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Saint Patrick's Day Snow Event

stormtracker

By stormtracker,
in Mid Atlantic

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CAPE

CAPE

Posted
Posted

Sorry I have to lol at the "awful hobby" comments. Some place is going to get a nice snow event. So maybe it ill be Richmond this time and not DC area. Thats life. I do recall central VA being in the bullseye initially, before the trend north in the guidance. The models are not awful, but people get too emotionally invested. This storm does look strikingly similar to March 3rd. Places a bit further south may cash in on this one. Good for them. Richmond probably has had less than 12 inches this winter. Worse snow hole than DC.

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arlwx

arlwx

Posted
Posted

LWX discussion snips:

 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
351 AM EDT SAT MAR 15 2014


&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...

MODELS CONTINUE TO SHOW OVERRUNNING/ISENTROPIC LIFT DEVELOPING
SUNDAY AND SUNDAY NIGHT. EARLY SUNDAY MORNING LOOKS DRY...THEN
PRECIPITATION IS EXPECTED TO DEVELOP FROM SOUTHWEST TO NORTHEAST
THROUGH THE DAY ALTHOUGH POSSIBLY NOT REACHING THE BALTIMORE-
WASHINGTON METRO UNTIL LATE AFTERNOON OR EARLY EVENING.

BOUNDARY LAYER IS STILL RATHER WARM DURING THE DAYTIME SUNDAY...AND
ONSET OF PRECIPITATION MAY BE RAIN OR A RAIN/SNOW MIX BEFORE
CHANGING OVER TO SNOW DUE TO WET BULBING AND AS A COLD WEDGE
DEVELOPS. IMPACT DURING THE DAYTIME SUNDAY EVEN IF THE CHANGEOVER
OCCURS SOONER IS EXPECTED TO BE MINIMAL DUE TO THE THE HIGH MARCH
SUN ANGLE AND LIGHT PRECIPITATION FALLING.

THE OVERALL EVENT CONTINUES TO BE A CHALLENGING ONE WITH CONTINUED
UNCERTAINTY. SIMILAR TO MODEL RUNS PRIOR TO THE MARCH 3 EVENT...MOST
GUIDANCE FOR THIS EVENT IS TRENDING SOUTH WITH THE QPF. THIS RAISES
UNCERTAINTY REGARDING QPF AND THUS SNOW AMOUNTS FOR THIS EVENT /NOT
TO MENTION TIMING UNCERTAINTY WITH PHASE CHANGE/.

IN ADDITION...AT NIGHTTIME THE SNOW WILL LIKELY BE ABLE TO
ACCUMULATE AND AN IMPACT DURING THE MONDAY MORNING RUSH IS EXPECTED.
BUT GIVEN THE HIGH MARCH SUN ANGLE...THERE IS UNCERTAINTY AS TO HOW
MUCH ACCUMULATION/IMPACT WILL OCCUR DURING THE DAYTIME MONDAY.

ANOTHER ASPECT TO CONSIDER IS THE POTENTIAL FOR TWO PIECES OF THIS
STORM...THE OVERRUNNING/ISENTROPIC PART AND THEN MORE INFLUENCE
FROM THE LOW /THE LATTER THAT SOME GUIDANCE HAS FOCUSED MORE
SOUTHEAST OF THE CWA OR IN THE CASE OF THE GFS LATER IN TIME/.

THESE ISSUES WILL NEED TO BE RESOLVED WITH TIME. DUE TO CONTINUED
UNCERTAINTY REGARDING MULTIPLE VARIABLES AND THE FACT THAT THIS
STORM WOULD BE A 4TH AND 5TH PERIOD EVENT FOR SNOWFALL
ACCUMULATIONS...IN COLLABORATION WITH NEIGHBORING OFFICES WILL BE
REFRAINING FROM ISSUING A WINTER STORM WATCH FOR NOW BUT WILL NEED
TO BE A CONSIDERATION FOR THE DAY SHIFT.


&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...

