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Pre-Thanksgiving Sou'easter Observation and Nowcasting Thread

IsentropicLift

By IsentropicLift,
in New York City Metro

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SnoSki14

SnoSki14

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In all honesty this storm is probably just a bit more than your typical run of the mill late autumn storm system. For some it'll be a bit worse than that but for us it'll be a quick shot of heavy rain with some wind, below advisory criteria, and it moves through to give us a cold Thanksgiving. There won't be any flooding issues with 2-2.5" of rain because of 3 month long dry conditions, and the only reason we're even talking about this storm is because of the timing of it. 

 

The reason there are headlines about it is because it's affecting Thanksgiving travel, but if it were any other time, then we'd probably brush it off. 

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IsentropicLift

IsentropicLift

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In all honesty this storm is probably just a bit more than your typical run of the mill late autumn storm system. For some it'll be a bit worse than that but for us it'll be a quick shot of heavy rain with some wind, below advisory criteria, and it moves through to give us a cold Thanksgiving. There won't be any flooding issues with 2-2.5" of rain because of 3 month long dry conditions, and the only reason we're even talking about this storm is because of the timing of it. 

 

The reason there are headlines about it is because it's affecting Thanksgiving travel, but if it were any other time, then we'd probably brush it off. 

3"+ of rain is noteworthy any day of the year, and the wind threat is being largely brushed under the rug in this sub-forum. The combination of frozen ground in spots and clogged storm drains will lead to some street flooding. This is the heaviest rain most of us have seen since Irene. 

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Snowlover11

Snowlover11

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In all honesty this storm is probably just a bit more than your typical run of the mill late autumn storm system. For some it'll be a bit worse than that but for us it'll be a quick shot of heavy rain with some wind, below advisory criteria, and it moves through to give us a cold Thanksgiving. There won't be any flooding issues with 2-2.5" of rain because of 3 month long dry conditions, and the only reason we're even talking about this storm is because of the timing of it.

The reason there are headlines about it is because it's affecting Thanksgiving travel, but if it were any other time, then we'd probably brush it off.

wrong, it's going to cause localized flooding, you got a ton of leaves clogging up drains. Rivers will be fine.
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IsentropicLift

IsentropicLift

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wrong, it going to cause localized flooding, you got a ton of leaves clogging up drains. Rivers will be fine.

Some of the flashier rivers might have issues, especially if anyone gets into the 4"+ territory. Don't forget that it hasn't been nearly as dry in NW sections as it's been for the coast.

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IsentropicLift

IsentropicLift

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The two low idea has no support. It's going to be one low

Then how come the 00z ECMWF had two lows?

 

Hour 42 shows a sub 988 low near Springfield MA and a second sub 988mb low over NNJ. At least know what you're talking about before you say someone is wrong.

 

Even the 06z GFS arguably had two lows, instead it shows one elongated low which is why it shows so much less QPF.

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jm1220

jm1220

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A 150kt+ jet streak is going to pass right over the region. It's going to pour. It's really not even up for debate.

 

nam_namer_036_250_wnd_ht.gif

Any storm that comes right out of the Gulf and is going negative tilt will be a very active, rainy system. I don't think the 3-4" rain amounts are far out there. Also, the wind threat is real on the south coastal areas, I wouldn't be surprised to have some 60 mph gusts tomorrow morning around where I live. Hopefully we have power for Thanksgiving. :axe:

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IsentropicLift

IsentropicLift

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Any storm that comes right out of the Gulf and is going negative tilt will be a very active, rainy system. I don't think the 3-4" rain amounts are far out there. Also, the wind threat is real on the south coastal areas, I wouldn't be surprised to have some 60 mph gusts tomorrow morning around where I live. Hopefully we have power for Thanksgiving. :axe:

The wind threat for coastal sections is real. The 12z NAM had surface winds south of Long Island close to Hurricane force for a period tomorrow.

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Guest Imperator

Guest Imperator

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The wind threat for coastal sections is real. The 12z NAM had surface winds south of Long Island close to Hurricane force for a period tomorrow.

 

Can you practice meteorology for once instead of humping your personally preferred model's output? Upton regarding the NAM winds:

 

