Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 070818
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
318 AM CDT THU MAY 7 2015

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 318 AM CDT THU MAY 7 2015

REGIONAL VAD WIND PROFILES INDICATE MODERATE SOUTHERLY LOW LEVEL
FLOW CONTINUES...AVERAGING 20 TO 30 KNOTS ACROSS THE LOWER OHIO
VALLEY. THIS PERSISTENT FLOW PATTERN HAS BROUGHT WARM AFTERNOON
TEMPS IN THE 80S...BUT MOISTURE HAS BEEN SLOW TO INCREASE. THE
CLEAR NIGHTS AND LINGERING DRY AIR HAVE ALLOWED TEMPS TO FALL INTO
THE 50S ON RECENT NIGHTS.

THE DRY AIR IS ABOUT TO GIVE WAY TO A SIGNIFICANT INCREASE IN
MOISTURE...BOTH NEAR THE SURFACE AND ALOFT. WATER VAPOR IMAGERY
INDICATES A SLOW EASTWARD PROGRESSION OF MOISTURE FROM THE PLAINS.
BOTH THE NAM AND GFS RAISE PRECIPITABLE WATER VALUES TO AROUND 1.5
INCHES TODAY...AND THEN HOLD THEM STEADY THROUGH THE REST OF THE
SHORT TERM PERIOD. THE GENERAL TREND WILL BE FOR A GRADUAL
INCREASE IN CLOUDS AND PRECIP CHANCES...ALONG WITH MILDER
NIGHTTIME LOWS.

TODAY WILL BE THE DRIEST DAY OF THE NEXT FEW DAYS. THOUGH DEEP
LAYER MOISTURE WILL BE INCREASING...THERE WILL BE LITTLE IN THE
WAY OF FORCING FOR PRECIP. EXPECT A FEW DIURNALLY INDUCED SHOWERS
IN THE MARGINALLY UNSTABLE AND UNCAPPED AIR MASS THIS AFTERNOON.
THE HIGHEST CHANCE WILL BE OVER SOUTHEAST MISSOURI...WHERE A FEW
RUMBLES OF THUNDER ARE POSSIBLE. WILL FORECAST SLIGHT CHANCE POPS
THERE...BUT COVERAGE ELSEWHERE SHOULD BE TOO LOW TO MENTION.

TONIGHT AND FRIDAY...THE FIRST IN A SERIES OF 500 MB SHORTWAVES
WILL EJECT NORTHEAST FROM THE CLOSED LOW OVER THE DESERT
SOUTHWEST. EXPECT SCATTERED SHOWERS TO ARRIVE LATE
TONIGHT...MAINLY WEST OF THE MISSISSIPPI RIVER. WITH DIURNAL
HEATING ON FRIDAY...SCATTERED ACTIVITY WILL MOVE OR DEVELOP
EASTWARD ACROSS THE LOWER OHIO VALLEY. THE MODELS INDICATE
SOMEWHAT STRONGER INSTABILITY ON FRIDAY WITH NO CAP BY EARLY
AFTERNOON. THE PROXIMITY OF A NARROW UPPER RIDGE OVER THE
TENNESSEE VALLEY WILL KEEP MID LEVEL WINDS TOO WEAK FOR AN
ORGANIZED SEVERE WEATHER EVENT ON FRIDAY.

FRIDAY NIGHT THROUGH SATURDAY NIGHT...THERE IS NOT A REAL DEFINED
TRIGGER FOR SHOWERS AND STORMS. THERE WILL BE AT LEAST ONE MORE
SHORTWAVE IMPULSE EJECTING NORTHEAST FROM THE UPPER LOW...POSSIBLY
MORE IF ANY MESOSCALE CONVECTIVE VORTICES ARE GENERATED. GIVEN
THE ABUNDANT DEEP MOISTURE...MODERATE INSTABILITY...AND LACK OF A
CAP...SCATTERED SHOWERS AND STORMS WILL BE EASILY INITIATED BY ANY
IMPULSES. THEREFORE...WILL KEEP MAINLY CHANCE POPS GOING THROUGH
THE REMAINDER OF THE SHORT TERM. THERE WILL BE LIKELY POPS OVER SE
MISSOURI AND SOUTHERN ILLINOIS ON SATURDAY...ACCOMPANYING A 500
MB SHORTWAVE. THE CONTINUED WEAK MID-LEVEL WIND FIELDS WILL LIMIT
ORGANIZED SEVERE WEATHER POTENTIAL.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 318 AM CDT THU MAY 7 2015

FAIRLY HIGH CONFIDENCE THROUGHOUT THE EXTENDED PORTION OF THIS
FORECAST.

