Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 212321
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
721 PM EDT MON APR 21 2014

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 358 PM EDT MON APR 21 2014

A COLD FRONT WILL MOVE THROUGH LATE TONIGHT AND THIS WILL KEEP
CHANCES FOR RAIN AND ISOLATED THUNDERSTORMS IN THE FORECAST
THROUGH THE NIGHT. HIGH PRESSURE WILL USHER IN DRY WEATHER TUESDAY
INTO THURSDAY. COLD TEMPERATURES TUESDAY NIGHT COULD LEAD TO SOME
FROST. ANOTHER FRONTAL PASSAGE THURSDAY NIGHT WILL BRING MORE
THUNDERSTORM CHANCES AND COOLER WEATHER IN ITS WAKE.

&&

.NEAR TERM /TONIGHT/...

ISSUED AT 358 PM EDT MON APR 21 2014

FORECAST FOCUS IS ON POPS AND TIMING WITH FRONTAL SYSTEM TONIGHT.
MODELS ARE IN GOOD AGREEMENT AND WILL USE A CONSENSUS.

AT 19Z WSR88D SHOWED A FEW ECHOES ACROSS THE NORTHWEST PART OF THE
AREA...BUT AS OF YET NO OBSERVED RAIN AT THE GROUND WITH DEW POINTS
STILL IN THE MID 40S TO AROUND 50 AND TEMPERATURES IN THE 70S. THE
COLD FRONT WAS GETTING INTO WESTERN ILLINOIS AND A FEW THUNDERSTORMS
WERE ACROSS NORTHERN ILLINOIS WITH SCATTERED SHOWERS IN CENTRAL
ILLINOIS AND KENTUCKY. WITH THE DRY DEW POINTS IT IS TAKING SOME
TIME FOR THE COLUMN TO SATURATE.

THE BEST FORCING WILL REMAIN ALONG/JUST AHEAD OF THE COLD FRONT
TONIGHT. WITH SOME INSTABILITY AROUND WILL CONTINUE TO INCLUDE
ISOLATED THUNDER. BROUGHT LIKELY POPS INTO THE NORTHWEST BY 0Z AND
OVERSPREAD THE AREA THROUGH 3Z WITH DECREASING POPS IN THE NORTHWEST
BY 12Z. ALSO HI RES MODELS SHOW FRONTAL FORCING DECREASING WITH TIME
SO DROPPED TO ONLY CHANCE POPS IN THE SOUTHEAST BY 9Z EVEN WITH THE
FRONT STILL MOVING THROUGH.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...

ISSUED AT 358 PM EDT MON APR 21 2014

BY TUESDAY MORNING 12Z THE COLD FRONT SHOULD BE THROUGH THE AREA AND
CLOUDS SHOULD START CLEARING OUT FROM THE NORTHWEST. CLEARING WILL
LAG FRONTAL PASSAGE BY A BIT BUT BY MIDDAY SHOULD SEE MOST OF THE
CLOUD COVER MOVING OUT OF THE AREA. FOR TEMPERATURES USED AN AVERAGE
WITH MOS BEING CLOSE.

FORECAST FOCUS IS ON LOW TEMPERATURES ON TUESDAY NIGHT. TIME HEIGHTS
AND UPSTREAM LOCATION OF UPPER RIDGE AXIS INDICATE SOME POTENTIAL
FOR CIRRUS TUESDAY NIGHT. SURFACE HIGH PRESSURE WILL STILL BE
BUILDING IN FROM THE NORTH SO PRESSURE GRADIENT NEVER QUITE GOES
SLACK WHICH SHOULD ALLOW WINDS TO STAY AROUND 5 KTS OR SO AND NOT GO
CALM. THESE CONDITIONS DO NOT LINE UP FOR IDEAL RADIATIONAL COOLING
SO PREFER TO STICK CLOSER TO THE WARMER MAV GUIDANCE NUMBERS WITH
LOWS FROM 33 TO THE UPPER 30S. THE WIND COULD ALSO HELP SOMEWHAT
DECREASE THE POTENTIAL FOR FROST FORMATION...BUT THIS WILL STILL BE
A CLOSE CALL. FOR NOW WILL ADD PATCHY FROST TO THE FORECAST BUT IF
WINDS LOOK LIGHTER IN SUBSEQUENT FORECASTS WILL HAVE TO BEEF UP
COVERAGE AND POTENTIALLY GO WITH A HEADLINE.

