Thursday Evening Techinical Discussion

Synopsis

 A ridge of high pressure will build into the region early Friday. Behind this ridge, an area of low pressure system will move over southwestern Pennsylvania on Friday night. After this low pressure, another above period with warm weather will return for the first part of the week. However, an upper level trough and associated cold front could move through Pennsylvania late in the day on Tuesday.

 

Short Term

With clear skies and light northerly winds, temperatures will below freezing in most areas. Temperatures will warm up quickly Friday before clouds increase in the afternoon. An associated surface low pressure system will move into the region Friday night/Saturday morning. Scattered showers and generally cool conditions are expected for the duration of the event.

 

Long Term

A high pressure system will build into the Eastern U.S. during the day Sunday. Mild and calm conditions will follow and remain into early next week. Temperatures should be above normal as a result. There is a chance for a cold front to pass through the area on Tuesday evening.

Wednesday Night

Synopsis

Conditions will cool off greatly tonight in the wake of a cold front that passed through the region earlier this evening. A short-lived area of high pressure will build into region late Thursday. A shortwave will race across the state bringing a chance of precipitation Friday and Saturday. Warmer conditions will make their way back into the forecast on Sunday and remain into early next week as a high pressure builds into the Eastern U.S.

Short Term

Winds are currently turning north-west and overnight a northwesterly flow will dominate the state. This flow will allow for some cloud cover and some cold air advection. As a result, conditions will be much cooler on Thursday than Wednesday. As the winds calm down on Thursday, clouds will begin to clear up. Clear skies will prompt temperatures to dip into the upper 20s causing a freeze in a large portion of the state. 

Long Term

Friday evening a shortwave will move into the region from the Midwest. An associated surface low pressure system will move into the region Friday night/Saturday morning. Scattered showers and generally cool conditions are expected for the duration of the event. At the moment there is a lot of uncertainty pertaining the timing of the shortwave. Precipitation could impact the commonwealth anytime between Friday afternoon and Saturday afternoon. A high pressure system will build into the Eastern U.S. during the day Sunday. Mild and calm conditions will follow and remain into early next week.

Synopsis: A cold front will move through the state later this evening. Northwesterly winds behind the front will usher in much cooler air. An area of high pressure will move through the region later tomorrow into Friday, bringing fair weather. An area of low pressure will move south of the state later Friday night into Saturday bringing the threat of showers.

Short Term (Tonight into Thursday Night): A brief shower is possible as the front passes through later tonight. Behind the front, a gusty northwesterly breeze will develop ushering much colder air. Temps will be at least 15 to 20 degrees cooler tomorrow than what it was today. Clouds will decrease throughout the day as high pressure moves over region. Tomorrow night will be a cold one with clear skies and light winds, however, temperatures will not be as cold as Tuesday morning.

Long Term (Friday Through Saturday): Clouds will increase on Friday ahead of the next disturbance, which will pass south of the state. There is general consensus among the European and GFS models that showers will spread into Western PA by late afternoon and through the rest of the state throughout Friday night. The showers end by late Saturday morning. Fair weather will return on Sunday as the area of low pressure exits off the east coast.

Tech Disco 3-26

Synopsis

The unseasonably warm air that has given the state record breaking temperatures for the past two weeks is gone and reality has finally set in. A cold front associated with cold outflow from Canada, will bring the state to its climatological norms for the week, with just one day showing a warm spike associated with an incoming storm system in the middle of the week.

Short Term

For the remainder of tonight, a tight pressure gradient will persist prior to midnight tonight, leaving breezy conditions throughout the state this evening. As the surface ridge approaches, high pressure will settle in and fully dominae early Tuesday afternoon, killing the winds and leaving only the sun to warm the state into the lower 50s. Behind this ridge, and incoming system with weak frontogenesis on the southern part will approach the state overnight Tuesday, bringing with it high clouds and faster winds ahead of its core as the afternoon and evening progress.

