00:00 - From the band Family Studios in the Department

00:03 - of Meteorology and Atmospheric Science at Penn State.

00:07 - This is Weather World.

00:20 - Good evening, Pennsylvania, and welcome to Weather World.

00:22 - On this Friday it is now May.

00:25 - I'm Marissa Berger alongside Rob light.

00:27 - Rob this morning a crisp start with lots of sunshine.

00:30 - It felt good once the sun came up, but, things have changed very quickly here

00:34 - across the Commonwealth. Yeah, quickly had a storm system move in.

00:36 - Now, some folks seeing some rain.

00:38 - We'll see some of the rain showers subside this evening.

00:40 - Another frost freeze on the way.

00:42 - Okay, well, Rob will give us all the details

00:44 - of the forecast coming up in just a moment.

00:47 - Also tonight,

00:47 - I'll have the extended forecast, which will take us through the next workweek

00:51 - and will feature some ups and downs in the temperature category.

00:55 - And Giannis will be here with two trends.

00:57 - But first here's Rob and thanks a lot Marissa.

00:59 - It certainly felt like a crisp fall morning across the Commonwealth

01:03 - as we began temperatures below freezing in several spots

01:06 - across the northwest plateau down to 28 degrees this morning in Bradford.

01:11 - A low to mid 30s in several spots in the Laurel Highlands.

01:14 - Also, some, temperatures actually in some parts of Center County

01:17 - that were below freezing this morning off to the south and east,

01:20 - upper 30s to near 40, but certainly another cold start on the way

01:24 - as we go through both weekend nights of this weekend.

01:28 - Because of that, we do have some frost and freeze alerts to talk about.

01:30 - Freeze warning in effect for all of the county shaded here in purple.

01:33 - That includes the spine of the laurels.

01:36 - Also a Frost advisory, excuse me across southwest Pennsylvania

01:40 - includes the Pittsburgh Metro, these counties shaded here in blue.

01:43 - A freeze watch in effect for the Wyoming Valley,

01:45 - and some of the hollows there could drop near freezing.

01:48 - Make sure you cover those plants both weekend nights.

01:51 - As we take a look at our cam this morning at the Penn State golf courses,

01:54 - you actually see some of the frost on some of the grass here.

01:57 - Beautiful start to the day.

01:59 - And then we saw some more clouds move in and eventually some rain showers.

02:02 - As we went into the afternoon.

02:03 - Western and central Pennsylvania

02:05 - seeing some rain showers continue as we go through this evening.

02:09 - You can see our on our satellite radar perspective here.

02:11 - This is a pretty weak storm system.

02:13 - A lot of the rain that has fallen

02:14 - only totaling around a 10th of an inch in many locations.

02:17 - Some lucky spots seeing close to a quarter of an inch,

02:20 - staying dry off to the south and east.

02:22 - You'll see less as we go through this evening,

02:24 - but some of those showers continue to make their way from west to east,

02:26 - and eventually clearing overnight will set the stage for more frosty conditions,

02:31 - especially in the west.

02:32 - Once again,

02:34 - where we had had the clouds and the rain showers today, temperatures

02:37 - have been held back.

02:37 - Certainly not feeling like May 1st, 40 in Bradford.

02:41 - We were in the mid 50s

02:42 - in the central mountains, but down to the upper 40s as of 430,

02:45 - with some downsloping winds, we've had temperatures

02:48 - make it to the low to mid 60s off to the south and east,

02:50 - but generally temperatures around 8 to 15 degrees below average.

02:54 - And we'll stay there both Saturday and Sunday

02:57 - as we take a look across the lower 48.

02:59 - Really no big heat to be found with the exception of Florida,

03:02 - they're expecting temperatures there in the 90s this weekend, 84 in Phoenix

03:06 - will eventually see

03:07 - the return of warmth

03:08 - across the Pacific Northwest, with some 90s likely there this weekend.

03:12 - But across Texas, where they've had some heavy rain today,

03:15 - most of those locations anywhere from 15 to 20 degrees below average,

03:19 - I mentioned the cool air continues

03:20 - to be locked in across the Midwest and Northeast this weekend.

03:25 - Here on the satellite radar perspective, we've had a series of weak storm systems

03:28 - kind of rotating through the Great Lakes.

03:29 - That's one storm system that will be passing by tonight.

03:32 - Another disturbance will provide a shower chances

03:34 - as we go into the day on Saturday, but not widespread.

03:37 - This storm system stays off to our south, eventually develops a coastal low

03:41 - that will provide for some much needed rainfall in the Deep South and Florida,

03:44 - where they've been dealing with drought conditions and wildfires as of recent

03:49 - year.

03:49 - That storm system that will cross us as we go through tonight.

