Respite Coming..But so is More Rain

 7:30 PM Update-

Unfortunately, the break in the rain I talked about 90 minutes ago below is filling in already. This means even more rain than I was expecting in the last post. That in turn means more flooding. Certainly not good news at all.

Wednesday- 6PM

For the past few hours, very heavy rain has been falling across our area. Major flooding is going on nearby, with some flooding also occurring within the Grotonweather area. Flash Flood Warnings are widespread across Central New York and Pennsylvania with numerous Flash Flood Emergencies and State of Emergencies in effect for neighboring counties. This will easily end up as the most destructive flood event in the region since the deadly June 2006 flood, which mostly missed the Grotonweather area, and may surpass that in some areas.

For all the bad, there is a little glimmer of good. The current band of heavy rain is quickly lifting to the north. By 7pm, we should be in another respite with just a few showers around. THIS DOES NOT MEAN THE FLOOD THREAT WILL DIMINISH JUST BECAUSE IT IS NOT RAINING. Runoff will continue to inflate streams, which will continue to rise and create major flooding in areas. The flooding just will not be getting rapidly worse.

Until the next batch of rain, that is. Models are indicating yet another batch of heavy rain streaming northward from the Mid-Atlantic. This rain should arrive here well after dark and during the overnight hours, making it particularly dangerous. Flooding dangers at night are enhanced because it is hard to see flood waters and impossible to tell how deep they may be (not that you really can in the day time either).

This is what the HRRR (high-res rapid refresh) model predicts the radar to look like at 11pm tonight. It looks a lot like what the radar has looked like most of the day, meaning more heavy rain will be impacting our area tonight.

If you have to travel tonight: take it slow, DEFINITELY DO NOT ATTEMPT TO CROSS A FLOODED ROADWAY, and be aware that many roads south and east of our area and some roads in our area are closed. For example, every road in Chenango County has been closed. States of Emergency, in addition to Chenango County, are in effect for Broome, Otsego, and Bradfield, PA, to name a couple.

If you live near a creek, stream, river, or drainage area: Chances are you already have an excess amount of water rushing through many times the normal amounts. Additional rain could increase the amount of water attempting to flow through there. Be prepared to have to leave your home at any time, even in the middle of the night. Keep an eye on the water levels as much as you can. If you have a weather radio, keep it on tonight. There are also lots of website that will send updates to your phone...you may want to sign up.

This remains a very dangerous situation, even while the rain lets up for a while. Please, please be safe. Continue to check the Grotonweather website, facebook and twitter pages for updates. Please share this blog with others so that they can stay informed and safe as well.

Growing Flood Concern

 4:30PM Update-

Everything is progressing as I feared and a FLASH FLOOD WARNING has been issued for Tompkins and southern Cayuga Counties. The ENTIRE Grotonweather forecast area is now under FLASH FLOOD WARNINGS. This is going to be a long night for our area.

Wednesday- 2:15PM

So far, the Grotonweather.com tri-county area has more or less been spared of major problems, at least that I am aware of. Our neighbors to the south and east in Tioga, Broome and Chenango counties have not been as fortunate. Massive and widespread flooding has prompted Flash Flood EMERGENCIES for all three counties, with a State of Emergency also in effect for Broome County. Many roads are under water and bridges are in danger of washing out. This is a very dangerous and deadly situation in these areas. Under no circumstances should you be traveling to those areas tonight.

Here is what is really worrying me though...our luck could soon run out. In the image below, you can see a band of very heavy rain moving north through Pennsylvania right towards our area, which is outlined in red. The heavy rain to our east will continue to move to the northeast.

This band of rain extends all the way down past Washington DC and seems to only be increasing in size and intensity. If the flooding that is occurring to our south and east is any indication what a couple more inches of rain will do, our area may be in trouble.

I urge everyone to be extra vigilant this afternoon, evening and overnight. This is one of the most dangerous situations in Grotonweather history, if not for our immediate area, then for our neighbors directly nearby. DO NOT drive or walk in flood waters. If the water is flowing, chances are that you will need to be rescued. If you are told to evacuate, do so. In fact, if you live near a stream that is already full or near...be prepared to leave on a moment's notice. The time to prepare is now.

