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December 21-22nd Winter Storm Part 3


Chicago Storm

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I don't think the GTA will see much PL/SN from this event at all. Whether precip falls as RN or ZR is going to depend on sfc temps IMO as its going to be very close. The 850-700mb level definitely looks warm enough to melt the SN completely with thicknesses above 155 for majority of the event besides a few hours at the onset where soundings favour more of a PL situation, especially north of the 401.

 

Depending on the rest of the 12z suite, might have to go with a compromise. A scenario which unfortunately might maximize icing.

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. If model amounts verify, many parts of the GTA are going to be looking at major power outages.

 

Umm..... my 35 yrs. of closely watching  GTA weather  tells me that typically we won't get ice storm in downtown T.O as per usual, due to lakes moderating influence. When 1,0, -1 is forecast, models don't take geographical influence (proximity to big Lake Ontario) into account.. We will get mist, drizzle, freezing drizzle, a little light snow, light rain, bit of accumulating ice pellets and probably have to scrape a bit of glaze/ PL stuck to car window Sun. morning before it mostly melts Sun. aft.

 

North and east of GTA will have some problems as usual. lol

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Umm..... my 35 yrs. of closely watching  GTA weather  tells me that typically we won't get ice storm in downtown T.O as per usual, due to lakes moderating influence. When 1,0, -1 is forecast, models don't take geographical influence (proximity to big Lake Ontario) into account.. We will get mist, drizzle, freezing drizzle, a little light snow, light rain, bit of accumulating ice pellets and probably have to scrape a bit of glaze/ PL stuck to car window Sun. morning before it mostly melts Sun. aft.

 

North and east of GTA will have some problems as usual. lol

Downtown TO is just a small part of the GTA. Sure, it will be warmer and less intense downtown but it makes little sense to ignore what is going on along and north of the 401, including the SW burbs where impacts could be very significant if model forecasts hold.

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Umm..... my 35 yrs. of closely watching GTA weather tells me that typically we won't get ice storm in downtown T.O as per usual, due to lakes moderating influence. When 1,0, -1 is forecast, models don't take geographical influence (proximity to big Lake Ontario) into account.. We will get mist, drizzle, freezing drizzle, a little light snow, light rain, bit of accumulating ice pellets and probably have to scrape a bit of glaze/ PL stuck to car window Sun. morning before it mostly melts Sun. aft.

North and east of GTA will have some problems as usual. lol

Normally the downtown core doesn't get big ice storms, but there was one back on January 14, 1968 in which an inch of ice fell. Temperatures hovered around -2 or -1C. The 00z ECMWF text output from last night actually has 2m temperatures falling during the day tomorrow into tomorrow night into Sunday morning before rebounding to above freezing late in the day Sunday. Temps fall to -3 or -4C by Sunday morning. Hopefully the ECMWF solution is not correct, but I'm concerned that it might be.

