000
FXUS61 KILN 151804
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
204 PM EDT SAT JUN 15 2013

.SYNOPSIS...
HIGH PRESSURE ACROSS THE REGION WILL SHIFT EAST TODAY AS WEAK LOW
PRESSURE APPROACHES FROM THE WEST. THE LOW WILL PASS NORTH OF OUR
AREA SATURDAY NIGHT WHICH WILL DRAG A BOUNDARY ACROSS THE AREA.
THIS BOUNDARY WILL BE THE FOCUS FOR SHOWER AND THUNDERSTORM
ACTIVITY SATURDAY NIGHT THROUGH SUNDAY NIGHT.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LIGHT ECHOES ON RADAR OVER NORTHERN INDIANA HAVE LARGELY
DISSIPATED...AND IR SATELLITE DEPICTS THE GRADUAL WARMING OF THE
AREA OF CLOUDS OVER INDIANA AND ILLINOIS. THE GENERALLY-THIN AREA
OF CIRRUS OVER THE ILN CWA RIGHT NOW SHOULD ALLOW FOR
MOSTLY-UNINHIBITED WARMING (AT LEAST EARLY IN THE DAY AND BEFORE
CUMULUS DEVELOPMENT). HIGH TEMPS WERE MOVED UP A DEGREE OR TWO AS
A RESULT...BACKED ALSO BY HRRR/RAP RAW MODEL FORECASTS (WHICH BOTH
SEEM TO GO EVEN TOO HIGH IN BRINGING THE CWA INTO THE UPPER 80S).
ALSO MADE SOME MINOR CHANGES TO PRECIPITATION TIMING
TONIGHT...ALLOWING FOR A SLIGHT CHANCE IN THE NORTHWESTERN CWA BY
LATE AFTERNOON.

PREVIOUS DISCUSSION >
SFC HIGH PRESSURE WILL RETREAT INTO THE APPALACHIANS TODAY.
MEANWHILE...H5 RIDGING WILL BUILD E FROM THE MS VALLEY TO LOWER
GREAT LAKES/OH VALLEY...BUT A S/W RIDING ACROSS THE TOP OF THE
RIDGE WILL CAUSE IT TO FLATTEN OUT. THE UPPER LEVEL ENERGY WILL
COMBINE WITH LOW LEVEL RETURN FLOW AND INCREASING DEWPOINTS TO
PRODUCE WEAK ISENTROPIC LIFT ACROSS THE NW. ADDED A 20 POP ACROSS
THE NW COUNTIES FOR LATE THIS WEEK.

TEMPERATURES WARMED MORE THAN ANTICIPATED YESTERDAY. WITH WARMER
AIR ON THE BACKSIDE OF THE HIGH...HIGHS SHOULD BE A COUPLE OF
DEGREES WARMER. SO PUSHED THEM INTO THE LOWER 80S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
ANOTHER S/W WILL PUSH A LOW PRESSURE CENTER ACROSS THE GREAT
LAKES TONIGHT. WEAK INSTABILITY AND INCREASING LOW LEVEL JET
OVERNIGHT SHOULD KICK OFF SOME CONVECTION IN THE VICINITY OF A
TRAILING FRONTAL BOUNDARY. IT LOOKS LIKE THE BEST CHC OF PCPN
TONIGHT WILL BE LATE IN THE PERIOD...WITH THE HIGHEST POPS IN THE
NW.

THE FRONT TRIES TO PUSH ACROSS THE FA SUNDAY...BUT WEAKENS AND
STALLS. THERE SHOULD BE ENUF CONVERGENCE FOR CONVECTION TO POP UP ON
SUNDAY. KEPT POPS IN THE CHC CATEGORY HOWEVER. LIFT GRADUALLY
SLIPS SOUTHEAST OF OUR AREA OVERNIGHT SUNDAY NIGHT...WITH
DECREASING POPS FROM NORTHWEST TO SOUTHEAST EXPECTED DURING THAT
TIME.

