Heavy Snow in Michigan, February 9, 2016

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1148 PM EST MON FEB 8 2016

.AVIATION...

AREA OF LIGHT SNOW CONTINUES TO GRADUALLY INCREASE IN COVERAGE AND
PIVOT SOUTHWARD INTO AREA AROUND DEVELOPING LOW PRESSURE CENTER NEAR
THE SOUTHERN TIP OF LAKE HURON. WHILE WNW FLOW AROUND THIS LOW WILL
ACT TO DRY OUT LOW LEVELS TO SOME EXTENT...STILL EXPECT ENOUGH LOW
LEVEL MOISTURE TO WORK AROUND THIS LOW INTO AREA AND BRING MVFR CIGS
AND ALSO VSBYS AS SHSNS BECOME INCREASINGLY PREVALENT...FIRST FOR
KMBS/KFNT/KPTK AND EVENTUALLY SOUTH INTO THE I-94 CORRIDOR. WITH THE
LOW BASICALLY STATIONARY DURING THIS FORECAST PERIOD...MVFR TO LOWER
VFR CONDITIONS SHOULD PREVAIL INTO TUESDAY EVENING. SHSNS WILL BE
POSSIBLE AREA-WIDE...BUT MOST PERSISTENT KMBS/KFNT WHERE INTERVALS
OF IFR WILL ALSO BE POSSIBLE.

FOR DTW...A GRADUAL TRANSITION TO MVFR CIGS...AND AT TIMES VSBYS...
IS EXPECTED LATE TONIGHT INTO THE DAY TIME AS PERIODIC SHSNS
INCREASE. FLOW WILL REMAIN LARGELY WNW...WITH GUSTS APPROACHING 25
KNOTS DURING AFTERNOON AS THE PRESSURE GRADIENT TIGHTENS.

//DTW THRESHOLD PROBABILITIES...

* MEDIUM IN CIGS AOB 5KFT OVERNIGHT...HIGH DURING DAY.

* HIGH CONFIDENCE IN PRECIPITATION TYPE BEING SNOW OVERNIGHT
  THROUGH THE DAY.

* LOW CONFIDENCE IN NORTHWEST CROSSWIND DURING AFTERNOON.

&&

.PREV DISCUSSION...ISSUED 314 PM EST MON FEB 8 2016

DISCUSSION...

WITH SURFACE TEMPS HOLDING IN THE UPPER 30 TO LOW 40S THIS
AFTERNOON...BOUNDARY LAYER WARMTH HAS REMAINED SUFFICIENT IN KEEPING
THE RETURNS STREAMING INTO PORT HURON AND THE EASTERN THUMB REGION
ALL RAIN. THIS PRECIPITATION WILL UNDERGO A TRANSITION TO ALL SNOW
THIS EVENING DUE BOTH TO NIGHTTIME BOUNDARY LAYER COOLING AND WEAK
LOW LEVEL COLD AIR ADVECTION. THESE RETURNS ARE ASSOCIATED WITH AN
AXIS OF MID LEVEL DEFORMATION EXTENDING FROM NRN OHIO INTO SRN LAKE
HURON. THE REGIONAL WATER VAPOR LOOP TODAY HAS INDICATED SOME
MOISTURE ADVECTION INTO THIS SYSTEM AHEAD OF A SHORT WAVE IMPULSE
NOW OVER THE OH/KY BORDER. THIS SHORT WAVE FEATURE IS ASSOCIATED
WITH THE BROAD UPPER LOW CENTERED OVER LAKE MI. THE SHORT WAVE
IMPULSE WILL BE DRIVEN TOWARD SRN LAKE HURON OVERNIGHT AS THE UPPER
LOW SLIDES INTO NRN INDIANA. THIS WILL IN TURN DRIVE THE MID LEVEL
DEFORMATION ACROSS THE THUMB REGION DURING THE NIGHT. LATEST HI RES
SUITE ALL GENERALLY SUGGEST THE STRONGER PUSH OF DEFORMATION WILL BE
A LITTLE SLOWER TO MOVE THROUGH THE THUMB REGION TONIGHT AS IT
APPEARS THE MID LEVEL IMPULSE WILL FOSTER A MORE COMPACT REGION OF
FORCING. MEANWHILE SOME CONVECTIVE SHOWERS HAVE EMERGED UNDER THE MID
LEVEL COLD POOL OVER SRN LAKE MI/SW LOWER MI. SOME OF THESE SHOWERS
MAY IMPACT THE FAR SOUTHERN SECTIONS OF THE FORECAST AREA THIS
EVENING.

