7-14 May 2009: Rain, then maybe hot again

CanisLupusArctos · 05-06-2009, 06:34 PM

Expect the next few days including the weekend to be cloudy at best, and heavy rain possible Thursday into Friday morning. Cold air digging south from Canada has touched off a round of severe storms along a line from Virginia to the deep south, and this moisture will travel northeastward tonight through Friday. The severe component of this weather will not hold together but the moisture-wringing will. This should give us up to an inch of rain by Friday morning. Bulk of this storm will probably head over New York State, keeping to our west. However, because of the localized nature of this rain's origins (severe thunderstorms) I would expect that there will be pockets of heavy rain (former thunderstorms) mixed in with a general area of moderate rain, while it is over us. Amounts will average around 3/4 of an inch across the area. Where the pockets of heavy rain hit, and also on south-facing slopes, I would expect an inch of rain and possibly 1.25 inch.

Friday we will see a break but it doesn't look like a sunny one... just a letup in the rain. Friday night we go back in the rain. The weekend looks showery and cool as well.

However, 10-day GFS is hinting at yet another occurance of Bermuda high pressure from Tuesday onward. That is when high pressure--which has a clockwise flow of air several thousand miles in diameter--puts its center over or near Bermuda. That puts the south-to-north portion of the clockwise flow on the east coast. It draws air from the Gulf of Mexico and sends it right up I-95 to New England.

The Bermuda high is what gave us the 90-degree weekend in April. I wouldn't be surprised to see a recurrence IF the Bermuda high actually sets up as the GFS says it might. That is still several days away. Right now I would go with the model and say "70s" until I become more confident that the Bermuda high will materialize. If that does happen, you'll see me bump up my temperature forecast.

As always, the latest current weather for the lake is available from the Black Cat Island weather station at www.blackcatnh.com/weather.

CanisLupusArctos · 05-08-2009, 12:41 PM

This morning I awoke to sunshine and knew I blew this forecast. The island did get 0.70" rain from the main event, which was close to the 0.75" I had forecast as an average. I am glad, however, to be wrong this time. It was nice to wake up and see the sun.

The weather pattern remains unsettled, as it was around here at this time last year. The air is still generally cold, but the sun is trying to heat things up. The resulting mixing of new warmth plus old cold is creating showers (this is the simple version of the story.) Just like this time last year, expect the best chance of sun each day to be in the morning, with afternoon showers in some places, just clouds in others.

Still looking good for the middle of next week.

ApS · 05-08-2009, 01:20 PM

Quote:

Originally Posted by CanisLupusArctos

"...This morning I awoke to sunshine and knew I blew this forecast..."

Don't be too rough on yourself: It's started raining again, so you were only wrong between 9AM and 2:20PM.

CanisLupusArctos · 05-09-2009, 10:09 AM

A warm front is lifting to the north of the area today. Behind it, satellite imagery shows breaks in the overcast over New York state, moving this way. These breaks are allowing enough sun to warm temps there into the 70s.

Humidity is higher today than it's been all winter -- spring is definitely here. Dewpoints are near 60 in many parts of New England, while around here we are in the mid 50s. Combine this with the fact that a cold front is approaching from the St. Lawrence Valley and you get thunderstorms.

They are already forming in far western NY state, with the sunshine ahead of them providing fuel.

The Storm Prediction Center in Norman OK has placed New England in a risk for severe weather today, based on elevated humidity levels ahead of the cold front. There is enough cold air present so that hail will be a threat in some thunderstorms today. SPC even mentioned a tornado is a possibility somewhere in New England today.

How strong these storms get depends on how much sun we get this afternoon. We must wait for the warm front to move north of the area before we'll know how big the breaks in the overcast are by the time the warm sector moves over us.

SPC discussion...

...NY/MA/VT/NH...
A COMPACT UPPER TROUGH IS CURRENTLY MOVING ACROSS LOWER MI...AND
WILL BEGIN TO AFFECT NY AND NEW ENGLAND BY EARLY AFTERNOON.
SCATTERED THUNDERSTORMS ARE LIKELY TO INTENSIFY IN THIS REGION AS
COMBINATION OF DAYTIME HEATING AND SURFACE DEWPOINTS IN THE 50S
YIELD MLCAPE VALUES OF 500-1000 J/KG. FAST-MOVING STORMS CAPABLE OF
DAMAGING WINDS AND HAIL WILL SPREAD FROM CENTRAL/EASTERN NY INTO
CENTRAL NEW ENGLAND BY LATE AFTERNOON. ISOLATED SUPERCELLS WILL
ALSO BE POSSIBLE DUE TO FAVORABLE LOW LEVEL AND DEEP LAYER VERTICAL
SHEAR...WITH A RISK OF A TORNADO OR TWO.

