Sandy

Here is my blog on tornadotitans.com, whom I work for part time.

http://www.tornadotitans.com/hurricane-sandy-to-impact-northeast/

More later.

Thursday Morning Sandy Update

Hurricane Sandy rapidly gained strength last and also made a second landfall over Eastern Cuba.  Winds were sustained at 110 MPH and the Barometric Pressure was 957 mb (28.26 in).  So far the forecast is on track.  It will not be until later tonight or tomorrow before the track will lock in.  There is still some divergence from global weather models but they all are capturing the same basic pattern evolution.  The block over the Atlantic will not allow Sandy to escape out to sea without some sort impact in the Northeast. First lets start with the National Hurricane Center forecast and cone of uncertainty.

I added the Blue line (wind and rain impacts) and Red (potential snow event)

The environment in front of Sandy is favorable for strengthening, although it may not be reflected in the maximum wind speed.  Instead it is more likely that Sandy spreads its wind field out several hundred miles.  For a densely populated region like the Mid Atlantic and New England this is not a good thing.  The widespread wind field will send an intense storm surge onshore for several days.  There is also a full moon on Monday which means tides will already be higher regardless of whether Sandy roars in or not (it will in some form).  Here is Sandy are a few satellite images of Sandy.

Sandy can still get better organized.  Once in the Bahama's Sandy will begin to grow  as a storm

IR image.  Sandy has all the energy on its Northern edge to consolidate  

So why is it that this system cannot escape out to sea?  The atmosphere behaves as a fluid.  Imagine a rock in a river.  It "blocks" the water from taking a straight path so the river diverts around the rock (or any barrier).  In this case the atmosphere is blocked by High pressure near Greenland.  The high pressure sets up a large ridge in the Atlantic.  Meanwhile, a strong cold front is marching east from the Midwest.  Sandy is moving to north in between these two systems at the moment.  The block won't move; in fact the latest NAO forecast is negative for the duration of the forecast period.  In a negative NAO high pressure is dominant near Greenland and thus the block will not break down.  So that leaves the cold front to capture Sandy.

Observed and forecast NAO (North Atlantic Oscillation)

The trough digging in the Midwest and Great Lakes is very strong.  This will allow the trough to take a "negative" tilt.  Here is the North American Model 500 mb (mid level of atmosphere pressure decreases with height.  Surface is around 1015 mb).  The blue line indicates the negative tilt.

06/25 NAM 500 mb vorticity map

Sandy is likely to try and turn out to the northeast, but will be caught by this trough and will resume a NW and eventually WNW track.  The question is rapidly becoming not if we get hit, but how bad we get hit.  Since I do not believe Sandy can escape out to sea, the question is whether the storm makes a direct hit on Southern New England or the Mid Atlantic.  I lean towards New England because it will be hard for any system to bend into the Mid Atlantic this big and strong.  Although New York City is a compromise it frightens me to think what a warm tropical system, transitioning to extra-tropical all while interacting with an Arctic front could do to New England and NYC with a direct hit.  I will leave everyone with the HPC 6 day forecast.  After today if the trends hold impact maps and timing will be drawn up.  I'll have a post on www.tornadotitans.com tomorrow which I will link here.

Morning Thoughts

After reviewing the overnight computer model data there isn't much to add for Tropical Storm Sandy.  Sandy will become a Hurricane today before striking Jamaica and then Cuba.  The interaction with Cuba will not take as great a toll on Sandy as it has on previous cyclones due to a S-N movement, rather than WNW along the island.  That still leaves us in the Bahama's with a Hurricane tomorrow night.  Very impressed with the energy Sandy has to work with and its slow organization.  Here is Sandy on the water vapor this morning.

Sandy is on left; Tony is weak system in top right

All of this energy will interact with a cold front moving east in the day 5-6 range.  Even if Sandy escapes out to sea a Nor'Easter will develop along the coast and would be intense.  I'm not a forecaster that likes to change with every model run, however guidance has slowly trended to a Northeast landfall of Sandy.  The entire Eastern Seaboard will feel the affects of Sandy.  South Florida has just been placed under a Tropical Storm Watch as Sandy will have such a large circulation.  A loaded Tropical system interacting with a cold arctic air mass with a block near Greenland...wild times in the weather world.  Best advice is to have a plan ready in the growing likelihood Sandy slams into the Northeast.

Finally while the American model insists on an out to sea track (though it wants to develop a coastal low; it just doesn't show it yet) many of its ensemble members (same physics, slightly different initial conditions) shows most members re curving back into New England.  This is a trend west so we'll see if it continues.

Image courtesy Dr. Ryan Maue Weatherbell

We'll get a warm up Friday and Saturday with temps near 70.  This may linger into Sunday.  In the near term today is Mostly cloudy with a high around 60.  Showers and fog will burn off slowly.  Northern MA and points north will see the most sun today.  Tomorrow is mostly sunny for the majority of region.  Next rain chance is with Sandy/Sandy's daughter.  I wonder if the Weather Channel is going to name Sandy's snowstorm.  That's right while New England gets whipped with heavy rain and wind other portions of the Northeast (western NY, PA, WV) will be having a raging snowstorm.