THE REST OF THE SHORT TERM WILL BE PRETTY QUIET UNDER HIGH PRESSURE.
USED AN AVERAGE OF MOS FOR HIGHS AND LOWS. NEXT CHANCE FOR
THUNDERSTORMS MOVES IN THURSDAY AFTERNOON AS A COLD FRONT MOVES INTO
THE NORTHWEST BY AROUND 0Z FRIDAY.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
ISSUED AT 300 PM EDT MON APR 21 2014

THE LONG TERM PERIOD WILL START OUT WET AND END WET. HOWEVER THERE
ARE A LOT OF DIFFERENCES BETWEEN MODELS ON HOW QUICKLY THE RAIN
RETURNS LATE IN THE LONG TERM.

A COLD FRONT WILL MOVE RAPIDLY EAST ACROSS OUR REGION THURSDAY NIGHT
PRODUCING NUMEROUS SHOWERS AND A FEW THUNDERSTORMS THURSDAY
EVENING.  THESE WILL GRADUALLY END OVER NIGHT AS THE COLD FRONT
MOVES RAPIDLY EAST.

FRIDAY THROUGH SATURDAY WILL BE MOSTLY DRY.  WILL MENTION A SLIGHT
CHANCE OF SHOWERS IN OUR FAR NORTH SATURDAY AS SEVERAL MODELS
INDICATE NEAR TRACE QPF AMOUNTS THERE AND IT IS ALSO CLOSER TO THE
SURFACE LOW OVER THE GREAT LAKES.

MODELS MOVE STRONG HIGH PRESSURE INTO SOUTHERN CANADA NORTH OF THE
GREAT LAKES.  THEY ALSO DEVELOP A WARM FRONT OVER THE LOWER
MISSISSIPPI VALLEY AS LOW PRESSURE MOVES INTO THE CENTRAL PLAINS
SUNDAY.  THE EURO IS AGGRESSIVE IN SPREADING RAIN INTO OUR REGION AS
EARLY AS SATURDAY NIGHT...WHILE THE GFS ALL BUT FAR SOUTHWEST
SECTIONS DRY THROUGH THE PERIOD.  THE GEMNH MODEL IS NOT AS SLOW AS
THE GFS...BUT SOMEWHAT IN BETWEEN MODELS.  WILL LEAN IN THAT
DIRECTION AS THIS SEEMS A GOOD COMPROMISE.

MADE A FEW TWEAKS IN TEMPERATURES...BUT OVERALL ALL BLEND
TEMPERATURES SEEEM OK MOST PERIODS.

&&

.AVIATION /DISCUSSION FOR THE 220000 TAF ISSUANCE/...

ISSUED AT 701 PM EDT MON APR 21 2014

MOSTLY VFR...HOWEVER A PERIOD OF MVFR CEILINGS POSSIBLE AFTER
MIDNIGHT TONIGHT TO NEAR SUNRISE TUESDAY. MODERATE TO BRISK WINDS
WILL OCCUR TUESDAY ALONG A COLD FRONT AND POST FRONTAL PASSAGE.

SCATTERED SHOWERS WILL INCREASE ACROSS OUR REGION EARLY TONIGHT.
WILL GO WITH PREVAILING SHOWERS...BUT SINCE MUCH OF THE CONVECTIVE
ACTIVITY HAS ABATED UPSTREAM HAVE OPTED TO REMOVE VCTS AND CB
GROUPS AT THIS TIME. MODELS INDICATE MVFR CEILINGS WILL OCCUR ALONG
AND JUST BEHIND FRONT AS SHOWERS INCREASE ALONG THE COLD FRONT
OVERNIGHT. AND THIS HAS BEEN ACCOUNTED FOR IN THE TAFS.

FOLLOWING THE COLD FRONT MUCH DRIER AIR SPREAD IN FROM THE NORTHWEST
CAUSING RAPID CLEARING BY MID OR LATE MORNING. SOUTHWEST WINDS
WILL BE DECREASING A LITTLE THIS EVENING AND THEN BECOMING
NORTHWEST AND INCREASING UP TO 15 KNOTS AND GUSTS TO 25 KNOTS
TUESDAY MORNING.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM...JH
AVIATION...SMF

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