Re: March 20th Storm

by **NjWeatherGuy** Wed Mar 18, 2015 1:35 pm

12z runs seem to show 4-6 in this neck of the woods which would be robust for this time of year and a nice final storm and a good trend. Question is can it hold for 2 days because I cant see how it trends a whole lot better. Dont want to see trends start to burn us in the wrong direction.

by **amugs** Wed Mar 18, 2015 1:38 pm

A word from the meteorlogical prophet Scott!!

AMEN!!!

by **sroc4** Wed Mar 18, 2015 1:54 pm

rb924119 wrote:
rb924119 wrote:
sroc4 wrote:Hey rb or whomever. Do you recall where the discussion about the jet streak quadrants that rb wrote up are. If so can seine let me know?

It starts here and then goes through a few more of the following pages. I think there's also another discussion about other synoptic-scale forcing here too. I can't remember, though lol

https://www.njstrongweatherforum.com/t496p50-sunday-monday-snowstorm-2nd-call-snow-map

Here's the second discussion:

https://www.njstrongweatherforum.com/t496p150-sunday-monday-snowstorm-2nd-call-snow-map

Perfect! Thanks rb. I will eventually move this to the education thread.

by **docstox12** Wed Mar 18, 2015 1:56 pm

NWS has me maybe 2 to 3, Inaccuweather 3 to 6.Will be colder up here so it should be all snow and stick.This could get me above 70 inches for the season, pretty darn good since we missed Juno.

by **Frank_Wx** Wed Mar 18, 2015 2:04 pm

EURO a little warm at surface, but if precip is coming down at a steady rate I think it should stick on colder surface or side roads. Not sure about main roads. 850's warm up toward the end.

March 20th Storm - Page 2 ECMWF_MSLPThickQPF_ne_f57

March 20th Storm - Page 2 ECMWF_MSLPThickQPF_ne_f57

March 20th Storm - Page 2 ECMWF_MSLPThickQPF_ne_f60

March 20th Storm - Page 2 ECMWF_MSLPThickQPF_ne_f63

Either way, this looks like a solid 3-6" event as of now but will have to take a closer look at the upper levels tonight when I make my snow map.

by **rb924119** Wed Mar 18, 2015 2:28 pm

Hmmm, I haven't done a thorough investigation, but it would seem that the numbers that the globals are putting out for this event seem overdone, quite a bit, in fact. Here are my reasons:

1) H3 jet streak, while located favorably, is relatively weak and highly elongated. This reduces the amount of synoptic-scale forcing for ascent in our area

2) H5 is only a strip of shear vorticity, and is associated with a WEAKENING shortwave. This will likely lead to a decrease in the forcing for ascent that it provides as it continues eastward.

3) Low-level warm air advection is not that strong, given that a gradient of ~8*C exists over a horizontal distance of approximately 300 miles (northern Virginia into northeastern Pennsylvania) at the 850 hPa level. Doing the math, this equates to a drop of 1*C per 40 miles (about). Combine this with a quartering upglide of about 20-30 knots (isentropic lift) for much of the area, with the best lift (30-40 knots of more perpendicular flow to the pressure surfaces) occurring over southern PA/Mid-Atlantic coast, I think we just see steady light precipitation at best, with much of it ending by sunset as the front rolls through.

The problem lies in the fact that where the best low-level forcing will be occurring, it will be too warm for snow, but in the areas that will be, they will likely not see the best precipitation rates. I am thinking a general 1-3/2-4" type event right now, with mixing issues along the coastal plain.

by **Frank_Wx** Wed Mar 18, 2015 2:57 pm

rb924119 wrote:Hmmm, I haven't done a thorough investigation, but it would seem that the numbers that the globals are putting out for this event seem overdone, quite a bit, in fact. Here are my reasons:

1) H3 jet streak, while located favorably, is relatively weak and highly elongated. This reduces the amount of synoptic-scale forcing for ascent in our area

2) H5 is only a strip of shear vorticity, and is associated with a WEAKENING shortwave. This will likely lead to a decrease in the forcing for ascent that it provides as it continues eastward.

