941
FXUS61 KILN 041939
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
339 PM EDT SAT JUL 4 2009
SYNOPSIS
WIDESPREAD RAIN WILL MOVE ACROSS THE REGION TONIGHT AS LOW PRESSURE
MOVES THROUGH THE LOWER OHIO VALLEY. RAIN MAY LINGER INTO SUNDAY
MORNING...BEFORE WEAK HIGH PRESSURE BUILDS IN FOR THE FIRST PART
OF THE WORK WEEK.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
LARGE AREA OF PCPN OVERSPREADING THE FCST AREA FROM THE WEST THIS
AFTN. MUCH OF THE PCPN IS LIGHT ATTM...WITH RATES AT 0.05 IN/HOUR
AND LESS. THIS IS ASSOCD WITH A LEAD S/WV IN UPR LVL NW FLO
PATTERN. TEMPS WERE BEING HELD DOWN BY THE CLOUDS AND PCPN THIS
AFTN...RUNNING FROM THE U60S WEST INTO THE M70S OVER THE EAST
WHERE BNDRY LYR HEATING HAD BEEN GREATER EARLIER TODAY.
PCPN ARRIVING AS EXPECTED AND LIKELY TO HANG AROUND TO SOME DEGREE
THRU TONIGHT...WHICH UNFORTUNATELY WILL RUIN A LOT OF HOLIDAY
PLANS. MODEL GUIDANCE IN EXCELLENT AGREEMENT WRT TO TRACK OF SFC
LO CURRENTLY LOCATED OVER NRN MISSOURI THIS AFTN. THIS SYSTEM HAS
A WINTER-LIKE SETUP TO IT WRT TO SFC LO TRACK AND MID/UPR LVL
FORCING PROPERTIES...FEATURES YOU WOULD TYPICALLY SEE WITH A
STRONG CLIPPER. LIGHTER PCPN CURRENTLY OVER AREA WILL GRADUALLY
INTENSIFY INTO THE EVNG HOURS AS SECONDARY STRONGER S/WV DIVES
INTO REGION AND SFC LO MOVES INTO WRN KY. APPEARS AN AXIS OF
HEAVIER RAIN WILL ALIGN ALONG AND JUST SOUTH OF THE OHIO RIVER
THIS EVNG AND INTO THE OVERNIGHT WHERE LO LVL CONV STRENGTHENS AT
NOSE OF 850 LLJ. RUC/NAM/GFS ALL INDCG MID LVL DEFORMATION BAND
SETTING UP ALONG THE OHIO RIVER JUST NORTH OF THE BAROCLINIC ZONE
AROUND 00Z AND PERSISTING THRU THE NIGHT AS SFC LO MAKES SLOW
PROGRESS SOUTHEAST ACRS WRN/SRN KY. PRESENCE OF DEFORMATION AXIS
AND UPR LVL DIFFLUENT FLO AS UPR JETLET PASSES THRU REGION WILL
ACCENTUATE RAINFALL OVER SRN 1/2 FCST AREA.
EXPECT AXIS OF HEAVIEST RAINFALL WILL RUN ROUGHLY FROM JUST SOUTH
OF KIND...THRU THE CVG METRO AND NRN KY E/SE TOWARDS ERN KY AND
KHTS WHERE PWATS WILL MAX BTWN 1.75 AND 2 INCHES. NAM REALLY CRANKING
OUT QPF VALUES OVERNIGHT (IN EXCESS OF 3 INCHES WITHIN THE
HEAVIEST AXIS OF RAIN) AND CONSIDERING RAINFALL TOTALS THAT WERE
EXPERIENCED IN CNTRL MISSOURI THIS MRNG (3-4 INCHES)...CANNOT
ENTIRELY RULE OUT NAM QPF TOTALS. SREF/GFS/GEM ALL FAVORING MORE
OF A 1-2 INCH SWATH WITH IN THE AXIS OF HEAVIEST RAINFALL WHICH
SEEMS VERY REASONABLE...WITH THE POSSIBILITY OF LOCALLY HIGHER
AMOUNTS. AM ALSO GROWING CONCERNED THAT WARM RAIN PROCESSES MAY BE
IN PLAY OVER THE SOUTH TONIGHT WITH THE FREEZING LVLS ROUGHLY
HOLDING IN THE 13-14KFT RANGE FOR THE DURATION OF THE NIGHT. WITH
SUCH A DEEP WARM LAYER BELOW THIS LVL...THIS COULD ADD EVEN MORE
OPPORTUNITY TO AN EXTENDED PERIOD OF HEAVY RAINFALL. FOR ALL OF
THESE REASONS...WILL INCLUDE HVY RAINFALL MENTION IN THE ZONE
FCST. BRIEFLY TOYED WITH IDEA OF A FLOOD WATCH IN FAR SOUTH
TONIGHT...BUT RIVERS AND STREAMS REMAIN AT CLIMATOLOGICALLY LOW
LEVELS AND 6/12 HOUR FFG VALUES ARE AROUND 3 INCHES. NEVERTHELESS...