Please share this post with your friends and family.

Heavy Rain Update: 4PM

4:40PM UPDATE: FLOOD WARNING ISSUED FOR S.CORTLAND AND TOMPKINS COUNTIES THROUGH 7:15 PM.

Very heavy rain has been falling across the area and will continue to do so for the remainder of the afternoon and into tonight. The regional radar loop is showing the rain tapering a bit to just showers, but not until far Southern Pennsylvania. Even then, there is still some heavy rain...just not as widespread. We very well may only be about half way through this event, and already rainfall totals are getting quite high. Take a look at some of these reports:

Game Farm Road Climate Station, Ithaca: 1.36" through 3PM
Freeville: 1.41" through 3:42 PM
Virgil: 1.54" through 3:42PM
Binghamton Airport: 1.36" through 3PM
Deposit, NY (Deleware County): 2.99" between 7AM-1:22PM

If we double these amounts, most places will be up around 3-4", as expected. There are no flood warnings in the Grotonweather.com forecast area, but most of the counties to our south, east and north are under flood warnings. Most of these flood warnings are for larger rivers in anticipation of this additional rain. No flash flood warnings are in effect yet.

There are actually some more intense areas of rain and wind within the main area of heavy rain. A severe thunderstorm warning was even issued for Broome County a little while ago! I changed the scaling on the radar program I use to make these areas stick out. The brighter the color, the heavier the rain. The heaviest rain seems to be concentrated over the Finger Lakes, with some of those heavier cells moving through Cayuga and Cortland Counties, as indicated by the dark reds and pinks. It is where these cells hit that the greatest chance for rainfall totals over 4" will occur.

As we go into the evening hours, I am anticipating starting to see some flash flooding problems as we start to approach the upper limits of what the ground and streams can handle. I will get the word out about any Flash Flood Warnings as soon as possible. Remember, NEVER drive through a flooded roadway! If you come to a roadway, turn around. There is no telling just how deep the water is. Just 6" of quick moving water can sweep a car away! It is especially dangerous at night, when it is even harder to see flood waters. Anytime you get rainfall of this magnitude in such a short (about 12-18 hours) time span, the runoff can produce dangerous conditions. Please stay safe tonight, and stay tuned to Grotonweather.com for the latest! Do not forget to visit the chat room by clicking the "Open Chat" icon to the right. The Chat will be open through the early evening. Furthermore, make sure you tune in for tomorrow's podcast as we talk about this event!

Note: One of the quickest ways to get updates from Grotonweather.com is on our facebook page! Become a fan now by clicking here!

Friday Afternoon's Severe Weather Outlook for 7/11

I spent the morning and early afternoon down at the National Weather Service in Binghamton, where I am an intern this summer, and used some of their in-house tools to try to get a better handle on the severe weather threat tomorrow. I will mention that the meteorologists there this morning believe tomorrow will be an active day and seem to have a high confidence level.

One of the tools I used this morning was a form called the 'severe weather checklist'. This form has you enter in forecasted values for a variety of severe weather parameters. After doing so, it returns the 5 most similar severe weather days in recent Central New York history. When completing this checklist this morning, it returned 4 days of 'isolated supercells', including May 16th, 2009, which had 3 tornadoes in the area, and May 31, 2002, which had 4 tornadoes. The fifth day was classified as a 'broken line'. Hail was the primary threat from the five days collectively. That tells me that not everywhere tomorrow will see a strong thunderstorm....some areas may barely even get any rain. However, there is certainly potential for some severe weather, and someone will likely have to deal with a damaging storm.

Here is a glance at where I have my threat levels, and an in depth look at exactly what I mean by each threat level, as well as what would need to happen for an upgraded risk:

Thunderstorms: moderate-
Thunderstorms are likely across much of the area. A few places, however, will be missed and get little to no rain. Frequent lightning will accompany some of the storms.

High Winds: slight-
Some storms may contain strong winds. Wind damage will be isolated to scattered, with 3 to 10 reports in Central New York. Sunshine in the morning would increase the chances of wind damage, and could get this bumped up to a moderate risk.

