January 2/3 Event - Disco., Nowcasting, and Obs.

[HighStakes]

The details is what makes things so interesting.

They do, but I need a break from driving myself crazy.

[North Balti Zen]

BWI didn't report anything on 3/6/13?

 

Doubt it. I got hosed that day at my house in NE Balt City. And BWI did way better than me on 3/25. That was a very localized hit there.

[snow.]

Here's the latest CWG forecast and map.  Should have my quote as soon as Jason drops it in. 

 

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/01/02/snow-and-crashing-temperatures-tonight-the-latest/

 

nice article...I really don't like the maps at all, but that is just my opinion...Dusting to 2" with bust/boom scenarios covering 50% and a confidence level?...that map doesn't really tell me anything other than there is medium confidence I could get a cartopper to 4"

[HighStakes]

Doubt it. I got hosed that day at my house in NE Balt City. And BWI did way better than me on 3/25. That was a very localized hit there.

Both storms were kinda weird. On the other hand I don't think you will get hosed tonight.

[Eskimo Joe]

LWX late morning AFD is a nice read:

 

 

 

000
FXUS61 KLWX 021608
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1108 AM EST THU JAN 2 2014

.SYNOPSIS...
LOW PRESSURE SYSTEM IS OVER KENTUCKY WITH A STATIONARY FRONT EXTENDING
FROM IT INTO THE MID ATLANTIC. THE LOW WILL RAPIDLY TRACK EAST OF
THE DELMARVA OVERNIGHT. HIGH PRESSURE WILL RETURN FOR FRIDAY AND
SATURDAY. LOW PRESSURE IS EXPECTED TO IMPACT THE REGION SUNDAY AND
MONDAY. HIGH PRESSURE WILL BRING A SECOND ROUND OF VERY COLD AIR
INTO THE REGION EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...

A SFC MAP SIDENOTE - THIS MRNG'S ANLYS SHOWS 47 BLO ZERO AT CWPK
IN CENTRAL QUEBEC!

YDA THE MDLS PROJECTED THE SFC LOW TO MOVE FM OK TO KY BY MON
MRNG...AND THAT IS WHERE IT CURRENTLY RESIDES. ALOFT A FAST MOVG
LONG WV STRETCHES DOWN THE MS VALLEY. WINT WX ADVSRIES ARE IN
EFFECT ACROSS THE NRN TIER OF MD..ERN W.V...AND NWRN VA. AS HAS
BEEN DISCUSSED FOR THE PAST FEW DAYS THIS IS A FAR FM OPTIMUM
SITUATION FOR SNOW GENERATION. TO BEGIN - E OF THE MTNS BOTH THE
12Z IAD AND APG SNDGS ARE XTRMLY DRY IN THE LOW LVLS - DWPT
DEPRESSIONS OF OVR 30 DEG BASICALLY THRU FL 100. SO ONCE THE
INITIAL MOISTURE FM THE LOW PUSHES E OF THE MTNS SOME TIME IS GOING
TO BE SPENT MOISTENING THE COLUMN. DO NOT FEEL THE NEED TO XTND
THE ADVSRIES FURTHER S THAN WHAT IS CURRENTLY IN EFFECT.

IN A SIDE NOTE THERE IS HZ/BR THIS MRNG. THIS IS MOST LKLY A
PRODUCT OF LGT WINDS AND A TRAPPING INVRSN XTNDG THRU FL 040 -
POLUTANTS/HZ HV NOWHERE TO GO.

BACK TO THE MAIN TOPIC: FEEL THE 2-4" WHERE THE ADVSRY IS IN
EFFECT IS PRBLY REPRESENTATIVE. THE POSN OF THE LOW IS NOT WHAT
WE'D LK TO SEE IN ORDER TO ENTRAIN COLDER AIR INTO THE SYSTEM -
IT'S TOO FAR N. AND THERE IS NO BLOCKING HIGH OFFSHORE...SO THE
LOW/UPR WV WL BE GONE BY 12Z FRI.

FOR TDA WL DROP THE TEMPS A FEW DEGS - XTNSV CLD CVR/LOW SUN ANGLE
MEANS TEMPS WL MOST LKLY STRUGGLE TO TOP 40.

