Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 261649
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1149 AM EST MON JAN 26 2015

.SYNOPSIS...
ISSUED AT 355 AM EST MON JAN 26 2015

WEAK HIGH PRESSURE WILL BE ACROSS THE AREA TODAY. CLOUDS ARE
EXPECTED TO INCREASE THIS AFTERNOON AND TONIGHT. THERE IS A
CHANCE FOR VERY LIGHT SNOW ACROSS NORTHEAST ILLINOIS...INDIANA...AND
FAR SOUTHWEST LOWER MICHIGAN THIS EVENING AND TONIGHT. HIGHS TODAY
WILL BE IN THE IN THE 20S...BUT AREAS WHICH SAW SEVERAL INCHES OF
SNOW MAY STRUGGLE TO GET OUT OF THE TEENS. LOWS TONIGHT WILL BE IN
THE TEENS...EXCEPT COLDER SINGLE DIGITS IN THOSE SAME AREAS WITH
DEEPER SNOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 351 AM EST MON JAN 26 2015

CLIPPER SYSTEM WHICH BROUGHT OUR SNOW ON SUNDAY IS QUICKLY MOVING
AWAY AND WILL EVENTUALLY BECOME MASSIVE STORM OFF THE EAST COAST.
LIGHT SNOW SHOULD END BEFORE DAYBREAK OVER FAR SOUTHEAST. CLOUDS
WERE DECREASING ACROSS THE REGION AS DRIER AIR WORKS IN FROM THE
NORTH. THIS HAS ALLOWED TEMPS TO FALL QUICKLY AND SHOULD SEE SOME
SINGLE DIGITS BY SUNRISE. WINDS WERE ALSO DECREASING BUT STILL
EXPECT A LIGHT WIND WHICH WILL ALLOW WIND CHILLS TO FALL TO AROUND
ZERO EARLY THIS MORNING.

GENERALLY A QUIET SHORT TERM PERIOD BUT A WEAK SHEARED WAVE WILL
DROP INTO THE WESTERN GREAT LAKES REGION LATER THIS AFTERNOON AND
TONIGHT. FORCING WEAK BUT MID LEVELS WILL SATURATE THIS AFTERNOON.
SHOULD SEE MID AND HIGH CLOUDS INCREASE TODAY AND LOWER. MODEL SOUNDINGS
SHOW A RATHER PRONOUNCED DRY WEDGE IN THE LOWEST 6KFT WHICH WILL BE
TOUGH TO SATURATE FOR MEASURABLE PCPN. SOUNDINGS DO SHOW SOME
SATURATION THIS EVENING AND COULD BE ENOUGH TO SQUEEZE OUT SOME VERY
LIGHT QPF. DGZ LOOKS TO BE SATURATED SO EXPECT ANY PCPN TO BE IN
FORM OF LIGHT SNOW AT THIS TIME. HAVE KEPT A LOW CHANCE POP IN THE
FAR WEST AFTER 21Z TODAY AND JUST A CHANCE FOR FLURRIES CENTRAL.

FRESH SNOWPACK...DEEPEST ACROSS THE SOUTH AND SOUTHEAST...SHOULD
HINDER TEMPERATURE RISES TODAY. HAVE LOWERED MAX TEMPS AND WENT WITH
COOLER MET MOS NUMBERS. THESE MAY STILL BE TOO WARM IN THE SOUTH
DEPENDING ON HOW MUCH RADIATIONAL COOLING OCCURS WITH CLEARING EARLY
THIS MORNING. LOWS TONIGHT ALSO TRICKY AS CLOUD COVER WILL BE
INCREASING BUT WINDS LIGHT OVER FRESH SNOWPACK. LOWERED TEMPS ACROSS
THE SOUTHEAST WHERE CLOUDS WILL BE THIN INITIALLY. ADDITIONAL
DOWNWARD ADJUSTMENTS OF SEVERAL DEGREES MAY BE NEEDED IF CLOUD COVER
IS LACKING OR ARRIVAL IS DELAYED.

&&

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 351 AM EST MON JAN 26 2015

QUIET CONDITIONS WILL PREVAIL ON TUESDAY AND WEDNESDAY. RAPID HEIGHT
RISES WILL COMMENCE AS DEEP EAST COAST TROUGH LIFTS AND NEXT WAVE
APPROACHES. DOWNSTREAM AMPLIFICATION FROM THIS NEXT TROUGH WILL ALSO
DEVELOP DECENT SHORTWAVE RIDGING WITH ASSOCIATED AVA GENERATING
STRONG SUBSIDENCE. THIS LEADS TO YET ANOTHER DIFFICULT CLOUD
FORECAST WITH POTENTIAL FOR BOUNDARY LAYER MOISTURE TO BE TRAPPED
UNDER STRONG INVERSION AND KEEP STRATUS DECK IN PLACE. NAM SHOWING
ITS TYPICAL BOUNDARY LAYER MOISTURE BIAS WITH GFS SOUNDINGS MUCH
MORE OPTIMISTIC. SUSPECT WE WILL SEE SOME BREAKS IN THE CLOUDS BY
THE AFTERNOON BUT WILL PROBABLY TAKE SOME TIME. MIDLEVEL WAA WILL
ALSO GENERATE INCREASING MID AND UPPER LEVEL CLOUDS...ESPECIALLY BY
WEDNESDAY...SO WILL HOLD WITH PARTLY CLOUDY AT BEST. TEMPS WILL BE
NEAR AVERAGE FOR LATE JANUARY WITH HIGHS NEAR THE FREEZING MARK AND
LOWS TUESDAY NIGHT IN THE MID TO UPPER TEENS.