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Dtx

THE UPPER LOW NOW ADVANCING INTO THE NRN BAJA PENINSULA IS FORECAST

TO ROTATE ACROSS THE TX PANHANDLE ON SATURDAY...POSSIBLY PHASING

WITH SHORT WAVE ENERGY NOW ADVANCING ACROSS THE GULF OF ALASKA. THE

00Z MODEL SUITE ARE IN GOOD AGREEMENT IN SHOWING THIS WAVE SHEARING

OUT AS IT RAPIDLY LIFTS INTO THE GREAT LAKES REGION ON SUNDAY. THERE

WILL HOWEVER BE A DEEP FRONTAL ZONAL IN PLACE FROM THE OHIO VALLEY

INTO THE GREAT LAKES REGION. THE APPROACH OF THIS WAVE ALONG WITH AN

INTENSIFICATION OF AN UPPER JET STREAK OVER QUEBEC /TO AN IMPRESSIVE

230 KTS BY 06Z SUN/ WILL INVOKE A HEALTHY FRONTOGENETICAL RESPONSE

ALONG THIS BAROCLINIC ZONE. 00Z UPPER AIR ANALYSIS AND RECENT WATER

VAPOR IMAGERY ALREADY SUPPORT A GOOD FEED OF MOISTURE INTO THIS

FRONTAL ZONE. THIS WILL ONLY INCREASE AS THE UPPER WAVE LIFTS OUT OF

TEXAS AND DRAWS GULF MOISTURE INTO THE OH VALLEY AND SRN GREAT

LAKES. MEANWHILE...ARCTIC HIGH PRESSURE IS FORECAST TO BUILD ACROSS

NRN ONTARIO AND QUEBEC SAT INTO SAT NIGHT. STRENGTHENING NORTHEAST

LOW LEVEL FLOW WILL IN TURN ADVECT COLDER AND DRIER AIR NEAR THE

SURFACE INTO SE MI. THIS COUPLED WITH WARM AND MOIST AIR ADVECTION

ALOFT WILL SET THE STAGE FOR A POTENTIAL ICE STORM OVER PORTIONS OF

SE MI SAT NIGHT.

DESPITE THE OVERALL AGREEMENT ON THE LARGER SCALE...SUBTLE MODEL

DIFFERENCES WITH RESPECT TO THE AMPLITUDE OF THE WAVE LIFTING UP

FROM TX AND THE PORTION OF THE FRONTAL ZONE WHICH BECOMES MORE

ACTIVE WILL HAVE BIG IMPACTS NOT ONLY TO PRECIP TYPE ACROSS SE MI

BUT ALSO QPF AMOUNTS. THE NAM SOLUTION DAMPENS THE WAVE MORE QUICKLY

AND IS WEAKER WITH THE SFC HIGH TO THE NORTH AND IS THEREFORE MUCH

WARMER OVER SE MI. IN LIGHT OF THE DYNAMICS...PREFERENCE LIES TOWARD

THE GFS/ECMWF/CANADIAN SOLUTIONS WHICH ARE COLDER.

CROSS SECTIONS ACROSS THE FRONTAL ZONE INDICATE A DEEP LAYER OF

CONVECTIVE INSTABILITY ACROSS THE OHIO VALLEY...SUGGESTING THIS MAY

BE THE MORE ACTIVE PORTION OF THE FRONTAL ZONE. THIS COULD KEEP THE

HEAVIER PRECIP SOUTH OF MI. THE 00Z ECMWF/CANADIAN MAINTAIN A DEEPER

UPPER WAVE AND THUS LIFT THE LOWER TROPOSPHERIC FRONTAL ZONE FARTHER

NORTH...SUGGESTIVE OF HEAVIER PRECIP INTO THE SRN HALF OF THE

FORECAST AREA /OVER AN INCH QPF/. DESPITE THESE DIFFERENCES...THE

INTENSE FGEN MAY TIGHTEN THE THERMAL GRADIENT MORE DRAMATICALLY THAN

SHOWN IN CURRENT MODEL SOLUTIONS AND SUGGESTS A SHARP TRANSITION IN

PRECIP TYPE FROM SOUTH TO NORTH. IN LIGHT OF THE RECENT MODEL

GUIDANCE...THE PRECIP IS EXPECTED TO OVERSPREAD THE AREA SAT

AFTERNOON AND END EARLY SUN MORNING AS THE MID LEVEL DRY SLOT

ADVANCES ACROSS THE AREA. AT THIS STAGE IN THE FORECAST... PRECIP

TYPE FROM DETROIT/ANN ARBOR SOUTH SHOULD BEGIN AS FREEZING RAIN AND

TRANSITION TO RAIN. FROM THE NRN DETROIT SUBURBS TO THE I-69

CORRIDOR PRECIP SHOULD BEGIN AS SNOW THEN TRANSITION TO FREEZING

RAIN. THE SAGINAW VALLEY AND THUMB SHOULD SEE PRIMARILY SNOW WITH A

POSSIBLE TRANSITION TO FREEZING RAIN SUN NIGHT. SOME SNOW

ACCUMULATIONS ARE CERTAINLY POSSIBLE NORTH OF M-59. THERE IS ALSO A

GOOD CHANCE OF SOME ICE ACCUMULATION /ESPECIALLY SOUTH OF SAGINAW/.

