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klw

NNE Spring 2013 Thread

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Yeah if we get 1/2-3/4" QPF at 3:1 ratios..lol, 2-3" of snow/sleet.

Anything coming down over there or is it just virga?

 

bgm.gif

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I'm going with 3-6" for the ski area forecast up here... really doesn't seem like all that difficult of a forecast for the higher elevations.  Mid-layer warming might be the only issue if its snow or sleet, but its freakin' cold up there already.

 

 

Thanks for the heads up and the map PF; the point forecast for the higher elevations of Mansfield seems in line with your thoughts.  Roger Hill was certainly speaking about a good shot of snow for the area in his early morning broadcast – obviously with a focus on the higher elevations.  For the North-Central Vermont area he was going with T-3”, with the 3” in the higher elevations, but that may be the “populated” higher elevations.  It seemed like he felt that the mountain peaks were going to do well.

 

There’s nothing on the advisories map for the northern 2/3 of Vermont, although a lot of the surrounding advisories seem to be focused on the potential for ice, and that doesn’t seem to be as big a deal around here:

 

11APR13A.jpg

 

The anticipated totals on that map certainly falls off to the south, and it’s at a level of detail that it even drops to the black “none” for the lowest elevations in the Winooski Valley.  That’s consistent with what we’ve got in our point forecast, but with the marginal temperatures it can go either way.

 

11APR13B.jpg

 

It’s nice that there’s getting to be some discussion about the event in the general weather discussion thread though; for a while there it seemed as if that was just sort of focused on temperatures, grass, grills, etc.

 

Oh, I just saw the updated maps that bobbutts posted.  The advisories map is substantially updated as well, so I’ll get those to show the progression for archiving – I’ll see if any changes happen after the afternoon update.

 

 

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I think IP is going to be the soup dejour here

 

I agree. The depth of that cold wedge is so impressive that even if the surface creeps to 34, just a couple hundred feet up with be -2 C or something. Instead of 34 and RA you get 34 and a scalping.

 

I think icing will be confined to the higher elevations. They won't have the depth of the low level cold that the lower elevations do, less time to refreeze.

 

I do think BTV may have been overplaying the warmth card last night. I like what they say in their discussion from this afternoon though, pretty much right on line with our thinking from last night. Sleet should dominate, and though we have on real criteria for sleet and headlines, it can create some pretty bad driving conditions and it is late enough in the season that this will catch people by surprise. Sort of like we lower the thresholds for the first event of the year, the same goes for the last.

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I agree. The depth of that cold wedge is so impressive that even if the surface creeps to 34, just a couple hundred feet up with be -2 C or something. Instead of 34 and RA you get 34 and a scalping.

 

I think icing will be confined to the higher elevations. They won't have the depth of the low level cold that the lower elevations do, less time to refreeze.

 

I do think BTV may have been overplaying the warmth card last night. I like what they say in their discussion from this afternoon though, pretty much right on line with our thinking from last night. Sleet should dominate, and though we have on real criteria for sleet and headlines, it can create some pretty bad driving conditions and it is late enough in the season that this will catch people by surprise. Sort of like we lower the thresholds for the first event of the year, the same goes for the last.

 

Most definitely, Folks will be caught with there pants down.........

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I agree. The depth of that cold wedge is so impressive that even if the surface creeps to 34, just a couple hundred feet up with be -2 C or something. Instead of 34 and RA you get 34 and a scalping.

 

I think icing will be confined to the higher elevations. They won't have the depth of the low level cold that the lower elevations do, less time to refreeze.

 

I do think BTV may have been overplaying the warmth card last night. I like what they say in their discussion from this afternoon though, pretty much right on line with our thinking from last night. Sleet should dominate, and though we have on real criteria for sleet and headlines, it can create some pretty bad driving conditions and it is late enough in the season that this will catch people by surprise. Sort of like we lower the thresholds for the first event of the year, the same goes for the last.

 

Taber writes some phenomenal AFD's for BTV... you can tell he put some time into this one (copied below). 

 

I'm also curious if tomorrow is a situation where we are getting freezing rain at like 25F at near 4,000ft, while its sleeting at 1,500ft at 30F or something like that.  The summits are so cold right now in the upper teens and low 20s.