Long Term

The aforementioned storm system will cross over the state Wednesday afternoon. There is a cold front within the surface trough, but within the presence of little PVA and no ither surface perturbations to help it organize, the front is weak and only shows a broken line of showers moving west to east and falling apart over the mountains. This cluster will move through Wednesday afternoon, and will develop after passing the state. The low's development will be enhanced by PVA aloft that was lagging the low well behind during Wednesday afternoon, but a 500mb shortwave trough will catch up to this system overnight Wednesday into Thursday, allowing for storm development along the front (at this time toward our south) but also will give us low clouds and enhanced cold advection during the overnight hours. The shortwave will stick around throughout the afternoon, keeping the clouds and advection above and within the state, but a high will be moving on through Friday, calming the winds, nd working together with the ridge aloft to provide more sun to help us get back to the warm spring ythe state was experiencing before.

Steve Engblom Dos

WED NIGHT

SYNOPSIS: A strong upper level ridge will continue to bring unseasonable warmth to the region through Friday. A low pressure system will bring unsettled and cooler weather for the weekend.

 

SHORT TERM: A strong upper level pattern will continue to impact the region through Friday, though it will begin to lose its grip on the region by the beginning of the weekend. Dense Fog can be expected Thursday morning, but will diminish by late-morning. Temperatures will remain well above normal for Thursday and Friday. A mid-latitude cyclone, developing over the southern portion of the country, will begin its slow track northeastward. This will bring showers as early as friday night.

 

LONG TERM: The breakdown of the strong upper level ridge will allow a low pressure system to slowly impact the area this weekend. Light to moderate showers can be expected most of the day saturday and sunday, as the system moves to our south. Cooler conditions will result from this. Behind that system another upper level ridge will bring tranquil conditions for early next week.

Wed Afternoon: Very Warm then Wet & Cool

Synopsis:

Despite an upper level ridge and surface high pressure in control for the rest of the work week, fog will occur tomorrow. When that burns off and when the clouds move out will largely determine whether temperatures pass or fall short of the 80-degree mark tomorrow and Friday. Meanwhile, a large cut-off upper-level low currently producing severe weather in the Lower Mississippi River Valley will make its way NEwd throughout the week. This should lower temperatures and the formation of a surface low on Saturday will increase the chance for precipitation in the form of RAIN. Skies clear next week as high pressure returns and temperatures begin to rebound.

Models Used: 12Z Runs GFS & Hi-Res NAM

Short-term:

An easterly flow north of an area of weak upper-level divergence is bringing clouds and moisture into the region tonight. The moisture will allow for fog to form in the valleys. Tomorrow morning, the temperature should rebound nicely into the mid-70s due to afternoon sunshine and some warm air advection. If the cloud cover doesn't break up until late, the high will struggle to get past 80, but if the fog burns off quickly and the clouds disappear quickly, then we could break the record high of 82 set back in 1938 tomorrow. Aw for Friday, cloud cover increases ahead of the cut-off low. Temperatures should be near 75 despite the late clouds. Lows will remain in the 50s.

Long-range:

The cut-off low will head toward us, arriving on Saturday morning. A surface low will begin to develop offshore and head north-northeast, but it is too far off the coast to produce a lot of rainfall. Regardless, it will be wet and cool, but still above average temperature-wise during the week. Also, a weak cold front will stall to our north, but this feature will have no effect on our weather what-so-ever.

-Jaron Breen

Tuesday Midday

Synopsis:  Morning fog burns off, upper level disturbance finally leaves, high pressure dominates until cold front pushes through late Thursday.  Cut off low in Midwest affects us Saturday.

Short-term: Everyone is cloudy and foggy.  The fog should burn off to partly sunny skies, allowing for scattered showers to develop as the upper level disturbance lingers during the day.  This disorganized disturbance will push out overnight.  Wednesday everyone will see sun, but we cannot rule out an isolated shower.  Same for Thursday.

Long-term:  As Thursday evening pulls up, a backdoor cold front will push through, bringing slightly back to normal for Friday.  The cut off low in the Midwest will start to enter the Commonwealth Friday Night.  Both the GFS & EURO have similar solutions; they maybe off by 3 hours or so.  Saturday looks to be a rainy day across the Commonwealth.

Kept temperatures near previous shift, with minor changes.

