Winter Storm Watches Posted for Wednesday

A coastal storm will bring accumulating snow Southern New England Wednesday into Wednesday night/early Thursday morning.  Without any true Arctic air locked in there will be a fine line between rain/snow.  As it stand now this line should work back towards 495, but will struggle to get much further.  The Cape, Southern RI, and Coastal CT will likely be shut out.

NWS Boston Headlines

General Overview

Low pressure forms in the Gulf of Mexico tomorrow afternoon

WPC 1 PM surface forecast Tuesday

By Wednesday AM the system will begin to deepen off the North Carolina coast.  This storm will not "bomb" on its way up the coast nor will it phase with another low diving through the Midwest; the pattern is moving too fast.  

WPC 7 am surface forecast Wednesday

There is some relatively warm water off the East Coast so that will enable some strengthening 

OSPO NOAA Sea Surface Temperatures (C)

More importantly this system will develop in the Gulf meaning it will bring lots of tropical moisture with it.  Here are the 3 day precipitation totals, ending Thanksgiving night at 7 PM

WPC 3 day precipitation forecast, valid through Thursday 7 PM

Timing and Impacts

Precipitation will begin after the Morning Rush, but before lunchtime on Wednesday.  Temperature profiles are not ideal as mid level temperatures are initially warm.  This means many places begin as rain, but the colder spots will begin as the dreaded freezing rain.  As the intensity of the precipitation increases interior locations will flip to snow.  This looks to happen shortly after noontime.

Around 4-5 PM, as the sun sets, the snow should really begin to stick.  The heaviest is Wednesday PM.  So how much snow

Guidance is suggesting a possibility of more snow.  I may bring totals up closer to 495/95; it will depend on the temperatures.  

On Thanksgiving morning this should be pulling away.  The football games will be interesting on Thursday morning.  Temperatures will be in the low 30's with 15-25 mph wind gusts.  

12 years ago 6-10 inches of snow fell the day before Thanksgiving cancelling school for the day

NWS Boston snowfall map 11/27/2002

We also woke up to snow Thanksgiving morning 2005, though not as much and it warmed up nicely that day.

NWS Boston 11/24/2005 snowfall map

Its also been 65 (2003, 2007, 2009) or pouring with rain (2004, 2006).  

Questions? twitter @zgreenwx .

Significant Flood Situation in SE MA Tonight

There have been reports of 3-5" of rain in the New Bedford area already today as Hurricane Arthur races Northeast towards the Canadian Maritime.  An additional 3-6+ inches of rain is likely in Bristol and Plymouth counties which will lead to a significant flooding event in that portion of the state.  

NWS Northeast Regional Radar

That band of yellow and red along the S MA coast has been nearly stationary all afternoon.  Flash Flood Watches are up for most of the state, with warnings in effect for the South Coast

NWS Boston Hazards

Tropical Storm Warnings remain in effect for the Cape and Islands with a Hurricane Warning for the waters offshore.  Here is the latest advisory from the Hurricane Center

NHC 2 PM Hurricane Arthur Advisory

The winds are not going to be a major deal outside of the Cape, but a few gusts over Tropical Storm force are possible across Eastern MA.  Gusts up to 60 are possible in Nantucket/Outer Cape.  The Upper Cape/Vineyard are looking at 45-55 in general.  The major story will be the rain.  The WPC has issued a precipitation discussion for Southeast New England and it is a not a pretty outlook

WPC MPD 

Basically a front is stalled out in Eastern MA.  While this front contributed to keeping Arthur offshore, it is setting the stage for a flood event.  Here is the local surface analysis

WPC 2 PM Surface Analysis

As I type this the NWS has upgraded to Major Flood Emergency in New Bedford.  Flash flooding is likely in other areas as the rainfall rates increase.  Do not drive through a flooded roadway.  The rain ends around midnight west to east.  Rest of the weekend is great.

-Zack Green

Hurricane Arthur Will Bring Rain to SNE

We officially have our first Hurricane of the 2014 North Atlantic Hurricane Season.  Arthur has been upgraded by the National Hurricane Center as of 5 am.  The storm will still track south and east of the Cape, but some heavy rain is expected tomorrow.  Tropical Storm force winds are likely on the Outer Cape/Islands. 

