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Dec 11-13 MW/Lakes/OV Snow Event? Part III

Chicago Storm

By Chicago Storm,
in Central/Western States

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Ajdos

Ajdos

Posted
Posted

dtx

AN INTENSIFYING LOW PRESSURE SYSTEM WILL TRACK THROUGH THE CENTRALGREAT LAKES BRINGING A MIX OF PRECIPITATION FROM SATURDAY NIGHT INTOSUNDAY. MEANWHILE CYCLOGENESIS WILL OCCUR AHEAD OF THE DEEPENINGUPPER LEVEL TROUGH ALONG THE EAST COAST WITH THE TWO SURFACE LOWSCOMBINING AND TRACKING NORTH INTO QUEBEC ON MONDAY. A COLD AIRMASSORIGINATING OVER THE NORTHWEST TERRITORIES WILL PLUNGE SOUTH INTOTHE GREAT LAKES REGION BEHIND THE DEPARTING SYSTEM WITH VERY COLDAND BLUSTERY CONDITIONS EXPECTED BY MONDAY.INVERSION HEIGHTS STEADILY LOWER FROM TONIGHT INTO SATURDAY MORNINGTRAPPING A SHALLOW LAYER OF MOISTURE AND CLOUDS BENEATH IT. JUST ASTHE LOW CLOUDS SHOW SIGNS OF STARTING TO ERODE FROM THE SOUTH ONSATURDAY...MID LEVEL CLOUDS WILL BE STARTING TO THICKEN AS DEEPSOUTHERLY FLOW DEVELOPS AHEAD OF THE TROUGH. A DEEP LAYER OF DRY AIRWILL BE OVERCOME AS THE THETA-E RIDGE NOSES UP INTO SOUTHEASTMICHIGAN.NAM/GFS/ECMWF HAVE NARROWED IN ON A SURFACE LOW TRACK FROM SOUTHERNWISCONSIN NORTHEAST ACROSS CENTRAL LOWER MICHIGAN...REACHING LAKEHURON BY 12Z SUNDAY. THE GEM AND UKMET KEEP THE SURFACE LOW TRACKGENERALLY SOUTH OF THE STATE LINE WHICH IS NOT PREFERRED GIVEN THESTRONGER PV ANOMALY DROPPING SOUTH ACROSS CENTRAL CANADA ANDTENDENCY FOR THIS FEATURE TO PULL THE SOUTHERN SYSTEM FURTHER NORTH.PRECIPITATION IS EXPECTED TO OVERSPREAD THE FORECAST AREA QUICKLYSATURDAY EVENING WITH A BRIEF BUT DEEP SHOT OF ISENTROPIC ASCENT INTHE 280-300K LAYER. MAIN DIFFERENCES IN THE MODELS AT THIS POINTREVOLVE AROUND THE THERMAL AND MOISTURE PROFILES OVER SOUTHEASTMICHIGAN ON SATURDAY NIGHT. THE NAM IS AS MUCH AS 2-3C WARMER AROUND900MB THAN THE GFS WHOSE TRACK IS JUST A TOUCH FURTHER SOUTHEAST ANDOCCLUDES MORE QUICKLY. AFTER 06Z THE NAM WRAPS A SIZABLE DRY-SLOTUP OVER ALL OF SOUTHEAST MICHIGAN WHILE THE GFS IS DEEPENING THROUGHTHE COLUMN AND ONLY PULLS THE DRY-SLOT UP TO THE METRO-DETROIT AREA.POSITIVES CAN BE SEEN IN BOTH MODELS AND PREFER A BLEND OF THETHERMAL PROFILES AT THE ONSET OF PRECIPITATION...TRENDING TOWARDSTHE GFS AS WE HEAD INTO SUNDAY WITH THE NAM RUNNING A LITTLE SLOWWITH THE ENERGY DROPPING SOUTH OUT OF CANADA. THIS WOULD SUGGEST ARAIN/SNOW MIX LIFTING UP TO THE M-59 TO I-69 CORRIDORS...TRANSITIONING BACK TO SNOW AS THE SYSTEM DEEPENS AND WRAPS COLDERAIR BACK IN OVERNIGHT. WE WILL NEED TO IRON OUT THE DETAILS WITH THE TRACKAND WARM LAYER LIFTING IN TO SOLIDIFY POTENTIAL SNOWFALL TOTALSAND EXPECT MODELS TO CONTINUE TO IMPROVE WITH THE 12Z RUN ASENERGY OFF THE PACIFIC NORTHWEST COAST MOVES ONSHORE AND GETSSAMPLED BETTER. THIS FORECAST PACKAGE GENERALLY KEEPS THEACCUMULATING SNOW ALONG AND NORTH OF THE I-69 CORRIDOR ON SATURDAYNIGHT WITH HIGHEST ACCUMS OF 3-4 INCHES IN THE SAGINAW VALLEY.SNOW SHOWERS WILL BE LIKELY ACROSS ALL OF SOUTHEAST MICHIGAN INTOSUNDAY AS THE UPPER LOW CLOSES OFF OVERHEAD AND PULLS THE COLDFRONT THROUGH. DEEP LAYER CYCLONIC FLOW MAY BE ABLE TO GRIND OUTANOTHER INCH OR TWO.THE AIRMASS BEHIND THE LOW PRESSURE SYSTEM WILL BE VERY COLD AS850MB TEMPS FALL TO AROUND -17C WITH THE TIGHT PRESSURE GRADIENTKEEPING STRONG WINDS OVER THE STATE. TEMPERATURES WILL FALL THROUGHTHE DAY ON SUNDAY...WITH WIND CHILL VALUES APPROACHING ZERO DURINGTHE AFTERNOON. NORTHWESTERLY WIND GUSTS MAY EXCEED 35 MPH LATESUNDAY WITH WIND CHILL VALUES AROUND -10F ON SUNDAY NIGHT.INCREASING INSTABILITY OVER THE LAKES WE REQUIRE US TO KEEP AN EYEON LAKE EFFECT SNOW IN THE THUMB REGION...MAINLY THROUGH MONDAYBEFORE THE FLOW BACKS TO THE NORTHWEST ORIENTING SNOW SHOWERSOFFSHORE. HAVE LOWERED HIGHS THROUGH MOST OF THE UPCOMING WEEK WITHGUIDANCE LIKELY STRUGGLING TO GET A HANDLE ON THE WELL BELOW NORMALAIRMASS.

