Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 210817
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
317 AM CDT THU MAY 21 2015

.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 317 AM CDT THU MAY 21 2015

LOW LEVEL DRY/COLD ADVECTION FINALLY BEGINNING TO EDGE ITS WAY
INTO THE WESTERN SECTIONS OF THE WFO PAH FORECAST AREA AT THIS
HOUR...BUT THE GRADIENT IS ALSO WEAKENING TO THE WEST AS SURFACE
HIGH PRESSURE BUILDS ACROSS THE AREA.

WILL STILL LIKELY SEE SOME PATCHY DRIZZLE PERSIST IN THE SHARPER
PRESSURE GRADIENT OVER SOUTHWEST INDIANA AND THE PENNYRILE REGION
OF WEST KENTUCKY THROUGH DAYBREAK.

AS A VORTICITY LOBE FROM A LOW AMPLITUDE UPPER MIDWEST TROUGH
SWINGS THROUGH, GRADUAL CLEARING SHOULD TAKE DURING THE AFTERNOON.

THE SURFACE HIGH WILL BE CENTERED OVER SOUTHERN MISSOURI TONIGHT.
THE COMBINATION OF CLEAR SKIES...ETC...SHOULD FAVOR SOME FOG
DEVELOPMENT AFTER MIDNIGHT. IT WILL BE SOMEWHAT UNCERTAIN WHETHER
SOME OF THE FOG WILL BECOME DENSE AT THIS TIME. SREF PROBABILITIES
FOR VISIBILITIES LESS THAN A MILE ARE NON-EXISTANT AT THIS TIME.

A GRADUAL WARM UP CONTINUES INTO THE WEEKEND. SLOWED THE ONSET OF
RAIN TO THE SOUTHWEST SATURDAY NIGHT A LITTLE MORE GIVEN THE
WEAKER FLOW WITHIN LOW LEVEL AND UPPER RIDGE INFLUENCE OVER THE
AREA.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 317 AM CDT THU MAY 21 2015

THER THAN SOME MODEL VARIANCE WITH THE SMALLER SCALE FEATURES...THE
ENSEMBLE SUITES FROM THE GFS/EC LINE UP FAIRLY WELL WITH OPERATIONAL
MODEL OUTPUT. ON THE LARGER SCALE...AN UPPER LEVEL RIDGE WILL REMAIN
STRONG OVER THE SE U.S. AND OFF THE ATLANTIC COAST...WHILE A
TRANSITIONAL WEST U.S. UPPER TROF GRADUALLY BREAKS DOWN ALLOWING FOR
A MORE ILL-DEFINED REGIME WITH BROAD WSW FLOW ACROSS A GOOD PART OF
THE CONUS. AT THE SURFACE...HIGH PRESSURE WILL HOLD STRONG OFF THE
ATLANTIC COAST WITH BROAD ANTICYCLONIC FLOW ABOUT THE HIGH PROVIDING
A PERPETUAL FLOW OF WARM...MUGGY GULF AIR ACROSS OUR REGION THROUGH
MOST OF THE LONG TERM PERIOD.

DESPITE THE LACK OF A SFC/LOW TROP FRONTAL FOCUS...THE WEATHER IS
FORECAST TO BE UNSETTLED GIVEN SEVERAL DISTURBANCES WILL LIKELY MOVE
ACROSS THE REGION IN THE ACTIVE SW FLOW PATTERN. LONG RANGE MODEL
OUTPUT USUALLY STRUGGLES WITH TIMING SUCH FEATURES IN THIS TYPE OF
FLOW REGIME. THEREFORE...DESPITE SOME OF THE HIGH POP VALUES SHOWING
UP IN OUR BLEND OUTPUT...WE WILL KEEP POPS IN AT MOST...THE HIGH
CHANCE CATEGORY...GIVEN OUR CONFIDENCE TIMING THESE WAVES IS SIMPLY
NOT HIGH ENOUGH FOR ANY 12 HOUR PERIOD TO DO OTHERWISE. WILL ALSO
LOWER POPS OUT TOWARD DAYS 6 AND 7 AS CONFIDENCE CONTINUES TO LOWER.
DESPITE MEDIUM TO LOW CONFIDENCE IN TIMING...WE HAVE HIGH CONFIDENCE
THAT IT WILL BE UNSETTLED WITH ON AND OFF CHANCES OF CONVECTION THE
ENTIRE DAYS 4-7 PERIOD. TEMPS WERE A BLEND OF MOS AND BASE MODEL
OUTPUT.

&&

.AVIATION...
ISSUED AT 624 PM CDT WED MAY 20 2015

LIGHT SHOWER ACTIVITY DEPARTING EASTERN TERMINALS MAY LINGER THE
FIRST 1-3 HOURS OF FORECAST...SO WILL CARRY A VICINITY MENTION AT
KEVV AND MVFR RESTRICTED VSBY MENTION AT KOWB TO ACCOUNT FOR THAT.
OTHERWISE IFR CIGS DEVELOPING AS TIME/HEIGHTS SHOW LOW LAYER
SATURATION. MVFR VSBYS COMMONPLACE IN LIGHT MIST/DRIZZLE/FOG.
CONDITIONS IMPROVE TO MVFR CIGS DURING THE LATTER MORNING HOURS
AND COULD SCATTER DURING THE PM HOURS...MORE LIKELY AT KCGI/KPAH
THAN FURTHER EAST.


&&

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

$$

SHORT TERM...SMITH
LONG TERM...CN



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