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03/13/17 East Coast Storm Update

We are now within hours of the onset of our big East Coast snowstorm, but there have been some minor changes.  For one, the models have a storm that is farther west or closer to the coast. . .a negative for big snows closer to the coast.  The thermal profiles, time of year, and stronger storm (on the models) may cause some precipitation type problems for the I-95 corridor, NJ shore, and southeastern New England.  This update will not be much different from yesterday’s, but will account for these changes.

Bottom Line:

DC-Baltimore to coastal NJ:  The I-95 corridor may end up the dividing line between heavy snowfall and rain/sleet mix.  I don’t expect any freezing rain (typically tough to do in March), but DC up 95 to Baltimore to Wilmington, DE to Sandy Hook may see a few hours of sleet, possibly heavy.  All areas may see some thundersnow or thundersleet and increasing winds through the night. I’m not thinking it ever changes to pure rain near I-95, but closer to the Bay that may be the case, especially near Annapolis and from Toms River, NJ south, a change to heavy rain may occur.  North and West of I-95, heavy snow with the best banding in the deformation zone.  

Snow totals:  I like the National Weather Service maps below, but any delay to changeover could result in more snow, especially from Annapolis, DC, Baltimore, Wilmington, and Toms River on north.  My best guess:  DC area (5″-8″), Baltimore area (9″-12″), Toms River area (10″-12″), Monmouth County (10″-14″), Princeton area (15″-18″)

(*NOTE, sleet will likely cut into the totals I mention, but I’m trying to account for it.)

Start Time:  Around 6-7 pm near DC, 7-9 pm northern MD, 9-11 pm NJ, overnight farther north

The model snowfall maps below show some of the changes from yesterday, yet the GFS/Euro have been consistent, while the Canadian/UKMET have lesser snow near I-95 due to a closer storm and warm mid-levels.

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0000 UTC 03/13/17 GFS snowfall map ending 1800 UTC on 03/14/17 (courtesy of WxBell)
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0600 UTC 03/13/17 3 km NAM snowfall map ending 1800 UTC on 03/14/17 (courtesy of Tropical Tidbits)

The NWS snowfall maps are available below.  Please click on the individual maps to zoom in.

 

Thanks for reading and enjoy the storm!

 

March wants to play winter!

After a winter that has produced well-below normal snowfall in the Mid-Atlantic (largely the DC-Baltimore area is in the snow-hole this year), March has decided to provide a rather unique situation.  Models are coming into better agreement on what looks to be a significant snowstorm from northern VA up through ME with the metros of DC, Baltimore, Philadelphia, New York City, and Boston possibly getting big numbers.  Prior to this event, here are some of the season snowfall totals:

BWI:  0.7″, DCA:  1.4″, IAD:  1.7″, ORF:  5.3″, RIC:  7.1″, ACY:  7.7″, PHL:  9.0″, NYC:  22.6″, BOS:  39.2″

Notice as you head north, the seasonal totals are much higher and closer to normal snowfall.  So, where do we go from here?

The Bottom Line:  A significant snowstorm looks to be taking shape from Monday evening through early Wednesday morning with snow starting south in the early evening Monday, then spreading north through the night.  There is the chance many areas along and west of the I-95 corridor may see snow rates approach 1″-3″ per hour, thundersnow, and increasing winds through the overnight period into Tuesday.  The main show should last about 12-15 hours, but the upper-low may produce another period of snow for mainly MD, VA, DE, southern PA, and southern NJ Tuesday night.  

My initial thoughts:

DC-Baltimore:  I am thinking a solid 10″-15″ from DC (lower side) to Baltimore (higher side), but there is the possibility of 18″+ mainly Baltimore area north and west.  

Coastal NJ:  10″-12″ is my first guess, but be prepared for high winds and coastal flooding as well.  There might even be a mix to rain/sleet.

Philadelphia/Trenton up through NYC:  15″-18″, but possibly as high as 24″ in spots.

Boston area:  15″-20″, again possibly up to 24″ in spots.