THERE IS SIGNIFICANT UNCERTAINTY WHETHER ENERGY WILL BE CLOSE ENOUGH
TO THE CWA MONDAY NIGHT OR TUESDAY TO CONTINUE TO BRING A CHANCE OF
PRECIPITATION. PREFER CONTINUITY AND LATEST WPC GUIDANCE WHICH
FAVORS THE STORM DISCUSSED IN THE SHORT TERM EXITING MONDAY NIGHT
AND A DRY TUESDAY.

SHORTWAVE IS POISED TO AFFECT THE AREA WEDNESDAY INTO
THURSDAY...STILL UNCERTAINTY IN TIMING THIS FAR OUT. MODERATING
TEMPERATURES WOULD FAVOR RAIN AS THE PREDOMINANT P-TYPE IN
ASSOCIATION WITH THE SHORTWAVE.


 

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BristowWx

BristowWx

Posted
Posted

I guess I'm in the minority, but I think they've performed pretty well for the most part.

I agree. This situation is complex so 12Z could be different again. But seeing a mostly snow situation in mid March is still a blessing....most times/years we'd be looking at mostly rain.

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CAPE

CAPE

Posted
Posted

I dont know why some people are even freaking out. GFS is turning out to be steadier(and more realistic) in recent model cycles. I dont really worry about the Euro being suddenly drier/weaker this close in. Seen that before. The NAM? Last nights epic run, to the the 6z near shutout. 12z runs things should stabilize and give a better idea where the sharp cutoff will be. This is not going to be a juicy storm, so expectations should be low end warning criteria at best.

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Huffwx

Huffwx

Posted
Posted

LYH may be the "dud" champ of the year. Climo is 17 inches and the official number is 14.4, I'm at 15.8. I doubt there are many, if any cities below normal this winter east of the MS. Most of well above normal. 

 

So, year-- I'd like an official 2.6 to get above normal. 

 

 

Sorry I have to lol at the "awful hobby" comments. Some place is going to get a nice snow event. So maybe it ill be Richmond this time and not DC area. Thats life. I do recall central VA being in the bullseye initially, before the trend north in the guidance. The models are not awful, but people get too emotionally invested. This storm does look strikingly similar to March 3rd. Places a bit further south may cash in on this one. Good for them. Richmond probably has had less than 12 inches this winter. Worse snow hole than DC.

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CAPE

CAPE

Posted
Posted

Pretty amazing how this thing has been trending identically to the early march event. The 6z gfs is beautiful, cold with 3-6 inches of snow overnight.

Yes very similar, with the cold air undercutting. Just not quite as cold. I think we do ok, but would not be surprised to see places further south jackpot this time.

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WxMan1

WxMan1

Posted
Posted

After walking into work this morning, and diagnosing the 00Z ECMWF, I can see why the overnight crews tossed it aside. It seems too fast with the dissipation of the SE low before re-development occurs off the NC Outer Banks, although that is always a concern when we have a transfer of energy from one side of the CAD wedge (west of the far southern Appalachians) to the other (off the coast).  Not a "true" Miller A in the sense that we don't have one Gulf low that stays east of the mountains and can continue to deepen while lifting NE along or off the coast.  And yet, not a "true" Miller B in the sense that the initial low is not coming in from the OH Valley (which is textbook Miller B ), instead this one is more of a lower MS Valley/lower TN Valley cutter.  

 

Examples:

 

http://www.americanwx.com/bb/index.php/topic/1415-miller-a-vs-miller-b/

 

https://www.nc-climate.ncsu.edu/climate/winter_wx/Patterns.php

 

 

At any rate, I've taken a look at the 00Z EC Ensemble members, and here's what they're looking like for DCA:

 

00Z Operational ECMWF: 3"

 

00Z EC Mean: 4"

 

Number of EC Ens members with 0": 3

Number of EC Ens members with 1": 4

Number of EC Ens members with 2": 2

Number of EC Ens members with 3": 9

Number of EC Ens members with 4": 9

Number of EC Ens members with 5": 7

Number of EC Ens members with 6": 7

Number of EC Ens members with 8": 5

Number of EC Ens members with 10": 2

Number of EC Ens members with 12": 0

Number of EC Ens members with 15": 2

 

The mode would thus be 3-4", with the bulk of the members  between 3-6".

