALLY MIDDAY THROUGH THE AFTERNOON. ALL THE MODELS
ADVECT UPPER 50S TO AROUND 60 DEW POINTS INTO THE REGION...WITH
SURFACE BASED LI/S FALLING TO 0 TO -4...WITH MU CAPES PUSHING 1000
J/KG EAST 1/2 OF THE AREA ON GFS...NAM CLOSER TO 1500. MAIN DRIVER
FOR SEVERE CONVECTION WILL BE A VERY STRONG MID AND UPPER JET
PUNCH H5/H3 RISING TO OVER 100 KTS NOSING IN FROM THE SOUTHERN
PLAINS AND ACROSS THE OZARKS BY MID AFTERNOON. SURFACE AND
BOUNDARY LAYER WILL BE RATHER VEERED WITH MINIMAL DIFFERENTIAL
SPEED AND DIRECTIONAL SHEAR IN LOWEST 5K FT. THINK PRIMARILY LARGE
HAIL AND DAMAGING WINDS...BUT THE TORNADIC POTENTIAL CANNOT BE
RULED OUT ENTIRELY...DESPITE NEAR TO SLIGHTLY LESS FAVORABLE LOWER
TROPOSPHERIC PARAMETERS VS. WHAT WE SAW WITH THE MARCH 28TH EVENT.
POPS WILL BE HIGH CHANCE AND LIKELY TODAY...AROUND CATEGORICAL NE
THIS AFTERNOON.

MUCH COLDER AIR WILL INVADE THE REGION TONIGHT IN THE WAKE OF COLD
FRONTAL PASSAGE. UPPER LOW AND DEEPENING EAST U.S. TROF WILL ALLOW
DECENT CANADIAN HIGH PRESSURE TO MOVE SOUTH THROUGH THE NATION/S
MID SECTION...BRINGING THE REGION CLOUDS...OFF AND ON LIGHT PRECIP
AND MUCH BELOW NORMAL TEMPERATURES MONDAY INTO TUESDAY. LOW TROP
FORECAST THERMAL PROFILES CONTINUE TO SUPPORT LIGHT RAIN/LIGHT
SNOW CHANCES TONIGHT THROUGH MONDAY NIGHT. TAPERED OFF POPS
MORE SO ON TUESDAY AS THE MODELS ARE SLIGHTLY MORE PROGRESSIVE AND
A LITTLE QUICKER WITH THE EASTWARD ADVANCEMENT OF THE TROF...AND
MID LEVEL RIDGE COMING IN FROM THE MID CONUS.

NO CHANGES WERE MADE TO THE FORECAST BEYOND TUESDAY. INCLUDED BELOW
IS THE LONG RANGE OUTLOOK FROM YESTERDAY/S SHIFT...

/ ISSUED 321 PM CDT SAT APR 4 2009 /
THE 00Z ECMWF AND 06Z/12Z GFS ARE IN AGREEMENT IN BRINGING ANOTHER
STORM SYSTEM INTO THE REGION FOR THURSDAY INTO FRIDAY. THE GFS
SOLUTIONS ARE MORE PROGRESSIVE...WHILE THE ECMWF HOLDS ONTO THE
GREAT LAKES DEEP-LAYER TROUGH LONGER AND SUPPRESSES THE SYSTEM AS IT
COMES OUT OF THE PLAINS AND INTO THE QUAD STATE. APPARENTLY THE
MODELS HAVE BEEN SLOWING DOWN IN GENERAL WITH THE LONG WAVE
PATTERN...SO THE ECMWF SOLUTION IS FAVORED BY HPC. SEE NO REASON TO
BUCK THE TREND...SO WILL FOLLOW THE HPC/ECMWF SOLUTION FAIRLY
CLOSELY. THIS WILL RESULT IN THE WARM FRONT DEVELOPING IN OR JUST
NORTH OF THE QUAD STATE THURSDAY AND THURSDAY NIGHT.

