Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 221838
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
138 PM EST THU JAN 22 2015

.SYNOPSIS...
ISSUED AT 1030 AM EST THU JAN 22 2015

HIGH PRESSURE WILL BUILD INTO THE REGION TODAY AND REMAIN IN PLACE
THROUGH FRIDAY. CLOUDY SKIES WILL PERSIST WITH NO SIGNIFICANT
PRECIPITATION EXPECTED. HIGHS TODAY WILL RANGE FROM THE UPPER 20S
IN MICHIGAN TO THE MID 30S ACROSS CENTRAL INDIANA AND OHIO. LOWS
TONIGHT WILL BE IN THE UPPER TEENS TO LOWER 20S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM EST THU JAN 22 2015

GENERALLY A QUIET SHORT TERM PERIOD BUT SOME MINOR ISSUES TO
ADDRESS. BROAD MID LEVEL TROUGHINESS WILL LINGER ACROSS THE GREAT
LAKES TODAY WITH LOW LEVEL MOISTURE TRAPPED BENEATH INVERSION
SITTING AROUND 3-4KFT. THIS HAS LOCKED LOW CLOUDS IN ACROSS THE
REGION AND EXPECT CLOUDY TO MOSTLY CLOUDY SKIES TODAY. SEVERAL SMALL
SCALE VORT CENTERS EXPECTED TO MOVE THROUGH TODAY AS TROUGH SETTLES
THROUGH THE REGION AND SHEAR ZONE REMAINS OVERHEAD. CONCERN THAT A
PERIOD OF FLURRIES OR LIGHT FREEZING DRIZZLE COULD DEVELOP EARLY
THIS MORNING WITH THE LOW LEVEL MOISTURE AND WEAK SHORTWAVES.
UPSTREAM RADARS AND OBS INDICATE FLURRIES ACROSS NORTHERN IL EARLY
THIS MORNING WHERE DGZ WAS PARTIALLY SATURATED. NOT CONFIDENT THIS
DEEPER SATURATION WILL MAKE IT INTO OUR AREA WHICH WOULD RESULT IN
FREEZING DRIZZLE OVER FLURRIES IF LIGHT PCPN WERE TO OCCUR. ON THE
FLIP SIDE...COMBINATION OF DRIER AIR ALOFT AND SUBSIDENCE FROM
APPROACHING HIGH PRESSURE WILL WORK TO COUNTERACT WEAK FORCING. HAVE
OPTED TO BE CAUTIOUS AND ADD A CHANCE FOR FLURRIES AND SLIGHT CHANCE
FOR FZDZ FOR A FEW HOURS THIS MORNING.

AS RIDGING MOVES IN LATER TODAY ANY SMALL CHANCES FOR PCPN SHOULD
QUICKLY END WITH CLOUDS LINGERING INTO THIS EVENING. MODEL SOUNDINGS
SUGGEST DRY AIR AND SUBSIDENCE WILL BEGIN TO ERODE CLOUDS AND ALLOW
PARTIAL OR EVEN FULL CLEARING. TIME OF YEAR AND CLIMATOLOGY WILL BE
WORKING AGAINST CLEARING. NAM12 HAS ITS USUAL HIGH LOW LEVEL RH BUT
THIS CANNOT BE TRUSTED AS IT SEEMS TO ALWAYS BE PRESENT IN THESE
SITUATIONS. HAVE TRENDED SKY COVER GRIDS TO AN OPTIMISTIC PARTLY
CLOUDY OVERNIGHT IN FAVOR OF HIGH PRESSURE WINNING THE BATTLE. IF
CLEARING INDEED OCCURS THEN WE WILL HAVE TO WATCH FOR FOG
POSSIBILITY LATE TONIGHT WITH RECENT MELTED SNOWPACK AND SHALLOW
MOISTURE.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 333 AM EST THU JAN 22 2015

A NORTHERN STREAM SHORTWAVE AND ATTENDANT SFC REFLECTION TRACKING
EAST ACROSS ONTARIO/JAMES BAY WILL FORCE A WEAK/TRAILING COLD FRONT
ACROSS THE LOCAL AREA LATER FRIDAY NIGHT INTO SATURDAY MORNING.
DRY/"MILD" SOUTHWEST FLOW EXPECTED IN ADVANCE OF THIS FEATURE...WITH
MAINLY JUST AN INCREASE IN CLOUDS WITH FROPA INTO SATURDAY GIVEN
VERY MARGINAL THERMAL/SHALLOW MOISTURE PROFILES PROGGED.