REGARDING WINDS...THE NAM APPEARS TO BE AN OUTLIER IN BOTH THE STRENGTH AND DURATION OF ITS 950-850 HPA JETS. AS A RESULT...BASED WIND FORECAST ON BLEND OF GFS/ECMWF 950-850 HPA WINDS. EVEN IF ACCEPTED NAM WIND MAXIMUM AT 950 HPA OF 70-75 KT...NOTING THAT LITTLE IF ANY MIXING EXPECTED DUE TO 950 HPA FORECAST TO BE ABOVE BASE OF MARINE INVERSION PER BUFKIT SOUNDINGS BY MID EVENING...AND TOOK A VERY GENEROUS 60 PERCENT OF 950 WINDS GIVEN THIS STILL END UP BELOW HIGH WIND WARNING THRESHOLD OF 50 KT. A GFS/ECMWF BLEND TAKES A 60-70KT 950 AND 75-90 KT 850 JET MAINLY TO THE E/SE OF NYC FROM LATE TONIGHT INTO WEDNESDAY EVENING. THUS HAVE HIGHEST CONFIDENCE IN A WIND ADVISORY LEVEL EVENT ACROSS NYC/LONG ISLAND/COASTAL SW AND ALL OF SE CT...SOUTHERN WESTCHESTER COUNTY AND HUDSON COUNTY. GIVEN FORECAST TRACK OF SURFACE LOW TO BE OVER NYC BY EARLY WEDNESDAY AFTERNOON...EXPECT A LULL IN THE VICINITY OF THE LOW AS A RESULT HAVE SPLIT THE WIND ADVISORY UP WEST-EAST. HAVE NYC/NJ/WEST CHESTER/COASTAL SW CT + N MIDDLESEX COUNTY FROM 5Z-19Z WEDNESDAY AND LONG ISLAND/COASTAL SE CT + NORTHERN NEW LONDON COUNTY FROM 5Z WEDNESDAY-5Z THURSDAY. WHILE CANNOT COMPLETELY RULE OUT AN ISOLATED GUST TO 50+ KT FEEL THIS IS MOST LIKELY IN ISOLATED EMBEDDED STRONGER CONVECTION - AND THUS CAN BE HANDLED BY CONVECTIVE WARNINGS IF NEEDED.

 

In their Marine Section:

 

AS NOTED IN THE SHORT TERM SECTION OF THE AFD...NAM 950-850 WINDS ARE AN OUTLIER IN TERMS OF THEIR STRENGTH AND DURATION...SO USED A GFS/ECMWF BLEND TO DERIVE WIND GUSTS WITH THE COASTAL STORM. GIVEN EXPECTED MARINE INVERSION...AND USING PREFERRED BLEND...DO NOT HAVE REQUIRED 80 PERCENT CONFIDENCE IN STORM FORCE WINDS TO GO WITH A STORM WARNING. NOTE THAT EVEN NAM BASED BUFKIT SOUNDINGS DO NOT SHOW STORM FORCE GUSTS AT THE OCEAN BUOYS. HOWEVER...AM HIGHLY CONFIDENT IN WIDESPREAD GUSTS TO GALE FORCE FROM LATE TONIGHT THROUGH WEDNESDAY NIGHT ACROSS ALL WATERS. TO COVER THE STEP-UP TO GALE CONDITIONS DURING THE EVENING HOURS...HAVE ISSUED A GALE WARNING FROM 23Z TONIGHT THROUGH 11Z THURSDAY TO REFLECT THIS FOR ALL WATERS. CANNOT COMPLETELY RULE OUT OCCASIONAL GUSTS TO 50 KT OVER THE EASTERN COASTAL OCEAN ZONES WEDNESDAY WITH THE PASSAGE OF THE CORE OF THE LOW LEVEL JET...SO THE FORECAST REFLECTS THIS. WILL USE SPECIAL MARINE WARNINGS TO ADDRESS ANY WIND GUSTS OF 48 KT OR HIGHER IN ISOLATED STRONGER CONVECTION.

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Allsnow

Allsnow

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Can you practice meteorology for once instead of humping your personally preferred model's output? Upton regarding the NAM winds:

REGARDING WINDS...THE NAM APPEARS TO BE AN OUTLIER IN BOTH THE STRENGTH AND DURATION OF ITS 950-850 HPA JETS. AS A RESULT...BASED WIND FORECAST ON BLEND OF GFS/ECMWF 950-850 HPA WINDS. EVEN IF ACCEPTED NAM WIND MAXIMUM AT 950 HPA OF 70-75 KT...NOTING THAT LITTLE IF ANY MIXING EXPECTED DUE TO 950 HPA FORECAST TO BE ABOVE BASE OF MARINE INVERSION PER BUFKIT SOUNDINGS BY MID EVENING...AND TOOK A VERY GENEROUS 60 PERCENT OF 950 WINDS GIVEN THIS STILL END UP BELOW HIGH WIND WARNING THRESHOLD OF 50 KT. A GFS/ECMWF BLEND TAKES A 60-70KT 950 AND 75-90 KT 850 JET MAINLY TO THE E/SE OF NYC FROM LATE TONIGHT INTO WEDNESDAY EVENING. THUS HAVE HIGHEST CONFIDENCE IN A WIND ADVISORY LEVEL EVENT ACROSS NYC/LONG ISLAND/COASTAL SW AND ALL OF SE CT...SOUTHERN WESTCHESTER COUNTY AND HUDSON COUNTY. GIVEN FORECAST TRACK OF SURFACE LOW TO BE OVER NYC BY EARLY WEDNESDAY AFTERNOON...EXPECT A LULL IN THE VICINITY OF THE LOW AS A RESULT HAVE SPLIT THE WIND ADVISORY UP WEST-EAST. HAVE NYC/NJ/WEST CHESTER/COASTAL SW CT + N MIDDLESEX COUNTY FROM 5Z-19Z WEDNESDAY AND LONG ISLAND/COASTAL SE CT + NORTHERN NEW LONDON COUNTY FROM 5Z WEDNESDAY-5Z THURSDAY. WHILE CANNOT COMPLETELY RULE OUT AN ISOLATED GUST TO 50+ KT FEEL THIS IS MOST LIKELY IN ISOLATED EMBEDDED STRONGER CONVECTION - AND THUS CAN BE HANDLED BY CONVECTIVE WARNINGS IF NEEDED.