AFTR MDNGT SHOULD BE INTERESTING AS COLDER AIR IS DRAWN INTO THE
MID ATLC ONCE THE LOW REACHES THE BAY. PCPN WL TURN TO ALL
SNOW...BUT IT PRBLY WON'T BE A LOT - THE ONLY TIMES THAT HAPPENS
HERE IS WHEN THERE IS A BLOCKING HIGH - OCCASIONALLY WE'VE SEEN
REALLY BIG TOTALS ON THE WRN SIDE OF THE CHES BAY...BUT AGN THIS
WON'T BE THE CASE TNGT - THE LOW WL BE RAPIDLY ON ITS WAY TO BRING
HVY SNOW TO NY/NEW ENGLAND.


&&

.SHORT TERM /FRIDAY/...

FRI WL COME AS A SHOCK TO A LOT OF PEOPLE IN TERMS OF COLD AND
WIND. I DID A CHECK OF THE PAST TEN YRS TO SEE "WHAT WERE SOME
REALLY COLD DAYS?" IN A NUTSHELL..JAN 17 2009:

DCA LOW TEMP BWI LOW TEMP IAD LOW TEMP
1/17/09 8 1/17/09 2 1/17/09 0
1/10/04 8 1/18/03 5 1/29/04 2
2/16/07 10 1/10/04 6 1/18/03 3

WE WON'T BE THAT COLD FRI MRNG (ALTHO TUE MRNG MIGHT)...BUT THE
COMBO OF DROPPING TEMPS AND STRONG NWRLY WINDS WL DROP THE WIND
CHILLS INTO THE SINGLE DIGITS OVR MUCH OF THE AREA DURG THE DAY.

SNOW WILL COME TO AN END EARLY FRIDAY MORNING BUT WINDS WILL
STILL BE HOWLING FROM THE NORTHWEST AND SHOULD PERSIST THROUGH THE
DAY. STRONG HIGH PRESSURE WILL USHER IN VERY COLD AIR. WIND GUSTS
WILL EXCEED 30 MPH MUCH OF THE TIME.

&&

.LONG TERM /FRIDAY MIGHT THROUGH WEDNESDAY/...

HIGH PRESSURE WILL MOVE OVERHEAD FRIDAY NIGHT AND ALTHOUGH WINDS
WILL RELAX RADIATIONAL COOLING WILL LEAD TO A COLD NIGHT ACROSS THE
MID ATLANTIC. TEMPS WILL DROP TO THE SINGLE DIGITS IN THE POTOMAC
HIGHLANDS AND IN THE TEENS ELSEWHERE. SOUTHERLY FLOW WILL BEGIN
SATURDAY AS THE HIGH MOVES OFF THE COAST LEADING TO TEMPS IN THE MID
30S...BELOW NORMAL FOR EARLY JANUARY. RETURN FLOW WILL CONTINUE
SATURDAY NIGHT AND INTO SUNDAY AS AN UPPER LEVEL RIDGE AMPLIFIES
ACROSS THE WESTERN ATLANTIC. A SHORTWAVE TROUGH FROM THE NORTHERN
STREAM WILL DIG INTO THE GULF STATES SUNDAY NIGHT. TEMPS WILL
REBOUND TO NORMAL SUNDAY AS CLOUDS AND MOISTURE INCREASE IN THE MID
ATLANTIC. A FEW DISTURBANCES AHEAD OF AN APPROACHING LOW MAY PRODUCE
LIGHT RAIN SHOWERS SUNDAY AFTERNOON.

LOW PRESSURE WILL CROSS THE MID ATLANTIC SUNDAY NIGHT AND DUE TO
THE TRACK OF THE LOW...AREAS SOUTH AND EAST OF THE TRACK WILL LIKELY
BE RAIN AND NORTH AND WEST WILL LIKELY BE SNOW. AT THIS TIME ECMWF
HAS TRACK FURTHER NORTH WHICH WILL KEEP THE MID ATLANTIC ON THE WARM
SIDE. GFS TAKES THE LOW THROUGH THE MID ATLANTIC WHICH WILL BRING
DOWN COLDER AIR QUICKER AND AREAS WEST OF THE BLUE RIDGE HAVE THE
POTENTIAL FOR SNOW. CONFIDENCE IS LOW AT THIS TIME.

