Synopsis

 

Sunny skies will remain through the evening. Clouds will be on the increase Saturday. There is a chance of some precipitation starting Saturday night which will continue through the remainder of the forecast period.

 

Short Term (Friday Night – Sunday Night)

 

The high pressure that is currently dominating the northeastern United States will move out the region Saturday night. For the time being, skies will remain clear and no precipitation is to be expected. A low pressure system centered in Wisconsin will be the cause of some precipitation Saturday night. The precipitation is expected to be a mixture of rain and snow. Warming temperatures during the day on Sunday will switch the precipitation over to rain.

 

Long Term (Monday Morning – Tuesday Night)

 

Another low pressure system will form in Southern Ohio and move northeastward through Pennsylvania and up into New York. This process will occur over the course of the beginning of the week. Precipitation is expected to occur through Tuesday, and the precipitation should end by Tuesday night, but skies will be mostly cloudy. High temperatures will be well above average into the mid to upper 40s during the entire forecast period, so the precipitation will be all rain. 

tech disco 12-13-2012

Synopsis

With High Pressure looming in the state and across the Appalachians, this stagnant high will remain in place until a strong low pressure cell passé to our northeast this Sunday. This will be a rain system primarily, but next week will show some intrigue with I midweek coastal storm followed by a Nor'easter potential for next weekend, starting off the official winter season with real winter cold

Short Term (Now thru Saturday Morning)

High pressure will remain stagnant in the state from now until Saturday morning, maintaining our current pattern of sunshine and average cool weather. The pattern will progress as southerly flow increases with the progression of a ridge, allowing some warmer air to creep up, putting our highs for Friday and Saturday in the mid to upper 40s mosly, and keeping lows scattered in the mid 20s to low 30s. As  day turns to night Saturday, hings will begin to change.

Long Term (Saturday Evening thru Monday)

During the night Saturday, an approaching trough will shake things up as the surface pressure gradient intensifies, bringing stroner winds overnight into Sunday morning. The 12z GFS ensemble members show little disagreement on the shape of the storm, mostly, but some outliers place the rain to our south, however the members uin agreement start precipitating here around 12z to 15z Sunday.  Then, as the PVA begins to deform the system, only 5 of the 12 members keep rain here on Monday. In comparison, the 18z NAM locates the omma further north, has bringing in rain starting 3 to 6z Sunday, and leaves just a stray shower by 6z Monday. The 12z Euro, widens the precip area across the East Coast, starting rain around 6z Sunday and not leaving until Tuesday. These discrepancies are due to the poor phasing of the 500mg height pattern with all models, so this should be looked into more as time progresses, but for now, we can say no snow this weekend, a low chance for next wefnesday, and a high chance for snow with the Nor'Easter hat's due next weekend (12z Euro shows it 10 days out)

Steve Engblom Dos

Wednesday Afternoon:

Synopsis: As a potent storm system will slide well to our south, high pressure remains the dominant controller of weather in the commonwealth. Calm and sunny weather will be name of the game during the forecast period. A low pressure will approach the region on Sunday bringing cloudiness and a chance of precipitation.

Short-term: A few cirrus clouds will pass overnight as a trough moves off the coast. Other than that, skies will be clear overnight and into Saturday.  Clear skies will allow for temperature to jump into the mid 40s tomorrow and dip down into the mid 20s overnight. 

Long-term: As high pressure remains in control, calm conditions and sunny skies will be prevailing throughout the forecast period. Temperatures will not vary all that much and remain seasonable into the weekend. The next weather-maker will approach the area Saturday night bringing clouds and a chance of rain on Sunday. Unsettled weather will remain into early next week.

Some Rain and then Some Sunshine

Synopsis: 

I hate to be the bearer of bad news, but we won't be seeing a break from the rain here in Pennsylvania for at least another day. A strengthening low pressure system (Winter Storm Ceasar) is currently producing blizzard conditions in portions of the northern plains and is forecast to move across the Great Lakes and up into Canada tomorrow. So, we won't get the worse of this system, but we will get the associated cold front swinging through the commonwealth Monday night. In the wake of the storm, temperatures will plunge to more seasonable levels in the lower 40's and the skies will begin to clear, leaving us with a lovely second half of the week.

This Week:

The front looks to pass through the center of the commonwealth around 00Z Tuesday morning and leave much cooler temperatures in it's wake.  The temps will drop surprisingly from Monday (we're looking at a ~20 degree drop over a 24hr period) but will be level out in the upper 30's, which is average for this time of year.

Overall, after the rain clears out, expect clearing skies and building high pressure throughout the rest of the work week.

Sun. PM: Rain and Temperature Swings

Synopsis:

A warm front will slide across the state from SW to NE tonight, bringing us gradual warming after showers move on through. The cold front is expected to move through tomorrow afternoon and evening, bringing us showers, perhaps a rumble of thunder. Behind the front, we'll return to cold air for a day or so; high pressure will gradually build in with plenty of sunshine. As the high heads offshore late in the work week, the southerly flow will warm things up come early this weekend. Temperatures will hover around 40 before midnight and then climb near 60 tomorrow depending on when the cold front moves through.

