Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 171038
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
638 AM EDT WED SEP 17 2014

.SYNOPSIS...
HIGH PRESSURE WILL KEEP DRY CONDITIONS ACROSS THE AREA THROUGH
SATURDAY. A COLD FRONT WILL APPROACH THE AREA ON SUNDAY BRINGING
THE NEXT CHANCE FOR SHOWERS AND THUNDERSTORMS.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
STRATUS DECK FROM 3-4KFT IS DEVELOPING OVER CWA AND LIMITING MOST
OF THE AREA FROM SEEING ANY FOG BECOMING DENSE. THE STRATUS WILL
MIX OUT AS DAYLIGHT HITS THE COLUMN AND GENERALLY SUNNY SKIES
WITH FAIR WX CU IS EXPECTED FOR THE REMAINDER OF THE DAY. HIGHS
WILL TOP OUT WITHIN A FEW DEGREES OF 70 ACROSS MUCH OF THE REGION.
THE AXIS OF THE HIGH PRESSURE WILL BE CENTERED OVER THE REGION
WITH GENERALLY LIGHT WINDS TURNING NORTHWEST BY THE END OF THE
DAY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
A GENERALLY BENIGN WEATHER PATTERN WITH THE HIGH PRESSURE SETTLED
OVER THE REGION WILL BE IN THE OFFING FOR THE REST OF THE WORK
WEEK. NORTH WINDS WILL PUSH THE CORE OF COLD AIR OVER THE CWA
EARLY THURSDAY...AND HIGHS WILL ONLY BE A DEGREE OR TWO WARMER
THAN WEDNESDAY WITH SUNNY SKIES. WITHOUT THE COLD PUSH...THE CLEAR
SKIES WOULD NORMALLY INDICATE A GOOD 5-7 DEGREE INCREASE FROM THE
PREVIOUS DAY GIVEN THE DRY AIRMASS AND SUNNY SKIES. THIS INCREASE
IN HIGHS WILL OCCUR ON FRIDAY WHEN READINGS ACROSS THE REGION RISE
TO THE MIDDLE AND UPPER 70S.

THE AXIS OF THE HIGH WILL SLIDE EAST ON FRIDAY AND SOUTHEAST WIND
WILL TURN SOUTHWEST FRIDAY NIGHT.

OVERNIGHT LOWS THROUGH THE PERIOD WILL BE IN THE 40S UNDER
GENERALLY GOOD RADIATIONAL COOLING...RISING INTO THE 50S BY
FRIDAY NIGHT.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
SURFACE HIGH PRESSURE WILL CENTERED OVER SOUTHERN ONTARIO AND QUEBEC
ON FRIDAY MORNING...MOVING OFF THE EAST COAST BY SATURDAY MORNING.
ALONG WITH A SHORT-TERM FLATTENING OF THE MID-LEVEL
PATTERN...LEADING TO HEIGHT RISES OVER THE OHIO VALLEY AS THE EAST
COAST TROUGHING DISSIPATES...THIS WILL SIGNAL A PATTERN CHANGE
HEADING INTO THE WEEKEND. AS A RESULT...SURFACE WINDS WILL TAKE A
SOUTHERLY COMPONENT...LEADING TO A WARM ADVECTION PATTERN FOR FRIDAY
AND SATURDAY. THE REMAINING INFLUENCE OF THE SURFACE HIGH WILL
PROVIDE FOR A DRY STARTING POINT...AND MOSTLY SUNNY CONDITIONS. THE
WARM ADVECTION PATTERN WILL STRENGTHEN ON SATURDAY...WITH SURFACE
WINDS TURNING TO THE SSW...AND A TROUGH OVER THE NORTHERN PLAINS
BEGINNING TO GET A LITTLE CLOSER TO THE AREA. FRIDAY TEMPERATURES
WILL LIKELY STILL REMAIN JUST BELOW NORMAL...BUT NEAR TO SLIGHTLY
ABOVE NORMAL TEMPERATURES ARE EXPECTED WITH THE WARMER FLOW ON
SATURDAY. THROUGH SATURDAY...FORECAST MODEL AGREEMENT IS STRONG.