The 0000 UTC GFS and 0600 UTC NAM show generous amounts of snow for the I-95 corridor, though less on the NAM due to difference in storm location.  The notable shift overnight was colder and more southerly.  All of the energy that will come together for this storm is now being sampled well over the Pacific Northwest, so confidence is growing.  For comparison, the 0000 UTC ECMWF (can’t show) had 8-14″ from DC-Baltimore, then goes crazy around Philadelphia through northern NJ and into NYC with amounts topping 20″.  The UKMET and CMC models also show heavy snowfall, so model agreement has increased.  The questions are still on the southern end near DC.  (NOTE:  It’s wise to not keep paying attention to the snowfall or precipitation maps during events like this as they will waffle the most, so look for trends, especially with 500 mb and sfc feature placement.)

gfs_6hr_snow_acc_nj_17
0000 UTC GFS Total Snowfall ending on 03/16/17 (courtesy of WxBell)
namp_3hr_snow_a_nj_29
0600 UTC NAM total snowfall ending 03/15/17 (courtesy of WxBell)

The 0000 UTC GEFS spread from 11 March and 12 March show the shift in the low placement with a nice clustering  now being depicted off the Delmarva and in a great spot for big snows in the I-95 corridor.  The left image would show less snow for the I-95 corridor, while the right image is much better.

Finally, the snowfall maps from the various National Weather Service Forecast Offices are presented below for your convenience.

 

As always, thanks for reading!

So, it can snow in February?

Ok, I know, I’m being snarky as two days over 70 degrees in the DC-Baltimore area have been bummed about this winter.  But. . .there will be snow. . .for some.  Currently, temperatures in the I-95 corridor of DC-Baltimore are in the low 50s with showers and even some thunderstorms popping up.  This does not bode well for much snow around here and based on this winter so far. . .I’m not surprised.  So, here’s a quick update on the storm and snow totals from DC up through Boston.

Bottom Line:  Rain overnight will change to snow from NW-SE across most areas and there may be some rumbles of thunder.  Temperatures will drop into the morning hours and snow intensity will pick up, especially from Eastern PA east through NYC and eventually to Boston.  Thundersnow is a real possibility and winds will increase through the day.  While the snow ends in the morning from DC-Baltimore, afternoon snow showers and squalls will still cause problems and some light accumulation.

Below are the various snowfall maps from your local NWS forecast offices.

stormtotalsnowweb1_lwx_20170209_0018lst
Sterling WFO Snowfall Map valid for 02/09/17.
stormtotalsnowweb1_phi_20170208_2049lst
Mt. Holly WFO Snowfall Map valid for 02/09/17.
stormtotalsnowweb_ctp_20170208_2219lst
State College WFO Snowfall Map valid for 02/09/17.
stormtotalsnowweb1_okx_20170208_2154lst
Upton WFO Snowfall Map valid for 02/09/17.
stormtotalsnowweb_box_20170208_1843lst
Taunton WFO Snowfall Map valid for 02/09/17.

Thanks for reading and enjoy the snow (if you get it)!

Light Snow Event on the way!

It’s sad when I’m excited about a light snow event, but thus is the winter of 2016-2017.  The pattern this winter has featured cold arriving when the storm track was not conducive, to very warm periods that have left snow lovers crying in our cereal bowls (or while drinking some fine craft beer).  But alas, we have our first clipper from Sunday night into Monday morning.

Bottom Line:  A light snow event starting Sunday late evening and ending Monday morning (mid-morning MD, midday DE-NJ).  Southern NJ may get the better snows (3″-4″) as this small storm strengthens, while the I-95 corridor will see closer to 1″, 2″ east of there, and 1-3″ central NJ, including coastal Monmouth and Ocean Counties.  Any mesoscale banding could make things more interesting with isolated higher amounts.

Discussion:  The 0000 UTC models came in with a bit more moisture and dynamics to produce a quick dusting to 2″ of snow from DC up through Ocean County, NJ.  Some parts of the Eastern Shore of MD and DE will see closer to 2″-3″.  Interestingly enough, the NAM was rather enthusiastic with amounts in the latter areas approaching 6-7″ or more, while providing the I-95 corridor with 2″-3″ and up to 5″-6″ from southern NJ up to about Point Pleasant, NJ.