NEXT SYSTEM WILL IMPACT THE AREA WEDNESDAY NIGHT INTO THURSDAY.
DECENT MIDLEVEL DYNAMICS NOTED WITH THIS SYSTEM BUT THERE ARE
SEVERAL NEGATIVE FACTORS. REMNANT VORT MAX FROM CUTOFF BAJA LOW WILL
PHASE WITH ANOTHER NORTH PACIFIC SHORTWAVE AS THEY SWING THROUGH THE
UPPER MIDWEST. UPPER JET SUPPORT IS NOTICEABLY ABSENT/WEAK FOR THIS
EVENT THOUGH. BULK OF THE HEAVY LIFTING WILL HAVE TO BE DONE BY
SIMPLE CVA AND THE TWO WAVES APPEAR DISJOINTED ON SEVERAL MODEL RUNS
WITH SOME QUESTION AS TO HOW MUCH ENERGY WILL BE LEFT FROM OLD
SHEARED OUT UPPER LOW. WILL BE PLENTY OF MOISTURE DRAWN NORTH WITH
THIS SYSTEM AS STRONG SOUTHWEST FLOW ADVECTS 850MB MIXING RATIOS OF
ALMOST 6 G/KG INTO THE REGION. HOWEVER...THIS ALSO LEADS TO LOW
LEVEL THERMAL PROFILES THAT ARE ABOVE FREEZING. MODELS STILL SORTING
OUT EXACT TRACK OF THE LOW AND IT IS FUTILE TO TRY TO PREDICT
SPECIFICS THIS FAR OUT. SUFFICE IT TO SAY...CURRENTLY EXPECT A MIX
OF LIGHT RAIN AND SNOW ACROSS THE AREA LATE WEDNESDAY NIGHT THROUGH
THURSDAY. TRANSITORY SLEET AND FREEZING RAIN ARE ALSO LIKELY BUT
STRONG S/SW LOW LEVEL FLOW WILL PREVENT ANY MEANINGFUL ICE
ACCUMULATION. ANY SNOW ACCUMULATION IS ALSO EXPECTED TO BE LIGHT
THOUGH SOME MODERATE TOTALS ARE POSSIBLE IN OUR FAR NORTHEASTERN
COUNTIES IF PRECIP TYPES MANAGE TO REMAIN ALL SNOW. RETURN TO COOLER
CONDITIONS BEHIND THIS SYSTEM BUT NOTHING OUT OF THE ORDINARY FOR
THIS TIME OF YEAR.

ANOTHER WEAK LOW/FRONTAL PASSAGE POSSIBLE OVER THE WEEKEND. GFS AND
ECMWF STILL DISAGREE ON TIMING AND LOCATION OF POTENTIAL ARCTIC AIR
INTRUSION EARLY NEXT WEEK WITH EUROPEAN SUGGESTING 850MB TEMPS BELOW
-20C IN OUR AREA BY NEXT MONDAY. NEWEST 00Z GFS IS LATER WITH THE
COLD AIR ARRIVAL BUT DOES SHOW OUR CWA GETTING CLIPPED. WILL ONCE
AGAIN STAY CLOSE TO CONSENSUS INITIALIZATION FOR DAY7 TEMPS WITH THE
ADDED DISCLAIMER THAT LARGE ADJUSTMENTS ARE POSSIBLE IN THE COMING
DAYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1148 AM EST MON JAN 26 2015

WEAK HIGH PRESSURE OVER THE GREAT LAKES AND PRONOUNCED DRY LAYER
IN THE LOWEST 5 KFT WILL KEEP TERMINALS MAINLY VFR INTO TOMORROW.
AREA OF LIGHT SNOW AND ASSOCIATED VIS/CIG RESTRICTIONS ALONG A
TIGHT THERMAL GRADIENT SHOULD REMAIN JUST WEST OF SBN/FWA LATE
THIS AFTN INTO TONIGHT AS SHEARED VORT MAX SLIDES SE THROUGH
ILLINOIS. ALTHOUGH CANNOT RULE OUT A FEW FLURRIES DURING THIS TIME
ACROSS NORTHERN INDIANA. OTHERWISE...WINDS WILL GENERALLY REMAIN
UNDER 6 KNOTS INTO TONIGHT. BE LIGHT/VARIABLE.

&&

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

$$

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


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