AS THE TROUGH APPROACHES THE OHIO VALLEY ON SUNDAY MORNING...SURFACE
LOW PRESSURE IS EXPECTED TO DEVELOP IN THE NORTHERN GREAT LAKES. A
COLD FRONT WILL EXTEND SOUTH FROM THIS LOW...AND WILL MOVE THROUGH
THE ILN CWA ON SUNDAY. THESE BASIC DETAILS ARE FAIRLY CERTAIN...BUT
THERE IS MUCH GREATER MODEL SPREAD IN THE SPECIFICS OF HOW THE
TROUGH AND FRONT ARE BEING DEPICTED. THE AMPLITUDE OF THE UPPER
TROUGH...IN PARTICULAR...SHOWS MARKED DIFFERENCES BETWEEN THE GFS
AND ECMWF (AND EVEN WITHIN THE INDIVIDUAL GFSE MEMBERS). AMONG THE
FLATTEST SOLUTIONS IS THE 12Z ECMWF...WHICH PIVOTS THE FRONT IN AN
ORIENTATION THAT WOULD PROVIDE LITTLE IN THE WAY OF FORCING OR SHEAR
OVER THE OHIO VALLEY. THE 12Z OPERATIONAL GFS IS AMONG THE STRONGEST
SOLUTIONS...WITH A CLOSED 500MB LOW THAT IS NOT SUPPORTED BY ITS
ENSEMBLE MEMBERS. THUS...IT IS NOT SURPRISING THAT TIMING AND
STRENGTH DIFFERENCES WITH THE SURFACE FRONT ARE A FORECAST
CHALLENGE. THOUGH PRECIPITATION IS FAIRLY LIKELY TO OCCUR ON SUNDAY
FOR THE ILN CWA...POPS HAVE BEEN LIMITED TO 40 PERCENT UNTIL TIMING
AGREEMENT IN THE MODELS BECOMES STRONGER. ALSO UNCERTAIN IS THE
EVENTUAL MAGNITUDE OF THE FLOW ALOFT AND WARM ADVECTION AT THE
SURFACE...WHICH WILL CERTAINLY IMPACT WHETHER OR NOT SHEAR AND
INSTABILITY (RESPECTIVELY) ARE ABLE TO BECOME A CONCERN.

BEHIND THE FRONT (FROM SUNDAY NIGHT INTO NEXT WEEK)...A COOLER AND
DRIER AIR MASS OF CANADIAN ORIGIN WILL MOVE INTO PLACE. THIS LARGE
AREA OF HIGH PRESSURE IS FORECAST TO COVER A SIGNIFICANT PORTION OF
THE MIDWESTERN STATES AND INTO THE OHIO VALLEY. AFTER A DAY ON
SUNDAY THAT IS LIKELY TO FEATURE A TEMPERATURE GRADIENT (WITH WARM
CONDITIONS REMAINING IN THE SOUTHEASTERN CWA)...THE FIRST PART OF
THE WEEK WILL FEATURE TEMPERATURES FALLING WELL BELOW NORMAL.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AREA OF STRATUS HAS DEVELOPED ACROSS THE MAJORITY OF THE TAFS. THE
WESTERN EDGE OF THE DECK HAS SOME MVFR CIGS IN IT. THE CLOUDS HAVE
HELPED MITIGATE SOME OF THE DENSE FOG.

EXPECT THE STRATUS TO LINGER ACROSS THE TAFS FOR THE MORNING HOURS
BEFORE SCATTERING OUT AROUND NOON.

AN H5 S/WV IS FORECAST TO PUSH INTO THE AREA AFT 18Z. EXPECT SOME
MID LEVEL CLOUDS WITH THE PASSAGE OF THE S/W. MODELS ARE
SUGGESTING THAT THE SRN TAFS WILL BE AFFECTED BY MORE MID CLOUDS
THAN THE NRN TAFS. BACK EDGE OF THE AC WILL WORK EAST OF THE TAFS
BY 06Z...LEAVING JUST SOME SCT CLOUDS AND THE POSSIBILITY OF SOME
SCATTERED MVFR FOG.

OUTLOOK...THUNDERSTORMS POSSIBLE SUNDAY.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.

&&

$$
SYNOPSIS...FRANKS
NEAR TERM...FRANKS
SHORT TERM...FRANKS
LONG TERM...HATZOS
AVIATION...SITES






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