Tropical Storm Sandy potential New England Impacts

The meteorology world has been buzzing about a potential storm system impacting the northeast next Monday, Tuesday, and Wednesday.  Most forecasters have tried to hold off issuing any dire announcements or declarations about this system because it is just too early to be sure of any specifics.  However there has been too much consistency from some of our weather models and quite frankly the solutions of several of these models are downright scary.  Rather than alarm anyone I feel tonight is a good time to tell the public what may be coming so we can keep an eye on it.  Here is a breakdown that will be somewhat technical but this will be the first of potentially many blogs on this system.

Overview
Tropical Storm Sandy developed yesterday afternoon in the western Caribbean Sea.  Sandy is forecast to strengthen as she heads north over Jamaica, then Cuba, and into the Bahama's.  Here is the National Hurricane Center forecast track

Hurricane Warnings for Jamaica, Cuba

 Up until Friday at 2 PM most of the computer guidance is in remarkable agreement about this.  In fact, there is roughly a 90% chance that Sandy is a hurricane in the Bahama's on Thursday evening.  For my meteorology friends here are the relative measure of predictability from the 00z/23 model suite.  For causal readers I hope you will be able to read this chart.

The ridge over the east is highly predicted; the diving trough is in the Midwest is not.

In terms of the computer models some of the global guidance (NOGAPS, EURO) and ensembles (EURO, GFS) are indicating that Sandy will try to come north and not escape out to sea, which is favored for October tropical cyclones. However a developing atmospheric block will eject the system to the northwest.  There is also a very cold air mass diving south into the Midwest and southeast from Canada.  Here is the 18/23 GFS 2 m temperature anomaly charts courtesy of Dr. Ryan Maue of weatherbell.com at several points in the next week to illustrate the coming cold.  Note that anomaly charts measure the departure from average so negative anomalies are colder than average and vice versa.

Tuesday 2 PM

Thursday 2 PM

Monday 2 PM

This is a major temperature clash so there is already a strong baroclinic zone forecast, with or without a tropical system.  A big question is how "deep" the trough will dig into the south.  A friend of mine who works for the National Weather Service down south noted that there have been some unusually strong trough's that have dug deep this year.  The deeper the trough the more likely it is Sandy is captured and ejected into New England.  

Related to the trough is a developing block in the Atlantic Ocean.  This "omega" block will not allow Sandy to escape out to sea.  Some models do not have this block being as strong and thus allow the system to meander further out to sea.  However the American Global Forecast System model (GFS) has the system eventually finding its way back towards Southern New England.  From a synoptic and physical standpoint I cannot see Sandy escaping out to sea.  I will not predict strength or impacts this early, nor will I pick a model .  Track is important but this will be a large system.  For my meteorology friends I am leaning towards a hybrid of Sandy impacting the Northeast early next week.  Hopefully the EURO is wrong.

What does this mean?

It means its time to make an emergency plan.  Make sure you have working flashlights, batteries, radio's, water, non perishable foods.  Clear the gutters of leaves on roofs.  If you live near the coast and make preparations for winter storms its a good time to think about when to secure property.  This could be all hype; if that's the case no lives will be lost.  This also could be the real deal, a storm of this magnitude hasn't occurred in generations.  

For what its worth here is the seven day forecast from the Hydrometeorological Prediction Center (HPC), one of the best government meteorological agencies.

Updates will be made each day.  Questions comments tweet me @zgreenwx .  

Temporary "Cool Down" Tomorrow

A back door cold front (BDCF) is currently stalled out in Eastern Massachusetts creating a sharp temperature divide in New England.  A BDCF moves from the east to west instead of the typical west to east motion.  These are notoriously difficult to forecast; my professor of meteorology at Umass-Lowell, Dr. Frank Colby, gave a great presentation on the topic my freshman year.  He showed the differences between what the computer models were forecasting to happen and what actually happened.  That is why some of our weather has been "unexpected" this week.  Take last night...severe thunderstorms ripped across Southern NH and Northern MA.  Click here to read storm reports.  Severe hail ( > 1 inch diameter) was reported for the first time in the month of March since at least 1950, when record keeping began (h/t to Climate Data Center).  Some asked me if that was really lightning that was occurring last night when there were clear skies.  The answer is yes and that is an indication of the strength of these thunderstorms.  In fact the storms exhibited a tornado signature for a time, although due to a temperature of 53 one did not form.  Thankfully I see none of that in the next 5 days or so.

NOAA-NCEP real time temperatures, click to enlarge (will not be blurry)

10 Meter Wind (~30 ft to eliminate friction effects)

Notice the way the contours sharply cut as one nears the coast in the temperature chart and notice the wind barbs are moving in two different directions in western and eastern MA.  That shows where the cold front is right now.  It will make its way into Central MA, RI and eastern CT tonight.  This will drop temperatures into the upper 40's for awhile before rebounding into the lower 50's tomorrow afternoon when the sky is less cloudy.  On Friday a typical cold front will push across the region and this will have two effects.  First temperatures will be raw and showers and even a thunderstorm or two will develop as the energy moves past.  Secondly, it will help move an area of high pressure offshore and flip winds back to the west and southwest.  That means warm temperatures will return this weekend and downright HOT temperatures early next week.  It hit 80 degrees today in Chicago and that will be moving east.