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Ajdos

Ajdos

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Posted

grr interesting.

MODELS CONTINUE TO SHOW A LOW MOVING ACROSS LWR MI SATURDAY/NIGHT.THE OPERATIONAL RUNS OF THE GFS AND ECMWF ARE FARTHER NORTH THAN THEENSEMBLE MEANS OF BOTH THE GFS AND ECMWF. THUS WE/RE LEANING TOWARDA SOLUTION WHERE THE LOW TRACKS ACROSS FAR SRN LWR. FORECASTSOUNDINGS INDICATE THAT FREEZING RAIN WON/T BE A PLAYER. BUT MIXEDRAIN/SNOW LOOK GOOD AT THE START ACROSS THE SRN CWA. PCPN SHOULDBEING LATE MORNING/AFTERNOON AS STRONG ISENTROPIC LIFT QUICKLYSATURATES THE LOWER ATM. ADIABATIC COOLING WILL QUICKLY CHANGE THERAIN TO SNOW. WOULDN/T BE SURPRISED TO SEE 2-4 INCHES ACROSS THE NRNCWA LATE SATURDAY/NIGHT AND ANOTHER 2-4 SUNDAY AS THE DEFORMATIONSNOW DEVELOPS IN THE TROWAL AND MOVES ACROSS. LIGHTER AMOUNTS CAN BEEXPECTED ALONG/SOUTH OF I-96 WHERE A RAIN/SNOW MIX WILL BEGIN THEEVENT.

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Omahawx

Omahawx

Posted
Posted

NWS Quad Cities saying that the energy looking at water vapor is stronger then models depicted and they think it will go further south;

THE LATEST WATER VAPOR LOOPS IT APPEARS THE THE VERY STRONG COMPACT

SHORT WAVE TROF WHICH IS FORECAST TO BECOME THE UPPER LOW BY 24

HOURS IS STRONGER THAN NEARLY ALL MODELS WOULD SUGGEST.

ADDITIONALLY...THERE APPEARS TO BE NO RIDGING AHEAD OF THIS

WAVE...THUS IT MAY MOVE SLIGHTLY SOUTH OF DUE EAST TODAY AS IT

ENTERS THE MEAN TROF OVER THE CONUS. THIS SLIGHT DIFFERENCE OF A

EAST TRACK OR SLIGHTLY SOUTH OF DUE EAST TRACK WILL DETERMINE

WHETHER WE SEE A SIGNIFICANT WINTER PCPN EVENT/SNOW OR JUST A FEW

WIND BLOWN INCHES. IT IS A RATHER BINARY FORECAST...SINCE A

NORTHWARD POSITION OF THE MID LEVEL LOW WOULD LIKELY DRY SLOT THE

ENTIRE CWA SATURDAY AFTERNOON...VS A MORE PROLONGED PCPN EVENT

CHANGING TO MODERATE TO HEAVY SNOW. CONFIDENCE IS LOWER THAN 50

PERCENT ON THE SIGNIFICANT SNOW OCCURRING AT THIS TIME...AND WE WILL

NOT ISSUE A WINTER STORM WATCH AS OF YET. HOWEVER...IF THE MORE

SOUTHERLY UPPER LOW TRACK DOES VERIFY ON 12Z MODELS...ONE MAY

CERTAINLY BE NEEDED FOR AT LEAST THE NORTH 1/3 OF COUNTIES.

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wishforsnow

wishforsnow

Posted
Posted

sucks to see the snow band really explode just east of me past the Missouri river

I know how you feel. When I lived back home in Central Iowa we would miss lots of snowstorms. The worse is when they predict a snowstorm then it pours down rain. This is why now I am glad to live in the Keweenaw, even if the storm misses us we are usually blessed with lake effect snow.

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MadTown

MadTown

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yep one heck of a job for the mets in wisconisin. Just was watching a couple of them, one was trying to explain how we could only get one inch with a winter strom warning, the other flat out said we don't know at this point and the other covered everything by saying anywhere from 3-10"

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Chicago WX

Chicago WX

Posted
Posted

Mildly interesting to me, but the 6z NAM actually turns the initial slug of precip over to snow at the end here, to the tune of 1.2". Obviously we've seen hints of that with the RGEM, so I guess it can't be totally ruled out. Or at the very least, something to keep my attention locally in an otherwise MN, WI, MI snowstorm.

EDIT: It does the same at ORD, but with 4.4" falling.

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