Tech Disco 3-19

Synopsis

The unseasonable warmth that we've been experiencing for the last week is showing no signs of leaving as a well pronounced ridge will dominate the weather pattern for the upcoming week, maintaining a stagnant area of high pressure over the entire Eastern U.S. An Atlantic high will generate a dominant southerly component to the wind, allowing more heat and humidity to fuel this late-Spring like winter right at the official start of spring.

Short term

A shortwave at 500mb is generating the clouds that we are seeing now, and the enhanced lifting from topography is helping for scattered showers to develop across the ridges within the state. This shortwave is nestled within a large ridge along the Eastern U.S. and will gradually get sucked into the tropics as the week progresses.  The NAM and GFS have showers around the area tonight into Tuesday morning, but the 4km Nam and 3km HRRR show the showers slowly progressing east and leaving the state by Tuesday morning. The shortwave also follows this general path, but it will curve South throughout the day Tuesday and the Atlantic high will begin to dominate, advecting warmer air as it slowly tracks south throughout the week. 

Long Term

Little changes come for Wednesday and Thursday, but with the shortwave out of the state, fewer clouds and added sunshine combined with warm advection will help break some records in the temperature department. The Atlantic high will continue moving down the coast, adding more southerly flow and warm advection, but also, a large trough in the West being blocked by the immense ridge in the East will cut off a large portion of positive vorticity, and this cutoff low will begin churning up a storm over Oklahoma and Texas Thursday afternoon. Cyclogenesis here will be rapid, with strong vorticity creating a well occluded surface low in a matter of a half-day. On Friday, this low will move closer, and the warm advection induced from sandwiching between this low and the Atlantic high will send PA high temps around 80 for many spots around the southern half of the state. Although MOS caps the State at around 78, the dynamics are there, something MOS cannot factor in too well. The storm will finally dump it's contents overnight Friday into Saturday, but this is too far range to determine the severity of these storms just yet, but the synoptics  suggest that the storm at this point is transitioning into the decaying phase, leaving us knowing that tornadic storms are somewhat possible, just like those we saw this past week.

WED NIGHT

Synopsis: An upper level ridge, currently over the region, will remain in place for at least a week. Temperatures will continue to rise to above normal values. A weak area of low pressure will bring showers and thunderstorms late in the day Thursday into Friday. Tranquil conditions will return for the weekend, with temperatures cooling slightly but remaining above normal. Dry weather and warmth is expected into at least early next week.

 

Short Term: Temperatures will soar into the mid-70's for much of the region on Thursday. Depending on how much sun the region gets, some highs may be even higher. A warm front associated with a weak area of low pressure will move through the region late in the day on Thursday. The effects of moisture advection, unseasonable warm temperatures, and vertical sheer leads to the possibility of some severe storms tomorrow evening, especially in the western portions of the state. As the system moves through, a cold front will pass during the day on Friday. This will provide another threat for showers and thunderstorms.

 

Long Term: Slightly cooler conditions, accompanied with dry weather will be the story for the weekend. It should be noted that temperatures will still be well above normal for this time of year. As we progress into early next week, the current upper level ridge will amplify, bringing a prolonged period of dry weather. This will last through the work week.

Synopsis:

High pressure will remain in control through at least tomorrow afternoon, before a weak disturbance coming in from the Great Lakes will bring a chance of showers and thunderstorms later Thursday afternoon into Friday. High pressure will build in for the weekend bringing drier weather. An anomalous strong upper-level ridge will build in across the Eastern U.S. through next week, with well above normal temperatures continuing.

Short Term: (Tonight through Friday Afternoon)

High pressure will provide for mainly clear skies through tonight with temperatures dropping in the upper 30s across the northwest to upper 40s to near 50 across the southeast. The main weather story for Thursday will be the warm temperatures and the chance for precipitation. With abundant sunshine and southerly winds, most places should see highs reaching into the lower to mid-70s, with a few spots near the southern border flittering with 80 degrees.  With a weak disturbance approaching from the Great Lakes, the threat for pop up thunderstorms exists. CAPE is forecast to be between 500-1000 J/KG with decent lapse rates, however, the 0-6km shear will remain between 10-20 knots and forcing will be rather weak. Therefore, widespread convection is not very likely.  The threat for showers will continue into Friday afternoon, before high pressure builds in later Friday night.

