Weather for Friday, April 30, 2010; Warm weather on the way!

Tomorrow is going to be the start of a beautiful stretch of weather coming up. Tomorrow is going to be a beautiful day. West-southwest flow will develop in the lower levels, while west flow dominates in the upper levels. What does this mean? Increasing heights aloft and much warmer weather. Looking at the WV imagery, there is strong WAA going on to the west of the area as a mid-level ridge builds from the G/L down into the southern states. In the NE/MA, a strong 300mb jet roared in at 120 knots, which brought the strong winds earlier as deep mixing occured. The ULL, which has plagued us over the last several days has finally moved out. Temperatures in the 70's can be found in most areas tomorrow. Dry conditions will be found tomorrow, aside from some clouds as moisture content increases a little bit.

Pattern Change On The Way; Warmer And More Humid By The Weekend!!

A pattern change is on the way folks and a welcome one at that! The ULL, currently spinning through New York State, is treking to the east today. The surface low, well off  the coast, is treking to the northeast as a kicker upper level disturbance is shunting the low off to the NE. It's also dragging a cold front through as winds have switched over the northwest, ushering in much cooler and drier air. Dewpoints have since dropped into the 30's and 40's. Tomorrow will be a rather cool day however, as the pressure gradient tightens as the upper disturbance over the Tennessee Valley phases with the surface low offshore and the upper cold pool moves over the area.

Once that pesky ULL moves out, there will be a rapid moderation in temperatures as a ridge begins to build in from the west. The computer models are having a difficult time with the possible break-down of the blocky regime we've had over North America.

Let's throw up the 12Z GFS 500mb pattern for a second.

See that ULL to the east of Maine. That ULL has been associated with a -NAO. However, the models want to breakdown the blocky regime. That ULL will begin to shift to the northeast. You can clearly see the ridge over the Eastern US. That is called the SE ridge. We've seen over the past several weeks, average to below average temperatures, marine airmasses, and slow moving low pressure systems. That is due to that ULL and the -NAO. That ULL will shift north of the Canadian Maritimes, and the ridge axis can build up into Southeastern Canada, leading to a SW flow aloft and at the surface. What does that mean? Warm, dry and humid conditions through the weekend. By early next week, a backdoor cold front will try to move south from Ontario. Each day will feature scattered showers and thunderstorms as impulses move up and over the ridge. Temps in the 70's and 80's can be expected each day. Summer is here now folks!!!!!!!!!

Outlook for Monday, April 26, 2010; Rainy, raw day on tap

Tomorrow is not looking like a very nice day. The ULL will be treking east over the area by tomorrow night. The warm front should stay south of the NYC/LI area, thus keeping the area cool sectored and in persistent easterly to northeasterly flow. The sreadiest rain should let up in intensity by tomorrow afternoon, but one last wave of low pressure will trek along the warm front and east off the Jersey coast, resulting in one rounbd of steadier rainfall. Temperatures will hover in the 50's north of the front. All in all, a wet, cold day.

Afternoon Discussion for April 25, 2010; Rainy weather continues

Hello folks. As you can see, it's a miserable day outside. Many areas picked up over an inch of rain this morning, however moist easterly flow continues to keep in the clouds, drizzle, and cool temperatures. Let's look at the WV imagery for a second.

The troublemaker responisble for this dreary weaather is currently spinning in the MW. The ULL is tracking eastward through Indiana ATM. Moisture continues to be transported up the coasr in SW flow aloft, while easterly flow continues in the lower levels, with high pressure anchored off the NE coast.

Now let's look at the current surface analysis from TWC.

The warm front is still south of Long Island, as of 4:38 PM. The warm front shouldn't make much more progress either northward or southward due to the upper flow running parallel to the front. A potent shortwave trough is dropping southeastward out of Eastern Canada into New England, and that is helping to keep those northern areas drier as it shunts the deeper moisture and associated lifting southward.

The light rain/drizzle should transition into stratiform rain again later tonight as a shortwave rotating around the ULL moves eastward along the warm front. Moisture should deepen again and instentropic lift should increase. Another 0.50 to 0.75 inches of rain should fall into tomorrow afternoon.Models advertise a third and final shortwave treking eastward along the front, but most of the rainfall should stay off the coast. On Tuesday, the ULL moves through into New England, and we could see some showers in cyclonic flow aloft s the ULL's associated cold pool aloft works on through. Winds should shift to the North Northwest by Tuesday, ushering in cooler, drier air and conditions should slowly improve on Wednesday.