In their Marine Section:

AS NOTED IN THE SHORT TERM SECTION OF THE AFD...NAM 950-850 WINDS ARE AN OUTLIER IN TERMS OF THEIR STRENGTH AND DURATION...SO USED A GFS/ECMWF BLEND TO DERIVE WIND GUSTS WITH THE COASTAL STORM. GIVEN EXPECTED MARINE INVERSION...AND USING PREFERRED BLEND...DO NOT HAVE REQUIRED 80 PERCENT CONFIDENCE IN STORM FORCE WINDS TO GO WITH A STORM WARNING. NOTE THAT EVEN NAM BASED BUFKIT SOUNDINGS DO NOT SHOW STORM FORCE GUSTS AT THE OCEAN BUOYS. HOWEVER...AM HIGHLY CONFIDENT IN WIDESPREAD GUSTS TO GALE FORCE FROM LATE TONIGHT THROUGH WEDNESDAY NIGHT ACROSS ALL WATERS. TO COVER THE STEP-UP TO GALE CONDITIONS DURING THE EVENING HOURS...HAVE ISSUED A GALE WARNING FROM 23Z TONIGHT THROUGH 11Z THURSDAY TO REFLECT THIS FOR ALL WATERS. CANNOT COMPLETELY RULE OUT OCCASIONAL GUSTS TO 50 KT OVER THE EASTERN COASTAL OCEAN ZONES WEDNESDAY WITH THE PASSAGE OF THE CORE OF THE LOW LEVEL JET...SO THE FORECAST REFLECTS THIS. WILL USE SPECIAL MARINE WARNINGS TO ADDRESS ANY WIND GUSTS OF 48 KT OR HIGHER IN ISOLATED STRONGER CONVECTION.

Thank you

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IsentropicLift

IsentropicLift

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Can you practice meteorology for once instead of humping your personally preferred model's output? Upton regarding the NAM winds:

 

REGARDING WINDS...THE NAM APPEARS TO BE AN OUTLIER IN BOTH THE STRENGTH AND DURATION OF ITS 950-850 HPA JETS. AS A RESULT...BASED WIND FORECAST ON BLEND OF GFS/ECMWF 950-850 HPA WINDS. EVEN IF ACCEPTED NAM WIND MAXIMUM AT 950 HPA OF 70-75 KT...NOTING THAT LITTLE IF ANY MIXING EXPECTED DUE TO 950 HPA FORECAST TO BE ABOVE BASE OF MARINE INVERSION PER BUFKIT SOUNDINGS BY MID EVENING...AND TOOK A VERY GENEROUS 60 PERCENT OF 950 WINDS GIVEN THIS STILL END UP BELOW HIGH WIND WARNING THRESHOLD OF 50 KT. A GFS/ECMWF BLEND TAKES A 60-70KT 950 AND 75-90 KT 850 JET MAINLY TO THE E/SE OF NYC FROM LATE TONIGHT INTO WEDNESDAY EVENING. THUS HAVE HIGHEST CONFIDENCE IN A WIND ADVISORY LEVEL EVENT ACROSS NYC/LONG ISLAND/COASTAL SW AND ALL OF SE CT...SOUTHERN WESTCHESTER COUNTY AND HUDSON COUNTY. GIVEN FORECAST TRACK OF SURFACE LOW TO BE OVER NYC BY EARLY WEDNESDAY AFTERNOON...EXPECT A LULL IN THE VICINITY OF THE LOW AS A RESULT HAVE SPLIT THE WIND ADVISORY UP WEST-EAST. HAVE NYC/NJ/WEST CHESTER/COASTAL SW CT + N MIDDLESEX COUNTY FROM 5Z-19Z WEDNESDAY AND LONG ISLAND/COASTAL SE CT + NORTHERN NEW LONDON COUNTY FROM 5Z WEDNESDAY-5Z THURSDAY. WHILE CANNOT COMPLETELY RULE OUT AN ISOLATED GUST TO 50+ KT FEEL THIS IS MOST LIKELY IN ISOLATED EMBEDDED STRONGER CONVECTION - AND THUS CAN BE HANDLED BY CONVECTIVE WARNINGS IF NEEDED.