EXPECT SOME LOCALIZED FLOODING ISSUES LATER TONIGHT...ESPECIALLY
WITHIN THE HEAVIER AXIS OF RAIN.
WILL ROLL WITH CAT POPS OVER THE SOUTH TONIGHT. MODELS CONTINUE TO
ADVERTISE WEAK ELEVATED INSTABILITY NEAR AND SOUTH OF THE OHIO
RIVER AND FOR THAT REASON...HAVE CONTINUED WITH SCHC TSTMS.
AMOUNTS WILL DROP OFF QUICKLY FURTHER NORTH THRU FCST AREA...WITH
LESS THAN A QUARTER INCH NORTH OF THE I-70 CORRIDOR. THERE IS
LIKELY TO BE A SHARP DELINEATION TO THE PCPN AREA THAT WILL ALIGN
SOMEWHERE ALONG THE NRN FRINGE OF THE FCST AREA OR JUST NORTH ACRS
NORTH CNTRL OH OVERNIGHT. BACK EDGE OF PCPN SHIELD WILL SLOWLY
DROP SOUTHEAST PRIOR TO DAWN...BUT CONTINUED MID LVL DEFORMATION AXIS
SHOULD ENSURE RAINFALL CONTINUES ACRS FAR SRN FCST AREA THRU
DAYBREAK.
TEMPS...WENT SLIGHTLY ABV MOS FOR LOWS OVER THE SOUTH TONIGHT...
AND NEAR MOS GUID ELSEWHERE AS TEMPS FALL INTO THE U50S/L60S.
SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/
MODEL CONSENSUS HAS COME IN SLOWER WITH SOUTHEAST PROGRESSION TO
SFC LO AND THUS...PCPN SHIELD NORTH OF THE LOW WILL TAKE SOME TIME
GETTING OUT OF SRN FCST AREA SUN MRNG. HAVE HELD ON TO POPS FOR
MAINLY SUN MRNG SOUTHEAST OF I-71 WITH LKLY POPS OVER FAR SE FCST
AREA. PCPN MAY TAKE GOOD PART OF THE DAY TO COMPLETELY CLEAR THE
FAR SE COUNTIES (SCIOTO/LEWIS) WITH ONLY WEAK SFC HI PRES BUILDING
IN FROM THE NORTHWEST. MODEL SOUNDINGS SHWNG A LOT OF LO LVL
MOISTURE HANGING AROUND SUNDAY. WITH MID LVL TROF AXIS NOT
SHIFTING EAST UNTIL LATE AFTN...LIKELY TO BE SOME CU/SC REDVLPMNT
FURTHER NORTH/WEST. HAVE INCREASED CLOUDS QUITE A BIT FROM PREV
FCST WITH JUST A SLOW DECREASE IN CLOUDS FROM THE NORTH INTO THE
AFTN HOURS. SKIES WILL REMAIN MSTLY CLDY OVER SRN FCST AREA FOR
MUCH OF THE DAY.
AS MENTIONED ABV...WEAK SFC HI PRES WILL BUILD INTO THE REGION SUN
NIGHT. YET ANOTHER UPR LO WILL BEGIN ITS SOUTHWARD TREK FROM JAMES
BAY SUN NIGHT...DROPPING INTO NRN GRT LKS BY DAYBREAK MON. S/WV
ROTATING AROUND THE BASE OF THE TROF WILL MOVE FROM LWR MICHIGAN
INTO NE OHIO MON MRNG. MUCH OF THE MOISTURE ASSOCD WITH THIS
FEATURE WILL REMAIN DISPLACED NORTHEAST OF THE REGION THRU 12Z
MON...SO WILL MAINTAIN MSTLY CLR SKIES SUN NIGHT. MORE WITH
REGARDS TO THIS TROF IN THE LONG TERM DISCUSSION.