WITH THE FRONT STALLED TO THE S OF THE FA ON MONDAY...COULD SEE
SOME CONVECTION DEVELOP AGAIN ACROSS THE S ON MONDAY.

INCREASING CLOUDS TONIGHT WILL HELP KEEP LOWS GENERALLY IN THE MID
60S. TEMPERATURES WILL WARM INTO THE LOWER 80S SUNDAY AND MONDAY.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
HAVE USED A BLEND OF NCEP/WPC GUIDANCE...14.00Z ECWMF AND 14.12Z CMC
FOR THE IMMEDIATE AND LONGER TERM FORECAST. THE OPERATIONAL 14.12Z
GFS IS SUFFERING SUBSTANTIALLY FROM CONVECTIVE FEEDBACK AND HAVE
DISCOUNTED IT.

FOR TUESDAY INTO TUESDAY NIGHT...COLD FRONT WILL PUSH SOUTH AND EAST
AWAY FROM THE REGION AS AN EXPANSIVE AREA OF SURFACE HIGH PRESSURE
BUILDS IN FROM THE NORTHWEST. PCPN APPEARS TO BE MAINLY ALONG AND
AHEAD OF THE COLD FRONT SO MOST OF THIS MAY BE OVER WITH BY TUESDAY
MORNING ACRS THE SOUTH WHILE SKIES CLEAR FROM THE NORTH.

FOR THE PERIOD WEDNESDAY THROUGH FRIDAY...OUR REGION WILL BE
DOMINATED BY NORTHWEST FLOW ALOFT. SPRAWLING SURFACE HIGH WILL
GRADUALLY MOVE OFF TO THE EAST. WILL CONTINUE WITH DRY WEATHER
ATTM...ALTHOUGH SOME EMBEDDED DISTURBANCES IN THE FLOW ALOFT MAY
AFFECT THE WRN PARTS OF THE AREA FRIDAY OR SATURDAY.

TEMPERATURES WILL FALL TO BELOW SEASONAL NORMALS INTO MID WEEK THEN
RECOVER TO TYPICAL LATE JUNE READINGS TOWARD THE END OF THE WEEK.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
ALTHOUGH MOST OF TODAY WILL BE DRY...SHOWERS THAT HAVE DEVELOPED
IN NORTHERN INDIANA WILL POSSIBLY AFFECT THE NORTHERN TAF SITES
LATER THIS AFTERNOON. WITH GENERALLY DRIER AIR OVER OHIO (COMPARED
TO INDIANA)...IT IS UNLIKELY THAT PRECIPITATION WILL BE
SIGNIFICANT...AND CLOUD BASES IN THE REGION SHOULD REMAIN FAIRLY
HIGH.

A MORE SIGNIFICANT CHANCE FOR PRECIPITATION WILL COME DURING THE
OVERNIGHT HOURS...AND INTO EARLY SUNDAY MORNING. THIS ACTIVITY
WILL FIRST AFFECT THE NORTHERN TAF SITES...BEFORE GRADUALLY MOVING
SOUTHEAST. A TEMPO GROUP WAS REFINED TO ACCOUNT FOR THE MOST
LIKELY TIME FRAME FOR THESE SHOWERS...BUT THE GENERALLY SLOW
MOTION OF THE APPROACHING FRONTAL BOUNDARY WILL MEAN THAT SHOWERS
MAY BE POSSIBLE THROUGH THE MORNING HOURS.

ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING THE
AFTERNOON ON SUNDAY...BUT A SPECIFIC FORECAST FOR THIS ACTIVITY
WILL HAVE TO BE MADE AFTER THE SITUATION OVERNIGHT IS MORE
CERTAIN. REDUCED AVIATION CONDITIONS WILL BE POSSIBLE WITH STORMS
OR HEAVIER SHOWERS.

OUTLOOK...SHOWERS AND THUNDERSTORMS ARE POSSIBLE SUNDAY THROUGH
MONDAY NIGHT.

&&

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

&&

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