 

Also, as I was mentioning earlier, I've seen SE upslope flow on the east side result in more snow and less mix, though I'm not sure if upslope cooling on terrain that's below H85 will have any impact on warming up at H7.  Brooke mentions it in his AFD, but the warming in this event just seems so high up there, that I'm not sure what low level upslope processes have on that.  I would think the same in the GYX CWA with the SE flow into the foothills would be causing upslope cooling and heavier precipitation rates.

 

 

.NEAR TERM /THROUGH FRIDAY/...

AS OF 145 PM EDT THURSDAY...HAVE ISSUED WX WINTER ADVISORY FOR

ENTIRE NORTH COUNTRY FROM MIDNIGHT TONIGHT THRU FRIDAY...FOR A MIX

OF WINTRY PRECIPITATION. THINKING SLEET MAYBE THE PRIMARY FORM OF

PRECIPITATION...ESPECIALLY ON FRIDAY MORNING.

A DIFFICULT MORNING COMMUTE IS LIKELY ACRS THE NORTH COUNTRY ON

FRIDAY...WITH PERIODS OF MODERATE MIXED PRECIPITATION LIKELY.

A VERY DIFFICULT AND COMPLEX FCST WITH REGARDS TO LLVL THERMAL

PROFILES AND ASSOCIATED PRECIP TYPE. LATEST TRENDS IN MODELS HAVE

BEEN FOR A SLIGHTLY COOLER SOLUTION WITH MORE FROZEN PRECIP LIKELY

ACRS THE NORTH COUNTRY. STILL THINKING A MIX OF SNOW/SLEET WITH

SOME POCKETS OF FREEZING RAIN ABOVE 1500 FT. DIFFICULT TO HAVE

FREEZING RAIN AND ICE ACCUMULATION DURING THE DAYTIME...DUE TO

HIGH APRIL SUN ANGLE WARMING THE SFC...SO ICE IMPACT FROM FREEZING

RAIN WL BE LIMITED...BUT STILL EXPECT PLENTY OF SLEET ON

FRIDAY...CREATING HAZARDOUS DRIVING CONDITIONS.

LETS FIRST START WITH CRNT OBSERVATIONS...TEMPS ALOFT ARE COLD

WITH WHITEFACE AT 18F OR -8C...VERY DRY SFC DWPTS WITH VALUES IN

THE SINGLE DIGITS AND TEENS. 12Z BUF SOUNDING SHOWS WARM LAYER OF

+5C AIR AT 800MB...PLEASE NOTE WARM NOSE IS ABOVE 850MB...AND THIS

RESULTS IN A GREATER POTENTIAL FOR SLEET. SFC ANALYSIS SHOWS ARCTIC

HIGH PRES ACRS CENTRAL CANADA WITH LOW PRES NEAR CHICAGO IL ATTM.

GREATEST 3HR PRES FALLS SHOW ELONGATED LOW PRES DEVELOPING TWD THE

SOUTHERN MID ATLANTIC STATES...WHICH COULD LIMIT LOW/MID LVL WAA.

PWS ANALYSIS SHOWS UPSTREAM VALUES AROUND 1.0"...WHICH IS >200% OF

NORMAL...SO PLENTY OF MOISTURE AVAILABLE ASSOCIATED WITH DEEP FULL

LATITUDE SYSTEM...WITH GULF MOISTURE AND SOME CONVECTION NOTED

ACRS THE MS RIVER VALLEY.