ON TUESDAY...THE MID LEVEL SHORT WAVE WILL HOLD NEARLY STEADY IN THE
VICINITY OF EITHER THE ERN THUMB/SRN LAKE HURON OR JUST EAST OF
METRO DETROIT INTO TUES AFTERNOON. THE MID LEVEL IMPULSE WILL THEN
LIFT NORTHEAST AS THE UPPER LOW OPENS UP AND LIFTS EAST LATE IN THE
DAY. THERE REMAINS SOME DEGREE OF MODEL UNCERTAINTY AS TO HOW
QUICKLY THE DEFORMATION REGION OPENS UP AND TRANSITIONS WEST AND
SOUTH. RECENT MODEL TRENDS SUGGEST IT WILL TAKE UNTIL TUES
AFTERNOON/EVENING FOR THE REMNANT LARGE SCALE FORCING TO PUSH
THROUGH THE SAGINAW VALLEY AND INTO METRO DETROIT/ANN ARBOR AND PTS
SOUTH. STEADY COLD AIR ADVECTION THROUGH THE DAY WILL BEGIN TO BOOST
INSTABILITY OVER LAKE HURON. THE DEPARTURE OF THE SYSTEM TO THE EAST
TUES NIGHT MAY BE ENOUGH TO FORCE A LAKE ENHANCED SFC TROUGH INTO
THE THUMB REGION...POSSIBLY BOOSTING SNOWFALL RATES ACROSS HURON
COUNTY TUES NIGHT. EXPECT THE REMAINDER OF THE FORECAST AREA WILL
SEE SNOW TRANSITION TO NMRS/SCT SNOW SHOWERS. RESIDUAL DEEP LAYER
MOISTURE AND STEEP LOW LEVEL LAPSE RATES COULD HOWEVER SUPPORT SOME
INTENSE SNOWFALL OUT OF SOME OF THESE SNOW SHOWERS.

AS FAR AS THE WINTER WEATHER ADVISORY...THERE WILL BE NO AREAL
EXTENSION OF THE ADVISORY ATTM. THE POTENTIAL FOR LAKE ENHANCEMENT
WITHIN THE MID LEVEL DEFORMATION WILL HOWEVER SUPPORT EXTENDING THE
ADVISORY END TIME A LITTLE LATER INTO TUES EVENING. THE MAIN
FORECAST UNCERTAINTIES ATTM REVOLVE AROUND HOW FAR WEST INTO FLINT
AND THE TRI CITIES REGIONS THE STRONGER DEFORMATION WILL OCCUR ON
TUESDAY AND HOW WELL THE LARGE SCALE FORCING HOLDS TOGETHER LATE IN
THE DAY SOUTH OF THE M 59 CORRIDOR. GIVEN FAIRLY RESPECTABLE
MOISTURE QUALITY WITH 850MB MIXING RATIOS BETWEEN 2 AND 3 G/KG AND
GIVEN A FAIRLY DEEP LAYER OF LOW STATIC STABILITY WITH THE MID LEVEL
COLD POOL IN THE VICINITY...THERE IS LIKELY TO BE SOME REGIONS OF
ENHANCED FORCING WHICH MAY SUPPORT PERIODS OF HIGH INTENSITY
SNOWFALL RATES. THESE FACTORS SUGGEST SOME NEAR TERM FORECAST
UPDATES WILL BE NEEDED AS THIS EVENT UNFOLDS. TAKING INTO
CONSIDERATION LIQUID TO SNOW RATIOS AROUND 10:1 TONIGHT RISING TO
ROUGHLY 12:1 BY LATE TUESDAY AND WITH TOTAL QPF /TONIGHT THROUGH
TUES NIGHT/ POSSIBLY OVER A HALF INCH IN THE THUMB TO A TENTH OR
LESS SOUTH OF M 59...TOTAL FCST SNOWFALL OF 3 TO 7 INCHES LOOK
REASONABLE IN THE ADVISORY AREA /DROPPING TO AN INCH OR LESS SOUTH
OF THE M 59 CORRIDOR/.