TEMPS...HAVE LOWERED HIGHS EVERYWHERE SUN...AND UNDERCUT MOS GUID
OVER SRN FCST AREA WHERE CLOUD COVER AND SOME PCPN WILL BE MORE
PREVALENT. RANGED HIGHS FROM THE L70S OVER THE SOUTHEAST INTO THE
U70S OVER WEST CNTRL OH WHERE EXPECT SOME SUNSHINE DURING THE
AFTN. LOWS WILL DROP INTO THE M/U50S SUN NIGHT.
LONG TERM /MONDAY THROUGH SATURDAY/
HAVE DISCOUNTED THE NAM-WRF FOR MONDAY AND TUESDAY WHICH GENERATES
PCPN IN NW FLOW ALOFT...AND ALSO SHOWS MORE OF A BOUNDARY PASSING
ACROSS THE AREA ON TUESDAY. IN CONTRAST...ECMWF AND LATEST GFS KEEP
REGION DRY WITH SFC HIGH PRESSURE BUILDING OVER THE AREA MONDAY
NIGHT THROUGH TUESDAY NIGHT. THEREAFTER...SFC HIGH MOVES OFF TO THE
EAST AND MID LVL RIDGING TRIES TO POKE NE INTO THE OHIO VALLEY FOR
THURSDAY AND FRIDAY. THIS SCENARIO WILL ALLOW TEMPERATURES TO
GRADUALLY WARM TO NEAR AND SLIGHTLY ABOVE NORMAL READINGS BY THE END
OF THE WEEK. LONG RANGE MODELS INDICATE THAT THE NEXT FRONT SHOULD
PASS ACRS THE REGION BETWEEN THE FRIDAY NIGHT THROUGH SATURDAY TIME
FRAME. HAVE SIDED WITH THE ECMWF MODEL WHICH BRINGS THE FRONT THROUGH
FRIDAY NIGHT INTO SATURDAY MORNING. TEMPERATURES WILL COOL SLIGHTLY
BEHIND THE FRONT.
AVIATION /19Z SATURDAY THROUGH THURSDAY/
GENERALLY LIGHT WINDS FROM THE SOUTH ARE FOUND AHEAD OF THE RAIN
AREA THIS AFTERNOON. VFR LIGHT RAIN WILL CONTINUE OVER CVG FOR A
FEW HOURS BEFORE HEAVIER SHOWERS REDUCE CIGS AND VSBYS TO MVFR AND
THEN OCCASIONALLY IFR OVERNIGHT AS A NICE HEAVY RAIN BAND SETS UP
HERE. TRIED TO INDICATE LESS RAIN AT KLUK EVEN THOUGH THEY HAVE
VERY LITTLE SEPARATION IN SPACE AS MODELS ARE REALLY INDICATING A
STRONG NORTH/NORTHEAST GRADIENT TO THE HEAVIER SHOWERS.
BEST RAINFALL WILL OCCUR SOUTHEAST OF THE H7 LOW AS IT TAKES AIM
ON SOUTHERN OHIO. LOW BREAKS UP FROM 6-12Z AND THEN CROSSES CWA BY
18Z WITH RAIN ENDING FROM W-E IN ITS WAKE. DON'T THINK THAT CMH
WILL SEE ANYTHING BUT A PASSING SPRINKLE...AND DAYTON MAY GET A
FEW SHOWERS BEFORE SOURCE OF LIFT MAKES THE RAINFALL DIG FURTHER
SOUTH.
EVEN IF RAIN STOPS FOR A PERIOD...LLVL MOISTURE WILL RESULT IN
REDUCED VSBYS WITH SOME LOW CLOUDS...ESPECIALLY IN THE METRO CINCY
AREA.
OUTLOOK...MVFR/IFR CEILINGS AND VISIBILITIES WILL REMAIN POSSIBLE
THROUGH SUNDAY MORNING.
ILN WATCHES/WARNINGS/ADVISORIES
OH...NONE.
KY...NONE.
IN...NONE.
SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM...HICKMAN
AVIATION...FRANKS
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