Overview
The 5 AM advisory/track/warnings

5 am NHC Advisory Hurricane Arthur

A cold front is slowly moving east towards the coast.

WPC 5 am Surface Analysis

The line of thunderstorms died out as it entered Worcester County yesterday.  The same areas that saw some severe weather and flash flooding are expected to again today. 

SPC Day 1 Outlook

Heavy rain, gusty winds, and frequent lightning will be the primary hazards but hail and a brief tornado are not impossible back in NY/VT.  In anticipation of heavy rain there are flash flood watches up for many places in the interior Northeast (in green). 

NWS Eastern Region HQ hazards Page

For today there will be rounds of showers/thunderstorms throughout SNE.  Some places will stay completely dry, others will be hit multiple times.  Keep an eye to the sky.  Boston should be ok for the fireworks tonight.

Friday
Any overnight rain ends early enough that the first half of Friday is dry, albeit muggy.  Around early afternoon the rain from Arthur should arrive.

06z NAM hires Simulated Radar 2 PM Fri (image Weatherbell)

The heaviest winds are from about 5 PM-3 AM for SE MA.  I can't rule out a few stronger gusts in Central MA/E CT/N RI if a strong rain band works north but this is a low probability.  Here is the 3 day rain forecast from the WPC

WPC 3-day rainfall outlook

Worcester and Boston are looking at ~1.75", with  ~2" in Providence, Brockton, ~2.5 in Plymouth, Hyannis.  3"+ likely Outer Cape/Islands.  This is not a major storm for New England, in fact many recent Nor'Easters have had a greater impact.  However it is distruptive.  The good news is after this clears high pressure builds for the rest of the weekend. 

-Zack Green

Tropical Storm Arthur Update (UPDATE 206 PM)

A severe thunderstorm watch has been posted for much of Southern New England

STSW 386 (SPC)

Most of the thunderstorm activity will be north and west of Hartford-Worcester-Portsmouth.  Here is the short range high resolution computer simulation for 4 PM

16z HRRR simulated radar valid 4 PM (image weatherbell)

The action should wane this evening before firing back up tomorrow.  Our buddy Arthur is looking better this afternoon

NOAA  GOES_Tropical Floater visible satellite 145 PM

He may be a Hurricane by the end of the day.  The latest EURO computer model just arrived and is showing significant rainfall in Eastern New England.  More tonight/tomorrow morning.
________________________________________________________________________________
Good Morning.  As expected Tropical Depression 1 was named Tropical Storm Arthur yesterday at 11 am.  Since that time the pressure has fallen and winds have increased.  The storm is still fighting dry air

GOES_floater Water Vapor Loop (NOAA)

Notice the dark colors north of the system.  That is dry air that is killing some of the thunderstorm growth in the center of the storm.  We do see thunderstorms making a comeback in more recent images.

NWS Southeast Regional Radar

The National Hurricane Center has been consistent with the track.  It should pass either right over or just to the east of the Outer Banks before racing south and east of the Cape

NHC Forecast track/intensity, watches & warnings

Most guidance shifted slightly west overnight.  It still appears rounds of tropical downpours are likely tonight through Friday with a chance for stronger bands later Friday night as Arthur passes.  As of now I recommend keeping plans North and West of the Pike.  I would be prepared to deal with Tropical Storm conditions in SE MA/RI.  A clear picture will emerge today as to where any potential heavy rain sets up. 

Here is the WPC 5-day outlook

WPC 5 day precip outlook

It does appear the heaviest rains will be in the Mid-Atlantic and up through Albany as well as the Cape/Islands.

WPC Surface Forecast Thursday 8 PM

Again tropical systems are difficult for the models to handle.  There is a 10-20% chance much of Southern New England sees tropical storm force winds which could bring down some trees/power lines.  That's a 80-90% chance it won't happen, but something to keep an eye on. 

Have a good day
-Zack

1st Tropical System to Impact July 4th Plans

A tropical depression has formed off the Florida coast and is forecast to strengthen into a Tropical Storm/Hurricane by the end of the week.  It will impact the 4th of July holiday up and down the East Coast.

