First Nor'easter of the Season...

By: Zachary Labe , 3:35 PM GMT on October 11, 2010

Share this Blog
0
+

The trailing cold front will pass through north to south on Monday and Tuesday leaving behind a drier and cooler airmass for Wednesday. 1016mb high pressure will dominate the region's weather on Wednesday with seasonal temperatures and low dewpoints under clear blue skies. Low dewpoints will allow for a frost potential in the northern valleys of Pennsylvania for Tuesday and Wednesday nights. Meanwhile a trough will be deepening to our west as a shortwave begins to dig along the trough axis in the Ohio Valley. This setup will lead to cyclogenesis along the Northeast coastline as the first nor'easter of the year is underway.

October nor'easters are quite common to the Northeast and small details of their development often foreshadow critical signs to the winter makeup. By Thursday the 1020mb high pressure will lift to our northeast in a favorable location for cold air damming near Nova Scotia while the 850hPa low tracks south of the Mason-Dixon line slowly organizing. As often noted in many situations, the exact track of the 850hPa low is critical to the position of the heaviest precipitation axis and temperatures aloft. Being that it is only early to mid October, 1000-500mb thicknesses will not be of importance for the most part. Current GFS and ECMWF prognostics are in similar correspondace tracking the 850hPa low across northern Maryland. This would position the heavy rain axis about 50-100mi to the north. Current GFS surface rains agree with this rule showing heavy rain in northern Maryland to about interstate 80. More convective rains would be likely south of the 850hPa low track across southern Maryland and the Delmarva.

By Thursday night, the 1004mb surface low will track across Delaware and begin to deepen off the coast. Current Atlantic SST anomalies have waned from their impressive deviations during the summer courtesy of the tropical systems, which stirred a bit of the cooler water wells to the surface. In any case the low will undergo cyclogenesis Thursday night progresses slowly to the northeast. As the low deepens, 1020mb high pressure over Newfoundland will funnel in cooler air into the Northeast with 850mb temperatures dropping to (+1)-(+3)C as far south as Maryland. Under the northeast flow, a thick stratus layer will promote very cool diurnal high temperatures. GFS 2m temperatures suggests highs only in the 50s for most areas. But considering past history of cold air damming, I would undercut those prognostics by a good 5F. Highs will likely be in the mid to upper 40s for most areas north of Baltimore for Thursday and Friday. The higher elevations above 1800ft may even only stay in the low to mid 40s especially towards the Poconos.

The nor'easter is supported by current teleconnections with a negative NAO and favorable phase 5/6 MJO.

10/11/10 06utc GFS shows a 996mb surface low about 25mi off the coast of central New Jersey by early morning Friday. 10/11/10 0utc ECMWF is in similar correspondance, but deepens the low about 75-100mi off the coast.

As the 988mb surface low becomes cutoff late Friday into Saturday, the heavy rain will shift into New England. But before, much of the day will Friday will feature a heavy rain deformation axis along the east coast. Positioning of this exact band is of course in question at this point. Current 10/11/10 morning GFS 700mb RH prognostics show the deformation axis along eastern Pennsylvania as far south as the Mason-Dixon line. GFS/ECMWF mean QPF is generally 1-4in of rain for all of Pennsylvania/Maryland/Delaware with the higher amounts in eastern Pennsylvania on northward. A tight pressure gradient is also likely especially as the low deepens off the coast by Friday morning with a northeast flow dominating. 10m ECMWF surface winds suggest sustained 35-45mph winds especially for coastal areas, but also elevations above 1200ft. Regionwide gusty winds will be likely at times reach advisory 50mph criteria, again especially for eastern and northern areas.

Being that it is early October, rain will be the dominate precipitation type. But a few GFS/ECMWF runs have hinted at cooler air being pulled into the system as the low becomes vertically stacked. 1000-500mb thicknesses drop to 545dm for parts of New England, which may be cold enough for some accumulating snow for elevations above 3000ft especially into the Presidentials in New Hampshire. This threat of elevation accumulating snow will need to be monitored later this week.

Other global models also support the nor'easter threat including the NOGAPS and GGEM, but they are a bit slow for intensification and a bit farther off the coast. None the less I think a general forecast can be made for Thursday into Friday for the northern Middle Atlantic with heavy rain, gusty winds, and cool temperatures. Highs will struggle to reach 50F northwest of the I-95 corridor during this period and gusty winds with rain will make it feel even cooler. Rainfall amounts will likely surpass one inch for most areas in the region with higher amounts likely north of the Mason-Dixon line and east of the State College-Lock Haven line. Coastal flooding is also possible, but should remain minor as winds will have a more northerly component as opposed to southerly. As the low pulls northeast near the 40/70 benchmark, high pressure will move in for a nice Fall weekend with highs in the 60s and lows in the 30s/40s for most areas under blue sky.

