Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 010829
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
429 AM EDT SUN MAY 1 2016

.SYNOPSIS...
ISSUED AT 419 AM EDT SUN MAY 1 2016

DRIZZLE AND FOG WILL DISSIPATE THIS MORNING...WITH SHOWERS AND
POSSIBLY A FEW THUNDERSTORMS DEVELOPING LATER THIS AFTERNOON INTO
THE EVENING HOURS. HIGH TEMPERATURES WILL RANGE FROM THE MIDDLE
50S NEAR LAKE MICHIGAN TO THE UPPER 60S SOUTH OF ROUTE 24. LOWS
TONIGHT WILL DROP INTO THE 40S. ADDITIONAL CHANCES FOR SHOWERS
WILL OCCUR MONDAY...AS WELL AS TUESDAY NIGHT INTO WEDNESDAY.

&&

.DISCUSSION...
ISSUED AT 419 AM EDT SUN MAY 1 2016

THROUGH TONIGHT...
A SERIES OF WAVES...ASSOCIATED WITH CLOSED UPPER LOW CENTERED OVER
SW NE/NW KS WILL MOVE EAST THROUGH THE DAY WITH THE MAIN FEATURE
SLOWLY OPENING AND SHEARING OUT AS IT CROSSES INTO THE OHIO VALLEY.
THE FIRST WAVE WAS MOVING THROUGH ILLINOIS TOWARDS THE FORECAST
AREA. A WARM FRONT WAS NOTED AT 6Z FROM SOUTH OF DANVILLE IL TO
NORTH OF MARION AND LIMA OHIO WITH UPR 50 DEWPOINTS SOUTH OF THE
FRONT.

A LULL IN PRECIPITATION IS EXPECTED UNTIL THE MAIN UPPER LOW ENTERS
EASTERN ILLINOIS DURING THE LATE AFTERNOON HOURS. SHOWERS AND A FEW
THUNDERSTORMS ARE STILL ON TAP...BUT COVERAGE MAY BE MORE SCATTERED
IN NATURE UNTIL THE SFC REFLECTION TAKES SHAPE DURING THE EVENING
HOURS. HAVE TONED DOWN POPS INTO EARLY AFTERNOON BUT CONTINUE WITH
RAMP UP TO LIKELY POPS IN SE AREAS TOWARDS 00Z. ALL GUIDANCE HAS
INCREASED POPS SIGNIFICANTLY AS WELL AS EXPANDED FURTHER
WEST...WARRANTING LIKELY POPS THIS EVENING FOR MOST AREAS. SOME
GUIDANCE SUGGESTS CATEGORICAL POPS...BUT NOT READY TO JUMP IN QUITE
YET. WITH REGARDS TO SEVERE THREAT...SWODY1 PUSHED MARGINAL RISK
SOUTH SOMEWHAT TO JUST AT THE EDGE OF OUR SOUTHERN COUNTIES.
CONCERNS LINGER AS SOME OF THE MODELS SUGGEST MOST UNSTABLE CAPE
VALUES OVER 500 J/KG WITH 0-6 KM SHEAR UPWARDS OF 40 TO 50 KNOTS.
KEY FACTORS IN DETERMINING RISK WILL BE 1)POCKETS OF HEATING LATE AM
INTO MID AFTERNOON IN BETWEEN WAVES 2)LOCATION OF WARM FRONT
3)AMOUNT OF MOISTURE IN PLACE OR QUICKLY ADVECTING IN. WILL GO WITH
MENTION OF STG STORMS WITH GUSTY WINDS/SMALL HAIL IN HWO FOR NOW AND
LET DAY SHIFT HANDLED ANY THREAT. TEMPERATURES WILL VARY GREATLY
FROM NW TO SE WITH HIGHS WELL INTO THE 60S SOUTHEAST AND STRUGGLING
THROUGH THE 50S IN THE NW.

MONDAY THROUGH SATURDAY...OMEGA BLOCK PATTERN WILL TAKE SHAPE
THROUGH MUCH OF THE PERIOD WITH REGION BEING ON THE COLD AND ACTIVE
SIDE OF IT THROUGH MUCH OF THE WEEK. ANOTHER WEAK SYSTEM WILL MOVE
IN MONDAY WITH CHC OF SHOWERS ARRIVING ONCE AGAIN. STRONGER WAVE AND
FRONTAL SYSTEM WILL ARRIVE TUES NGT INTO WEDNESDAY WITH CHANCE FOR
SHOWERS (THUNDER?) WITH THE SURFACE LOW EVENTUALLY CUTTING OFF TO
THE EAST WITH LINGERING SHOWER CHANCES IN THE FAR EAST INTO FRIDAY.

FINALLY BY THE WEEKEND...THE REGION WILL SEE AN INCREASE IN TEMPS
ABOVE NORMAL AS UPPER LOW SHIFTS TO THE EAST AND RIDGING TAKES
PLACE. BELOW NORMAL TEMPERATURES CAN BE EXPECTED THROUGH THURSDAY
WITH MODERATION BACK TO NEAR OR ABOVE NORMAL AFTER.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 136 AM EDT SUN MAY 1 2016

LEAD SHORT WAVE AND STRONGER ISENTROPIC ADVECTION SURGE ARE
DEPARTING NORTHERN INDIANA EARLY THIS MORNING. WEAK WARM ADVECTION
WILL CONTINUE OVERNIGHT IN ADVANCE OF NEXT UPPER LEVEL LOW
APPROACHING FROM THE WEST FOR LATER THIS AFTERNOON WHICH SHOULD
RESULT IN CONTINUED DRIZZLE/PATCHY LIGHT RAIN THROUGH THE
REMAINDER OF THE EARLY MORNING. EASTERLY FLOW NORTH OF SFC FRONT
AND A STRONG LOW LEVEL INVERSION WILL SUPPORT CONTINUED IFR/LIFR
CONDITIONS THROUGH MID MORNING...AND POSSIBLY AS LATE AS THE
16-17Z TIMEFRAME AT KSBN. SOME IMPROVEMENTS TO MVFR EXPECTED LATE
MORNING/EARLY AFTERNOON WITH SOME DIURNAL MIXING AS SFC BOUNDARY
TO THE SOUTH MAY TRY TO MIX SLIGHTLY TO THE NORTH. SCATTERED-
NUMEROUS SHOWERS AND PERHAPS A FEW THUNDERSTORMS ARE EXPECTED TO
REDEVELOP LATE AFTERNOON INTO EARLY EVENING AS UPPER TROUGH
APPROACHES. INSTABILITY WILL BE SOMEWHAT LIMITED...AND AT THIS
FORECAST DISTANCE HAVE HELD OFF ON THUNDER INCLUSION...BUT BEST
CHANCE OF THUNDER LATE AFTERNOON/EARLY EVENING WOULD BE AT KFWA IN
CLOSER PROXIMITY TO PRIMARY WEAK INSTABILITY AXIS.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...FISHER
DISCUSSION...FISHER
AVIATION...MARSILI


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