3) Low-level warm air advection is not that strong, given that a gradient of ~8*C exists over a horizontal distance of approximately 300 miles (northern Virginia into northeastern Pennsylvania) at the 850 hPa level. Doing the math, this equates to a drop of 1*C per 40 miles (about). Combine this with a quartering upglide of about 20-30 knots (isentropic lift) for much of the area, with the best lift (30-40 knots of more perpendicular flow to the pressure surfaces) occurring over southern PA/Mid-Atlantic coast, I think we just see steady light precipitation at best, with much of it ending by sunset as the front rolls through.

The problem lies in the fact that where the best low-level forcing will be occurring, it will be too warm for snow, but in the areas that will be, they will likely not see the best precipitation rates. I am thinking a general 1-3/2-4" type event right now, with mixing issues along the coastal plain.

I have not even looked at upper air yet, so I can not agree or disagree with your analysis right now. But I will say that it's valid and I would not be surprised if this event trends warmer. Will have to take a closer look tonight

by **amugs** Wed Mar 18, 2015 3:13 pm

15Z SREFS!!!

March 20th Storm - Page 2 SREFNE24Precip15066

by **amugs** Wed Mar 18, 2015 3:14 pm

Compare to 9Z SREFS!

March 20th Storm - Page 2 SREFNE24Precip09072

by chrism Wed Mar 18, 2015 3:17 pm

I think Long gets a coating-2 at most

by **sroc4** Wed Mar 18, 2015 3:23 pm

chrism wrote:I think Long gets a coating-2 at most

You think Long............................Island? geek

by chrism Wed Mar 18, 2015 3:25 pm

Haha,what a lame typo,sorry guys,yes Long Island gets a coating to 2 inches

by **snow247** Wed Mar 18, 2015 3:29 pm

FRI INTO SAT...
12Z GFS/ECMWF COMING INTO SOME AGREEMENT INTO WEEKEND. WE
DISCOUNTED 12Z NAM GIVEN ITS MORE SUPPRESSED SOLUTION WHICH DOES
NOT FIT LARGER SCALE PATTERN IN PLACE.

CONFIDENCE NOT AS HIGH AS WE WOULD LIKE FOR FRI INTO SAT.
TYPICALLY THESE LATE SEASON EVENTS CAN THROW A LOT OF COMPLICATING
FACTORS INTO MIX AND THIS IS NO EXCEPTION...INCLUDING HIGHER SUN
ANGLE AND AMOUNT OF LOW LEVEL WARMING AND POTENTIAL FOR AN
ISOTHERMAL ENVIRONMENT IN WHICH PRECIPITATION TYPE BECOMES VERY
DEPENDENT ON INTENSITY.

DESPITE SURFACE HIGH BEING LOCATED TO OUR E WHICH TENDS TO FAVOR
WARMER SOLUTION AND FASTER CHANGE TO RAIN...MODELS DO INDICATE
GOOD COLD AIR DAMMING SIGNATURE INTO AT LEAST INTERIOR WHICH
SHOULD KEEP COLD LOCKED IN LONGER...ESPECIALLY GIVEN NORTHERLY LOW
LEVEL AGEOSTROPHIC FLOW. IT IS ALSO RATHER COLD ALOFT WITH 925 MB
TEMPERATURES BELOW ZERO THROUGH AT LEAST FIRST HALF OF FRI NIGHT.

ALTHOUGH THERE ARE TRACK DIFFERENCES BETWEEN ECMWF AND GFS /WITH
ECMWF A BIT CLOSER TO COAST/ THERMAL PROFILES ARE ACTUALLY RATHER
CLOSE. THIS WOULD FAVOR SNOW AT ONSET FRI AFTERNOON AND EVENING...
BEFORE TRANSITION TO RAIN/SNOW MIX INTO NE NJ...NYC AND LONG
ISLAND FRI NIGHT AND POSSIBLY INTO COASTAL CT AS WELL. RIGHT NOW
LOCATIONS FARTHER N LOOK TO REMAIN MOSTLY SNOW.

AS FAR AS ACCUMULATIONS...WE ARE MOST LIKELY LOOKING AT AN
ADVISORY-LEVEL EVENT WITH HIGHER TOTALS FOCUSED ACROSS LOWER
HUDSON VALLEY AND POSSIBLY PORTIONS OF S CT AWAY FROM COAST.
HOWEVER SINCE SNOW SHOULD BEGIN FRI AFTERNOON THERE IS EXPECTED TO
BE SOME IMPACT TO FRI EVENING RUSH HOUR.