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CAPE

CAPE

Posted
Posted

I'm ok with any amount of accumulating snow, just hoping not to be shut out.

Yup. A few inches is realistic.  Like the early March event, this is cold air wedging in and undercutting milder air with a weak wave moving along the frontal boundary. Its not a classic juicy WAA overrunning an arctic air mass already in place. Like the last event, there could be a few places that see 8 inches, but most places should see something like 2-4 or 3-5.

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WxUSAF

WxUSAF

Posted
Posted

Knew something was wrong when i woke up to no watch.    On to the slightly north trend today....we hope...

I'm kinda surprised they didn't issue a watch with the overnight package, given that they can always downgrade to a WWA (or nothing) if this south trend of doom continues.  Probably this afternoon after the 12z Euro smokes us I guess. 

 

There has definitely been this 0z south/12z north split with this storm going back several days.  Bob and Hberg noticed it earlier this week. 

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Joshfsu123

Joshfsu123

Posted
Posted

I'll take 3-6 personally. Fine by me.

 

And the 0z euro has been disregarded by the professionals it seems... if it holds at 12z, then I will start to worry. The NAM while great last night continues to flip every run, which doesn't give me any confidence that it has a clue.

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mitchnick

mitchnick

Posted
Posted

My point of click forecast says 3-7 inches. By the by, assuming the models do tick north a bit, can we expect better rates than with the March 3 event due to the system being better consolidated/organized?

point and click is glorified gfs, so if the gfs is wrong so is your forecast

...and the gfs was late to the party and will likely be late to leave it (which I guess means it should have stuck with the southern solution it had in the first place    lol)

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Scraff

Scraff

Posted
Posted

Here is a good read for you guys:

Foot's Forecast

7:35 AM 3/15 - "Predict the High, and you predict the storm."

An update on the St. Patrick's Day Green-to-White Snow Gala

An old forecasting rule that I first learned at Penn State in the meteorology program still holds true today. Those were the days well before computer model maps could be posted online with the press of a button. At 4:30 AM in State College, PA students would enter (or rather, stumble) into the Campus Weather Service on the 6th floor of the Walker Building. There we would discover reams and reams of giant facsimile charts splayed out all over the floor. We had to quickly separate and hang up all the maps in the right location on the "Map Wall"- and THEN do the analysis.

When forecasting for a winter storm, the FIRST THING we looked for on those black and white maps with all the wavy lines? Yep, position of the High pressure system!

Especially this time of year, if the high was in ANY way placed incorrectly for a snowstorm, that idea was off the table. Only in very rare occurrences in March would we ever see a classic High in Ontario/Quebec, with a low crawling off the Carolina coast.

(http://www.wpc.ncep.noaa.gov/basicwx/bawx_nav.php?imgtyp=wbg&arrval=6&vtime=Mon_12Z&ptime=Mon_00Z&ntime)

Fast forward to the instagrammed, ultra-tweet, Facebook-flash world of today - there are no maps to hang on the wall anymore in some weather forecast centers. But the skills we learned still carry forward. By 8 AM on Monday morning, charts from the NOAA Weather Prediction Center have been showing for several days now the classic setup as described above, and yes, it's mid-March.

And yes, sun angle, liquid amounts, Sunday's high, the overnight low, surface wind direction, temps at 5000 feet, etc etc will ALL be important factors for how this storm evolves. But the ONE factor and trend that cannot be denied: Warm ups in our area have been fleeting, and all winter have been quickly replaced with a rush of cold air. This is due to more favorable placement of Canadian highs in recent months over a very dense and expansive snowpack.

WHAT'S THE BOTTOM LINE WITH THIS STORM?

