Thursday, December 7, 2017

First Snowfall of the Season Saturday

  It may not technically be winter yet (December 21st), but we're in for our first snowfall on Saturday.  Tuesday night's strong cold frontal passage has set us up for an extended stay of wintry, polar air.  This weekend, we'll see highs in the 30's and near 40° under our cold air mass, and this is one ingredient for the upcoming storm.

  Tuesday night's cold front is currently parked off the coast, and it'll act as a track for a low pressure system to ride along on Saturday.  A favorable setup in the upper atmosphere will allow for the evolution of the precipitation to build over our region throughout the day backing its way into eastern Pennsylvania.  The start of the snowfall will work from south to north throughout the morning hours with the southern-most portion of South Jersey being affected prior to sunrise, the Philadelphia metro area during the mid-morning (7-10am), and then North Jersey during the late morning/around noon.

  The snow will continue to fall throughout the day on Saturday at a general light to moderate, steady pace before ending from southwest to northeast during the evening.  Thanks to the majority of the snowfall occurring during the daylight hours and likely not falling at a continuous, heavy pace, treated road surfaces will mainly remain wet and slushy while most accumulation is confined to grassy and untreated surfaces. 

  The image below shows a representation of the widespread snowfall across NJ during the afternoon on Saturday from the NAM model.

Saturday Afternoon Radar from 18z NAM model run on 12/7/17 (Courtesy: tropicaltidbits.com)


  Onto my snow map...the immediate coastal, inland area will very likely be the jackpot area with decreasing totals as you move further west and northwest away from the center of the storm.  Immediate areas along the coast could potentially have some mixing issues due to marginal temperatures near the surface which could limit totals (not included on map).


My First Call Snow Map


Saturday, July 29, 2017

Dry, Comfortable Weather Follows Coastal Storm

  Friday night's coastal storm may have been a dud for our area, but it certainly wasn't for Southeast New Jersey where they racked up several inches of rainfall.  Below is a table from the Mt. Holly Office of the National Weather Service.  It shows high rain storm totals from the state's southern-most counties.

Rainfall totals reported to the National Weather Service

  Following the storm, a cool, and more importantly, dry air mass will flow into the region.  This is in the process of moving in, and we'll continue to see these conditions through the first half of next week.  Dew points will drop into the 50's for Sunday and Monday with highs near average into the 80's.

  Sunday will be the best weather day with wall to wall sunshine and highs into the low/mid-80's and no humidity issues.  The image below shows temperatures near 80° tomorrow afternoon on Saturday morning's run of the Hi-Res NAM.

Temperatures at 3pm Sunday afternoon (Courtesy of tropicaltidbits.com)

  Monday won't be much different from Sunday except with a slightly warmer high temperature into the mid- to upper-80's

  Finally, humidity gradually creeps back into the region come Tuesday and Wednesday when highs near 90°.  A cold front looks to approach the area to end the upcoming work week and bring the threat for showers and storms come Thursday/Friday.

Sunday, March 12, 2017

Details on the Pi Day Nor'easter

                Winter Storm Warnings for most of the state have been issued with Blizzard Watches into Northeast New Jersey and High Wind Watches along the coast.  Everything’s coming together for our first and probably last major winter storm threat of the season where a lot of places could actually double their current snowfall totals for the whole season.  For example, I’ve measured 11.5” for the winter at my station in Cinnaminson, and I would not be surprised at all if we approach and/or best that by Tuesday evening.

                Models have been consistently showing this system since the latter half of last week, and it looks like all the ingredients are coming together for it to come to fruition.  We’ll likely see the full platter of weather that comes along with a winter nor’easter in the Northeast: high winds, heavy snow, low visibility, coastal flooding, and beach erosion.

                At this time, the first flakes begin to fly from southwest to northeast between 9pm and midnight on Monday night and quickly pick up in intensity.  We’ll see the heaviest of the snowfall between midnight and 10am on Tuesday morning.  The precipitation should dwindle in intensity and taper off during the afternoon hours. 

                Below is an image of this afternoon’s Hi-Res NAM model run showing a depiction of conditions at 8am on Tuesday morning.