"Here north of Harrisburg 2010 statistics"
(Severe Weather Stats...)
Severe Thunderstorm Watches- 13
Severe Thunderstorm Warnings- 10
Tornado Watches- 2
Tornado Warnings- 1
Total Thunderstorms- 20

(Precipitation Stats...)
Flood Watches- 4
Flood Warnings- 4
Monthly Precipitation- 1.70inches (October)
Yearly Precipitation- 33.73inches

(Temperature Stats...)
Heat Advisories- 5
Excessive Heat Watches- 1
Excessive Heat Warnings- 1
90degree days- 38
Highest Temperature 101F (x2)

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 141 - 91

Page: 1 | 2 | 3Blog Index

141. Zachary Labe
3:50 PM GMT on October 23, 2010
Quoting TheRasberryPatch:
Blizz will have an explanation. I am actually at the coldest for the morning. I have dipped below 39F

31.0F here this morning. Remember earlier this week when I dropped to 33F, you were warmer weren't you? Anyways I have a couple possible reasons. First off your location may be on a slight hill. Even a gradual 50-100ft (not necessarily a hill, but a gradual slope) will cause the winds to not decouple especially considering the mixing levels were not too high aloft. Also some locations radiate better than others depending on wind direction. I radiate wonderfully with a southwest flow, but terribly in an easterly flow. For KMDT, it is the opposite. In any case full frost here and end of growing season.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
140. TheRasberryPatch
1:13 PM GMT on October 23, 2010
yes it is ono. Blizz better have his dissertation ready to explain this phenomenon. hahahaha
Member Since: January 26, 2007 Posts: 72 Comments: 6256
139. onoweather
1:08 PM GMT on October 23, 2010
TRP-I got down to 32.5 with a decent frost. Quite a difference over a couple miles.
Member Since: December 3, 2008 Posts: 0 Comments: 58
138. TheRasberryPatch
12:03 PM GMT on October 23, 2010
Blizz will have an explanation. I am actually at the coldest for the morning. I have dipped below 39F
Member Since: January 26, 2007 Posts: 72 Comments: 6256
134. TheRasberryPatch
11:31 AM GMT on October 23, 2010
P451 - to my West like less than 5 miles the temps are in the low to mid 30's with heavy frost. very amazing
Member Since: January 26, 2007 Posts: 72 Comments: 6256
133. TheRasberryPatch
11:21 AM GMT on October 23, 2010
I will guess Blizz that most areas around me did see heavy frost. it looks like I have that, what did you call it, around me. hahahaha
Member Since: January 26, 2007 Posts: 72 Comments: 6256
131. TheRasberryPatch
10:54 AM GMT on October 23, 2010
not even close to frost here this morning. a low of 40
Member Since: January 26, 2007 Posts: 72 Comments: 6256
126. pittsburghnurse
10:43 PM GMT on October 22, 2010
Hunter's moon = la bella luna! Big, bright, beautiful.
Member Since: October 14, 2006 Posts: 1 Comments: 639
125. TheRasberryPatch
9:32 PM GMT on October 22, 2010
Blizz - oh right...i guess i was braindead for a minute...0.2" would be more would i said.

dewpt. is 29F. how long do you think it will take to warm up in the morning?
Member Since: January 26, 2007 Posts: 72 Comments: 6256
124. Zachary Labe
9:01 PM GMT on October 22, 2010
cchamp6- Wow, you sure have a microclimate there in northwestern CT.

TheRasberryPatch- No, it would have only been a dusting 10:1 ratio. It will be interesting to see how cold areas get tonight; already a low 30F dewpoint here.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
123. TheRasberryPatch
8:35 PM GMT on October 22, 2010
Blizz - a 322 streamer...wow. now to get that come winter, huh. 0.02" of rain would be maybe 2 or more inches of snow?

i won't mind warm temps next week. it won't be long before the cold winds start blowing. today was kind of a chilly windy day. Really, we haven't had it that bad this October. No real cold fronts have passed through. I recall some Octobers where we might get passing flurries with temps in the 40's from a front.

