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 220810 CCA
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
254 AM CDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 254 AM CDT FRI MAY 22 2015

THE TREND FOR THE DOMINATION OF RIDGING ALOFT CONTINUES WITH THIS
FORECAST CYCLE...KEEPING PRECIPITATION AT BAY ACROSS THE WFO PAH
THROUGH LATE SATURDAY NIGHT. IF ANYTHING, THE SIGNAL HAS BECOME A
LITTLE STRONGER IN THE LAST 24-36 HOURS. THIS IS WELL REPRESENTED
BY SEVERAL MEMBERS OF THE SHORT TERM HIGH RESOLUTION AND MEDIUM
RANGE NUMERICAL MODEL GUIDANCE.

THE CLOSED LOW CURRENTLY OFF THE CENTRAL CALIFORNIA COAST IS
SERVING AS THE GENESIS POINT FOR THE AMPLIFICATION OF THE RIDGE
AND THE EVENTUAL IMPINGING SOUTH/SOUTHWESTERLY FLOW AND SOURCE
REGION FOR VORTICITY LOBES ROTATING AROUND THE LOW. ONCE THE LOW
MOVES INTO THE CENTRAL ROCKIES LATE SATURDAY, IT WILL TAP INTO AND
ENHANCE THE FLOW OF MOISTURE FROM THE GULF OF MEXICO BEHIND THE
SURFACE RIDGE OFF THE EAST COAST.

THE AFOREMENTIONED SCENARIO WILL SET UP A WEST TO EAST POP
GRADIENT ACROSS THE WFO PAH FORECAST AREA, AS A MORE UNSTABLE
THERMAL PROFILE COMES INTO PLAY IN THE WEST UNDER THE WEAKENING
INFLUENCE OF THE DEPARTING UPPER RIDGE AXIS. THIS WILL ALSO PLACE
THE WESTERN 1/3 TO 1/2 OF THE WFO PAH FORECAST AREA IN THE FAVORED
ZONE FOR ISENTROPIC LIFT WITHIN THE WARM CONVEYOR BELT. THE
POTENTIAL FOR GREATER PRECIPITATION EFFICIENCY AND LOCALLY HEAVY
RAINS WILL BE MORE LIKELY IN THIS AREA ON SUNDAY.

DIFFERENTIAL HEATING DURING THE DAY ON SUNDAY IN THE WESTERN 1/2
OF THE WFO PAH FORECAST AREA MAY PLAY IN THE DEVELOPMENT OF
DIURNALLY INDUCED AND ISOLATED STRONG STORMS. THERE MAY BE A MIX
OF ISOLATED PULSE TYPE THUNDERSTORMS ON THE LEADING EDGE WITH
DOWNDRAFT POTENTIAL... WITH SOME MULTICELL STORMS FURTHER WEST
WITH MARGINAL HAIL AND LOCALIZED WIND GUSTS AND OUTFLOW MERGERS
SUPPORTING RENEWED DEVELOPMENT. THE KEY WILL BE THE DEGREE OF
0-3/0-6KM BULK SHEAR...WHICH AT THIS POINT IS PRETTY MEAGER...AROUND
25 KNOTS OR LESS.

DESPITE ADJUSTING MAX/MIN TEMPERATURES DOWNWARD THIS WEEK, MAX/MIN
TEMPERATURES HAVE STILL BEEN SLIGHTLY WARMER THAN OBSERVATIONS.
TRIED TO ADJUST FOR THE WARM BIAS...BUT STILL MAY BE TOO WARM
THROUGH THE WEEKEND.

.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 254 AM CDT FRI MAY 22 2015

RESPECTABLE MODEL RUN TO RUN CONSISTENCY HAS PERSISTED OVER THE PAST
72 HOURS WITH RESPECT TO THE OVERALL MID TROPOSPHERIC PATTERN ACROSS
NORTH AMERICA. A RIDGE BOTH SURFACE AND ALOFT OVER THE SE U.S. IS
EXPECTED...WHILE SOME SEMBLANCE OF AN UPPER TROF OVER THE WEST 1/2
OF THE CONUS BREAKS DOWN AND RESULTS IN A BROAD WSW FLOW ALOFT
ACROSS MUCH OF THE COUNTRY BY MID TO LATE WEEK. WARM AND MUGGY
CONDITIONS CAN BE EXPECTED DURING THE LONG TERM. A BLEND OF ENSEMBLE
MOS...AND EXISTING NUMBERS WERE USED FOR TEMPS.

FOR MEMORIAL DAY...WILL HOLD ONTO LIKELY POPS. BUT AGAIN...TO OFFER
ANY DETAIL ON PLACEMENT OF HIGHER VS. LOWER POP VALUES IS NOT
ATTAINABLE GIVEN MODEL OUTPUT (ECMWF AREA WIDE...GFS NOW HIGHER POPS
EAST VS. WEST 2/3 OF THE AREA). BEST POPS SHOULD SHIFT EAST MONDAY
NIGHT...THEN RISE AGAIN FROM THE SOUTH TUESDAY IN RESPONSE TO A MID
LEVEL S/WV FORECAST TO EJECT NE INTO THE PLAINS.

CONSIDERABLE SPREAD REMAINS WITHIN THE ENSEMBLE SUITES...WHICH IS
IMPORTANT FOR THE MID TO LATE WEEK PERIOD. THE OPERATIONAL MODELS
SHOW GREATER RESOLUTION WITH AND EMPHASIS ON THE AFOREMENTIONED
UPPER LEVEL TROF FORECAST TO MOVE FROM THE PLAINS TO THE OHIO VALLEY
REGION AND GREAT LAKES TUESDAY NIGHT THROUGH THURSDAY. THE ENSEMBLES
MEANS DO NOT RESOLVE THIS FEATURE TO THE SAME DEGREE. THEREFORE OUR
CONFIDENCE DECREASES IN THE OVERALL STRENGTH...FORECAST MOISTURE AND
RESULTANT PRECIP CHANCES ASSOCIATED WITH THIS FEATURE. WILL CONTINUE
WITH LOW TO MODERATE CHANCE POPS BUT NOTHING HIGHER FOR NOW. WE
BELIEVE THE BLEND SUITE WEIGHTED WITH WPC GUIDANCE OFFERS TOO MUCH
DETAIL AND OCCASIONALLY TOO HIGH POPS FOR SUCH UNCERTAINTY.


&&

.AVIATION...
ISSUED AT 1113 PM CDT THU MAY 21 2015

SFC HIGH PRESSURE HAS MOVED OVERHEAD WITH CLEAR SKIES AND LIGHT
WINDS. VFR CONDITIONS EXPECTED THROUGHOUT THE TAF FORECAST PERIOD
WITH SUNNY SKIES TMRW AND SW WINDS NEAR 10 KTS AT EVV/OWB AFTER
14Z.


&&

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

$$

SHORT TERM...SMITH
LONG TERM...CN
AVIATION...SP


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