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Halloween Spooktacular Storm General OBS/Discussion


hm8

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System looks moderately exciting for YYZ and area.

 

GFS indicates the peak winds will occur around 2am Friday morning, NAM a little bit slower indicating the morning rush hour will be gusty. Both models indicating surface winds in the 25-35km/h range, with potential for gusts in the 80-90km/h range, maybe even a few reports of 100km/h.

 

WRF slightly more aggressive on the surface winds, up to 40km/h. The model also shows a broad area of 55-65kt winds at 900mb over southern Ontario so if those winds can mix down I wouldn't be surprised to see wind warnings raised by Environment Canada.

 

Rainfall I suspect will be in the range of 20-30mm. If some convective precip can form behind the warm front Thursday daytime we may come in more towards the higher end of that range but instability will be limited.

 

Temperature of above 15C will certainly be achievable Thursday due to strong WAA during the daytime as the system deepens.

 

Most models including the ECMWF now agree the system will be at or below 980mb with the GFS the most aggressive at 973mb Friday morning. System will be deepening as the center crosses the MI/ON border over Lake Huron on Thursday night.

 

Tight :) :

3g2yk.gif

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IND

INTENSE LOW LEVEL JET WILL INCREASE TO 70+KTS BY THURSDAY AFTERNOON AS THE SYSTEM STRENGTHENS...TRANSPORTING DEEP GULF MOISTURE RAPIDLY NORTH INTO THE OHIO VALLEY. MODEL SOUNDINGS INDICATING WINDS APPROACHING 50KTS AT JUST ABOUT 2KFT. PRECIP WATER VALUES WILL INCREASE TO NEARLY 250% OF NORMAL IN EXCESS OF 1.5 INCHES AT THEIR MAX. INCREASING DIFFLUENCE ALOFT WILL ENHANCE HEAVY RAINFALL POTENTIAL...WITH A 130-140KT UPPER JETLET POISED TO LIFT ACROSS THE REGION BY EARLY EVENING. ALL OF THESE FEATURES SUPPORT THE POTENTIAL FOR HEAVY RAINFALL...MAINLY DURING THE AFTERNOON AND EVENING. HIGH LIKELIHOOD FOR A SOLID ONE TO TWO INCHES OF RAINFALL FOR THE ENTIRE FORECAST AREA THROUGH THURSDAY NIGHT...WITH LOCALLY HIGHER AMOUNTS POSSIBLE. WILL INCLUDE HEAVY RAINFALL WORDING IN THE FORECAST FOR THURSDAY AND THURSDAY NIGHT.

THE STRENGTH OF THE LOW LEVEL WIND FIELDS ALSO POSES THE POTENTIAL FOR WINDY CONDITIONS DURING THE AFTERNOON AND EVENING. MODEL SOUNDINGS INDICATING WINDS APPROACHING 50KTS AS LOW AS 2KFT OFF THE GROUND BY MIDDAY THURSDAY...WITH 60KTS AT 3KFT BY MID AFTERNOON. MOMENTUM TRANSFER BELOW THE BOUNDARY LAYER ALONE IS SUGGESTIVE OF MAX WIND GUSTS APPROACHING 40MPH DURING THE AFTERNOON AND EVENING... WITH POTENTIAL THAT SHOWERS MAY BE SUFFICIENT TO PULL DOWN STRONGER GUSTS. WILL OBVIOUSLY BE HIGHLIGHTING THE GUSTY WINDS IN THE HWO...BUT POTENTIAL IS THERE FOR A WIND ADVISORY TO EVENTUALLY BE NEEDED FOR THURSDAY AFTERNOON AND EVENING CONSIDERING THE VALUES.

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Non-severe OBS/Discussion

 

d13_fill.gif

 

Gonna be some pretty quick deepening of this thing....GFS showing 8-10mb drops in 6hrs.

 

My 6yr old daughter has been bumming about the rain for days. I actually wish the city would delay the night until Saturday,

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System looks moderately exciting for YYZ and area.

GFS indicates the peak winds will occur around 2am Friday morning, NAM a little bit slower indicating the morning rush hour will be gusty. Both models indicating surface winds in the 25-35km/h range, with potential for gusts in the 80-90km/h range, maybe even a few reports of 100km/h.