1. Liquid amounts are still expected to be 0.50-0.75" for northern Maryland, (Up to 0.50" in southern PA), and near 1.0" in southern Maryland/eastern shore. Source - NOAA: (http://www.wpc.ncep.noaa.gov/qpf/fill_99qwbg.gif)

2. Much colder air will filter in starting tonight, with Sunday's highs fully 10 degrees or more colder than today's 50s.

3. Several waves of low pressure riding near the coast will pull on the cold air in that high and wrap it down over Maryland and along the Blue Ridge. In this setup, rain Sunday changes to snow at nightfall, and continues into Monday morning. More details at our main site this morning: (http://www.footsforecast.org/)

Unless something major changes in the setup, to this old-time forecaster, the rule looks to hold true, yes even for a mid-March storm. We'll continue watching for you, but the evidence shows that winter is not done with us. If you would like to "Predict the high" with us, we welcome your thoughts on where this puppy will end up by Monday!

(Forecaster Foot - and Proud Penn Stater, Class of '96)

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mitchnick

mitchnick

Posted
Posted

Here is a good read for you guys:

Foot's Forecast

7:35 AM 3/15 - "Predict the High, and you predict the storm."

An update on the St. Patrick's Day Green-to-White Snow Gala

An old forecasting rule that I first learned at Penn State in the meteorology program still holds true today. Those were the days well before computer model maps could be posted online with the press of a button. At 4:30 AM in State College, PA students would enter (or rather, stumble) into the Campus Weather Service on the 6th floor of the Walker Building. There we would discover reams and reams of giant facsimile charts splayed out all over the floor. We had to quickly separate and hang up all the maps in the right location on the "Map Wall"- and THEN do the analysis.

When forecasting for a winter storm, the FIRST THING we looked for on those black and white maps with all the wavy lines? Yep, position of the High pressure system!

Especially this time of year, if the high was in ANY way placed incorrectly for a snowstorm, that idea was off the table. Only in very rare occurrences in March would we ever see a classic High in Ontario/Quebec, with a low crawling off the Carolina coast.

(http://www.wpc.ncep.noaa.gov/basicwx/bawx_nav.php?imgtyp=wbg&arrval=6&vtime=Mon_12Z&ptime=Mon_00Z&ntime)

Fast forward to the instagrammed, ultra-tweet, Facebook-flash world of today - there are no maps to hang on the wall anymore in some weather forecast centers. But the skills we learned still carry forward. By 8 AM on Monday morning, charts from the NOAA Weather Prediction Center have been showing for several days now the classic setup as described above, and yes, it's mid-March.

And yes, sun angle, liquid amounts, Sunday's high, the overnight low, surface wind direction, temps at 5000 feet, etc etc will ALL be important factors for how this storm evolves. But the ONE factor and trend that cannot be denied: Warm ups in our area have been fleeting, and all winter have been quickly replaced with a rush of cold air. This is due to more favorable placement of Canadian highs in recent months over a very dense and expansive snowpack.

WHAT'S THE BOTTOM LINE WITH THIS STORM?

1. Liquid amounts are still expected to be 0.50-0.75" for northern Maryland, (Up to 0.50" in southern PA), and near 1.0" in southern Maryland/eastern shore. Source - NOAA: (http://www.wpc.ncep.noaa.gov/qpf/fill_99qwbg.gif)

2. Much colder air will filter in starting tonight, with Sunday's highs fully 10 degrees or more colder than today's 50s.

3. Several waves of low pressure riding near the coast will pull on the cold air in that high and wrap it down over Maryland and along the Blue Ridge. In this setup, rain Sunday changes to snow at nightfall, and continues into Monday morning. More details at our main site this morning: (http://www.footsforecast.org/)

Unless something major changes in the setup, to this old-time forecaster, the rule looks to hold true, yes even for a mid-March storm. We'll continue watching for you, but the evidence shows that winter is not done with us. If you would like to "Predict the high" with us, we welcome your thoughts on where this puppy will end up by Monday!

(Forecaster Foot - and Proud Penn Stater, Class of '96)

he's pure weenie and always goes with the snowiest forecast.....toss it

if he's right, it's luck

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