Long Term: (Saturday through Next Week)

High Pressure will build in off the New England Coast through the weekend providing for dry conditions. An easterly flow will keep temperatures cooler with highs reaching into the 60s. By early next week, all model guidance is showing an anomalous strong 500mb ridge building in across the Eastern U.S, providing for potential record warmth across the commonwealth.

Tuesday Midday

Synopsis:  Trailing cold front pushes through with scattered showers, high pressure builds in for the middle of the week before a disorganized system pushes through on Friday.

Short-term: Line of scattered showers pushes through today, but things will not cool down.  All the models agree with clearing behind the front coupled with high pressure building back in for Wednesday.

Long-term:  High pressure in control until late Thursday as it gets pushed off to sea, as a disorganized shortwave moves in for Friday.  Clearing occurs afternoon on Saturday.  The models are still trying to pin down the disorganized shortwave for Friday, went with the faster solution.

Kept temperatures near previous shift, with minor changes.

Tech Disco 3-12

Synopsis

Today we saw how a ridge aloft combined with warm advection can warm the state well above average in terms of temperature, and this wamth will remain persistent throughout the week as well as next week as higher heights remain within our general vicinity for a long time to come. We'll have a few perturbations to this based on showers and fronts, but there are little dynamics helping to induce surface convergence, cyclogenesis, and frontogenesis leaving us to believe this week will be rather bland for activity, but pleasant for the "early taste" of Spring.

Short Term (Tonight through Tuesday)

With a low advancing and clouds starting to settle in, as well as rain falling in the west, tonight will be dominated by rainfall throughout the eastern 75% of the state. The current rainband is covering about a third of the state, and it took about 5 hours for it to completely cross the Ohio border. This shows that this first band should be out of the state by sunrise Tuesday, leaving about .10" in the east to 0.25" in the west in its wake.  There is a second band of rain oriented along the low's cold front set to impact around 12z in Erie with light rain, based upon lifting along the front over Lake Erie, with a northwesterly wind involved as well. This will be a short lived band, dissipating quickly over the mountains throughout the morning. To note about the models: the 12z GFS has a better grip on the rain right now, just slightly better than the NAM, making the GFS more believable. The GFS backs down on the lake enhanced rain, but it has a trace, and the GFS in general cannot resolve fine rainbands such as that one, giving us a good feeling for light rain in Erie in the morning. Behind this. An area of high pressure will begin to move in , allowing for decreasing clouds throughout the evening and overnight hours Tuesday. This is also when the next ridge will move in, allowing for temperatures to return to the mid 60s to near 70s regime, well above average for the state as a whole.  

Long term (Wednesday thru Friday)

 With this high moving in, there is a strong presence of a W to WNW wind.  The high's positioning implies a wind blowing perpendicular to the ridges and valleys, and even though the models stray away from clouds Wednesday afternoon, the dynamics in this situation imply low level gravity wave clouds that form,  implying for more clouds than what the models suggest.  This should not heavily impact the temperatures for the day, maintaining decent sunlight within a ridge and keeping temperatures above average. This ridge remains in place throughout the remainder of the week. The models, however, have isolated showers along the eastern U.S. Thursday afternoon. The oresence of this in a strong rideg makes in unfeasible, especially without PVA for it's accompanying low, but there is warm advection throughout the entire area, along with a cast area of radiation, implying that these cells are primarily the result of convection with showers forming from moisture collected from the Great Lakes. The net propagation of the system is eastward, so there is a decent chance for showers Thursday afternoon, and as the system moves further east Friday, the 12z long range GFS shows the low as merely a broad area of convergence with this convection. With this in mind, we could see convective clouds and showers Friday, atypical of late winter and more typical of mid Summer. However, this is an atypical late winter setup, so refreshed model runs will hopefully give us a better grasp on this late week scenario. Also, note the massive oblong ridge for next Tuesday, we have 500mb heights cveragin around 5800m for PA, which may induce record high temperatures for next week!