REMAINDER OF THE FORECAST FOCUSES ON SNOW SHOWER POTENTIAL WEDNESDAY
AND COLD TEMPERATURES WEDNESDAY THROUGH THE WEEKEND. SURFACE LOW
CONTINUES TO PULL AWAY WEDNESDAY WITH UPPER TROUGH AXIS SWEEPING
THROUGH. SURFACE FLOW TURNS NORTHWESTERLY WHICH IS TYPICALLY A DRIER
FLOW FOR SOUTHEAST MICHIGAN. HOWEVER...850 MB TEMPS DROP TO NEAR -20
RESULTING IN GOOD INSTABILITY OVER THE LAKES. IN ADDITION...MODEL
FORECAST SOUNDINGS SHOW THE COLUMN SATURATED WRT ICE UP PAST 10KFT
EARLY IN THE DAY...WITH DEEPENING BOUNDARY LAYER RESULTING IN STEEP
LAPSE RATES AND SUPERSATURATION WRT ICE IN THE DGZ. THINK WE WILL
SEE AT LEAST A SCATTERED COVERAGE OF SNOW SHOWERS WITH POTENTIAL FOR
LOCALLY AND BRIEFLY HEAVY BURSTS OF SNOW. TOTAL ACCUMULATIONS
WEDNESDAY STILL LIKELY AROUND AN INCH OR LESS FOR MOST AREAS.

HIGH TEMPS WED THRU FRI EXPECTED TO BE A FEW DEGREES EITHER SIDE OF
20 BEFORE A REINFORCING SHOT OF ARCTIC AIR BLASTS IN FRIDAY NIGHT
INTO THE WEEKEND. THIS WILL OCCUR AS THE ARCTIC CLOSED LOW SWEEPS
INTO SOUTHEAST CANADA...AND A BACKDOOR COLD FRONT TURNS SURFACE
WINDS TO A NNW DIRECTION. FAIRLY GOOD CONFIDENCE THAT THIS WILL BE
THE COLDEST AIRMASS ALL YEAR...WITH GEFS MEAN 850 MB TEMPS DROPPING
TO AROUND -25C. HEART OF THIS COLD AIR WILL BE FRIDAY NIGHT THROUGH
SUNDAY. CURRENT FORECAST CALLS FOR LOW TEMPS IN THE SINGLE DIGITS
ABOVE AND BELOW ZERO FRI/SAT NIGHT...WITH HIGHS MAINLY IN THE SINGLE
DIGITS SAT. ECMWF MOS GUIDANCE IS EVEN COLDER. THERE IS LIGHT
SNOWFALL POTENTIAL FRIDAY ALONG THE ARCTIC FRONT AREAWIDE...WITH
SOME CONCERN FOR LAKE EFFECT SNOW ALONG THE HURON SHORELINE FRIDAY
NIGHT AND SATURDAY.

MARINE...

LOW PRESSURE WILL SETTLE OVER FAR SOUTHERN LAKE HURON
TONIGHT...STRENGTHENING IN THE PROCESS...WHICH WILL ALLOW FOR
EXPANDING SNOW SHOWER ACTIVITY THROUGH TOMORROW. WINDS WILL BE LIGHT
TONIGHT...BUT GUSTING UP TO 20 KNOTS ACROSS FAR WESTERN LAKE HURON.
AS THE LOW SLOWLY PULLS AWAY TOMORROW AND COLD AIR RUSHES INTO THE
CENTRAL GREAT LAKES...NORTHWEST WINDS LOOK TO BE RAMPING UP TO 25 TO
30 KNOTS ACROSS MUCH OF LAKE HURON TUESDAY NIGHT...AND PERSISTING
WEDNESDAY...WITH JUST A SMALL DECREASE ON THURSDAY. WITH THE AMOUNT
OF COLD AIR COMING IN...FREEZING SPRAY IS EXPECTED...AND MAY BE
HEAVY. A RENEWED SURGE OF ARCTIC AIR ARRIVES BY SATURDAY...ALLOWING
FOR ANOTHER ROUND OF STRONGER WINDS AND LIKELY FREEZING SPRAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...WINTER WEATHER ADVISORY UNTIL 9 PM EST TUESDAY FOR MIZ049-054-055-
     062-063.