Discussion for April 25th-27th RainStorm

Okay, I have a lot to get through in this discussion, so let's get to it. First up is the WV imagery, so I can show you what's going on currently.

So, what are we looking at? Currently, the ULL is closed and spinning in the MW states. There is a sub-tropical jet feed right out of the Gulf of Mexico. A potent shortwave is tracking southeastward out of Central Canada, and another ULL is dropping south from Labrador. The MW ULL will slowly weaken and open as it slowly treks to the east, through the OH Valley and then eastward into New England. On the WV imagery, there is a clear -NAO pattern in place over the Northern Atlantic, which is important because it helps to slow the pattern down. However, the 12Z ECMWF is a little more progressive than the 12Z GFS in lifting everything out earlier.


Now, let's look at the current surface analysis.

This is from Intellicast, at 8PM Saturday. The warm front is slowly lifting through the OH Valley, there is a ripple of low pressure that developed on the warm front over Southwestern Virginia, and the ULL is back over the border of Iowa and Missouri. High pressure has since shifted offshore, but the ridge axis has yet to move off the coast.


There will be a persistent easterly to northeasterly fetch over the next several days. This is due to upper level confluence over Northern New England. This is important because it helps to maintain high pressure and CAD, or cold air damming to the east and northeast. The parent ULL is still well to the west. The ULL helps to lift the warm front northward overnight into Sunday morning. However, the warm front should stay south of Long Island, keeping the NYC Metro Area cool sectored. Climatology at this time of year also suggests the warm front won't move north of Long Island. An onshore moist marine flow can be expected into Tuesday, before the low level flow turns more north and northwesterly by Tuesday afternoon and evening.


Rain will enter the picture later on tonight. There could be a few hours of virga because the rain is entering a cool, dry airmass and the dry sub cloud layer. Insentropic lift is when warm, moist air overruns cool, dry air and the moisture becomes enhanced as the two air masses clash. It becomes apparent near the warm front. Omega increases at 700mb across the area. Also apparent is convergence in the 1000mb-500mb layer also near the approaching warm front. The warm front helps the lifting as moisture from the GOM overruns the warm front, resulting in a stratiform rain.


A round of rain will occur later on tonight into Sunday afternoon, before there is a break in the action. However, moist easterly flow will continue to keep in clouds, fog, and drizzle. The MW ULL could be far enough east at this point, so it provides its own lift. A second surface low, indicated by the NAM/GFS/GGEM will track from the Mid Atlantic coast eastward out to sea on Monday, resulting in another round of rain. The cold front, associated with the ULL will move through on Tuesday, bringing another round of showers as its asslociated anomalous cold pool (temperatures around -25c-30C) moves through as well.


One last thing to worry about in southern areas of the CWA is the potential for thunderstorms, in which a few could become severe. The warm front will help to destablize the atmosphere. However, positive LI indexes and very little CAPE values will help to hinder the threat. Not sure on how much sunshine we will see to help fire off convection. A few storms could become severe due to steep lapse rates and being near the warm front. Can't rule this out as dynamics should be pretty potent.


Now onto QPF values.


HPC Guidance

12Z GFS Guidance

12Z GGEM Guidance

12Z NAM Guidance

I don't foresee any flooding concerns. Some places could see over 2 inches of rainfall, but this will be spread out over the course of a few days. But expect a raw, rainy ugly couple of days!!

Weather for April 24, 2010: Nice day before the weather goes downhill!

Friday was just a gorgeous day. Plenty of sunshine, low humidity, a refreshing NW breeze, and temperatures in the 60's. This was due to high pressure building in from the west.


Tomorrow should feature more of the same. High pressure will move to the south of the NYC area, and because of that, an afternoon sea breeze will develop at the coast, leading to cooler conditions. Tomorrow should be sunny, I don't see any rain during the day as the upper level ridge in place holds on a little longer. Temperatures inland should be in the 60's, if not a few degrees higher than Friday's. Once the ridge axis moves off the coast tomorrow night, a warm front will attempt to push in due to a ULL spinning in the western states. So the best chances for rain will  be during the overnight hours. The 12Z ECMWF may be too quick to move out the ridge axis, and the best chances for rain may come much later at night.

