Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 221909
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
209 PM CDT SUN MAR 22 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 154 PM CDT SUN MAR 22 2015

THE MODELS TAKE A SURFACE LOW PRESSURE SYSTEM AND MOVE IT EAST ALONG
THE GULF COAST THRU 12Z MONDAY. THIS IS THE MOISTURE STREAMING AS
FAR NORTH AS INTO/OVERTOP OUR FA...BUT LOOKS TO STAY JUST CLOUDS
FOR THE MOST PART...AS RADAR AND SURFACE OBS SHOW PRECIPITATING
MOISTURE STAYING JUST TO THE SOUTH OF THE FA. THIS IS NOT TO SAY
AN ISOLATED LIGHT SHOWER OR SPRINKLES COULDNT WORK INTO THE
SOUTH...BUT WE`LL GENERALLY STAY DRY TONIGHT.

ON MONDAY-MONDAY NIGHT...SOME NW FLOW ENERGY WORKS ACROSS THE MID
MS VALLEY...RESULTING IN SOME SMALLISH CHC POPS AFFECTING MAINLY
JUST OUR FAR NORTHERN COUNTIES. WE`LL SEEK TO BLEND THE COLLAB
PICTURE ON THIS SLGT CHANCE MENTION...IF ANY.

TUESDAY...A DEVELOP WARM FRONT ARCS NORTH THRU/ACROSS OUR NORTHERN
COUNTIES...IN RESPONSE TO A SHARPER TROF DIGGING AND A SURFACE LOW
PRESSURE SYSTEM TAKING SHAPE/COMING TOGETHER JUST TO OUR WEST.
THIS WILL HEIGHTEN WAA RELATED SHOWER ACTIVITY...AGAIN...MAINLY
ACROSS OUR NORTHERN HALF OF THE FA. MOVING INTO TUESDAY
NIGHT...THIS WARM SECTOR LIFT/INSTABILITY INCREASES ENOUGH TO
EXPAND POPS FA-WIDE...INCLUDING THE CHANCE OF THUNDER...AS THE
DEVELOPING LOW SWEEPS NORTHEASTWARD TOWARD THE GREAT LAKES.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 154 PM CDT SUN MAR 22 2015

AN ACTIVE SPRING PATTERN IS EXPECTED IN THE LONG TERM. A DEEPENING
LOW PRESSURE SYSTEM WILL MOVE NORTHEAST ACROSS THE GREAT LAKES
REGION ON WEDNESDAY. PER WPC DISCUSSIONS...THE ENSEMBLE MEANS HAVE
BEEN SLOWER THAN THE OPERATIONAL RUNS TO LATCH ONTO THE DEEPENING
TREND. THE MODELS HAVE ALSO TRENDED SLOWER WITH THE PROGRESSION OF
THE SYSTEM. THIS WILL ALLOW MORE TIME FOR BETTER MOISTURE AND
INSTABILITY RECOVERY AHEAD OF THE TRAILING COLD FRONT. GFS/NAM BOTH
INDICATE BOUNDARY LAYER DEW POINTS IN THE LOWER 60S WILL NOSE INTO
THE MID MISSISSIPPI VALLEY BY WEDNESDAY NIGHT. THE NAM IS
CHARACTERISTICALLY MUCH HIGHER THAN OTHER MODELS WITH ITS SURFACE
BASED CAPES...AND ITS PROBABLY OVERDONE. IN ANY CASE...ALL MODELS
SHOW SUFFICIENT ELEVATED INSTABILITY FOR SCATTERED TO NUMEROUS
THUNDERSTORMS WEDNESDAY INTO WED NIGHT. THE POTENTIAL FOR ANY SEVERE
STORMS WILL DEPEND ON THE DEGREE OF SURFACE BASED
INSTABILITY...WHICH VARIES CONSIDERABLY BETWEEN MODELS.

THE STRONG MOISTURE FEED WILL LIKELY RESULT IN SOME LOCALLY HEAVY
RAIN. THE MODELS VARY ON THE PLACEMENT OF THE HEAVIEST QPF. THE 12Z
GFS/ECMWF SHOW QPF RANGING FROM ONE TO TWO INCHES IN THE HEAVIEST
SWATH. THIS COULD SLOW THE RECESSION OF MAINSTEM RIVERS.

FOLLOWING THE PASSAGE OF THE COLD FRONT LATE WEDNESDAY NIGHT OR
EARLY THURSDAY...COOLER AND DRIER AIR WILL BEGIN TO ARRIVE THURSDAY
AND THURSDAY NIGHT. THERE MAY STILL BE SOME LINGERING SHOWERS AS
ANOTHER SHORTWAVE TROUGH ROTATES SOUTHEAST INTO THE LARGER SCALE 500
MB TROUGH.

THE HEART OF THE COLDER AIR WILL LIKELY AWAIT THE PASSAGE OF A
SHARPLY AMPLIFYING 500 MB TROUGH ON FRIDAY. A FEW OF THE OPERATIONAL
RUNS HAVE SHOWN 850 MB TEMPS AS LOW AS MINUS 10 OVER THE LOWER OHIO
VALLEY UNDER THE THERMAL TROUGH AXIS EARLY SATURDAY. EVEN WITH
PLENTY OF LATE MARCH SUN...HIGHS SHOULD ONLY BE IN THE 40S ON
SATURDAY. OVERNIGHT LOWS WILL ALSO BE DEPENDENT ON CLOUDINESS...BUT
IT APPEARS LIKELY TEMPS WILL FALL BELOW FREEZING EVEN WITH PARTIAL
CLOUDINESS. FORTUNATELY...THE GROWING SEASON IS NOT YET UNDERWAY.

ON SUNDAY...THE CONSENSUS OF THE MODELS IS FOR A RELATIVELY WEAK
COLD FRONT TO APPROACH OR PASS ACROSS THE LOWER OHIO VALLEY.
SOUTHWEST RETURN FLOW MAY BRING JUST ENOUGH MOISTURE AND INSTABILITY
FOR A SMALL CHANCE OF SHOWERS.

&&

.AVIATION...
ISSUED AT 154 PM CDT SUN MAR 22 2015

CLOUDS INCREASING FROM THE SOUTH WILL RESULT IN LOWERING CIGS BUT
SHOULD MAINTAIN VFR STATUS FOR MOST TERMINALS...THOUGH SCATTERED
MVFR BASES MAY APPEAR AS THE NIGHT WEARS ON. PRECIPITATION SHOULD
STAY TO THE SOUTH AS WELL BUT MVFR VSBYS ARE A POSSIBILITY AGAIN
OVERNIGHT.

&&

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

$$


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