NOAA GOES-East IR rainbow satellite loop

Currently winds are 35 mph but the storm is expected to be named Arthur later today

NHC 5 am advisory/5 day track

By Friday Night/Saturday morning a hurricane may be passing south and east of the Cape.  Right now the storm is not moving much.  It will begin to move in response to a cold front pushing east out of the Midwest

5 am Surface Analysis (WPC)

This cold front/tropical interaction will create interesting weather for the next several days.  First of all, severe weather is likely in parts of the Northeast tomorrow, though not for Southeastern New England

SPC Day 2 Severe Weather Outlook

Overnight Wednesday into Thursday is when Southern New England may get into the severe action.  Of greater concern is the potential interaction between the tropical system and this front.  The NAM low res has precipitable water amounts of 2"

06z NAM op precipitable water Thurs 11 am (image weatherbell)

As of now it appears at least an inch of rain will fall across much of the area in the next 5 days.  There will be jackpot areas of much more rain but its tough to tell where these will be right now.

WPC 5 day precip forecast

Guidance will help today as the storm gets a bit stronger and starts to move slowly northward.   It is important to remember that sea surface temperatures are above normal along the east coast.  This system is small so strengthening is likely.  While unlikely, a more westerly track would have big time implications for coastal Southern New England.  Even with a track south and east high waves and rip currents will effect beaches this weekend.

OSPO SSTA 6.30.14

With a weak El Nino likely to develop this summer, most of the tropical action will be in close to the United States.  One can see the Eastern Gulf and SW-Central Atlantic as prime areas for development this season.  More to come. 

Mother's Day Weekend Forecast

It looks like a brief warm up is on the way for the weekend.  Enjoy it!  Here is the forecast for the rest of the week/weekend.

Short Term Forecast
Temperatures this afternoon are generally in the upper 50's.  However when there are breaks of sun and the wind relaxes temperatures jump into the mid 60's

3 PM 2 m temperatures (image Weatherbell)

Here is the current regional radar loop

NWS Northeast Regional Radar 428 PM

Here is the visible satellite

GOES_East Visible Satellite 430 PM (image NOAA)

These clouds and showers are driven by differences in ground temperature and cold air aloft.  Check the surface chart and notice flow is out of Northwest around high pressure in Ontario/Quebec

WPC Surface Analysis 2 PM

Also notice the front draped horizontally across the US.  This front will slowly push north and east as a trough in the west digs.  This will allow for some severe weather in the Central US over the next several days.  In the meantime tonight clouds will dissipate tonight so temperatures will fall into the upper 30's/low 40's.  

Wednesday

High pressure will remain in control tomorrow.  Winds will be lighter (except near coast).  Expect mid 60's in general with a few locations near 70.  It will be cooler at the coast.

Thursday

Rain breaks out in SW New England but will struggle to reach SE New England.  Temperatures in mid 60s with partly cloudy skies

Friday

Slight chance of showers in Western/Central MA/CT but SE MA and RI looks mostly dry.  Temps in the low 60s

Weekend Forecast

Warm front will finally move through Southern New England Friday night.  Some left over precipitation likely Saturday AM but it will clear and the sun will break out in the PM.  Temperatures rise into mid 70s.  

WPC Saturday 8 am Surface Forecast

The cold front trailing through the Ohio Valley will set off some showers/thunderstorms Saturday night into Sunday morning.  However I do not expect this to be widespread in Southern New England.  Looks heavier in Central/Northern New England.  Temperatures will rise into the low 70's.  There could be a light shower in the PM.

I teased the potential for 80 on Monday.  Its 6 days away so this could change, but I do like another warm day Monday.  

Enjoy it, temperatures look to return to below normal next week with more rain.

CPC 8-14 day temp outlook

I will fine tune the weekend forecast Thursday.  Have a great night.