Weather for Friday, April 23, 2010. Much Better Day On Tap!!

The weather tomorrow looks much better. The cold front should have cleared the NYC Metro Area by later on tonight and the winds will switch over to the northwest. Behind the front, a drier and slightly cooler airmass will take hold for both tomorrow and into Saturday. High Pressure should build in from the west throughout the day, and that will lead to a pleasant late April day. Temperatures should be at comfortable levels, with 60's to be had. Again, there could be a few 70 degree readings scattered about the region. Frost may be an issue tomorrow night in the interior, as conditions could be favorable.

Afternoon Update for April 22, 2010

Just going to throw up the WV, so I can show you guys a few things.

As of 12Z, the surface cold front was located back into NW PA and Upstate NY. Another interesting thing, clearly seen on the WV imagery, is the presence of a potent shortwave trough, clearly shown treking eastward through NY State. The trough will do two things: 1) help to steer the cold front eastward, and 2) to initiate convection.


Now, will we see showers and possible thunderstorms? That will be determined by how much surface based instability there is to work with. Less instability to work with, less thunderstorm activity to work with. Looking at dewpoints this morning, there not all that high, because the airmass in front of the cold front is not all that warm and steamy. Yes, there is drier air behind the front, but the airmass is not all that cold. So we're not going to see the classic clashes of airmasses. Dewpoints are only hovering in the 40's right now, not all that high. Like yesterday, there is a mid level cold pool aloft, as temperatures at 500mb range around -25C. So because of that, mid level lapse rates are fairly steep. So, we could see some surface cape develop out of and just along the cold front. This is from New Jersey into interior portions of CT. So with the developing surface cape and the approach of the shortwave trough, this may be enough to fire off some convection out ahead of the front. For the coastal areas, convection will fire west of the coast, because an afternoon seabreeze would have an stablizing effect on the atmosphere and convection should weaken once hitting the marine layer in place.


So a few thunderstorms could contain some hail, some gusty winds, and heavy rains. The front should clear the coast later on this evening, bringing with it, drier and slightly cooler air. Temperatures today will be in the 60's most places, with a few 70 degree readings to the SW.

Weather for Thursday, April 22, 2010; Better day?

Currently, a very potent s/w/vort max is moving eastward through Southern NJ, while its associated surface low, 1006mb is currently in NW Virginia. What has caused some showers and a few thunderstorms to break out is the combination of some lift, some instability, and cold air aloft in the mid levels, from 500mb to 700mb. As these showers translate eastward, they will weaken as they encounter the marine layer to the east.


Onto to tomorrow. There could be some breaks of sunshine early in the day, but that will be short-lived as a cold front crosses the area, bringing an increase in clouds. Not expecting much precip with the front, as there isn't a lot of moisture to work with. Cooler, drier air will follow behind the frontal passage tomorrow night with NW flow. Temperatures look to be in the 60's most areas, with a few 70 degree readings scattered about to the southwest.

Weather for Wednesday, April 21, 2010

Gonna throw up the WV Imagery from WeatherTap, as this will have implications on the weather for tomorrow.

What are we looking at? Currently, there is a rather potent s/w treking through theTennessee Valley. The HPC surface analysis shows a 1016mb surface high off Hatteras, and a 1015mb surface high over Chicago with a surface cold front centered off the Northern G/L. A surface trough can be found along the spine of the Apps. What does this all mean?

Well first, the infrared satelite image shows high clouds streaming in from the southwest, now overtaking Eastern PA, NJ, LI, and into Eastern CT. Clouds will increase tomorrow as the front continues to near and the s/w translates eastward. There is a risk for some showers during the afternoon, but any lifting mechanism will be quite weak, even though there is some frontogenesis, and the showers will be scattered in nature. Some instability can be found in southern areas in southern NJ, southern PA for example. I can't rule out a few rumbles of thunder as well. Highest temperatures to the NE, lowerst temperatures to the SW. Temperatures in the 60's can be found for most areas tomorrow.