LOW PRESSURE MOVES INTO NEW ENGLAND MONDAY AND NW-W FLOW WILL LEAD
TO CLOUDY CONDITIONS IN THE UPSLOPE REGION. STRONG CAA IS
EXPECTED NEXT WEEK WITH TEMPS DROPPING WELL BELOW CLIMO NORM. A
TIGHT PRESSURE GRADIENT BETWEEN THE APPROACHING HIGH AND DEPARTING
LOW WILL RESULT IN WIND CHILLS NEAR ZERO AS FAR EAST AS THE I-95
CORRIDOR. HIGH PRESSURE WILL RESIDE ACROSS THE MID ATLANTIC FOR
THE MIDDLE PART OF NEXT WEEK CONTINUING THE BELOW NORMAL TEMPERATURES.

[usedtobe]

nice article...I really don't like the maps at all, but that is just my opinion...Dusting to 2" with bust/boom scenarios covering 50% and a confidence level?...that map doesn't really tell me anything other than there is medium confidence I could get a cartopper to 4"

 

I suspect most people never get beyond the big printed dusting to 2".   I know when we get lambasted for a bust when we've made it clear the forecast was a iffy one, quite a few people never got past the big lettered part of the graphic.

[needbiggerboat]

IAD 32 @ 11am

12z NAM had 37.3

Might not mean anything, but could suggest lower max and less precip lost to rain....NAM currently has .2 of .24 QPF above 32.

I think 2-4 enters into the IAD equation alongside the <1 inch scenario.

[BTRWx]

Moisture reaching ground in WV, snowing at 'Shoe and Caanan. Elkins reporting mix and 31.

Beckley and Bluefield rain and 40 degrees.

Edit-also snowing in Highland County on traffic cam.

I would assume that they are both on the windward side of the Apps to get the uplifting?

[Ian]

The NWS has a table of 429 different options for snowfall probabilities now.  In a few years no one will have any clue what any forecast is. 

[WxUSAF]

I suspect most people never get beyond the big printed dusting to 2".   I know when we get lambasted for a bust when we've made it clear the forecast was a iffy one, quite a few people never get past the big letter part of the graphic.

Conveying uncertainty is hands-down one of the hardest things to do in the forecasting biz.  

[BTRWx]

IAD 32 @ 11am

12z NAM had 37.3

Might not mean anything, but could suggest lower max and less precip lost to rain....NAM currently has .2 of .24 QPF above 32.

I think 2-4 enters into the IAD equation alongside the <1 inch scenario.

Could the placement of the temperature gradient be a sign of where the moisture gradient may set up later?

[NoVaWx]

ABC futurecast is a great picture.  Has the snow arriving at three and then a pivot with bands rotating through tomorrow morning.  Looks like Feb 2010

[Don Cherry's Jacket]

The NWS has a table of 429 different options for snowfall probabilities now.  In a few years no one will have any clue what any forecast is. 

I think we're there already.

[Ian]

ABC futurecast is a great picture.  Has the snow arriving at three and then a pivot with bands rotating through tomorrow morning.  Looks like Feb 2010

Joe Bastardi's son called it like a week ago.

[snow.]

I suspect most people never get beyond the big printed dusting to 2".   I know when we get lambasted for a bust when we've made it clear the forecast was a iffy one, quite a few people never got past the big lettered part of the graphic.

 

as you know, educating the public is difficult...they hear and read what they want to...I would narrow the T-2" range and just go 0.5" - 1.5" and say medium confidence and just roll with it...

[BTRWx]

Joe Bastardi's son called it like a week ago.

I've learned my lesson using those maps. 

[TerpWeather]

FWIW. RAP is being snow happy

EDIT: referring more towards DC than Balt

[chris87]

I suspect most people never get beyond the big printed dusting to 2".   I know when we get lambasted for a bust when we've made it clear the forecast was a iffy one, quite a few people never get past the big letter part of the graphic.