 

In their Marine Section:

 

AS NOTED IN THE SHORT TERM SECTION OF THE AFD...NAM 950-850 WINDS ARE AN OUTLIER IN TERMS OF THEIR STRENGTH AND DURATION...SO USED A GFS/ECMWF BLEND TO DERIVE WIND GUSTS WITH THE COASTAL STORM. GIVEN EXPECTED MARINE INVERSION...AND USING PREFERRED BLEND...DO NOT HAVE REQUIRED 80 PERCENT CONFIDENCE IN STORM FORCE WINDS TO GO WITH A STORM WARNING. NOTE THAT EVEN NAM BASED BUFKIT SOUNDINGS DO NOT SHOW STORM FORCE GUSTS AT THE OCEAN BUOYS. HOWEVER...AM HIGHLY CONFIDENT IN WIDESPREAD GUSTS TO GALE FORCE FROM LATE TONIGHT THROUGH WEDNESDAY NIGHT ACROSS ALL WATERS. TO COVER THE STEP-UP TO GALE CONDITIONS DURING THE EVENING HOURS...HAVE ISSUED A GALE WARNING FROM 23Z TONIGHT THROUGH 11Z THURSDAY TO REFLECT THIS FOR ALL WATERS. CANNOT COMPLETELY RULE OUT OCCASIONAL GUSTS TO 50 KT OVER THE EASTERN COASTAL OCEAN ZONES WEDNESDAY WITH THE PASSAGE OF THE CORE OF THE LOW LEVEL JET...SO THE FORECAST REFLECTS THIS. WILL USE SPECIAL MARINE WARNINGS TO ADDRESS ANY WIND GUSTS OF 48 KT OR HIGHER IN ISOLATED STRONGER CONVECTION.

I never said that that a HWW was warranted. The advisories should handle everything for the most part.

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IsentropicLift

IsentropicLift

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SREF also hinted at that. Wouldn't be shocked at all. Really dynamic system. Too bad this wasn't further east. This could have been a big snowstorm for the coast.

I think if the track was further offshore it would have taken the precip offshore with it. And we really don't have a good cold air source either. With more blocking this probably would have cut to Buffalo. I think that this is probably the most impactful solution that we could have gotten. 

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IsentropicLift

IsentropicLift

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Plus doesnt upton always down play things, to only catch up at in the middle of events? Now I'm not saying they are wrong but 7/10 times they like to play catch up and join the party.

Upton isn't downplaying anything. Look at these forecasted rain totals. Sure the wind may not verify but it's not the only horse in the race.

 

StormTotalQPFFcst.png

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Guest Imperator

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Plus doesnt upton always down play things, to only catch up at in the middle of events? Now I'm not saying they are wrong but 7/10 times they like to play catch up and join the party.

 

They were very aggressive yesterday, they were in coordination with other WFO yesterday and Im sure today as well as they toned it down to reality.

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IsentropicLift

IsentropicLift

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.HYDROLOGY...
WIDESPREAD RAINFALL TOTALS FORECAST RANGE BETWEEN 3 AND 4 INCHES
MAINLY IN THE FORM OF RAIN. THERE WILL BE SOME LOCALLY HIGHER
AMOUNTS. DUE TO RECENT PROLONGED PERIOD OF DRY GROUND
CONDITIONS...MAIN STEM RIVER FLOODING IS NOT EXPECTED.
HOWEVER...THERE WILL A CHANCE OF FLOODING OF URBAN AREAS AND SMALL
STREAMS...ESPECIALLY WHERE STORM DRAINS ARE CLOGGED BY LEAVES AND
ESSENTIALLY WHERE THERE IS MORE RUNOFF.

CHANCE OF FLOODING IS IN THE 30 TO 40 PERCENT RANGE FOR THE REGION.
THIS IS NOT QUITE ENOUGH FOR A WATCH. THE POTENTIAL WILL BE ENHANCED
IN THE LOCALLY HIGHER AREAS OF PRECIP ESPECIALLY WHERE THERE IS
UPSLOPE FLOW. THINKING THAT AREAS NORTH AND WEST OF THE CITY HAVE A
RELATIVELY HIGHER CHANCE OF FLOODING PROBABLY CLOSER TO 40 PERCENT
CHANCE AT THE MOMENT SINCE THIS IS WHERE THE HIGHER TERRAIN IS WITH
MORE UPSLOPE ENHANCEMENT.

IF CONFIDENCE INCREASES FOR THE POTENTIAL OF WIDESPREAD
FLOODING...THEN A FLOOD WATCH MAY BE NEEDED.

 

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