DEEP CLOSED MID/UPPER LVL CIRCULATION WL TRACK TWD THE WESTERN

GREAT LAKES TONIGHT AND INTO SOUTHERN CANADA BY FRIDAY

NIGHT...WHILE ELONGATED SFC LOW PRES TRACK FROM NEAR CHICAGO INTO

THE OHIO VALLEY...THEN REDEVELOPS ACRS THE MID ATLANTIC COAST ON

FRIDAY...WHICH MAY LIMIT AMOUNT OF WAA ACRS OUR CWA. NAM/GFS/ECMWF

IN FAIR AGREEMENT WITH LARGE SCALE SYNOPTIC SETUP...BUT STILL

OFFERING DIFFERENT SOLUTIONS WITH REGARDS TO THERMAL PROFILES. NAM

IS THE COLDEST/SNOWIEST WITH GFS THE WARMEST...BUT TRENDING

COLDER...AND THE ECMWF IS A GOOD COMPROMISE. ALL SOLUTIONS SHOW

THE 1000 TO 500MB 540DM LINE LIFTING NORTH OF OUR CWA ON

FRIDAY...WHICH INDICATES THE POTENTIAL FOR SNOW CHANGING TO

SLEET/FREEZING RAIN...EVEN IN THE MTNS. HOWEVER...BAND OF VERY

STRONG FGEN FORCING...DEEP LAYER OMEGA...AND EVEN A WEAK ELEVATED

LAYER OF INSTABILITY LIFTS FROM SW TO NE ACRS OUR CWA BTWN 09Z AND

18Z FRIDAY...RESULTING IN A BAND OF MODERATE TO HEAVY MIXED

PRECIP. GFS/NAM SOUNDINGS SHOW WARM LAYER BTWN 800MB AND 700MB

BTWN 1-3C LIFTING ACRS OUR CWA...WHILE 925MB TEMPS HOLD IN THE -3C

TO -6C RANGE...SUPPORTING A SLEET TYPE PROFILE...ESPECIALLY

NORTHERN/CENTRAL VT AND PARTS OF NNY. THINKING STRONG

DYNAMICS/SOME COOLING FROM EVAPORATION WL CREATE A BURST OF

SNOW/SLEET INITIALLY WITH A QUICK DUSTING TO 3 INCHES

POSSIBLE...WITH TIMING VERY CLOSE TO MORNING COMMUTE.

ALSO...COOLING EFFECTS FROM SE UPSLOPE FLW...MAY KEEP LUDLOW TO

STOWE TO JAY PEAK PROFILES JUST COLD ENOUGH FOR A MORE SNOW TYPE

PROFILE WITH ACCUMULATIONS OF 4 TO 6 INCHES POSSIBLE...BEFORE

CHANGING TO SLEET/FREEZING RAIN. THINKING THE AMOUNT OF SLEET WL

CUT DOWN ON SNOW ACCUMULATIONS AND MAKE IT DIFFICULT TO REACH

ADVISORY CRITERIA...BUT GIVEN AMOUNT OF SLEET EXPECTED AND

POTENTIAL ICY ROADS AND TIMING...WARRANTS THE ADVISORY. ITS VERY

DIFFICULT TO PIN POINT EXACT THERMAL PROFILES GIVEN THE VERY TIGHT

THERMAL GRADIENT...BUT IF COLDER TRENDS CONT...ANTICIPATE EVEN

MORE SNOW ACRS THE NORTHERN MTNS.

QPF WL RANGE BTWN 0.40 TO 0.65" SE DOWNSLOPE REGIONS TO 1.5" IN

THE FAVORITE SE UPSLOPE REGIONS. GUSTY SE WINDS OF 40 TO 45 MPH WL

BE POSSIBLE LATE TONIGHT INTO FRIDAY ASSOCIATED WITH LLVL JET OF

45 TO 60 KNOTS. TEMPS WL COOL INTO THE 20S NEK TO L30S WARMER

VALLEYS TONIGHT AND ONLY WARM INTO THE MID/UPPER 30S CPV/WESTERN

SLV TO U20S/L30S MTNS/NEK. MID/UPPER LVL DRY SLOT WL IMPACT AREA

AFT 18Z FRIDAY WITH MIXED PRECIP TAPERING OFF TO SCATTERED

RAIN/SNOW SHOWERS.

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I’ve added the updated advisories map below – the advisories now cover the entire BTV forecast area as the headline indicates.  I’ve also added the BTV NWS storm total snow forecast map – it doesn’t look like it’s changed from the earlier version, but I’m surprised that those highest projected accumulations appear to be east of the spine and not on it.

 

11APR13C.jpg

 

11APR13D.jpg

 

The map has us in the 2-4” and the point forecast here sums to 2-5”+ through tomorrow, although the point forecasts in the area seem rather out of synch with lower numbers in the mountains.