 

i'm still torn about pro/cons of probabilistic maps such as this one -- there seems to be a steady push to protect one selves behind probability without any regard to how the public is able to digest the information (and have a tendency to not be able to comprehend uncertainty) -- i haven't seen a good argument for these types of maps other than it's a lot easier to defend your forecast post-event, not sure a compelling argument exists that these are value-added. 

 

edit: as stated above - educating the public is difficult so i'm not trying to understate that -- and if i was in the position of a media outlet and/or the NWS i'd prefer probabilistic type maps from a forecaster standpoint 

[snow.]

FWIW. RAP is being snow happy

 

RAP pivot is sweet..it has most of us snowing until like 5am

[wxdude64]

The NWS has a table of 429 different options for snowfall probabilities now.  In a few years no one will have any clue what any forecast is. 

 

 

I think we're there already.

Yep, adding more confusion to the confused.........

[BTRWx]

i'm still torn about pro/cons of probabilistic maps such as this one -- there seems to be a steady push to protect one selves behind probability without any regard to how the public is able to digest the information (and have a tendency to not to able to comprehend uncertainty) -- i haven't seen a good argument for these types of maps other than it's a lot easier to defend your forecast post-event, not sure a compelling argument exists that these are value-added. 

I think the public has basically been asking for them. I can't seem to go many places these days without hearing something about local met's being wrong. I think the probability maps may slowly get some of the crowd to be more trusting at least.

[needbiggerboat]

Could the placement of the temperature gradient be a sign of where the moisture gradient may set up later?

Others that understand those dynamics are much more qualified to answer that question.

IAD typically, but not in all cases, does better than DCA. I'm skeptical of a solution that shows more accumlation at DCA, even though we're talking minor numbers at this point. DCA always struggles with temps relative to IAD.

[Ian]

I think the public has basically been asking for them. I can't seem to go many places these days without hearing something about local met's being wrong. I think the probability maps may slowly get some of the crowd to be more trusting at least.

My take is they are more interested in knowing the multiple options at range. Keep it simple is still a pretty solid rule to live by... we risk losing people by going too far the other direction IMO.  

[HM]

i'm still torn about pro/cons of probabilistic maps such as this one -- there seems to be a steady push to protect one selves behind probability without any regard to how the public is able to digest the information (and have a tendency to not to able to comprehend uncertainty) -- i haven't seen a good argument for these types of maps other than it's a lot easier to defend your forecast post-event, not sure a compelling argument exists that these are value-added. 

 

Or.... you've got the forecast, like all other outfits with an accumulation range, and express how things could bust in one direction or another (should that actually happen). I think everyone understands that forecasts, particularly snowfall forecasts, do bust. I don't see the harm in telling the public that if it did bust, it would bust this way. I do agree, though, that a T-2" range is useless. There's a big difference between a spotty coating on the grass and 1" that covers everything.

 

Saying my forecast is "1-2 inches with medium confidence, could bust high/low depending on storm track" is the more usual approach. What's the harm in giving more information and telling the public how you would lean, what are the bust scenarios/range with this system and a confidence interval? Both approaches are really the same forecast, but the second one gives the public more knowledge...

 

Yeah, I know, I'm too idealistic and this debate's resolution is futile.

[Bob Chill]

Others that understand those dynamics are much more qualified to answer that question.

IAD typically, but not in all cases, does better than DCA. I'm skeptical of a solution that shows more accumlation at DCA, even though we're talking minor numbers at this point. DCA always struggles with temps relative to IAD.

 

Every degree below prog surface temp is a big net positive because most near the dca suburbs will waste some precip at onset. 850's are plenty cold for all snow. If I start out snow at onset with 36* surface it will be a big help. Same applies everywhere. 

[das]

Interesting list, anyone have one for BWI?

 

Here's the list for Clarksburg, 28mi NW of DCA.  I put Matt's numbers side-by-side for comparison.  It's like a completely different climate.  That's what 600' of elevation, little UHI and no water nearby can do.