THE 00Z GFS...ECMWF AND GEM ARE IN REASONABLY GOOD AGREEMENT IN
CONTINUING THE SUMMER-LIKE CONDITIONS THROUGH THE
WEEKEND...CULMINATING WITH SIGNIFICANT COVERAGE OF SHOWERS AND
THUNDERSTORMS NEXT MONDAY AHEAD OF A POORLY-DEFINED COLD FRONT.

SUNDAY MAY END UP RATHER DRY WITH THE AREA STILL IN THE WARM
SECTOR...AND ONLY WEAK UPPER-LEVEL IMPULSES IN WEAK SOUTHWEST FLOW
ALOFT TO HELP INITIATE CONVECTION. WOULD NOT WANT TO TRY TO TIME
IMPULSES THROUGH THE AREA...BUT THE SIGNAL FROM GFS AND GEM IS FOR
BETTER CHANCES IN THE MORNING WITH DRYING IN THE AFTERNOON. THE
ECMWF HAS MORE OF A DIURNAL SIGNAL. FIGURE THE COMBINATION OF THE
UPPER IMPULSES AND DIURNAL FORCING SHOULD YIELD THE BEST CHANCES IN
THE AFTERNOON. HAVE GOOD CHANCE POPS GOING...BUT THOSE MAY BE TOO
HIGH.

THE GFS IS A BIT FASTER WITH THE MAIN SURGE THROUGH THE REGION LATE
SUNDAY NIGHT INTO MONDAY MORNING...WHILE THE ECMWF AND GEM ARE
SLOWER...EMPHASIZING MONDAY FOR THE BEST CHANCES. GIVEN THAT THE
PRIMARY UPPER-LEVEL FORCING AND SURFACE LOW WILL BE LIFTING
NORTHEAST FROM THE PLAINS TO THE UPPER MIDWEST...FIGURE THAT THE
COLD FRONT WILL BE DRAGGING INTO/THROUGH THE AREA...WHICH WOULD
FAVOR THE SLOWER ECMWF/GEM SOLUTION.

WILL LIMIT LIKELY POPS TO THE FAR WESTERN PORTIONS OF SOUTHEAST
MISSOURI SUNDAY NIGHT...AND THEN SPREAD THEM OVER THE ENTIRE REGION
ON MONDAY. THE FLOW INCREASES SIGNIFICANTLY FOR MONDAY...BUT THERE
STILL WILL BE LITTLE LOW-LEVEL FORCING OR FOCUS FOR DEVELOPMENT...SO
WOULD NOT EXPECT MUCH SEVERE WEATHER. HOWEVER...A FEW NEAR-SEVERE
STORMS CANNOT BE RULED OUT...ESPECIALLY IN THE HEAT OF THE DAY
MONDAY.

ALL OF THE MODELS HAVE VERY LITTLE IF ANY QPF LINGERING INTO MONDAY
NIGHT...SO WOULD PREFER TO SEVERELY LIMIT THE WESTERN EXTENT OF
SLIGHT CHANCE POPS. HOWEVER...DUE TO SURROUNDING FORECASTS WILL
LEAVE IT IN FOR THE ENTIRE AREA.

SURFACE HIGH PRESSURE WILL BUILD OVER THE REGION MONDAY NIGHT AND
TUESDAY...AS TROUGHING IN THE UPPER-LEVELS DEVELOPS OVER THE GREAT
LAKES. THIS SHOULD KEEP THE AREA DRY THROUGH AT LEAST NEXT
WEDNESDAY...WITH TEMPERATURES NEAR OR A BIT BELOW NORMAL.


&&

.AVIATION...
ISSUED AT 1144 PM CDT WED MAY 6 2015

THE DIURNAL CU ROUTINE PICKS UP AGAIN ON THURSDAY WITH HIGH BASED
CU...PERHAPS IN THE 050-060 FT AGL RANGE GIVEN SIMILAR TEMPS AND
SLIGHTLY HIGHER DEW POINTS. MID AND HIGH LEVEL CLOUDINESS MAY ALSO
BEGIN TO RAMP UP LATER IN THE PERIOD. ENOUGH LOW LEVEL MOISTURE
COMBINED WITH UPPER LEVEL ENERGY AND DECENT INSTABILITY WILL
WARRANT A VCTS MENTION AT KCGI/KPAH AT LEAST DURING THE AFTERNOON
HOURS.

&&

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

$$

SHORT TERM...MY
LONG TERM...DRS
AVIATION...CW


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