Image courtesy of tropicaltidbits.com

                Though it is more likely for the coast and areas within maybe 20-30 miles of the coast, we could see the rain/snow mixing line approach the I-95 corridor from Wilmington to Trenton.  In areas that change over to sleet/rain, even briefly, snow totals would only likely hit the lower end of forecasted ranges along with eating away at snow that has already fallen.  As of now, it looks like it should stay away from the Philadelphia metro area, but it’s a possibility Tuesday morning if the storm's center tracks too far west and closer to the coast.

                As of now, the heaviest banding of snow is still questionable in exact location but likely occurs somewhere between eastern Pennsylvania and just east of the I-95 corridor.  During the AM hours overnight and into Tuesday morning, we could be looking at snow rates upward of 1-3” per hour which would cause visibilities to drop to a ¼” – ½” mile.  A blizzard is officially defined as a time period of 3 hours or more in which 35mph+ winds cause blowing snow with visibility of ¼” or less, and we could see that in some parts of the state during the storm.

                Speaking of winds, we’ll be looking at upward of 40mph wind gusts inland toward the Philadelphia metro area and gusts to 60mph+ along the coast.  That, as stated earlier, would lead to blowing snow and reduced visibility.  Also, this will be a heavier, wet snow that’ll tend to stick to wires and tree branches, so high winds could lead to the possibility of downed branches and power outages.  Again, this threat increases as you get closer to the shore. 

                Finally, for the coastal towns, we’ll be looking at moderate flooding with constant, high onshore winds on Tuesday morning combined with a high tide.  This wind and wave action will also lead to beach erosion as is a trademark of all major nor’easters.  High winds and coastal flooding/erosion are the two effects of this system with the highest confidence.


                Below is my second call snow map.  I’ve upped totals across the board with a jackpot area in North Jersey where heavy banding and no threat of mixing will have the best chance of occurring.  Then, the I-95 corridor of South/Central Jersey is the secondary jackpot area where we could see some high totals under heavy banding but any mixing of sleet and rain could do a number on snow totals if the rain/snow line makes it that far inland.  Then, totals decrease as you approach the shore due to the higher chances of mixing.

My Second Call Snow Map

Saturday, March 11, 2017

Initial Thoughts on the Pi Day Nor'easter

                It took until March for us to see our first true major winter storm threat, and it’s looking very likely that it’ll come to fruition.  Following a January at 5.5° above average and a February at 8.5° above average, it started to seem like an early spring was here to stay, but it looks like Winter 2017 isn’t over yet like the calendar states.

                This is an early post to just state that a nor’easter is very much possible for late Monday night into Tuesday, and all counties but Cape May County are currently under a Winter Storm Watch.  Being 48+ hours from the start, the exact track of the system is unknown and variations of even 50 miles in track can have great consequences on the rain/snow line and snow totals.  If that rain/snow line comes inland, we could be looking at vast differences in snow totals for areas just a couple dozen miles apart.

                Below is an image of this afternoon’s GFS model run showing inland snow for Tuesday at 7am and some mixing issues along the NJ southern coast.

Image courtesy of tropicaltidbits.com

                This post is just meant to put in the back of your mind that there’s potential for a major snowstorm for early next week and to state the possibilities of what we could expect.  The only real certainties we’d be looking at would be gusty winds and coastal effects like coastal flooding and erosion.  Wind-wise, we’d likely be looking at 30+mph gusts inland and 40+mph gusts along the coast.

                Our uncertainties lie, as stated earlier, in the storm track.  As of now, the only model guidance that has an inland and wetter track is the NAM which is used mainly within 36-48 hours of the event, so it’s still out of its main range of use.  Everything else suggests a track further off the coast which would lead to more or all snow, except for the coast.  It’s also uncertain where the heaviest banding of snow will set up, but it’s likely anywhere from just east of the I-95 corridor to eastern Pennsylvania.

                As for timing, generally speaking we’re looking at the first flakes likely falling after nightfall on Monday night and the bulk of precipitation occurring overnight and into Tuesday morning.  Precipitation would then dwindle in intensity and pull away from southwest to northeast during the PM hours.


                I’ll have an updated post tomorrow with more details and revised snow map.  My current map shows a ‘jackpot’ area in North Jersey where there should be no threat of mixing and better snow ratios.  The second is a strip along the I-95 corridor which is likely the biggest unknown of the system with regard to mixing. 