 

Date             DC         Clarksburg

1/28/2011     0.6         0.6

2/9/2011       0.1  

2/21-22/11    0.4         3.1

3/6/2011                     0.3 

3/27/2011     0.2  

10/29/2011                 2.7

12/29/2011                 0.1

1/3/2012                     0.1

1/9/2012       0.6         0.1

1/20-21/12    1.1        1.6

2/4/2012                    1.1

2/8/2012                    0.6

2/11-12/12    0.3       1.5

12/24/2012               1.9

12/26/2012   0.2       1.4

12/29/2012               1.3

1/24/2013     0.4       1.2

1/25/2013     0.4       1.4

1/28/2013     0.1       0.1

2/1/2013       0.2       0.6

2/2/2013       0.2       0.5

2/3/2013                   0.2

2/8/2013                   0.1

2/13/2013                 0.6

2/15/2013                 0.3

2/19/2013                 0.1

3/6/2013       0.2       3.2

3/18/2013                 0.2

3/25/2013     1.4       4.1

12/8/2013     0.6       5.1

12/10/2013   0.9       3.1

12/14/2013               0.4

12/17/2013               0.2

Total             7.9      37.8

 

[PrinceFrederickWx]

Here are the last 17 accumulating snow events for DCA (since 1/26/11),....I'm pretty sure we are properly conditioned to be let down...Sure..there will be some brief disappointment, but we know the drill

 

1/28/11 - 0.6"

2/9/11 - 0.1"

2/21-22/11 - 0.4"

3/27/11 - 0.2"

1/9/12 - 0.6"

1/20-21/12 - 1.1"

2/11-12/12 - 0.3"

12/26/12 - 0.2"

1/24/13 - 0.4"

1/25/13 - 0.4"

1/28/13 - 0.1"

2/1/13 - 0.2"

2/2/13 - 0.2"

3/6/13 - 0.2"

3/25/13 - 1.4"

12/8/13 - 0.6"

12/10/13 - 0.9"

 

Its actually not just a 2" snow drought at DCA like everyone talks about... its even a 1.5" snow drought.

[Sparky]

the thing I am looking forward to the most in this mini-storm is the powdery ending to the snow which will blow around and off roofs/objects for a while all day tomorrow.  I am thinking 2 inches for here should be doable.

[Ian]

Its actually not just a 2" snow drought at DCA like everyone talks about... its even a 1.5" snow drought.

2" is usually considered a "plowable" and "grass coverable" event. Plus using whole numbers is more fun. 

[ThePhotoGuy]

 

Here's the list for Clarksburg, 28mi NW of DCA.  I put Matt's numbers side-by-side for comparison.  It's like a completely different climate.  That's what 600' of elevation, little UHI and no water nearby can do.

 

Date DC Clarksburg 1/28/2011 0.6 0.6 2/9/2011 0.1   2/21-22/11 0.4 3.1 3/6/2011   0.3 3/27/2011 0.2   10/29/2011   2.7 12/29/2011   0.1 1/3/2012   0.1 1/9/2012 0.6 0.1 1/20-21/12 1.1 1.6 2/4/2012   1.1 2/8/2012   0.6 2/11-12/12 0.3 1.5 12/24/2012   1.9 12/26/2012 0.2 1.4 12/29/2012   1.3 1/24/2013 0.4 1.2 1/25/2013 0.4 1.4 1/28/2013 0.1 0.1 2/1/2013 0.2 0.6 2/2/2013 0.2 0.5 2/3/2013   0.2 2/8/2013   0.1 2/13/2013   0.6 2/15/2013   0.3 2/19/2013   0.1 3/6/2013 0.2 3.2 3/18/2013   0.2 3/25/2013 1.4 4.1 12/8/2013 0.6 5.1 12/10/2013 0.9 3.1 12/14/2013   0.4 12/17/2013   0.2 Total 7.9 37.8

 

 

Interesting! Thanks!

 

I am about 9 miles ESE of BWI. Totals would probably be much different here then BWI if I would track the totals. My area often has the precip but the issue is air/ground temperatures, low elevation, bay/water temperatures that lowers snow accumulation.