Quick Forecast...
Tonight-             Clouds Increasing lows upper 30's
Tomorrow-        Cloudy start gradually clearing, highs in low 50's
Thursday Night- Increasing Clounds, chance of shower, lows upper 30's
Friday-              Scattered showers, possible thunder, highs in low 50's inland, 40's coast
Friday Night-     Isolated showers, low around 40
Saturday-          Clearing skies, Highs upper 60's
Sunday-            Sunny, Highs lower 70's

Finally I do think we will approach 80 on either Tuesday or Wednesday next week (some towns both).  It also appears another back door cold front wants to develop at that time frame.  This is a long way out and subject to change however a repeat of last nights severe weather outbreak cannot be ruled out.  Despite the record warm winter and lack of snowfall in the United States snow cover in the Northern Hemisphere is still running above average.  With the cold air still locked to the north, any intrusion south into these warm temperatures is bound to fire more severe weather.  Thunderstorms ahead of regular cold fronts will need to be monitored as well. This is something to keep in mind as we enjoy the warm March.  Thanks for reading!

Warm Weather on the Way

500 mb vorticity  map (mid level of atmosphere) shows cut off low in SW, trough exiting  NE

The unseasonably warm weather will continue into middle to late March.  After approaching 70 on Thursday we cooled down yesterday and today.  I was expecting a quick burst of snow yesterday but I did not expect 3-6 inches north of Boston.  Here you can see the totals from last nights snow event.  That is behind us now as the energy is moving offshore of Cape Cod.  High pressure will build into the region and the warming trend will begin.  We have to get through today first as temperatures will only reach 40 or so.  Temperatures tonight will drop into the upper 20's before climbing into the upper 50's tomorrow.  The south coast will be held to the upper 40's due to  a southerly wind off the water.

The energy in Arizona and New Mexico has cut off from the general flow.  This will slowly move northeastward toward the Great Lakes.  Areas in the path of this low will see some heavy rainfall over the next several days.  This will help pull warm air into the Northeast.  High pressure will move offshore locking in a Southwesterly flow and setting up some of the warmest March weather in the last 100-125 years (that is how long records go back in the Northeast).  The lack of snow cover across the United States is not cooling off these air masses as they move across the country so we have more potential for higher temperatures.  (Hat tip to Eric Fisher of The Weather Channel).

Sunday- Highs Upper 50's inland, upper 40's coast DRY
Monday- Highs middle to upper 60's DRY Some exceed 70
Tuesday- Highs middle 60's, clouds increasing Rain likely (from the cut off)
Wednesday-Highs upper 50's windy

This looks to continue for the foreseeable meteorological future...(~2 weeks).  Enjoy it while we have it.

Wintry Precip Overnight, Heavy Rain Tomorrow

National NWS radar image

A powerful storm system sweeping across the United States will impact New England overnight.  This is the same system responsible for producing 53 tornadoes (and counting) across the Ohio Valley and the Deep South.  The storm will be weaker but there will still be some impacts around the region.  First off, a Winter Weather Advisory has been issued by the National Weather Service in the areas shaded below.  Image courtesy of NOAA

WWA txt here

Areas south of the Mass Pike will see very little snow and mainly a mixture of rain and sleet.  A warm front is surging north which will turn all precip over to rain by 3 am in the lower elevations.  Higher elevations will also turn over by 6 am.  The roads will be slick overnight so be careful on your way home.   Saturday will be warm, with highs near 50.  There will be a chance of a thunderstorm with this system as it moves through.  There will be no severe weather or tornadoes, but it will not be surprising to hear a few rumbles of thunder.  Most of the rain will be gone by 3-5 PM and skies will begin to clear for tomorrow night.

NOAA rainfall forecast for next 24 hrs

Next week is half winter/half spring.  On Sunday, Monday, and Tuesday it will feel more like winter, especially Monday and Tuesday when high temperatures will only be in the 30's.  The sun will be out from time to time.  One will notice a dramatic difference from Tuesday to Wednesday.  A subtropical ridge is looking to build in the Southwest Atlantic and funnel warm spring like weather into the northeast.  Highs right now look to climb in the upper 50's-low 60's.    This is the extended range of the forecast, but things are looking good.  Remember, if the pattern of the last few months remains in place, the nice long stretches of good weather will get progressively warmer and warmer as the sun continues to trek northward. 

Storm Prediction Center daily storm reports (so far)

Finally, thoughts and prayers to all those affected by the tornadoes this week.  Spring time is the beginning of tornado season due to the mixing of warm tropical air with cold arctic air.  This is a tornado outbreak to remember and its going to continue into the night.  Let us hope no more lives will be lost and all warnings are heeded.   Here you can view damage from today's storms.