Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 051812
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
112 PM EST THU MAR 5 2015

.SYNOPSIS...
ISSUED AT 436 AM EST THU MAR 5 2015

AN ARCTIC AIRMASS ACROSS THE AREA WILL PROVIDE MUCH BELOW NORMAL
TEMPERATURES TODAY...ALONG WITH THE POTENTIAL OF ISOLATED TO
SCATTERED LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES. A RIDGE OF
HIGH PRESSURE WILL MOVE INTO THE AREA TONIGHT PROVIDING LIGHT
WINDS...CLEAR SKIES...AND CONTINUED COLD CONDITIONS. THIS RIDGE OF
HIGH PRESSURE WILL BEGIN TO SHIFT EAST OF THE AREA ON FRIDAY WHICH
WILL MARK THE BEGINNING OF A MODERATING TEMPERATURE TREND THAT
WILL CONTINUE INTO NEXT WEEK.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 436 AM EST THU MAR 5 2015

POSITIVELY TILTED UPPER TROUGH WILL TRACK ACROSS THE GREAT LAKES
REGION TODAY...ALTHOUGH VERY DRY PROFILES WILL LIMIT PRECIP
CHANCES TO ANYTHING MORE THAN LIGHT LAKE EFFECT SNOW SHOWERS OR
FLURRIES. SOME EVIDENCE IN OBSERVATIONAL DATA IN PAST FEW HOURS
OF SOME SHARPENING OF LAND BREEZE/LAKE THERMAL TROUGHING BUT
CONTINUED LARGE SCALE SYNOPTIC SUBSIDENCE AND RELATIVELY LARGE
MID LEVEL DEW POINT DEPRESSIONS HAVE CONTINUED TO PROVIDE VERY
WEAK LAKE RESPONSE TO THIS POINT. PASSAGE OF AFOREMENTIONED
SYNOPTIC TROUGH IN THE 12Z-18Z TIMEFRAME MAY PROVIDE A BRIEF
PERIOD OF LIGHT SCATTERED LAKE EFFECT SNOW SHOWERS BUT SEE NO
REASON TO DEVIATE FROM PREVIOUS LOW POPS. PASSAGE OF UPPER VORT
MAX LATER THIS MORNING INTO THIS AFTERNOON COUPLED WITH STEEP LOW
LEVEL LAPSE RATES COULD BE SUFFICIENT FOR SOME FLURRIES FURTHER
INLAND NORTHEAST INDIANA/SOUTHERN LOWER MICHIGAN. ARCTIC AIRMASS
WILL BE ENTRENCHED ACROSS THE AREA TODAY BUT WILL CONTINUE TO
SIDE WITH THE "WARMER" ENVELOPE OF MOS NUMBERS GIVEN PRESENCE
WELL MIXED NORTHWEST FLOW...STEEP LOW LEVEL LAPSE RATES...AND
LOWERING SNOW ALBEDOS. GIVEN ABOVE FACTORS...THIS SHOULD SUPPORT
HIGHS IN THE UPPER TEENS TO AROUND 20 MOST LOCATIONS.

BY LATE AFTERNOON/EARLY EVENING LOW LEVEL WINDS WILL BEGIN TO
BACK IN RESPONSE TO APPROACHING LOW LEVEL RIDGE AXIS. UPPER
TROUGH TRACKING ACROSS EASTERN PORTIONS OF THE FORECAST AREA LATE
THIS AFTERNOON COMBINED WITH EASTWARD PROGRESSION OF LAKE
ENHANCED LOW CLOUDS MAY SUPPORT PARTLY-MOSTLY CLOUDY CONDITIONS
THIS EVENING ACROSS THE EAST...BUT TRENDING TO CLEAR/MOSTLY CLEAR
ACROSS ALL OF THE FORECAST AREA LATER THIS EVENING. DESPITE CORE
OF LOW LEVEL THERMAL TROUGHING TO MIGRATE EAST OF THE AREA
TONIGHT...GOOD RADIATIONAL COOLING CONDITIONS SHOULD SUPPORT LOWS
IN THE 5 ABOVE TO 5 BELOW ZERO RANGE...WITH WIND CHILLS AS COLD
AS 10 BELOW EARLY FRIDAY MORNING.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 436 AM EST THU MAR 5 2015

THE SURFACE HIGH PRESSURE AREA WILL HAVE SHIFTED SOUTHEAST OF THE
AREA AT THE START OF THIS PERIOD FRIDAY MORNING. TEMPERATURES
SHOULD TRY TO START TO CLIMB OUT OF THE DEEP FREEZE FRIDAY...BUT
UPSTREAM SNOW COVER AND PROXIMITY OF THE COLD AIR MASS WILL STILL
KEEP TEMPERATURES CLOSE TO 20 DEGREES BELOW NORMAL. FAVOR THE
NAM/MET WITH TEMPERATURES FALLING LITTLE FRIDAY NIGHT...BUT
RISING TO BETWEEN 35 AND 40 SATURDAY. TEMPERATURES SHOULD
CONTINUE TO REBOUND AND CLIMB ABOVE NORMAL EARLY NEXT WEEK.
NATIONAL OPERATIONAL HYDROLOGIC REMOTE SENSING CENTER SHOWS
MODELED SNOW WATER EQUIVALENT HIGHEST OVER FAR SOUTHWEST LOWER
MICHIGAN INTO EXTREME NORTHERN INDIANA WHERE AMOUNTS ARE 2 TO 4
INCHES WITH LOCALLY HIGHER AMOUNTS. CONCERN FOR THE POTENTIAL FOR
MELTING SNOW TO CAUSE LOWLAND FLOODING AND RISES ON AREA RIVERS.
VIRTUALLY NO PRECIPITATION IS EXPECTED THROUGH THE MIDDLE OF NEXT
WEEK...SO THIS WILL HELP ALLEVIATE THE FLOOD POTENTIAL SOMEWHAT.
HOWEVER...IT IS POSSIBLE THAT THERE MAY BE SOME EVENTUAL ICE JAMS
ON THE RIVERS AS THE SNOW MELTS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 110 PM EST THU MAR 5 2015

VFR MET CONDS THROUGH THE FORECAST PERIOD AS UPSTREAM RIDGELINE
SETTLES THROUGH SRN GRTLKS AND INTO LWR OH VLY BY DAYBREAK.
RAMPED SRLY SFC FLOW ASSOCD WITH STRONG WARM AIR ADVECTION IN
ADVANCE OF HIGH BELTED CLIPPER SYSTEM MOVG THRU SRN HUDSON BAY
LATE FRI AFTN. ELEVATED ERLY MARCH SUN ANGLE TO LIKELY AFFORD
MIXOUT OF GUSTS INTO LWR/MID 20KTS IN ERLY AFTN.

&&

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

$$

SYNOPSIS...MARSILI
SHORT TERM...MARSILI
LONG TERM...SKIPPER
AVIATION...MURPHY


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