THE UNCERTAINTY IN QPF AND THE THERMAL PROFILE SUGGEST WAITING AT

LEAST ANOTHER MODEL CYCLE TO DECIDE WHETHER OR NOT HEADLINES NEED TO

BE ISSUED.

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Wouldn't be surprised if the GFS comes west this run...Given more and more ensembles have been farther west the past two runs.

 

I'm thinking a tad west, but not much.  The NAM has been all over, yesterday's 0z run it was the furthest south and east with the deformation zone, and now this 12z run it is the furthest run of all recent model runs with that zone.

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Wow at the 12z RGEM in and around the GTA, especially along and north of the 401.

attachicon.gifpost-23784-1387552878_thumb.png

 

The Canadian has really held steady on the ZR threat for quite some time. Probably the most consistent of the models in this respect.

 

I'll be heading up to cottage country tonight until Monday, I have a feeling I'll be returning to a home without power.

 

Sadly I'll miss any good ice accretion, so if some of the Toronto posters could get some pics, it would be much appreciated :)

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The Canadian has really held steady on the ZR threat for quite some time. Probably the most consistent of the models in this respect.

 

I'll be heading up to cottage country tonight until Monday, I have a feeling I'll be returning to a home without power.

 

Sadly I'll miss any good ice accretion, so if some of the Toronto posters could get some pics, it would be much appreciated :)

I'll be out of town too, if my flight can get out tomorrow morning en route to Az. Missed the boxing day storm and july flood as well.
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ECMWF Deterministic FORECAST FOR: YYZ    LAT=  43.67 LON=  -79.63 ELE=   568

                                            00Z DEC20
                 2 M     850     SFC     SFC     700    6 HR     500    1000 
                 TMP     TMP     PRS     RHU     RHU     QPF     HGT     500 
                 ©     ©    (MB)    (PCT)   (PCT)   (IN)    (DM)     THK 

SAT 12Z 21-DEC  -0.7     1.8    1012      92      63    0.02     555     546    
SAT 18Z 21-DEC  -1.5     0.4    1015      88      86    0.09     557     546    
SUN 00Z 22-DEC  -1.6     0.0    1016      91      96    0.15     559     546    
SUN 06Z 22-DEC  -3.0     1.1    1011      92     100    0.61     558     549    
SUN 12Z 22-DEC  -3.6     3.1    1007      87      85    0.69     556     550    
SUN 18Z 22-DEC  -2.2     4.4    1005      90      23    0.06     550     547    
MON 00Z 23-DEC   4.0    -1.4    1006      87      53    0.02     550     545

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ECMWF Deterministic FORECAST FOR: YYZ    LAT=  43.67 LON=  -79.63 ELE=   568

                                            00Z DEC20

                 2 M     850     SFC     SFC     700    6 HR     500    1000 

                 TMP     TMP     PRS     RHU     RHU     QPF     HGT     500 

                 ©     ©    (MB)    (PCT)   (PCT)   (IN)    (DM)     THK 

SAT 12Z 21-DEC  -0.7     1.8    1012      92      63    0.02     555     546    

SAT 18Z 21-DEC  -1.5     0.4    1015      88      86    0.09     557     546    

SUN 00Z 22-DEC  -1.6     0.0    1016      91      96    0.15     559     546    

SUN 06Z 22-DEC  -3.0     1.1    1011      92     100    0.61     558     549    

SUN 12Z 22-DEC  -3.6     3.1    1007      87      85    0.69     556     550    

SUN 18Z 22-DEC  -2.2     4.4    1005      90      23    0.06     550     547    

MON 00Z 23-DEC   4.0    -1.4    1006      87      53    0.02     550     545

 

Well... that took a turn for the worst.

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