Area Forecast Discussion
Issued by NWS Paducah, KY

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KPAH 290702
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
202 AM CDT MON JUN 29 2015

.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 138 AM CDT MON JUN 29 2015

A WET PATTERN IS SETTING UP. WITH A RIDGE IN THE WEST AND A TROF
IN THE EAST...WE SEE SHOTS OF VORTICITY/ENERGY ROUNDING THE BASE
OF THE MEAN LONG WAVE TROF THAT SETS UP ACROSS THE OHIO RIVER
VALLEY FOR PRETTY MUCH THE ENTIRE SHORT TERM FORECAST PERIOD. A
BOUNDARY LAYS OUT BY MID WEEK...AND WITH THE WNW FLOW ALOFT AT
THAT TIME...IT SHOULD LEAD TO TRAINING OF DAILY THUNDERSTORMS THAT
RESULTS IN SOME NICE RAINS FOR OUR AREA GIVEN HIGH PW`S. A COUPLE
INCHES COULD FALL IN SOME LOCALES BY THE CLOSE OF THE MID WEEK
PERIOD...AND CHANCES EXTEND BEYOND. THE BEST CHANCE IN THE SHORT
TERM DEFINITELY LOOKS TO BE WED-WED NITE...WITH POPS THEN LIKELY
OR BETTER.

.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 138 AM CDT MON JUN 29 2015

THE (SHORTWAVE) TRAIN APPEARS TO MOVE THE MEAN TROUGH AXES OVER THE
WFO PAH FORECAST AREA ON NEARLY A 24 HOUR CYCLE, CENTERED ON 00Z
EACH DAY. OWING TO THE DIFFERENT PRECIPITATION PARAMETERIZATION
SCHEMES USED BY THE MEDIUM RANGE GUIDANCE, THIS PLACES THE VAST
MAJORITY OF THE PRECIPITATION GENERATION ACROSS THE AREA DURING THE
DAYTIME HOURS EACH DAY, NOT INCLUDING ANY INFLUENCE DUE TO
INSOLATION AND MESOSCALE PERTURBATIONS IN THE MEAN NORTHWEST FLOW
ACROSS THE AREA. THIS MAY BODE WELL FOR LATE EVENING FIREWORK
DEMONSTRATIONS ON THE FOURTH OF JULY.

THE CANADIAN AND GFS GUIDANCE ONCE AGAIN APPEAR TO INITIALIZE
WELL WITH THE MEAN WESTERN U.S. RIDGE AND EASTERN U.S. TROUGH
POSITION. BOTH ARE QUITE SIMILAR WITH UPPER LEVEL FEATURES THROUGH
12Z FRIDAY. AFTER THAT TIME, THE CANADIAN GUIDANCE IS 30-50
DEGREES OUT OF PHASE FROM THE GFS WITH RESPECT TO THE GREAT LAKES
TROUGH, A LITTLE SLOWER AND DEEPER. DESPITE THE GREATER BAROCLINIC
RESPONSE FROM THE CANADIAN, THE BIAS OF THE GFS PRESENTS A MORE
ROBUST QPF AND DEEPER AND MORE PERSISTENT SURFACE REFLECTION
(DEEPER SURFACE LOWS) THAN THE CANADIAN GUIDANCE.

WITH THIS IN MIND, UTILIZED A COMBINATION OF THE DEFAULT BLENDED
GUIDANCE WITH A MIX OF CANADIAN/GFE BLEND TO MUTE THE IMPACT OF
VARIABILITY OF BOTH THE GFS/CANADIAN GUIDANCE.

UNFORTUNATELY, THE DIURNAL CHANCE FOR RAIN APPEARS TO DOMINATE THE
ENTIRE PERIOD OF THE EXTENDED FORECAST PERIOD, WITH ONLY SOME
EASTWARD PROPAGATION OF THE UPPER RIDGE INTO THE AREA SHORTLY AFTER
THE END OF THE FORECAST PERIOD (TUESDAY FOLLOWING THE INDEPENDENCE
DAY WEEKEND).

MESOSCALE INFLUENCES TO DUE MCS/MCV INTERNACTIONS, DIABATIC
PROCESSES, AND ANTECEDENT BOUNDARY INTERACTIONS WILL COMPLICATE THE
DAILY FORECAST, SO ANTICIPATE DAY TO DAY VARIATIONS IN THE POP
WEATHER FORECAST. THIS ALSO APPLIES TO OTHER SENSIBLE WEATHER
ELEMENTS, SUCH AS TEMPERATURE, DEWPOINT, AND WIND FIELDS.  LUCKILY,
THE NUMERICAL GUIDANCE, BOTH MEDIUM AND SHORT RANGE, HIGH RESOLUTION
MODEL GUIDANCE WILL BENEFIT FROM IDENTIFICATION OF SHORTWAVE
FEATURES IN THE CANADIAN/U.S. OBSERVATION NETWORKS PRIOR TO THOSE
FEATURES MOVING INTO THE WFO PAH FORECAST AREA.

NEEDLESS TO SAY, THIS FORECAST WILL BE A FRUSTRATING FACTOR FOR
INDEPENDENCE DAY TRAVEL AND CELEBRATIONS THROUGH THE ENTIRE PERIOD.

&&

.AVIATION...
ISSUED AT 138 AM CDT MON JUN 29 2015

VISUAL FLIGHT RULES SHOULD PREVAIL THRU THE REMAINDER OF THE NIGHT
TIME HOURS...EXCEPT WHERE MARGINALLY RESTRICTED CIGS/VSBYS OCCUR
IN A SHOWER OR FOG. THIS WILL BE MOST LIKELY EAST
(KEVV/KOWB)...WHERE SHOWER ACTIVITY IS/WILL BE MORE ROBUST. DURING
THE DAYTIME...INSOLAR HEATING WILL ACTIVATE WARM/MOIST BOUYANT
PARCELS...DEVELOPING LOW VFR CIGS FOR PREVAILING CONDITIONS.
SHOWER/STORM CHANCES WILL CONTINUE TO BE BEST EAST...BUT WILL
REEVALUATE TOWARD 12Z ISSUANCE TIME AS TO THEIR INCLUSION INSIDE
TERMINAL BOUNDS OR NOT.

&&

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

&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.