LAKE HURON...NONE.

LAKE ST CLAIR...NONE.

MICHIGAN WATERS OF LAKE ERIE...NONE.

&&

AVIATION.....DG/BT
DISCUSSION...SC/DT
MARINE.......SF

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
350 PM EST MON FEB 8 2016

MIZ047-048-053-060-061-068>070-075-076-082-083-092100-
MIDLAND-BAY-SAGINAW-SHIAWASSEE-GENESEE-LIVINGSTON-OAKLAND-MACOMB-
WASHTENAW-WAYNE-LENAWEE-MONROE-
350 PM EST MON FEB 8 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
MICHIGAN.

.DAY ONE...THIS AFTERNOON AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A VERY DYNAMIC SYSTEM WILL POTENTIALLY PRODUCE LIGHT SNOW
ACCUMULATIONS OF 1 TO 3 INCHES TUESDAY...MOST LIKELY ALONG AND
NORTH OF THE M-59 CORRIDOR. UNCERTAINTY REMAINS UNUSUALLY HIGH.
PLEASE MONITOR THE FORECAST FOR THE LATEST INFORMATION.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT.

MIZ049-054-055-062-063-092100-
HURON-TUSCOLA-SANILAC-LAPEER-ST. CLAIR-
350 PM EST MON FEB 8 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
MICHIGAN.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A WINTER WEATHER ADVISORY IS IN EFFECT. SEE THE LATEST URGENT
WINTER WEATHER MESSAGE FOR DETAIL.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A WINTER WEATHER ADVISORY IS IN EFFECT TUESDAY. SEE THE LATEST
URGENT WINTER WEATHER MESSAGE FOR DETAIL.

MUCH COLDER AIR WILL SPILL INTO THE AREA THIS WEEKEND. MULTIPLE
NIGHTS OF SUB-ZERO TEMPERATURES AND WIND CHILLS APPROACHING -15
DEGREES WILL BE POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED. HOWEVER SPOTTER SNOWFALL
REPORTS WILL BE APPRECIATED.

LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-092100-
LAKE ST. CLAIR-
MICHIGAN WATERS OF LAKE ERIE FROM DETROIT RIVER TO NORTH CAPE MI-
LAKE HURON FROM 5NM EAST OF MACKINAC BRIDGE TO PRESQUE ISLE LT
BEYOND 5 NM OFF SHORE-
LAKE HURON FROM PRESQUE ISLE LIGHT TO STURGEON POINT MI BEYOND 5NM
OFF SHORE-
LAKE HURON FROM STURGEON POINT TO ALABASTER MI BEYOND 5NM OFF SHORE-
OUTER SAGINAW BAY SW OF ALABASTER TO PORT AUSTIN MI TO INNER SAGINAW
BAY-INNER SAGINAW BAY SW OF POINT AU GRES TO BAY PORT MI-
PORT AUSTIN TO HARBOR BEACH MI-HARBOR BEACH TO PORT SANILAC MI-
PORT SANILAC TO PORT HURON MI-
LAKE HURON FROM PORT AUSTIN TO HARBOR BEACH BEYOND 5NM OFF SHORE-
LAKE HURON FROM HARBOR BEACH TO PORT SANILAC BEYOND 5NM OFF SHORE-
LAKE HURON FROM PORT SANILAC TO PORT HURON BEYOND 5NM OFF SHORE-
350 PM EST MON FEB 8 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE ERIE...LAKE
HURON AND LAKE ST CLAIR.

.DAY ONE...THIS AFTERNOON AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

GALE FORCE WINDS AND HEAVY FREEZING SPRAY IS POSSIBLE OVER
PORTIONS OF LAKE HURON ON WEDNESDAY AS ARCTIC AIR SURGES ACROSS
THE REGION.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT.

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

SC