DECIDED TO REMOVE THE POPS FROM WEDNESDAY NIGHT...AND INCREASE
POPS A BIT THURSDAY AND THURSDAY NIGHT...WITH THE HIGHEST POPS IN
THE LIKELY CATEGORY IN THE SOUTH THURSDAY NIGHT. ALSO INCREASED
POPS IN THE EAST A BIT FOR FRIDAY FOR LINGERING PRECIPITATION.
ECMWF SHOWALTER INDICES SUPPORT THUNDER FOR THURSDAY NIGHT AND
FRIDAY...BUT DECIDED TO KEEP THE THUNDER IN THURSDAY AND THURSDAY
NIGHT AND PULL IT OUT FOR THE LINGERING PRECIPITATION ON FRIDAY.
WOULD NOT BE SURPRISED TO SEE THUNDER BASED ABOVE 850MB
THURSDAY...AS INITIAL SHORT WAVE TROUGH EJECTS NORTHEAST THROUGH
THE REGION.

&&

.AVIATION...
CIGS AND VSBYS WILL BE VFR MUCH OF THE DAY.  SHRA/TSTMS ARE EXPECTED
ALONG/AHEAD OF A STRONG COLD FRONT MOVING ACROSS THE REGION BETWEEN
15Z AND 22Z.  MVFR CIGS/VSBYS ARE POSSIBLE WITH SHRA/TSTMS AT KCGI
BY 15Z...KPAH AND KEVV BY 17Z...AT KOWB BY 18Z. SHRA/TSTMS WILL END
FROM W TO E DURING LATE AFTERNOON...WITH CIGS BECOMING PREDOMINANTLY
MVFR OVERNIGHT.  WINDS WILL INCREASE FROM THE S TO SW TO 12-18 KTS
GUSTING TO 25 KTS...BECOMING NW WITH GUSTS TO 30 KTS BEHIND THE
FRONT.

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PADUCAH KY
418 AM CDT SUN APR 5 2009

ILZ075>078-080>094-INZ081-082-085>088-KYZ001>022-MOZ076-086-087-
100-107>112-114-061000-
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-
418 AM CDT SUN APR 5 2009

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

.DAY ONE...TODAY AND TONIGHT

THERE IS A RISK OF SEVERE THUNDERSTORMS TODAY...PRIMARILY FROM
MIDDAY ON THROUGH THE AFTERNOON HOURS...ALONG AND EAST OF INTERSTATE
55...INCLUDING MUCH OF SOUTHERN ILLINOIS...WESTERN KENTUCKY AND
SOUTHWEST INDIANA.

STRONG MID AND UPPER LEVEL JET WINDS AT OR ABOVE 100 KNOTS ARE
FORECAST TO MOVE NORTHEAST FROM THE SOUTHERN PLAINS AND OZARKS
REGION...OVER THE AREA BY THIS AFTERNOON. DAYTIME HIGHS WILL
RANGE FROM THE UPPER 60S TO MID 70S...WITH SURFACE DEW POINTS
RISING WELL INTO THE 50S. THIS COUPLED WITH COLDER AIR ALOFT IN
RESPONSE TO AN UPPER TROF MOVING ACROSS THE REGION...MEANS IT WILL
BECOME INCREASINGLY UNSTABLE THROUGH THE DAY. IN THE LOWEST LEVELS
OF THE ATMOSPHERE...SPEED AND DIRECTIONAL SHEAR WILL BE MARGINAL
WITH WINDS VEERING SOUTHWEST THROUGH THE DAY. THUS THE EXPECTED
STORM MODE WILL LIKELY BE LINEAR / BOWING SEGMENTS. HOWEVER...
SUPERCELL STRUCTURES CANNOT BE RULED OUT...CAPABLE OF A BRIEF
TORNADO. THE PRIMARY HAZARDS WILL LIKELY BE LARGE HAIL AND DAMAGING
WIND. STORM MOTION IS FORECAST TO BE EAST NORTHEAST UP TO 50 MPH.

THE STORMS SHOULD MOVE EAST OF SOUTHWEST INDIANA AND THE PENNYRILE
REGION OF WEST KENTUCKY BY EVENING.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

NEAR FREEZING TEMPERATURES ARE FORECAST BOTH TUESDAY MORNING AND
WEDNESDAY MORNING.

THERE IS A CHANCE OF THUNDERSTORMS THURSDAY AND THURSDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUESTED TODAY.