For your convenience, I’ve included a few of the model snow maps below, but I caution you that these are only one possible model solution per model and the snow-to-liquid ratio is 10:1.  Another factor to consider is the potential for banding, which models have a tough time resolving.

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0000 UTC GFS accumulated snowfall valid at 0000 UTC (7 pm EST 01/30/17) on 01/31/17.  (Courtesy of Weatherbell)
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0600 UTC NAM (12 km) accumulated snowfall valid at 0600 UTC (1 am EST) on 01/31/17.  (Courtesy of Weatherbell)
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0600 UTC NAM (4 km) accumulated snowfall valid at 1500 UTC (11 am EST) on 01/30/17. (Courtesy of Weatherbell)

The ECMWF (European) model (can’t show it) was closer to the GFS with about 1″-2″ near and east of the I-95 corridor with southern NJ getting closer to 2″-3″ and the Eastern Shore of MD to central DE getting around 4″.  The Canadian was also in the 1″-2″ of snow area wide.

The National Weather Service (NWS) snowfall forecast maps are below.

stormtotalsnow_lwx_20170129_4am
The Sterling NWS WFO snowfall map for 01/29/17 – 01/30/17.
stormtotalsnow_phx_20170129_4am
The Mt. Holly NWS WFO snowfall map valid from 01/29/17 – 01/30/17.

I’ll update later today if there are changes to the forecast.

Thanks for reading!

Saturday Coastal Storm for the Southeast/Mid-Atlantic Coast

After last night’s light snow and for some, certainly not enough, we quickly turn to our next winter storm.  If you live in the Norfolk area, this is looking like quite a storm.  Farther north, coastal areas will do much better than farther inland.  Even much of NC and SC down through parts of LA are getting into the “fun” tonight with freezing rain, ice pellets, and some snow.

As for snow amounts, I have included the NWS snow maps below from Wakefield WFO, Sterling WFO, Mt. Holly WFO, Upton WFO, and Taunton WFO.  Some of the latest mesoscale models (HRRR in particular) are showing a slightly wetter solution along the I-95 corridor and there has been a general shift NW in the tracks of this storm, so be aware heading into tomorrow morning.  Regardless, I think the snow maps look reasonable with a chance that DC-Baltimore, mainly along I-95 and east could see amounts closer to 3″ with higher amounts closer to the ocean (I know, that doesn’t happen all the time!).  Coast NJ should see a general 5″, but could see slightly more.  A blizzard warning is in effect for Norfolk and Virginia Beach were winds will increase and channel down the Chesapeake Bay.

akq_snowmap_20170106_1530est
Wakefield WFO snow map issued at 3:30 pm EST on 01/06/17 valid until 7 pm on 01/09/17.
lwx_snowmap_20170106_1702est
Sterling WFO snow map issed at 5:02 pm EST on 01/06/17 valid until 6 pm on 01/07/17.
phi_snowmap_20170106_1619est
Mt. Holly WFO snow map issued at 4:19 pm EST 01/06/17 valid until 7 pm 01/07/17.
okx_snowmap_20170106_1626est
Upton WFO snow map issued at 6:26 pm EST on 01/06/17 valid until 6 am on 01/08/17.
box_snowmap_20170106_1503est
Taunton WFO snow map issued at 3:03 pm EST on 01/06/17 valid until 7 am on 01/08/17.

I’ll update later as necessary.

Thanks for reading!

Quick Arctic Wave with Snow, then. . .

Some of you may have noticed that it’s snowing or forecast to snow tonight.  This is due to a fast moving arctic wave or disturbance that is trailing the cold front that went through yesterday.  Snow has been falling at BWI in Baltimore for a couple hours, but only 0.1″ has been recorded thus far.  In general, I look for this to be a 1″-2″ event, with maybe someone getting 3″ due to possible localized mesoscale bands forming (very challenging to forecast in advance).

The Sterling WFO and Mt. Holly WFO snow maps are presented below.

lwx_snowfall_20170105_1800est
Sterling WFO snowfall map issued at 6:04 pm EST valid until 10 a.m. on 01/06/17.
phi_snowfall_20170105_1601est
Mt. Holly WFO snow map issued at 4:01 pm EST valid until 1:00 pm EST on 01/06/17.