WELL ADVERTISED AMPLIFICATION OF EASTERN CONUS TROUGH STILL ON TRACK
FOR SUNDAY INTO EARLY NEXT WEEK. ASSOCIATED MID-UPPER LEVEL JET
ENERGY DIVING INTO THE NORTHERN PLAINS/UPPER MIDWEST WILL LIKELY
BRING A STRONGER CLIPPER THROUGH THE AREA SUNDAY INTO SUNDAY
EVENING...WITH MID CHC TO LIKELY POPS WARRANTED GIVEN CONSISTENT
SIGNAL. ~120M 5H HEIGHT FALL CENTROID TRACK TOWARD THE OH VALLEY
OVER A MODEST 3-3.5 G/KG TAP (290K) SUGGEST ADVISORY LEVEL SNOW
AMOUNTS POSSIBLE ALONG PIVOT (JUST NORTH OF SFC LOW TRACK). WHERE
EXACTLY THIS OCCURS REMAINS HIGHLY UNCERTAIN GIVEN NORMAL MODEL
SPREAD REGARDING TRACK/AMPLITUDE/TIMING AT THIS RANGE...ALTHOUGH DID
CONTINUE TO TAILOR POPS/QPF/FIRST GUESS SNOW GRIDS TOWARD THE MORE
NORTHERLY 00Z GFS TRACK...PLACING OUR NORTHEAST ZONES IN THE MORE
FAVORABLE LOCATION FOR ACCUMULATING SNOW DURING THIS TIME. AREAS TO
THE SOUTHWEST WOULD LIKELY MISS OUT ON THE INITIAL WAA/FGEN SURGE
WITH SNOW SHOWERS/MINOR ACCUMS (POTENTIALLY MIXED WITH RAIN) UNDER
THE PRIMARY CIRCULATION TO END. WITH THIS SAID EXPECT ADJUSTMENTS TO
THE FCST AS GUIDANCE SLOWLY NARROWS IN ON A TRACK/STRENGTH.
OTHERWISE...TURNING COLDER SUNDAY NIGHT INTO MONDAY AS CAA/DRYING
COMMENCES IN WAKE OF WAVE.

WESTERN CONUS RIDGE ATTEMPTS TO BUILD EAST INTO THE PLAINS BY
TUE-WED. SHEARED SHORTWAVE ENERGY DROPPING SSE ON EASTERN FRINGE MAY
ALLOW AREAS OF SNOW TO DEVELOP ALONG AN EWD ADVANCING BAROCLINIC
ZONE....RESULTING IN A GRADUAL WARM UP AND NON ZERO SNOW CHANCES
INTO MID WEEK (ALTHOUGH MAINLY KEPT POPS BELOW MENTIONABLE VALUES
PER COLLABORATION).

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 122 PM EST THU JAN 22 2015

A WEAK WAVE RIDING OVER THE STRATUS FIELD CONTINUES TO GENERATE
VERY LIGHT SNOW / DRIZZLE OVER THE FAR SOUTHEAST PORTION OF THE
FORECAST AREA. VISIBLE SATELLITE SHOWS SEVERAL BANDS OF CLOUDS
RIDING OVER THE INVERSION AND THESE TOO COULD TRIGGER SEEDING OF
THE STRATUS FOR LIGHT SNOW/DRIZZLE THROUGH LATE AFTERNOON TODAY.

GIVEN THE SHORT RANGE MODEL SOUNDINGS HINTING THAT THE STRATUS
WILL BREAK UP DURING THE EARLY PART OF THE DAY ON FRIDAY. THIS
SHOULD BE SHORT LIVED AS THE STORM TO THE SOUTH SHIFTS INTO THE
SOUTHEASTERN STATES AND NORTHERN INDIANA IS AGAIN SUBJECT TO
OVERRUNNING AND EASTERLY SURFACE FLOW.

(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1224 AM EST THU JAN 22 2015

MVFR CIGS ACROSS A LARGE PART OF THE MIDWEST THIS MORNING AND
EXPECT THESE CONDITIONS TO CONTINUE TODAY AT TAF SITES. A SLIGHT
CHANCE FOR FREEZING DRIZZLE EARLY THIS MORNING...MAINLY AT KFWA.
REPORTS NEAR THE IN/MI BORDER INDICATE SOME PATCHY FREEZING
DRIZZLE AND MIST. RADAR SHOWS VERY WEAK RETURNS IN THIS AREA
SLIDING SOUTH BUT DISSIPATING. THUS NOT CONFIDENT ANYTHING WILL
REACH KFWA SO NO INCLUSION INTO TAF AT THIS TIME. HIGH PRESSURE
MOVES IN LATER TODAY WITH DRYING AND SUBSIDENCE. COULD SEE CLOUDS
BEGIN TO BREAK UP LATE WITH PARTIAL CLEARING OVERNIGHT. WENT
OPTIMISTIC WITH VFR CONDITIONS DEVELOPING TONIGHT.


&&

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

$$

SYNOPSIS...LEWIS
SHORT TERM...LASHLEY
LONG TERM...STEINWEDEL
AVIATION...LEWIS


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