SUN THROUGH WED...
COLD FRONT PASSES THROUGH EARLY SUN MORNING...FOLLOWED BY DRY BUT
SEASONABLY COLD WEATHER AS HIGH PRESSURE DOMINATES INTO EARLY NEXT
WEEK. THERE IS SOME POTENTIAL OF YET ANOTHER COASTAL LOW BY TUE OR
WED...BUT CONFIDENCE IS OBVIOUSLY LOW ONE WEEK OUT AND IT MAY VERY
WELL REMAIN OFFSHORE.

by **NjWeatherGuy** Wed Mar 18, 2015 3:33 pm

amugs wrote:15Z SREFS!!!

Careful, if it keeps up could trend warm for us and snow further north, its pretty marginal as it is.

by **snow247** Wed Mar 18, 2015 3:58 pm

I doubt it will trend north, everything seems to trend south lately.

by **docstox12** Wed Mar 18, 2015 4:06 pm

Exactly, snow.Look at that storm for next week.CNJ south and east get blasted while we are yet again on the northern fringe.Uncanny!

by **NjWeatherGuy** Wed Mar 18, 2015 4:39 pm

docstox12 wrote:Exactly, snow.Look at that storm for next week.CNJ south and east get blasted while we are yet again on the northern fringe.Uncanny!

Thats got more then enough time to trend to a friggin glc or there could be no storm at all. These spring setups are very delicate and climo always favorites northern areas over coastal plain. Yes i know what happened last year with the pv but i doubt the cold will be that suppressing. EURO has a SWFE which is a hit from CNJ north.

by **snow247** Wed Mar 18, 2015 5:10 pm

Uptons map is very elevation dependent, 2-3 for most and spotty 3-4 areas in northern higher mountains/hills.

by **sroc4** Wed Mar 18, 2015 5:14 pm

tehe he...Upton. Starting now we should count how many times that snowfall map changes. The over under is 4 by Friday 10pm

March 20th Storm - Page 2 StormTotalSnowFcst

March 20th Storm - Page 2 StormTotalSnowFcst

by **rb924119** Wed Mar 18, 2015 5:19 pm

sroc4 wrote:tehe he...Upton. Starting now we should count how many times that snowfall map changes. The over under is 4 by Friday 10pm

I'd agree with this map as it stands now.

by **CPcantmeasuresnow** Wed Mar 18, 2015 5:22 pm

NjWeatherGuy wrote:
amugs wrote:15Z SREFS!!!

Careful, if it keeps up could trend warm for us and snow further north, its pretty marginal as it is.

None of this dark green will ever hit the ground north of the TZ bridge even if it shows up as 30dbz bands on the radar. I learned that from the last storm. Expect nothing recieve nothing.

by **algae888** Wed Mar 18, 2015 5:23 pm

rb924119 wrote:
sroc4 wrote:tehe he...Upton. Starting now we should count how many times that snowfall map changes. The over under is 4 by Friday 10pm

I'd agree with this map as it stands now.
that map is from 8am this morning. In there disco upton mentions advisory level snow which i believe is at least 3". Their map should change shortly. Prob 3-4" for most

by **amugs** Wed Mar 18, 2015 5:27 pm

FOR the love of GOD UPTON! Playing the climo song here I see. I think they will be upping their snowfall amounts as we move closer to Friday due to the cold air that is taking hold with this -EPO - god I love that weather indicy along with its mutual partner +PNA!! The - NAO has a lot to be determined imb!

Prophet Scott Says over/under 4 - my bet is even money (4)!!

WPC says 4 - hahaha - inches that is!

March 20th Storm - Page 2 Post-86-0-84716900-1426709587

March 20th Storm - Page 2 Post-86-0-84716900-1426709587

by **NjWeatherGuy** Wed Mar 18, 2015 5:31 pm

Mt. Holly doing the same mugs, look at their map, 3+ confined to higher elevations in NWNJ, safe inital call with time to trend, if storm holds we know itll tick up each update in southern regions.

by **NjWeatherGuy** Wed Mar 18, 2015 5:34 pm

Just like that 18z NAM trended significantly south, lol model madness, must be why nobodys talking about it or posting maps haha.

by **sroc4** Wed Mar 18, 2015 5:44 pm

dat NAM

by **snow247** Wed Mar 18, 2015 5:46 pm

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