My First Call Snow Map


Friday, September 2, 2016

Hermine's New Jersey Weekend Impact


  Hurricane Hermine amazingly became the first Florida landfalling hurricane in eleven years and is now on its way up the East Coast this weekend.  New Jersey has already clouded over today with Hermine's outer cloud bands, and the state will start feeling the first real impacts tomorrow (Saturday).  Coastal regions will of course see the biggest efects from Hermine, but depending on its track, inland areas could see a major impact as well.  Below is the National Hurricane Center's projected track for Hermine.  The blue outline is a Tropical Storm Warning from the Central Jersey Coast through Georgia.

Forecasted Track for Hermine from the NHC

  Tomorrow, New Jersey will start experiencing the first effects from Hermine as winds start picking up across the region.  We'll see mostly cloudy skies near the Philadelphia metro area while the shore could see its first outer rain bands from the cyclone.  Winds will increase throughout the day as scattered areas of rain threaten inland portions of the state.  After nightfall, these areas could see winds nearing 30mph+ while the coast sees tropical storm force winds (40-60mph+).  Below is a map of probability for tropical storm force winds (39mph+), showing a 50-70% chance across New Jersey.

Probability of Tropical Storm Force Winds from the NHC

  The worst of Hermine will show itself on Sunday and Monday as the system stalls off the coast due to high pressure to the northeast and slowly backs its way toward the coast in all likelihood.  This will lead to dangerous winds working more closely inland.  On top of this, coastal communities will potentially experience major coastal flooding, dangerous wave action, and severe beach erosion.  If this system tracks closer to the coast, as models are showing, areas closer to Philadelphia would likely experience winds gusting to tropical storm strength and periods of rainfall, heavy at times.

  As Tuesday comes around, it looks like Hermine will very slowly move away north and eastward, but breezy/windy conditions will likely remain, especially along the coast.  At this time though, there is uncertainty on how long the cyclone persists just off the coast.

Below would be the potential impacts if Hermine moves as modeled:
-Heavy rainfall (more along the coast with 4-6"...upward of 1-2" inland)
-High winds (Tropical Storm force along the coast...upward of 30mph+ inland)
-Severe beach erosion
-Coastal flooding
-Rough and high seas (modeled wave heights as high as 25-30 feet offshore)
-Power Outages

Reminders:
-Regardless if Hermine becomes a "Post Tropical Storm", it will have the same impact as a tropical storm!
-If it tracks even closer to the coast, coastal impacts would be even more devastating, and inland areas would receive more rainfall and higher winds
-If the system shifts eastward away from shore, inland areas will see minimal rainfall and breezy conditions while coastal areas would still see strong impacts
-Weekend plans for the shore should be re-considered if they haven't already

Thursday, January 21, 2016

Mid-Atlantic Blizzard 24 Hours Away

    Blizzard Watches are now posted from Philadelphia to New York City (likely to become warnings for most by tomorrow), while Blizzard Warnings encompass large areas of Maryland and northern Virginia.  We're now roughly 24 hours from go-time in South Jersey, where the first flakes begin falling toward midnight tomorrow night.  The storm likely lasts for around 24-30 hours across the area and will bring a combination of wet and heavy snow, high winds, and coastal flooding/erosion (to the coast).  Below is a general depiction of the storm, from this afternoon's GFS, off of the Virginia coast, as it throws heavy snow bands and winds into New Jersey for the first half of Saturday.

This afternoon's GFS shows possible blizzard conditions for the first half of Saturday (tropicaltidbits.com)


Timing
Start time: 9pm through midnight from south to north across South Jersey
Heaviest: Overnight hours through Saturday afternoon (snowfall rates of 1-3" per hour likely); thundersnow is also a possibility, so keep an ear out for it!
End time: Still a bit uncertain, but snow looks to generally fizzle out late Saturday night

Impacts
    Overall, not much has changed in general since my last post in regard to the overview of the storm, so I'll just talk about the general impacts of this weekend's nor'easter:
-We'll see a heavy, wet snow out of this system, which will be tough to shovel and also weigh down on tree limbs, power lines, etc.
-Winds will be another major threat, as winds likely gust inland to 40-50 mph (20-30 mph sustained) and gust to 60+ mph along the coast
-The combination of heavy/wet snow and wind (possible blizzard conditions) could cause power outages across the state
-Very strong onshore winds, high tides, and a full moon will all combine to produce major coastal flooding which could devastate beaches and coastal communities

