Winter Weather in Michigan, February 22, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1237 AM EST FRI FEB 22 2013

.AVIATION...

DRY EASTERLY FLOW HAS CAUSED A SLIGHT DELAY IN THE ONSET OF SNOW
THIS EVENING BUT LATEST RADAR AND SURFACE OBS INDICATE SNOW WILL
BEGIN WITHIN THE NEXT HOUR OR SO AT BOTH TERMINALS. MAINLY MVFR
CONDITIONS ARE EXPECTED DURING THE NEXT FEW HOURS WITH IFR
BECOMING MORE LIKELY AS THE MORNING PROGRESSES. RELATIVELY NARROW
BAND OF ISENTROPIC ASCENT WILL SPREAD LIGHT SNOW...AND POSSIBLY
SLEET...THROUGH THE AREA DURING THE NEXT 4-6 HOURS BEFORE
APPROACHING DRY SLOT FORCES A CHANGEOVER TO PATCHY FREEZING
DRIZZLE BY LATER THIS MORNING. ABUNDANT LOW LEVEL MOISTURE WILL
THEN BRING THE THREAT OF IFR CONDITIONS FOR MOST OF THE
DAY...SUPPORTED BY UPSTREAM OBSERVATIONS AND LATEST 00Z NUMERICAL
GUIDANCE.

&&

.PREV DISCUSSION... /ISSUED 931 PM EST THU FEB 21 2013/

UPDATE...
MAIN ITEM FOR THE EVENING UPDATE WAS TO MOVE UP TIMING OF SNOW
ONSET ACROSS SOUTHWEST HALF OF AREA THIS EVENING ACCOMPANY PRIMARY
LOW LEVEL THETAE SURGE INTO THE AREA. A FAIRLY VIGOROUS SMALL
SCALE VORT ALSO APPEARS TO BE EJECTING NORTHEAST ACROSS WEST
CENTRAL INDIANA THIS EVENING. HAVE NOT MADE MANY ADJUSTMENTS TO
FORECASTED SNOWFALL AMOUNTS...ALTHOUGH SOME CONCERNS BEGINNING TO
TAKE SHAPE IN REALIZING THESE AMOUNTS. STRONGER UPPER VORT
MAX NOW APPEARS TO BE LIFTING THROUGH NORTHERN/WESTERN
MISSOURI. THIS SHORT WAVE SHOULD LIFT INTO THE AREA OVERNIGHT BUT
WEDGE OF MUCH DRIER MID LEVEL AIR WILL ALSO RAPIDLY ADVECT
NORTHWARD WITH THIS FORCING. INGREDIENTS METHOD APPROACH SHOWS
BEST OVERLAY OF MID LEVEL FORCING/INSTABILITY OVERNIGHT IN AREAS
VOID OF SIGNIFICANT MOISTURE DEPTH. THERMODYNAMICS ALSO NOT VERY
FAVORABLE FOR HEAVY SNOW POTENTIAL WITH HIGHLY ELEVATED DGZ OF
LIMITED DEPTH...AND RELATIVELY WARM LOW LEVEL PROFILES. EVENING
UPDATE SENT EARLIER TO ADD MIXED SLEET MENTION ACROSS THE FAR
SOUTH THIS EVENING...AND MAY SEND A LATE EVENING UPDATE TO
SLIGHTLY LOWER PREVIOUS ACCUMULATIONS BASED ON CURRENT TRENDS AND
CONCERN OF DURATION OF DEEPER/MORE FAVORABLE MOISTURE PROFILES.