Great Lakes storms? storms that move out of Colorado or Nebraska or Missouri and head into the Lakes?
Member Since: January 26, 2007 Posts: 72 Comments: 6256
122. cchamp6
7:59 PM GMT on October 22, 2010
Hail yesterday and first flakes of the year today. Bantam, Ct.
Member Since: December 21, 2006 Posts: 5 Comments: 1641
121. Zachary Labe
7:21 PM GMT on October 22, 2010
Quoting TheRasberryPatch:
I got 0.02" of rain overnight. I didn't realize we were going to get a bit of rain

A bit of lake effect rain from a 322 streamer believe it or not.

Quoting zotty:
Hey Blizz- do you see anything interesting in the next couple weeks, or should we just enjoy the foliage and the dry autumn air?

Warm weather next week with a few Great Lakes storms. Cold spell towards early November.

Stanb999- Hey! Thanks for the report! Yep, I am ready!
Member Since: December 14, 2007 Posts: 284 Comments: 15112
120. Stanb999
6:08 PM GMT on October 22, 2010
Hello Blizzard,

Just like to throw out there that today was the first snow flakes seen for the year....

Ready for winter?
Member Since: September 3, 2008 Posts: 0 Comments: 444
119. originalLT
3:33 PM GMT on October 22, 2010
Hi, P451, its not late fall yet! next week could be pretty mild!! But it's coming( the cold that is)!
Member Since: January 31, 2009 Posts: 0 Comments: 7500
117. zotty
12:53 PM GMT on October 22, 2010
Hey Blizz- do you see anything interesting in the next couple weeks, or should we just enjoy the foliage and the dry autumn air?
Member Since: August 19, 2009 Posts: 0 Comments: 738
116. TheRasberryPatch
12:38 PM GMT on October 22, 2010
I got 0.02" of rain overnight. I didn't realize we were going to get a bit of rain
Member Since: January 26, 2007 Posts: 72 Comments: 6256
115. Zachary Labe
9:51 AM GMT on October 22, 2010
Quoting SilverShipsofAndilar:
Ready for some snow. Who's with me?

Bradford, PA reported a bit of light snow last night in their observations.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
114. HeavySnow
4:50 AM GMT on October 22, 2010
Bring it on!
Member Since: July 7, 2004 Posts: 18 Comments: 2989
113. SilverShipsofAndilar
3:06 AM GMT on October 22, 2010
Ready for some snow. Who's with me?
Member Since: December 1, 2008 Posts: 0 Comments: 600
112. Gastonwxman
1:00 AM GMT on October 22, 2010
Watched a video from youtube and saw a run of the 18z GFS that shows a possible early snow event during the first week of November all the way down in NC and parts of TN and areas north from there!

http://www.youtube.com/watch?v=UBjG_6b66PA

Would be nice if that verified. :)
Member Since: October 3, 2010 Posts: 3 Comments: 3
111. TheF1Man
11:02 PM GMT on October 21, 2010
Hey everyone, we had HAIL today around 2 pm. I'm not sure how long it lasted because I was walking to class, but it was very cool!

Member Since: February 23, 2010 Posts: 0 Comments: 676
109. TheDawnAwakening
2:39 PM GMT on October 21, 2010
Major Nor'easter potential for the 28-31st of October, potentially a coastal, and the first week of NOV has a potential Great Lakes snowstorm.
Member Since: October 21, 2008 Posts: 245 Comments: 3817
108. zotty
2:09 PM GMT on October 21, 2010
more stink bugs- Hoy, I guess you are right, they are all over the place now, though I have not seen them yet. Here is a story in the from the local news- Link
Member Since: August 19, 2009 Posts: 0 Comments: 738
107. originalLT
1:04 PM GMT on October 21, 2010
P451, looks like you'll be getting some light showewrs in an hour or so, they shouldn't last that long though. Did you pick up one of those in-expensive rain guages yet?. They have them in my local hard-ware store, and they are pretty accurate, only about 10 bucks.
Member Since: January 31, 2009 Posts: 0 Comments: 7500
105. Zachary Labe
1:39 AM GMT on October 21, 2010
Quoting TheRasberryPatch:
you got that cold this morning Blizz? wow.

what is the forecast for next week? i see they have rain forecasted most of the week. Is it a stationary front sitting over us? the temps don't look cold

Rain should not be too heavy. Low pressure will held up slowly through the Great Lakes while a near stationary warm front is over our area giving way to dreary weather in the dirty warm sector. Temperatures will be very mild ahead of the cold front as it slowly moves west next week. In fact areas south of the warm front in central Maryland or so may top 80F.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
104. TheRasberryPatch
11:28 PM GMT on October 20, 2010
you got that cold this morning Blizz? wow.

