Area Forecast Discussion
Issued by NWS Northern Indiana

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KIWX 181926
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
326 PM EDT THU SEP 18 2014

.SYNOPSIS...
ISSUED AT 325 PM EDT THU SEP 18 2014

HIGH PRESSURE WILL REMAIN ENTRENCHED ACROSS THE OHIO VALLEY
THROUGH FRIDAY WITH DRY CONDITIONS AND MODERATING TEMPERATURES.
LOWS TONIGHT WILL DROP INTO THE 40S...AND RECOVER INTO THE LOW TO
MID 70S ON FRIDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 325 PM EDT THU SEP 18 2014

HEIGHT RISES ALOFT WITH SFC RIDGE AXIS HANGING BACK FROM A
STRENGTHENING SE CANADA SFC HIGH WILL ENSURE MORE OF THE SAME
(DRY/FAIR WX) THIS PERIOD. MAINLY CLEAR SKIES AND LIGHT EASTERLY
GRADIENT WINDS WILL SUPPORT ANOTHER COOL NIGHT WITH COOLER MOS
GUIDANCE FAVORED. ALSO...LOWS FALLING NEAR OR JUST BELOW XOVER
VALUES MAY BE ENOUGH TO HELP GENERATE SOME PATCHY/SHALLOW GROUND
FOG TOWARD DAYBREAK...WITH LOW CHANCES FOR LOW STRATUS TO FILL
INTO FAR NORTHEASTERN ZONES GIVEN LIGHT FLOW OFF OF LAKE ERIE.
OTHERWISE...GRADUAL WARMING TREND CONTINUES INTO TOMORROW WITH
BRIEF RELAXATION OF EASTERN CONUS TROUGH.

&&

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 325 PM EDT THU SEP 18 2014

FOCUS STILL ON MAIN COLD FRONT AND RAIN CHANCES SATURDAY AFTERNOON
INTO EARLY SUNDAY MORNING. LATEST 12Z GUIDANCE HAS CONTINUED TREND
OF SPEEDING UP ONSET OF PCPN WITH MODELS IN GOOD AGREEMENT ON
PRECIPITATION ACROSS NORTHERN HALF OF AREA BY LATE SATURDAY
AFTERNOON.

HIGH PRESSURE WILL BE SLIDING EAST FRIDAY NIGHT WITH RETURN FLOW
DEVELOPING. INITIAL THETA E SURGE WILL APPROACH AND MOVE INTO THE
NORTHWEST EARLY SATURDAY MORNING. LOW LEVEL JET OF 30 TO 40 KNOT
BEING SHOWN IN MODELS UPSTREAM ACROSS WI AND IMPINGING ON THIS
HIGHER MOISTURE. THIS ALLOWS SHOWERS AND FEW THUNDERSTORMS TO
DEVELOP OVERNIGHT IN THAT AREA. MODELS ARE TRYING TO BRING THIS
DECAYING PCPN INTO THE NORTHWEST SATURDAY MORNING WELL AHEAD OF MAIN
FRONT AND HEIGHT FALLS. GIVEN THE MODEL SIGNAL LAST SEVERAL RUNS
HAVE ADDED A VERY LOW POP TO THIS AREA SATURDAY MORNING. OTHERWISE
MODELS HAVE SPED UP APPROACH OF MAIN SHORT WAVE AND ARE SHOWING
AFTERNOON CONVECTIVE DEVELOPMENT IN THE NORTH. MODEL SOUNDINGS STILL
SHOW A GOOD LOW LEVEL INVERSION BUT INSTABILITY ALOFT IS LIKELY WHAT
MODELS ARE KEYING ON. THIS INVERSION AND ADDED CLOUD COVER IN
AFTERNOON TO ALSO LIMIT MIXING HEIGHTS MAKING TEMPERATURE FORECAST
DIFFICULT. WITH MODEL AGREEMENT ON MID AFTERNOON PCPN DEVELOPMENT
NOW HAVE INCREASED POPS CONSIDERABLY AFTER 18Z AND ESPECIALLY AFTER
21Z FAR NORTHWEST. ALSO BLENDED LATEST TEMP GUIDANCE BUT KEPT HIGHS
IN LOWER 80S FAR SOUTH WHERE BEST MIXING AND SUN POTENTIAL EXISTS.

FRONTAL BOUNDARY TO SWEEP THROUGH SATURDAY NIGHT. INSTABILITY
REMAINS LOW BUT PWATS ON BOTH NAM12 AND GFS40 AROUND 1.8 INCHES
WHICH IS ABOUT 2 STANDARD DEVIATIONS ABOVE NORMAL. CONVECTION
POSSIBLE WITH MARGINAL INSTABILITY BUT GOOD SHEAR SO KEPT TSRA IN
FORECAST. LOCALLY HEAVY RAIN ONCE AGAIN POSSIBLE BUT PROGRESSIVE
NATURE TO FRONT SHOULD KEEP FLOODING THREAT MINIMAL. QPF IN THE HALF
TO ONE INCH RANGE LOOKS LIKELY ESPECIALLY FOR CENTRAL AND NORTHERN
AREAS. STILL THINK SOME OF THIS MOISTURE IS MID TROPOSPHERIC
CONTRIBUTION FROM ODILE REMNANTS DESPITE MAIN CIRCULATION REMAINING
WELL SOUTHWEST OF AREA.

CLEARING EXPECTED SUNDAY IN WAKE OF FRONT WITH SEASONABLE
TEMPERATURES. SECONDARY SHORT WAVE AND FRONT WILL BRING COOLER
TEMPERATURES FOR MONDAY AND TUESDAY WITH HIGHS BACK INTO THE 60S.
STILL AN EYE ON LAKE EFFECT POTENTIAL AND SOME LIGHT SHOWER
POTENTIAL WITH SECONDARY SHORT WAVE BUT NOT ENOUGH MODEL SIGNAL IN
MOISTURE PROFILES TO WARRANT ADDING POPS AT THIS TIME. HIGH PRESSURE
THEN MOVES IN FOR REMAINDER OF LONG TERM WITH MODERATING
TEMPERATURES BACK INTO 70S AND DRY WEATHER.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 102 PM EDT THU SEP 18 2014

SFC RIDGING IN SUBSIDENT/DRY NORTHWEST FLOW SHOULD RESULT IN A
CONTINUATION OF VFR CONDITIONS/MAINLY CLEAR SKIES THROUGH THE TAF
CYCLE. COULD SEE SOME PATCHY FOG/STRATUS DEVELOPMENT TOWARD 9-12Z
FRIDAY...BUT COVERAGE/CONFIDENCE REMAINS TOO LOW FOR INCLUSION
THIS ISSUANCE.

&&

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

$$

SYNOPSIS...MCD/STEINWEDEL
SHORT TERM...STEINWEDEL
LONG TERM...LASHLEY
AVIATION...STEINWEDEL


VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSNORTHERNINDIANA
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.