PREV DISCUSSION... /ISSUED 334 PM EST THU FEB 21 2013/

SHORT TERM.../TONIGHT-FRI NGT/

UPR LOW OVER TX/OK PHDL TODAY WILL MOVE NE TO THE U.P. OF MI BY SAT
MORNING. NEG TILTED UPR TROF ACCOMPANYING THE LOW WILL MOVE ACROSS
OUR AREA TONIGHT COINCIDING WITH A LOW LEVEL THETA-E SURGE AT NOSE
OF A 60KT SOUTHERLY LLJ MOVG ACROSS THE OH VALLEY. THIS SHOULD
PROVIDE SUFFICIENT MOISTURE/LIFT TO SUSTAIN BAND OF SGFNT PRECIP
CURRENTLY OVER THE MID MS VALLEY THROUGH OUR AREA OVERNIGHT AND
EARLY FRIDAY. EVAPORATIONAL COOLING AFFECTS SHOULD RESULT IN
PTYPE AS PREDOMINANTLY SNOW... BUT ACROSS SE PORTION OF OUR CWA
MAY BE SUFFICIENT LOW LEVEL WAA FOR PRECIP TO CHANGE TO
SLEET/FREEZING RAIN BRIEFLY BEFORE MID LEVEL DRY SLOT MOVES IN.
ALSO... AFTER THE DRY SLOT MOVES THROUGH THE AREA LATE TONIGHT AND
EARLY FRIDAY... LINGERING LOW LEVEL WAA COMBINED WITH BY THEN
SATURATED LOW LEVELS SHOULD RESULT IN A PERIOD OF FREEZING DRIZZLE
ACROSS THE AREA BEFORE LOW LEVELS DRY OUT A BIT AND WAA WANES. 12Z
NAM/GFS QPFS HAVE TRENDED UP AND GIVEN UPSTREAM PRECIP AMOUNTS
TODAY... THIS SEEMS REASONABLE... THUS HAVE ADJUSTED QPF/SNOW
AMOUNT GRIDS UP. HIGH DGZ AND LARGE PORTION OF SOUNDING NEAR 0C
SHOULD KEEP SNOW TO WATER RATIO 10 TO 1 AT MOST. ACCUMS EXPECTED
TO RANGE FROM AROUND AN INCH EAST TO AROUND 3 INCHES WEST WITH
SOME LIGHT (LESS THAN A TENTH OF AN INCH) ICE ACCRUAL... MAINLY
ACROSS SERN ZONES. GIVEN POTENTIAL FOR BAND OF MOD SNOW MOVG
THROUGH THE AREA SHORTLY BEFORE AND INTO MORNING COMMUTE TIME
COMBINED OR FOLLOWED BY SOME FREEZING PRECIP... OPTED TO ISSUE A
WINTER WEATHER ADVISORY FOR TONIGHT AND FRI MORNING. TEMPS
EXPECTED TO JUST FALL OFF A FEW DEGREES TONIGHT AND THEN RISE INTO
THE M-U30S FRI AFTN AS FLOW BECOMES SOUTHERLY.

MODESTLY COLDER AIR SHOULD MOVE INTO THE AREA FRIDAY NIGHT BEHIND
THIS SYSTEMS OCCLUDED FRONT. CONSIDERABLE LOW LEVEL MOISTURE...
CYCLONIC FLOW... AND A WK SHRTWV LIFTING NE UNDER THE NRN GRTLKS LOW
ACROSS OUR AREA FRIDAY NIGHT SUPPORTS A LOW CHC OF LIGHT
SNOW/FREEZING DRIZZLE WITH LOW TEMPS EXPECTED TO BE IN THE M20S.