Models Used:

The 12Z HI-RES NAM handled the timing and extent of the rain well. For days 2-5 (and even slightly beyond), there was general agreement amongst the 12Z runs of the NAM, GFS, CMC, UKMET, and ECMWF.

-Jaron Breen

It's Gonna Rain!

Synopsis: 

A stationary front will stay over the region until Monday night. Until then, a series of low pressure systems will move through along the front bringing periods of rain throughout the weekend and into Monday night. The front will move south Monday night and the rain should be ending by Monday night too. High pressure will build back west behind the stationary front in the Midwest bringing cooler temperatures to our region for Tuesday and the rest of the week.

Weekend Outlook:

Rain continues through the day on Saturday across the commonwealth due to a strengthening low coming from the Ohio River Valley.  This system won't impact us with much rain or wind, but it is forecasted to strengthen significantly as it makes its way into the northeast and up into Canada.  A ridge builds in on Sunday between our next low, providing us with a brief respite from all the rain.  Then, a low from the northern plains and another low from the deep south will join forces to batter our region on Monday as the associated cold front sweeps through.  This front will bring the warm temperatures with it as it sweeps out of our region Monday night. 

Next Week:

Temperatures drop sharply in the wake of the cold front, with highs in the upper 30's across the commonwealth (a bit below average for this time of year).  Also, expect clearing skies and drier conditions starting Tuesday.  These excellent conditions will last for the next couple days through the end of the next work week.  Enjoy the sun when it finally comes out!

Thursday Aftn Technical Discussion

Synopsis: A very active pattern will plague the state over the next five days as pieces of energy ride along the jet stream and right through Pennsylvania. This pattern will keep the chilly weather in Pennsylvania, but even colder air should move in late in the period as a strong cold front pushes across the nation.

 

Short Term: High cirrus as well as some mid-level stratus clouds are pushing through Pennsylvania Thursday afternoon. Expect most areas in Pennsylvania to fall below freezing. This will set up some wintry precipitation Friday morning as a storm system moves west of Pennsylvania. At the moment it seems the GFS has a better handle on the storm than the NAM as far as precipitation coverage so am favoring the GFS solution. GFS sill is overdoing precipitation amounts at the moment so expect it to be high as well. Portions of central Pennsylvania will hold on to the cold air at the start of the rainfall leading to periods of freezing rain as the storm pushes west of Pennsylvania. The rain will be light at the onset and so rain will freeze to surfaces quickly. Most areas will see between a tenth to two tenths of an inch of ice at most. The freezing rain will switch to plain rain by mid-afternoon. All other portions outside of Pennsylvania should only see plain rain for the entire storm. All rainfall should end overnight on Friday leading to some dry conditions for at least part of the day Saturday.  

 

Long Term: Saturday should see some partial clearing before another piece of energy moves west of the state again. Since clouds will still be spread across the state, no areas will be able to fall to freezing and so am not expecting any wintry precipitation from the storm on Saturday. Periods of rain will move through Saturday before ending around midday Sunday. From here the forecast becomes tricky as all three of the major models have their own ideas on some large pattern changes for early next week. The GFS has the cold front much slower as it comes through Monday night with very cold air behind it. High pressure builds in behind the cold front leading to dry conditions for a least a few days. The NAM on the other hand brings it much quicker and occludes it into Ontario. It then brings a storm along the cold front as it pushes through which rides just off the coast. The EURO is the most interesting scenario as it is similar to the NAM and quickly occludes the low into Canada and then rides a storm up the front. The storm however stays on the coast and leads to a coastal storm with snow likely in western Pennsylvania and New York. Am favoring a NAM/EURO solution as the NAO should be around -2 to -3 during the time frame leading me to believe a coastal storm is likely. There are many things to watch over the next few days as many possibilities exist with this cold front. One thing is for sure, cold air will return after the cold front pushes through. 

Wed Afternoon

Synopsis: Northwest flow will continue to advect cooler air into the region as high pressure builds in for tomorrow. Seasonable temperatures and tranquil conditions are expected until a more unsettled pattern sets in for the weekend.

Short Term: Strato cumulus clouds will persist through the evening, before dissipating overnight. This clearing will allow for radiative cooling. Temps in the low 20's are not out of the question for upper elevations. 500mb ridge will approach the region tomorrow. Evident upper level convergence is expected. Dry and tranquil conditions will be the story for tomorrow. Persistence method could be used for temperatures, as there is not much change from today. As the ridge axis passes late tomorrow, we will find ourselves in warm advection, so tomorrow nights lows will not be as bone-chilling as tonights. 

Long Term: As high pressure departs, the upper level flow becomes zonal. Several disturbances will pass to our north in the long term. The first of these, a small area of 500mb shear vorticity, will set up in the Ohio valley early Friday. Upper level divergence ahead of it will cause upward motion over the commonwealth. Temperatures will be below freezing for points north of State College, after a very chilly night. There is a potential for freezing rain in northern zones early Friday, before changing to all rain as temps warm through the day. Another shortwave will move to our north on Saturday dropping a weak cold front through the region. Nothing more than a few showers is expected. The real threat comes early next week, as a classic winter cyclone approaches from the southeast. Models are converging on a solution that brings through the great lakes. This puts our region in the warm sector, meaning we can expect above average temperatures in the long term.