Snow Map
    There are still question marks in regard to snow totals despite my map not changing much since my first call.  The shore still likely sees less due to the threat of some mixing issues Saturday morning/early afternoon due to the strong onshore flow from the ocean.  As of now, the 'jackpot' area looks to be a strip of the state from Southwest Jersey through Central Jersey.  North Jersey, at this time, is on the border of a strong gradient between light accumulations and being in on plow-able snow.  Any shift north or south (there have been some very recent trends north) could either put North Jersey at even less snowfall or in on the high accumulations shown for the southern half of the state.  I'll have a final update tomorrow if needed!  

My Second Call Snow Map




Wednesday, January 20, 2016

Major Mid-Atlantic Snowstorm Incoming

    We're now roughly 48 hours away from go-time in New Jersey with the impending winter storm that has been talked about for days now.  Models have shown remarkable consistency with this storm for several days now, and as its energy begins its descent into the Southeast, they continue to show a major, even possibly historic, Mid-Atlantic nor'easter for the weekend.  The National Weather Service in Baltimore posted Winter Storm and Blizzard Watches earlier all across Maryland and northern Virginia, and the Mount Holly office followed with their own group of Winter Storm Watches for our area.  I wouldn't be surprised if portions of New Jersey saw Blizzard Watches/Warnings as well over the next 48 hours.  Below is a glimpse at what the GFS depicts as our storm on Saturday.

GFS model run depicting general conditions Saturday midday (tropicaltidbits.com)

Overview
    As stated in my post yesterday, energy that worked its way into the Pacific Northwest last night is currently diving south through the Plains states.  The system will then round toward the east as it descends into the Southeast.  Then it move northeast and exits the east coast around the Outer Banks of North Carolina Friday night.  During this time, the low pressure system will strengthen, bringing an onslaught of moisture (mainly in the form of snow) and high winds to the Mid-Atlantic, with the bulls-eye looking to set up over Maryland and northern Virginia.

GFS model run showing high winds across coastal and southern NJ Saturday (tropicaltidbits.com)

Impacts and Estimated Timing
    We'll likely start seeing the first flakes fly in New Jersey from south to north after 7pm on Friday evening.  Snow will quickly become heavier overnight and into Saturday afternoon, which is the time period where we likely see the heaviest snowfall rates and even the possibility of thundersnow.  Though I believe areas toward Philadelphia remain all snow for the storm, the mixing line will have to be watched, particularly on Saturday morning.  As the low continues to approach offshore, winds will reach a peak intensity, with inland areas seeing 20-35 mph sustained winds and gusts to 40-50 mph, while coastal areas likely see gusts of strong tropical storm strength (upward of 60+ mph).  It then looks like snow begins to fizzle out late Saturday or early Sunday morning.

    The snowfall with this system is going to be of the wet variety, which is good for snowballs but bad for shoveling.  This, combined with high winds, will cause the risk of power outages, especially for areas closer to the shore where winds will be at a maximum.  The wind and heavy snow combination with this storm is why I wouldn't be surprised if we saw Blizzard Watches/Warnings posted at some point.  Furthermore, for coastal areas, the combination of strong onshore winds, high tides, and a full moon will likely cause major coastal flooding and beach erosion.  This is a part of the storm that has been relatively unmentioned, and some spots are even forecasted to see tides rival, or possibly exceed, those seen during Hurricane Sandy!

First Call Snow Map
    Finally, at this time, the stripe of highest snow amounts looks to run from Southwest Jersey through Central Jersey, where we could see upward of 12-18" of snowfall.  Along the coast in South Jersey, things are more questionable due to the possibility of sleet and rain mixing in, so I left that area lower for now at 6-12" (higher if it remains all snow).  As you approach North Jersey, amounts likely lower as you move away from where the heaviest bands of snow look to set up.  Then, there will likely be a sharp cutoff in heavy snow amounts to lighter accumulations along the Northwest Jersey/New York border.  Below is my first call for this weekend's snowstorm, and I'll post an updated map and blog with any new details tomorrow!

My First Call Snow Map