LONG TERM / SAT THRU WEDS NIGHT /...
UPPER LOW WILL CONTINUE TO ROTATE ACROSS UPPER GREAT LAKES FOR START
OF LONG TERM. COLDER AIR AND LINGERING MOISTURE FROM SYSTEM MAY BE
ENOUGH FOR SOME LIGHT LAKE EFFECT SNOW SHOWERS/FLURRIES FOR NW AREAS
ON SATURDAY. SFC-850MB DELTA T VALUES WILL BE IN THE LOW TEENS AND
FETCH REMAINS RATHER SHORT/UNFAVORABLE FOR SUSTAINED DEVELOPMENT
GIVEN FLOW FROM THE WSW/W DIRECTION. WILL CONTINUE WITH SLGHT CHC
POPS ACROSS FAR NORTHERN PORTIONS OF AREA WITH LITTLE TO NO ACCUMS
EXPECTED. HIGH PRESSURE THEN BUILDS IN ACROSS THE MISSISSIPPI VALLEY
WITH DRY WEATHER EXPECTED THE REMAINDER OF THE WEEKEND. TEMPS WILL
REMAIN BELOW NORMAL WITH HIGHS IN THE LOW-MID 30S AND LOWS IN THE
LOW 20S.

RIDGE THEN BREAKS DOWN BY LATE SUNDAY IN ADVANCE OF NEXT SYSTEM
MOVING IN FROM THE PLAINS. MODELS STILL SHOWING SIG DIFFS WITH
MON/TUES SYSTEM AS STRONG LOW EJECTS FROM SOUTHERN PLAINS INTO THE
WESTERN GREAT LAKES BY MONDAY. 12Z GFS REMAINS JUST AS PROGRESSIVE
AS PREVIOUS 2 RUNS AND IS FASTEST SOLUTION OUT OF THE BUNCH. SLOWER
SOLUTIONS HAVE TENDED TO VERIFY BETTER WITH THE PAST FEW
SYSTEMS...THEREFORE HAVE CONTINUED TO DISCOUNT GFS AND STUCK TO MORE
OF A COMPROMISE BETWEEN SLOWER GFS/GFS ENSEMBLES/GEM. THIS RESULTED
IN CHANGE TO ALLBLEND INITIALIZATION AND HAVE LIMITED POPS UNTIL
AFTER 18Z MON. WITH STRONG WARM SURGE AND SLOWER ONSET OF
PRECIP...EXPECT SFC TEMPS TO WARM INTO THE 40S ON MONDAY. THIS WILL
ALLOW FOR PRECIP TO BEGIN AS RAIN BEFORE TRANSITIONING TO
RAIN/SNOW. GIVEN AMT OF UNCERTAINTY REMAINING AND DIFFERING THERMAL
PROFILES BETWEEN THE MODELS WILL CONTINUE WITH MENTION OF RAIN OR
SNOW IN GRIDS FOR MON NITE/TUES TIMEFRAME. 12Z ECMWF HAS COME IN
WITH STRONGER AND COLDER SOLUTION WHICH WOULD PROVIDE A GOOD
POSSIBILITY FOR DECENT ACCUMULATING SNOWFALL BUT TOO FAR OUT TO
TELL. REGARDLESS...AS COLDER AIR WRAPS IN BEHIND SYSTEM...LIGHT SNOW
POSSIBLE THRU END OF PERIOD.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL NOON EST /11 AM CST/ TODAY FOR
     INZ003>009-012>018-020-022>027-032>034.

MI...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR MIZ077>081.

OH...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR OHZ001-002-004-
     005-015-016-024-025.

LM...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR LMZ043-046.

&&

SHORT TERM...JT
LONG TERM...OBERGFELL
AVIATION...AGD
UPDATE...MARSILI

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE NORTHERN INDIANA
710 PM EST THU FEB 21 2013