 

 

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Taber writes some phenomenal AFD's for BTV... you can tell he put some time into this one (copied below). 

 

I'm also curious if tomorrow is a situation where we are getting freezing rain at like 25F at near 4,000ft, while its sleeting at 1,500ft at 30F or something like that.  The summits are so cold right now in the upper teens and low 20s.

 

Also, as I was mentioning earlier, I've seen SE upslope flow on the east side result in more snow and less mix, though I'm not sure if upslope cooling on terrain that's below H85 will have any impact on warming up at H7.  Brooke mentions it in his AFD, but the warming in this event just seems so high up there, that I'm not sure what low level upslope processes have on that.  I would think the same in the GYX CWA with the SE flow into the foothills would be causing upslope cooling and heavier precipitation rates.

 

Definitely a well stated AFD. I think because of the shift rotations we don't overlap very often, which is unfortunate.

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All sleet and freezing rain along the west slopes. Cars and sidewalks covered in a glaze and about a quarter inch of sleet. Roads just kinda slushy. No snow.

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Event totals: 0.2” Sleet/0.07” L.E.

 

As far as I could see, there’s only been sleet at the house thus far in terms of precipitation.  It was just cloudy at observations time, but there’s also some showery sleet around as well.  Although it continues to be a below average season in terms of snowfall (<90% of average), the number of storms has been above average; this is the 51st accumulating storm of the winter season, not far off from the highest value (53) recorded in 2007-2008.

 

Details from the 6:00 A.M. Waterbury observations are below:

 

New Snow: 0.2 inches (sleet)

New Liquid: 0.07 inches

Snow/Water Ratio: 2.9

Snow Density: 35.0% H2O

Temperature: 30.7 F

Sky: Cloudy

Snow at the stake: Trace

 

 

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No snow for me.  We did get a thick coating of sleet which was then frozen into place by a layer of freezing rain.  It made for a prolonged period of scraping the cars this morning.  Only one cut knuckle.

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Heavy sleet...scalping stuff. 

 

We have seen a few brief bursts (like 1-2 minutes at a time) of large aggregates so its gotta be pretty marginal still aloft, but definitely 95% IP.  Just had another brief burst of flakes.  Its funny, they fall quickly and fast, then all the sudden gone again.

 

Have several tenths of an inch of sleet but don't care enough at this point to keep track of it unless we get up to an inch or something.

 

We all need to head to Jay Peak where they say they are "certainly going to get at least a foot" today on their website.

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No snow for me.  We did get a thick coating of sleet which was then frozen into place by a layer of freezing rain.  It made for a prolonged period of scraping the cars this morning.  Only one cut knuckle.

Yeah, once I got the driver's door open, I just turned the car on, set defrost on high and let it sit for 20 minutes.  I'm sick of scraping.

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It’s certainly slow compared to snow, but the web cam is showing the accumulating sleet at the house – it looks like another 0.4” is down as of noontime.  We’ve got a pretty heavy combination of sleet and rain here in Burlington as the big slug of moisture comes into the area:

 

12APR13A.gif

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Posted in the other obs thread but it's sleeting up a storm out there, lol.

 

And yeah, like you guys said earlier, my truck was utterly encased in ice this morning--pretty solid stuff too, not the mushy, easy to scrape type.

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Anybody want to weigh in on timing for N. VT?  Specifically, is the day for skiing tomorrow in the snow or Saturday?

Judging by what it looks like out my window, I'd say tomorrow would be your best bet ;)  :D

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It is impressively cold... we continue to hold or drop in temperature up at the mountain.  This slug of precip is going to be interesting.

 

3,600ft...18F

2,600ft...22F

1,550ft...25F

 

MPV dropped 2F last hour, too.

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As of ~1:50 P.M., we just changed over to 100% snow here in Burlington, and it’s finally starting to accumulate in this area.  At the house it looks like we’re around 1.3” of total accumulation for the event thus far.

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On the web cam I can see that the precipitation is snow at the house, so it seems to be a fairly widespread changeover from sleet to snow.

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