Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 062349
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
649 PM EST FRI MAR 6 2015

.SYNOPSIS...
A RIDGE OF HIGH PRESSURE WILL DROP SOUTH TOWARD THE SOUTHEAST
U.S. OVERNIGHT. LOW PRESSURE AND AN ASSOCIATED WEAK COLD FRONT
WILL MOVE THROUGH THE GREAT LAKES AND OHIO VALLEY SATURDAY INTO
SATURDAY NIGHT. WEAK HIGH PRESSURE WILL BUILD BACK INTO THE REGION
FOR SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
A RIDGE OF HIGH PRESSURE WILL DROP SOUTH TOWARD THE SOUTHEAST U.S.
OVERNIGHT. AS IT DOES...LOW PRESSURE WILL MOVE TO THE WESTERN
GREAT LAKES. A PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS SHOULD
KEEP WINDS UP ACRS THE NORTHWEST OVERNIGHT. THE SOUTHEAST PART OF
THE FORECAST AREA WILL HAVE LIGHTER WINDS...AND WITH A DEEP SNOW
PACK...SOME VALLEY LOCATIONS MAY EVEN DECOUPLE AS TEMPERATURES
COOL. THE NAM AND GFS HAVE BEEN HAVING ISSUES WITH LOW LEVEL RH
LATELY...AND THIS WAS SEEN ON THE KILN 12Z SOUNDING IN WHICH THE
GFS HAD A MUCH HIGHER RH THAN REALITY. BELIEVE THE NAM AND GFS ARE
GROSSLY OVERDONE ON THE LOW LEVEL MOISTURE OVERNIGHT IN WHICH THEY
TRY TO DEVELOP LOW CLOUDS. THIS HAS TEMPERATURE IMPLICATIONS
(KEEPING IT WARMER) AS WELL AS THE WINDS AND CURRENT SNOW COVER.
THE RAP IS NOT AS MOIST AND IS MORE IN LINE WITH THE ECMWF. AS A
RESULT...AM FORECASTING JUST AN INCREASE IN HIGH AND MID LEVEL
CLOUDS OVERNIGHT WITH LOWS MORE WEIGHTED TOWARD THE ECMWF. HAVE
COOLED LOCATIONS IN OUR EAST/SOUTHEAST INTO THE SINGLE DIGITS AS
THESE LOCATIONS TEND TO DECOUPLE...AND EVEN MORE SO WITH SNOW
COVER.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
IN A WEST/NORTHWEST FLOW ALOFT...EMBEDDED S/WV ENERGY WILL MOVE
ACROSS THE REGION SATURDAY INTO SATURDAY NIGHT. THIS WILL BE
REFLECTED AT THE SFC BY LOW PRESSURE OVER THE GREAT LAKES WITH A
WEAK COLD FRONT PUSHING SOUTHEAST THROUGH THE REGION SATURDAY
NIGHT. AS STATED IN THE NEAR TERM...BELIEVE THE NAM AND GFS ARE
OVERDONE ON THE LOW LEVEL RH AND HAVE LEANED MORE TOWARD THE
ECMWF. WE SHOULD STILL SEE AN INCREASE IN CLOUDS IN THE WAA AHEAD
OF THE COLD FRONT. BELIEVE THE SYSTEM IS MOISTURE STARVED...AND
THE LIGHT QPF BEING GENERATED BY THE GFS AND NAM IS MORE A
REFLECTION OF ITS HIGH RH BIAS IN THE LOW LEVELS. HIGH RESOLUTION
MODELS CONCUR AND GENERATE WEAK PCPN NORTH OF THE AREA. THUS...WEAK
ISENTROPIC LIFT AHEAD OF THE FRONT SHOULD KEEP THE CHANCE OF
PCPN NORTH OF THE FORECAST AREA AND OVER THE GREAT LAKES. AGAIN...THE
PROSPECTS OF LOW CLOUDS ALONG WITH WIND AND SNOW COVER WILL PLAY A
HUGE PART ON HOW WARM IT WILL GET ON SATURDAY. WE WILL BE IN A WAA
PATTERN WITH A PRETTY GOOD SOUTH/SOUTHWEST FETCH WITH SOME
GUSTINESS. THE GFS AND NAM SEEM TO BE HOLDING TEMPERATURES DOWN
TOO MUCH GIVEN THE HIGH RH BIAS AND THE NAM/S TENDENCY TO KEEP
SKIN TEMPERATURES CLOSE TO FREEZING WHEN THEIR IS A SNOW COVER
DESPITE GOOD WAA. SO...HAVE TAKEN A BLEND OF THE PREVIOUS FORECAST
AND THE ECMWF WHICH YIELDS HIGHS IN THE UPPER 30S NORTH TO THE
LOWER 40S SOUTH. AS THE FRONT PUSHES THROUGH SATURDAY NIGHT...WINDS
WILL SHIFT TO THE WEST AND SKIES SHOULD EVENTUALLY BECOME PARTLY
CLOUDY. HAVE USED A BLEND OF MODELS/MOS GUIDANCE FOR OVERNIGHT
LOWS.