what is the forecast for next week? i see they have rain forecasted most of the week. Is it a stationary front sitting over us? the temps don't look cold
Member Since: January 26, 2007 Posts: 72 Comments: 6256
102. Zachary Labe
7:52 PM GMT on October 20, 2010
Near killing frost here this morning with a low of 33.2F. But there remained an abnormal of widespread frost this morning here.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
101. TheRasberryPatch
11:28 AM GMT on October 20, 2010
I had 0.52" of rain yesterday.

some light frost on some grass with a low of 37F
Member Since: January 26, 2007 Posts: 72 Comments: 6256
100. pittsburghnurse
12:02 AM GMT on October 20, 2010
No frost in Pittsburgh yet. Maybe tonite.
Member Since: October 14, 2006 Posts: 1 Comments: 639
98. Zachary Labe
8:25 PM GMT on October 19, 2010
0.54in of rain here this morning.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
97. originalLT
6:39 PM GMT on October 19, 2010
Hoynieva, pretty clear for a phone pic. They actually look alittle bit like lady bugs at that stage of developement.
Member Since: January 31, 2009 Posts: 0 Comments: 7500
96. Mason803
4:11 AM GMT on October 19, 2010
Quoting TheRasberryPatch:
Blizz - did you get frost this morning? I was at Hershey Links this morning and they said they had about a 30 min frost delay. Hershey Links is all bent grass and if you step on a frozen blade of bent grass it dies and turns black.


mountain view golf course in fairfield had a 1 hour frost delay monday morning. the low there was 35f
Member Since: November 5, 2008 Posts: 0 Comments: 1139
95. Hoynieva
11:31 PM GMT on October 18, 2010
stink bug babies

Ok, so they were actually on the backside of a spearmint leaf...my mistake, it was three months back. Also, this is a phone pic, so I couldn't do macro...

(if you look closely, you can see a couple of them still in their eggs)
Member Since: January 20, 2009 Posts: 0 Comments: 1503
94. Zachary Labe
11:03 PM GMT on October 18, 2010
Quoting TheRasberryPatch:
Blizz - did you get frost this morning? I was at Hershey Links this morning and they said they had about a 30 min frost delay. Hershey Links is all bent grass and if you step on a frozen blade of bent grass it dies and turns black.

Only a low of 38F here, so no.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
93. Hoynieva
10:42 PM GMT on October 18, 2010
TRP, that link Zotty posted talks about the vegetation damage they do in their native lands as well as what they're doing here thus far. As for my gardens, they took chunks out of many tomatoes as well as some peppers. They also liked to lay their eggs inside of some of the flower buds, which would of course ruin that particular bloom. I have a pretty cool/gross photo of some of the babies just after they hatched from their eggs on the backside of a tomato leaf. The armor/shield like exterior is not yet developed so they look a lot different. I'll try to see if I can find it and post it.
Member Since: January 20, 2009 Posts: 0 Comments: 1503
92. TheRasberryPatch
10:39 PM GMT on October 18, 2010
Blizz - did you get frost this morning? I was at Hershey Links this morning and they said they had about a 30 min frost delay. Hershey Links is all bent grass and if you step on a frozen blade of bent grass it dies and turns black.
Member Since: January 26, 2007 Posts: 72 Comments: 6256
91. Zachary Labe
10:24 PM GMT on October 18, 2010
zotty- Eh, probably not. Just a bit too early in the year for coastal areas to get a frost. Usually there first frost occurs when most of the inland region gets their first hard freeze, and that is not going to happen yet.

wunderstorm87- Maybe up around Saranac Lake or Watertown, but most areas will be snow free. The class is actually pretty long and takes a few hours if I remember, although I believe it varies.
Member Since: December 14, 2007 Posts: 284 Comments: 15112

Viewing: 141 - 91

Page: 1 | 2 | 3Blog Index

Top of Page

About Blizzard92

Cornell University- Atmospheric Sciences Undergrad; Research Assist.- Onset of Spring Indices Toolbox; Interests- Small spatial scale climatolology

Blizzard92's Recent Photos

Personal Weather Stations

Linglestown, PA
Elevation: 520 ft
Temperature: 24.2 °F
Dew Point: 15.2 °F
Humidity: 68%
Wind: Calm
Wind Gust: 9.0 mph
Updated: 10:37 AM EST on January 18, 2014

About Personal Weather Stations