-Zack Green

Hurricane Season A Month Away

In my opinion the worst forecast I have ever made was for the 2013 Atlantic Hurricane Season (some of you may debate that).  I looked at the Sea Surface Temperature Anomalies of March and April, the persistent cold of March 2013 and saw similarities to 1954 and 2005.  I tossed out 1993 as an analog which was probably the best match in hindsight.  Here is my post from March 2013.  Lessons were learned on my part namely trust the data and do not rush a forecast just to be first.

NHC 2013 Atlantic Tropical Cyclone Tracks

2013 forecast

20-25 named storms

8-12 hurricanes

4-6 major with 1 cat 5

Actual 2013

13 named storms

2 Hurricanes

0 Major Hurricanes

I am glad the United States was sparred and everyone got a year to relax.  I am also disappointed in myself for ignoring the data I've been collecting since my Sr year at Umass-Lowell.  Instead of going big with a 20-25 year I would have pulled back to 11-15 named storms, 4-8 hurricanes, and 2-4 major.  I still would have been wrong but I would have been closer.  With that said here are my thoughts for 2014

2014 Atlantic Hurricane Season

By most model and observational accounts an El Nino will develop during the summer.  See the model plume graph

Intermational Research Institute/CPC/Columbia U ENSO model plume 

The El Nino threshold is 0.5.  Here is the observational evidence of an oncoming warm event

NOAA/OSPO Sea Surface Temperature Anomaly 5/1/2014

For comparison lets look at this time a year ago, with no El Nino/La Nina coming on

NOAA/OSPO Sea Surface Temperature Anomaly 5/2/2013

Notice the colder blues off of NW South America in 2013.  That shows up welling of nutrient rich water which indicates stronger trade winds.  That does not allow the warm water of the Western Pacific warm pool to slosh east.  In 2014 the trade winds are weaker and the warm water is moving eastward along the equator.  The warm pool south of Alaska in 2013 is also what helped cause the record cold May of 2013 in the Midwest as it helped build a ridge in the Northeast Pacific.  That in turn led to a trough downstream that had an Arctic connection.  

Now that we have solid evidence that a warm event will occur, its time to find similar years.  There was a lot of hysteria over the past few months about a Super El Nino this year.  That of course is possible; never rule anything completely out in meteorology.  However it was questionable to those who study Pacific Ocean dynamics for two main reasons.  First of all El Nino prediction is weakest in late winter/early spring.  The model cannot handle the equinox for some reason and forecasts tend to be wild.  That didn't stop many people from comparing this event to the infamous 1997/98 Super El Nino.  Secondly the Pacific is in an overall cool phase.  Nearly all Super Nino's have occurred during the warm phase.  

El Nino AMO/PDO averages North Atlantic Hurricane Season (personal research)

The Atlantic warm phase is at its weakest point in about 20 years.  It remains to be seen if this is the midpoint of this cycle or if the downward turn has begun.  There was a similar dip in the late 40's before the AMO rebounded for another 15-20 years.  The PDO flipped for good around 2007, but it was cool from 98-02 following the 97/98 Super Nino event.  So my best two matches are 2002 and 2009.

Here is 2002 Sea Surface Anomaly

NOAA/OSPO Sea Surface Temperature Anomaly 5/3/2002 

Here is the 2002 tracks

NHC 2002 Atlantic Tropical Cyclone Tracks

Here is 2009 SSTA

NOAA/OSPO Sea Surface Temperature Anomaly 5/4/2009

And here are the 2009 tropical cyclone tracks

NHC 2009 Atlantic Tropical Cyclone Tracks

2002 at the moment looks like a better blend.  Statistically speaking we should expect 10 TS, 6 H, and 3 MH in 2014 with an ACE of around 100.  Looking closer to 2002

12 TS

4 H

2 MH

65 ACE

and 2009

9 TS

3 H

2 MH

51 ACE

Blending the stats & analogs my forecast is

11-13 TS

3-5 H

2-3 MH

60-80 ACE

It only takes one storm to make a hurricane season memorable.  With the far east Atlantic looking unfavorable for development everyone needs to watch closely for systems developing near the United States.  Don't let 2013 or the oncoming El Nino lull you into a false sense of security.  Irene was a weakening Tropical Storm and I was without power for 4.5 days.  Imagine a Category 2 Hurricane Southern New England?  

Have a good day

Zack Green