WRF slightly more aggressive on the surface winds, up to 40km/h. The model also shows a broad area of 55-65kt winds at 900mb over southern Ontario so if those winds can mix down I wouldn't be surprised to see wind warnings raised by Environment Canada.

Rainfall I suspect will be in the range of 20-30mm. If some convective precip can form behind the warm front Thursday daytime we may come in more towards the higher end of that range but instability will be limited.

Temperature of above 15C will certainly be achievable Thursday due to strong WAA during the daytime as the system deepens.

Most models including the ECMWF now agree the system will be at or below 980mb with the GFS the most aggressive at 973mb Friday morning. System will be deepening as the center crosses the MI/ON border over Lake Huron on Thursday night.

Tight :) :

Amazing write up man, I agree! With the rising instability given the placement of the trough we may see some weak non severe tstorms across southern ontario. The low level cooling working in from the stratosphere and strong WAA in place acorss the lower levels of the troposphere should create nice wind shear and may allow the tstorms to dump heavier rains locally so I wouldnt be surprised if some regions saw 2" or 50mm+. Winds should be vicious, going to be a breezy thursday and Friday, horrible for the kids on halloween. Overall I expect temperatues around 16-18C across the SW and around 14-17C in the GTA.

Weekend looks cool overall before temperatures rebound somewhat next week.

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Doppler underestimating precip amounts from LOT and ILX 2+ inches in some locations over NE IL ground truth but not even 1.5 on the radar

 

OOK IL-LAKE IN-  
849 PM CDT WED OCT 30 2013  
 
THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED AN  
 
* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...  
KANKAKEE COUNTY IN NORTHEAST ILLINOIS...  
LAKE COUNTY IN NORTHWEST INDIANA...  
NORTH CENTRAL FORD COUNTY IN EAST CENTRAL ILLINOIS...  
NORTHERN IROQUOIS COUNTY IN EAST CENTRAL ILLINOIS...  
NORTHERN JASPER COUNTY IN NORTHWEST INDIANA...  
NORTHERN NEWTON COUNTY IN NORTHWEST INDIANA...  
PORTER COUNTY IN NORTHWEST INDIANA...  
SOUTHEASTERN COOK COUNTY IN NORTHEAST ILLINOIS...  
WILL COUNTY IN NORTHEAST ILLINOIS...  
 
* UNTIL 300 AM CDT THURSDAY  
 
* AT 845 PM CDT...TRAINED WEATHER SPOTTERS REPORTED AN AREA OF HEAVY  
RAINFALL ACROSS THE ADVISORY AREA. TRAINED SPOTTERS AND OBSERVERS  
HAVE REPORTED 1.5 TO 2.5 INCHES OF RAINFALL. ADDITIONAL RAINFALL  
OF 1 TO 1.5 INCHES IS POSSIBLE OVER THE NEXT FEW HOURS.

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Valpo's PWS is showing 1.41" on the day.  I'm pretty surprised we've gotten that much so far.

 

The NAM has a stripe of >2" additional rain through NW IN after 06z tonight.  A partner and I have an internship forecasting for Porter County schools (usually snow/ice and fog) but I'm starting to wonder if we need to call and warn about flooding.

 

Do farm roads flood easily, or does all the water drain into the ditches?

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Valpo's PWS is showing 1.41" on the day.  I'm pretty surprised we've gotten that much so far.

 

The NAM has a stripe of >2" additional rain through NW IN after 06z tonight.  A partner and I have an internship forecasting for Porter County schools (usually snow/ice and fog) but I'm starting to wonder if we need to call and warn about flooding.

 

Do farm roads flood easily, or does all the water drain into the ditches?

 

More than often I see flooding in the city before I see flooding in the countryside. Ditches and unpaved surface definitely help mitigate the runoff volumes.

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More than often I see flooding in the city before I see flooding in the countryside. Ditches and unpaved surface definitely help mitigate the runoff volumes.

 

Ok thanks!  I'm originally from Philly, and we don't have farm grids like you guys do out here, so I didn't know.

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