Hail: slight-
Small hail will be possible with stronger storms tomorrow, but most hail should remain uner 1" in diameter. The strongest storms may produce up to 1.5" hail. 5-12 Severe hail (over 0.75") events can be expected in Central New York. This is still rather uncertain, and could be upgraded to a moderate risk should the models show a bit better conditions for hail tomorrow morning.

Tornadoes: slight-
Conditions are favorable for rotating storms, and tornadoes could form. My best current guess is that somewhere in Western, Central and Southern New York will see a weak tornado, but as many as 2 or 3 wouldn't surprise me. This would most likely not be upgraded to moderate unless numerous storms that have already developed are showing signs of becoming tornadic.

Expect the next website update to occur between 9 and 11 am tomorrow. A blog update should occur within 30 minutes of that. There also could be a quick blog update tonight. During the afternoon tomorrow, I plan to have the weather chat open and will be updating th blog and website as needed. Stay tuned!

A Look at Watch #280

The Storm Prediction Center has issued a Severe Thunderstorm Watch that stretches across almost all of New York State. It remains in effect until 7pm tonight. Here is a look at the exact counties it includes. As you can see, Tompkins, Cortland and S. Cayuga are right in the middle of it.


The main threat from this event is going to be damaging winds. Hail will also be possible, and my gut feeling is there will be a tornado somewhere in the watch box. The official probabilities that the SPC has put with the watch:
Tornadoes

Probability of 2 or more tornadoes	Low (20%)
Probability of 1 or more strong (F2-F5) tornadoes	Low (5%)

Wind

Probability of 10 or more severe wind events	Mod (60%)
Probability of 1 or more wind events > 65 knots	Mod (30%)

Hail

Probability of 10 or more severe hail events	Mod (30%)
Probability of 1 or more hailstones > 2 inches	Low (20%)

Combined Severe Hail/Wind

Probability of 6 or more combined severe hail/wind events

High (80%)

Since it is at the top of the hour, the current observations and indicies will not be in for another 20-40 minutes. Looking at the data from noon, though, it is obvious to me that the atmosphere is quickly destabilizing. Also, a pocket of strong winds in the upper atmosphere is beginning to move into Western New York, and will spread over the rest of the state, enhancing the thunderstorms. Storms are going to develop from west to east, and have already begun to fire up across Western New York, Lake Erie and Lake Ontario. These storms should organize into a squall line eventually, which is when the greatest threat for wind damage will be. The highest tornado and hail threat will be just prior to that, when the storms are more individual cells.

Be sure to keep checking back through the afternoon for the latest!

Nor' Easter, then Lake Effect

Our nor' easter is starting to really wind up off of the New Jersey coast this morning. This has spread a solid area of precipitation from the Finger Lakes, east. Most of what you see on the radar is rain, but it has already changed over to snow in Binghamton and Scranton.


At 9AM, it was 37 in Ithaca, so that, combined with where it is already snowing in Binghamton, has made me expect a change over to snow a bit earlier than I was anticipating last night. This has been reflected in the higher snow amounts on the snow map below. For Groton specifically, since I placed us on the boundary between two areas, I would expect to see 2 or 3, maybe 4 inches downtown, with as much as 5 or 6 on the hills.

This storm should be well on its way out by midnight tonight. However, just as that storm departs, the Lake Effect machine will kick in for Wednesday and Wednesday night before tapering off Thursday. It is still too early to tell where exactly the heaviest lake effect will set up, and whether or not it will remain snow, but here is my best guess for snow intensity at this time:

If you want to help me out with this, as I sit up here in Oswego, it is very hard for me to know what exactly the precipiation type is elsewhere. It would be very helpful if you could leave a comment on here letting me know when you first see snow, no matter where you are. Current data from spotters is very imporatant to meteorologists, so I would really appreciate your observations! Thanks!

TORNADO WATCH ISSUED

Tompkins County, along with all of Central and Eastern New York is now under a TORNADO WATCH until 6PM tonight!


A little known fact about watches is that they each have probablities of certain severe weather events occuring. For this watch, there is over a 95% chance of 10 or more wind damage reports, as well as over a 95% chance of 10 or more hail reports and a 40% chance of 2 or more tornado reports. That means the main threat is still damaging winds, but tornadoes are becoming an increasing threat.