INZ003>009-012>018-020-022>027-032>034-MIZ077>081-OHZ001-002-004-005-
015-016-024-025-230015-
LA PORTE-ST. JOSEPH IN-ELKHART-LAGRANGE-STEUBEN-NOBLE-DE KALB-STARKE-
PULASKI-MARSHALL-FULTON IN-KOSCIUSKO-WHITLEY-ALLEN IN-WHITE-CASS IN-
MIAMI-WABASH-HUNTINGTON-WELLS-ADAMS-GRANT-BLACKFORD-JAY-BERRIEN-
CASS MI-ST. JOSEPH MI-BRANCH-HILLSDALE-WILLIAMS-FULTON OH-DEFIANCE-
HENRY-PAULDING-PUTNAM-VAN WERT-ALLEN OH-
INCLUDING THE CITIES OF...MICHIGAN CITY...LA PORTE...SOUTH BEND...
MISHAWAKA...ELKHART...GOSHEN...LAGRANGE...TOPEKA...ANGOLA...
KENDALLVILLE...LIGONIER...AUBURN...GARRETT...KNOX...NORTH JUDSON...
WINAMAC...FRANCESVILLE...PLYMOUTH...BREMEN...ROCHESTER...WARSAW...
WINONA LAKE...COLUMBIA CITY...SOUTH WHITLEY...FORT WAYNE...
MONTICELLO...BROOKSTON...LOGANSPORT...PERU...WABASH...
NORTH MANCHESTER...HUNTINGTON...BLUFFTON...OSSIAN...DECATUR...
BERNE...MARION...HARTFORD CITY...MONTPELIER...PORTLAND...NILES...
BENTON HARBOR...ST. JOSEPH...BUCHANAN...DOWAGIAC...CASSOPOLIS...
STURGIS...THREE RIVERS...COLDWATER...HILLSDALE...BRYAN...WAUSEON...
ARCHBOLD...DEFIANCE...NAPOLEON...PAULDING...ANTWERP...OTTAWA...
PANDORA...VAN WERT...DELPHOS...LIMA
710 PM EST THU FEB 21 2013 /610 PM CST THU FEB 21 2013/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST OHIO...
SOUTHWEST LOWER MICHIGAN AND NORTHERN INDIANA.

.DAY ONE...TONIGHT

SNOW IS EXPECTED TO OVERSPREAD THE AREA FROM SOUTHWEST TO
NORTHEAST THIS EVENING INTO THE OVERNIGHT HOURS. SNOWFALL
ACCUMULATIONS OF 2 TO 4 INCHES ARE POSSIBLE BY DAYBREAK
FRIDAY...WITH THE GREATER AMOUNTS ACROSS NORTHWEST AND PORTIONS OF
NORTH CENTRAL INDIANA. PLEASE REFERENCE THE LATEST WINTER WEATHER
MESSAGE FROM THIS OFFICE FOR ADDITIONAL DETAILS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

SNOW WILL PERSIST ACROSS EXTREME NORTHEAST INDIANA...FAR NORTHWEST
OHIO...AND SOUTH CENTRAL LOWER MICHIGAN EARLY FRIDAY MORNING
BEFORE TAPERING. A PERIOD OF LIGHT FREEZING RAIN OR LIGHT FREEZING
DRIZZLE IS EXPECTED ACROSS THE ENTIRE AREA FRIDAY MORNING BEFORE
TEMPERATURES WARM ABOVE FREEZING IN THE AFTERNOON.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO REPORT PRECIPITATION TYPES AND AMOUNTS
TONIGHT INTO FRIDAY.

&&

STAY TUNED TO NOAA WEATHER RADIO FOR FURTHER DETAILS OR UPDATES...OR
CHECK OUR WEB SITE AT WEATHER.GOV/IWX

LMZ043-046-230015-
NEW BUFFALO MI TO ST JOSEPH MI-MICHIGAN CITY IN TO NEW BUFFALO MI-
710 PM EST THU FEB 21 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE NEARSHORE WATERS OF
SOUTHEASTERN LAKE MICHIGAN.

.DAY ONE...TONIGHT

EAST WINDS MAY GUST TO AROUND 25 KNOTS TONIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

HAZARDOUS CONDITIONS FOR SMALL CRAFT ARE POSSIBLE AGAIN FRIDAY
NIGHT AND SATURDAY.

&&

STAY TUNED TO NOAA WEATHER RADIO FOR FURTHER DETAILS OR UPDATES...OR
CHECK OUR WEB SITE AT WEATHER.GOV/IWX/?N=MARINE