FOR SUNDAY INTO SUNDAY NIGHT...WEAK SURFACE HIGH PRESSURE WILL
SETTLE OVER THE OHIO VALLEY. WE WILL REMAIN IN A WEST/NORTHWEST
FLOW ALOFT WITH EMBEDDED DISTURBANCES BRINGING CLOUDS TO REGION
FROM TIME TO TIME. NAM/GFS ARE A LITTLE STRONGER WITH POST
FRONTAL CAA ON SUNDAY WHILE THE ECMWF SHOWS LITTLE CAA. HAVE TAKEN
A BLEND OF MODELS SO AS NOT TO BIAS FROM ONE END OF THE SPECTRUM
TO THE OTHER END OF THE SPECTRUM. THIS RESULTS IN SLIGHT COOLING
IN THE NORTH WITH TEMPERATURES SIMILAR TO SATURDAYS HIGHS IN THE
SOUTH. LOWS SUNDAY NIGHT WILL RANGE FROM THE MID 20S NORTH TO NEAR
30 SOUTH.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
FAIRLY BENIGN EXTENDED PATTERN WITH THE AREA. THOUGH SOME MODEL
DIFFERENCES IN A SOUTHERN STREAM SYSTEM LIFTING THROUGH THE KY/TN
AREA...WHICH MAY BRING SHOWERS FOR TUE/TUE NIGHT. FOR NOW HAVE
BROUGHT SHOWERS UP TO FCST AREA AND AFFECTING THE FAR SOUTH...BUT
GENERALLY WENT WITH A GFS/ECMWF BLEND WITH THE ECMWF BEING FURTHER
NORTH WITH THIS SYSTEM...SO SUBSEQUENT SHIFTS MAY NEED TO TWEAK
UPWARD. STARTED OUT WITH BELOW NORMAL TEMPERATURES WITH THE
ANTICIPATION OF LINGERING SNOW COVER...THOUGH SOME WARMING AS THIS
SYSTEM APPROACHES BRINGING AMPLE WAA.

DRY CONDITIONS THROUGH THE REMAINDER OF THE PERIOD...BUT AHEAD OF A
SYSTEM WHICH COULD BRING A WARM/WET PATTERN FOR NEXT WEEKEND.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS TO START WITH HIGH PRESSURE CENTERED TO THE SOUTH.
A WEAK AND MOISTURE-STARVED WAVE OF LOW PRESSURE MOVING THROUGH
THE GREAT LAKES MAY BRING MVFR CEILINGS TO NORTHERN TAF SITES DAY
CMH LCK AND ILN. FARTHER TO THE SOUTH...WENT WITH VFR THROUGH THE
PERIOD AT CVG AND LUK. BACKED OFF ON LOWERED CEILINGS FROM
PREVIOUS FORECAST BASED ON CONDITIONS UPSTREAM AND LATEST DRIER
MODEL TRENDS. TIGHT PRESSURE GRADIENT WILL CAUSE WINDS TO BE AN
ISSUE WITH SPEEDS REMAINING UP AROUND 10 KNOTS TONIGHT BEFORE
INCREASING SATURDAY WITH GUSTS TOPPING 20 KNOTS OUT OF THE
SOUTHWEST.

OUTLOOK...MVFR CIGS AND VSBYS POSSIBLE INTO SUNDAY.

&&

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

&&

$$
SYNOPSIS...HICKMAN
NEAR TERM...HICKMAN
SHORT TERM...HICKMAN
LONG TERM...JDR
AVIATION...CONIGLIO





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