An update on that line of storms: The northern portion appears to be the stronger part, with numerous warnings now in effect. Stay tuned for more updates on these storms.



Also, the National Weather Service confirmed my belief about multiple lines of storms today when they issued this statement at 10:05AM:

... Severe thunderstorms are expected across the region today...

An initial line of thunderstorms will cross The Finger lakes
region... the twin tiers... the Mohawk Valley... and the southern Tug
Hill region this morning... generally between 930 am and 12 noon.
This includes Elmira... Corning... Syracuse... Utica... Binghamton...
and Montrose. Localized strong damaging winds and hail are
possible late this morning.

This afternoon... another round of thunderstorms is anticipated.
Additional lines of storms are expected to cross the area... generally
between 2 and 6 PM. Once again... strong winds and hail are the
primary threats.

Stay tuned to NOAA Weather Radio... or local media outlets... for the
latest updates. Watches and/or warnings may well be issued later
today.

Late Season Snow Storm Tonight!

A late season snow storm is in store for the area tonight as low pressure moves to our south along a stalled frontal boundary. As this low moves along the front, cold air from Canada will advance south. Meanwhile, the low will throw moisture up into the cold air.



The precipitation will likely start as some rain later this afternoon and tonight. As that cold air moves in, however, it will change the rain to snow overnight. As is often the case with storms at the beginning and end of winter, the higher elevations will end up with more snow than the valleys. The models haven't been doing a good job with this storm so far; just yesterday they had us getting barely anything. However, they seem to be in better agreement with this morning's runs, and looking at the radars to our west, I think we are in for a decent snow. The map below is a little confusing since its hard to incorporate the elevation factor into the map. For downtown Groton, I would say 3 or 4 inches will fall. In the hills surrounding Groton, more like 5 or 6 inches. I think the highest amounts will be in the hills north, east and south of Cortland, especially down towards Binghamton. I wouldn't be surprised to see someone down there get 8-10", maybe even a foot!

Surprise Storm Tomorrow Night!

The weather has been so active over the past week, including the rapid temperature drop and heavy snow squalls yesterday and the lake effect blizzard up here in Oswego, this storm has kind of snuck up on us. However, it now looks like this storm may be one of the biggest for the area so far this winter. I've run the morning models, which are agreeing with each other and last night's models, so here is my snow map.



Most of this snow will fall overnight Tuesday and early Wednesday. Since the majority of the storm will be during the overnight and early morning hours, I do think a snow day is a pretty decent bet Wednesday. I will keep updating and tweaking the map as I see fit, so stay tuned!

Why we should have a Winter Storm Warning, not an Advisory!

Note: This post is not intended to be a rant, but this is important and needs to be said.

The National Weather Service in Binghamton has issued a Winter Weather Advisory for Central New York for tomorrow's Ice Storm. Now, I think they are making a mistake in only issuing an advisory. Instead, I believe we should currently be under a Winter Storm Warning. Here is why:

Firstly, the National Weather Service in State College, PA, has issued Winter Storm Warnings for all their counties, while Binghamton and Buffalo have only issued advisories:


Now the very interesting thing is, the warnings issued by State College are for average ice amounts of 1/4". What does our winter weather advisory say? Average ice amounts of 1/4". Why are they the same amounts, yet not the same statement? If anything, I would think it would be reversed since the State College area will not see snow to start and will change to rain quicker.

One may wonder why Binghamton is in the wrong, and not State College? The reason for this is the main reason I am making this post:

Just 2 days ago, on Tuesday, the NWS in Binghamton issued a freezing rain advisory for the area. It certainly was slippery out, but there was just a coating of ice, so it wasn't a huge deal. Now, just two days later, we have another advisory. Its natural, therefore, to think that this next event will be comparable to Tuesday's, when in fact Friday will be much worse than Tuesday! A quarter inch of ice is a LOT more than a coating. A quarter inch can make travel very dangerous, bring down branches and cause some power outages.

Again, I can not stress enough that this storm is nothing at all like Tuesday's! We really should be under a WINTER STORM WARNING!