05-06-2009, 06:34 PM	#1
CanisLupusArctos Senior Member Join Date: Jan 2007 Location: Center Harbor Posts: 1,049 Thanks: 15 Thanked 472 Times in 107 Posts	7-14 May 2009: Rain, then maybe hot again Expect the next few days including the weekend to be cloudy at best, and heavy rain possible Thursday into Friday morning. Cold air digging south from Canada has touched off a round of severe storms along a line from Virginia to the deep south, and this moisture will travel northeastward tonight through Friday. The severe component of this weather will not hold together but the moisture-wringing will. This should give us up to an inch of rain by Friday morning. Bulk of this storm will probably head over New York State, keeping to our west. However, because of the localized nature of this rain's origins (severe thunderstorms) I would expect that there will be pockets of heavy rain (former thunderstorms) mixed in with a general area of moderate rain, while it is over us. Amounts will average around 3/4 of an inch across the area. Where the pockets of heavy rain hit, and also on south-facing slopes, I would expect an inch of rain and possibly 1.25 inch. Friday we will see a break but it doesn't look like a sunny one... just a letup in the rain. Friday night we go back in the rain. The weekend looks showery and cool as well. However, 10-day GFS is hinting at yet another occurance of Bermuda high pressure from Tuesday onward. That is when high pressure--which has a clockwise flow of air several thousand miles in diameter--puts its center over or near Bermuda. That puts the south-to-north portion of the clockwise flow on the east coast. It draws air from the Gulf of Mexico and sends it right up I-95 to New England. The Bermuda high is what gave us the 90-degree weekend in April. I wouldn't be surprised to see a recurrence IF the Bermuda high actually sets up as the GFS says it might. That is still several days away. Right now I would go with the model and say "70s" until I become more confident that the Bermuda high will materialize. If that does happen, you'll see me bump up my temperature forecast. As always, the latest current weather for the lake is available from the Black Cat Island weather station at www.blackcatnh.com/weather.

05-08-2009, 12:41 PM	#2
CanisLupusArctos Senior Member Join Date: Jan 2007 Location: Center Harbor Posts: 1,049 Thanks: 15 Thanked 472 Times in 107 Posts	Unexpected sunshine This morning I awoke to sunshine and knew I blew this forecast. The island did get 0.70" rain from the main event, which was close to the 0.75" I had forecast as an average. I am glad, however, to be wrong this time. It was nice to wake up and see the sun. The weather pattern remains unsettled, as it was around here at this time last year. The air is still generally cold, but the sun is trying to heat things up. The resulting mixing of new warmth plus old cold is creating showers (this is the simple version of the story.) Just like this time last year, expect the best chance of sun each day to be in the morning, with afternoon showers in some places, just clouds in others. Still looking good for the middle of next week.

05-09-2009, 10:09 AM	#4
CanisLupusArctos Senior Member Join Date: Jan 2007 Location: Center Harbor Posts: 1,049 Thanks: 15 Thanked 472 Times in 107 Posts	Severe Weather Possible today A warm front is lifting to the north of the area today. Behind it, satellite imagery shows breaks in the overcast over New York state, moving this way. These breaks are allowing enough sun to warm temps there into the 70s. Humidity is higher today than it's been all winter -- spring is definitely here. Dewpoints are near 60 in many parts of New England, while around here we are in the mid 50s. Combine this with the fact that a cold front is approaching from the St. Lawrence Valley and you get thunderstorms. They are already forming in far western NY state, with the sunshine ahead of them providing fuel. The Storm Prediction Center in Norman OK has placed New England in a risk for severe weather today, based on elevated humidity levels ahead of the cold front. There is enough cold air present so that hail will be a threat in some thunderstorms today. SPC even mentioned a tornado is a possibility somewhere in New England today. How strong these storms get depends on how much sun we get this afternoon. We must wait for the warm front to move north of the area before we'll know how big the breaks in the overcast are by the time the warm sector moves over us. SPC discussion... ...NY/MA/VT/NH... A COMPACT UPPER TROUGH IS CURRENTLY MOVING ACROSS LOWER MI...AND WILL BEGIN TO AFFECT NY AND NEW ENGLAND BY EARLY AFTERNOON. SCATTERED THUNDERSTORMS ARE LIKELY TO INTENSIFY IN THIS REGION AS COMBINATION OF DAYTIME HEATING AND SURFACE DEWPOINTS IN THE 50S YIELD MLCAPE VALUES OF 500-1000 J/KG. FAST-MOVING STORMS CAPABLE OF DAMAGING WINDS AND HAIL WILL SPREAD FROM CENTRAL/EASTERN NY INTO CENTRAL NEW ENGLAND BY LATE AFTERNOON. ISOLATED SUPERCELLS WILL ALSO BE POSSIBLE DUE TO FAVORABLE LOW LEVEL AND DEEP LAYER VERTICAL SHEAR...WITH A RISK OF A TORNADO OR TWO.

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