Snow should continue until about 2:00 am EST from DC-Baltimore area, but until 4-5 am farther north and east as the system quickly exits stage right.  Be careful if you have to be out and about tonight!

As for the next system, I’ll post on it tomorrow.  The models have generally trended farther to the north and west, which might now include portions of the I-95 corridor from DC up through NYC and Boston.  I’d like to see some more data before getting too excited.

Thanks for reading!

Severe Thunderstorm Threat for the Gulf Coast

The second day of the new year will feature the threat for severe thunderstorms with the main threat being high wind gusts (up to 30% threat) due to a 50 knots (60 mph) 700 mb jet, though there will be a 5% threat for tornadoes and 15% threat for large hail.  Since this update is occurring around 0600 EST, please refer to the following for further updates:

NWSSPC, WPC

NWS Lake Charles, NWS Slidell, NWS Houston, NWS Mobile, NWS Jackson

day1otlk_1200
Day 1 Convective Outlook issued at 0604 UTC 01/02/17
day1probotlk_1200_torn
Day 1 Tornado Outlook issued at 0604 UTC on 01/02/17
day1probotlk_1200_wind
Day 1 Wind Outlook issued at 0604 UTC on 01/02/17
day1probotlk_1200_hail
Day 1 Hail Outlook issued at 0604 UTC on 01/02/17

The latest High Resolution Rapid Refresh (HRRR) model (images courtesy of Weatherbell) shows parameters that look conducive for the development of strong to possibly severe thunderstorms by midday across much of eastern TX, LA, MS, and later into AL and the panhandle of FL.  Note the values of surface-based CAPE approaching 2500-3000, especially into central-southeastern LA.  Those values would be good in spring and summer!  Therefore, the air mass is more than sufficient to support thunderstorms.

hrrr_cape_tx_9
HRRR 8-hr forecast for surface-based Convective Available Potential Energy (CAPE – buoyancy) valid around 1200 EST or 1100 CST on 01/02/17

Looking at the HRRR forecast for Significant Tornado Parameter, one would look for values above 1 to assess the chance for tornadoes.  With values approaching 3+, this model would suggest the risk for significant tornadoes (EF2+) as the day matures, but note that this is one model run and we will have to see how the air mass adjusts after early morning storms.  Dewpoints of 68+F and veering winds with height would surely lend itself to rotating updrafts, but as the Storm Prediction Center (SPC) states in their overnight update, the main threat at this time appears to be wind gusts of 55+ mph in the strongest storms.

hrrr_tornado_tx_9
HRRR 8-hr forecast for the Significant Tornado Parameter valid at 1200 EST or 1100 CST on 01/02/17

One final threat to discuss is more heavy rain for much of the Gulf Coast today into tonight before this shifts northeast and up the East Coast into Tuesday.  As you can see from the HRRR radar reflectivity below, plenty of thunderstorms are possible and some training of cells may occur locally.  The WPC Day 1 QPF shows rainfall greater than 1″ for eastern TX into western LA tapering off a bit east, then another area of greater than 1.5″ to as much as 3″ from southeastern LA east to the FL panhandle and southern AL/GA.

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HRRR 9-hr forecast Radar Reflectivity valid at 1300 EST or 1200 CST on 01/02/17
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The Weather Prediction Center (WPC) 24-hr Day 1 Quantitative Precipitation Forecast (QPF) issued at 0832 UTC on 01/02/17

Mid-Atlantic Rain

Overnight, this current wave of precipitation has over-achieved slightly with 0.16″ recorded so far at BWI.  Expect occasional rain to continue through Tuesday with temperatures in the 40s to around 50.  Much colder weather is on the way later in the week.

Update on the potential East Coast winter storm

The jury is largely still out on this threat, but the 0000 UTC Euro is showing some light, non-issue snow late week, while the 0000 UTC GFS shows a significant snow event possible for the Mid-Atlantic next weekend (01/07-01/08).  More on this later.

Thanks for reading!