03:51 - Eventually, high pressure will make its way eastward,

03:54 - but we will still contend with the chance for a few spotty showers.

03:57 - I think in fact, in northwest Pennsylvania,

03:59 - there is a chance for a few isolated snowflakes

04:01 - in some of the higher elevations to begin the day tomorrow.

04:04 - Otherwise, we'll see clouds clear out once again and more sunshine

04:07 - on the way as we wrap up the weekend on Sunday.

04:09 - That's probably the pick of the weekend.

04:11 - The better of the two days.

04:13 - So as we take a look at our forecast for tonight, further frost and freeze

04:16 - likely and some of the same spots

04:18 - that had it last night, upper 20s across the Northwest Plateau,

04:21 - make sure you cover those plans

04:23 - and the evening showers will lead to some clearing

04:25 - before we see some drips and even flakes possible.

04:27 - By dawn, clouds will linger across the southeast, so temperatures

04:30 - stay in the 40s there, with showers tapering late across the Wyoming Valley

04:35 - as we go into the day

04:36 - on Saturday, temperatures still 8 to 15 degrees below average.

04:40 - Limited sunshine.

04:41 - We will contend with

04:42 - a few spotty showers off and on throughout the day in the West,

04:45 - mainly during the afternoon in the central mountains.

04:47 - A few sprinkles late in the day in the Poconos.

04:49 - Staying mostly dry there though, and temperatures low to mid 60s

04:53 - southeast with another frost freeze likely as we begin the day on Sunday.

04:57 - High clouds overhead after a chilly start.

04:59 - Otherwise a pretty pleasant day.

05:01 - The pick of the weekend.

05:02 - More afternoon

05:02 - clouds in the west with some rain showers possible at the exact moment.

05:10 - You. May is upon us during this extended forecast period,

05:32 - and it's going to feel like it at least in the early part of next week.

05:36 - But by the time we get to Thursday and Friday, oh boy.

05:39 - Taking a backwards step on the calendar, at least as far as temperatures

05:43 - are concerned.

05:44 - Before we get to that, here's the water vapor satellite imagery

05:46 - and we can really see this big, close low across eastern Canada.

05:52 - And that is impacting our weather not only now, but as we go through early

05:56 - next week.

05:56 - You can see it just sitting here over Hudson Bay as we start the week off.

06:01 - Now, it's going to send pulses of energy around it in the upper levels,

06:06 - and that's going to impact our weather here down at the surface Monday,

06:10 - not seeing too much to some partly sunny skies and maybe a few scattered showers.

06:14 - Big change on Tuesday is that with the way this is oriented,

06:18 - we're actually going to be getting some pretty strong southwesterly winds aloft

06:21 - that's going to actually usher in some warmer air at the surface.

06:25 - It's also going to help lead a cold front towards Pennsylvania

06:28 - that's going to move in sometime late Tuesday into Wednesday,

06:32 - and that's going to bring us,

06:33 - I think, our best chance of widespread showers and thunderstorms.

06:36 - Also the chance for a big temperature difference across the state on Wednesday.

06:42 - And then once that swings through, look at this.

06:44 - We see these, the winds change aloft and they're more northwesterly

06:48 - by the end of the week.

06:49 - Really cold air moving in for this time of the year.

06:52 - By the time

06:52 - we wrap up the end of next week, now we're taking things down to the surface.

06:56 - The precipitation tracker

06:57 - can also see our isobars, which are lines of equal pressure.

07:01 - And what we think this model thinks.

07:02 - The surface winds are going to be.

07:04 - We see this southerly flow on Monday.

07:06 - Again, not much going on, just a chance for a few isolated showers.

07:10 - Tuesday is when we see some big changes in a few ways.

07:14 - This is where this cold front

07:15 - is going to be located in the eastern Great Lakes ahead of it.

07:18 - Much warmer air streaming, and this is going to be the warmest day of our week,

07:22 - but this is also going to usher in the chance for some widespread showers

07:26 - and thunderstorms, especially throughout the day on Wednesday.

07:29 - This model, which is the European model, actually has the front bisecting the state

07:33 - on Wednesday, which means very warm day in southeastern Pennsylvania.

07:37 - But then the cold air starts flooding into northwestern Pennsylvania.

07:40 - By the time we get to that afternoon, and then Thursday and Friday,

07:44 - as this pushes eastward, we get the more northwesterly flow in

07:47 - and I think some instability showers,

07:49 - some of which in some of the northern counties and higher

07:52 - elevations could contain

07:53 - not just rain but a little bit of mixed precipitation as well.

07:57 - So our forecast shows us that Monday just a few

08:01 - isolated showers are best chance to see some sunshine.

08:04 - I want to point out this time of the year across

08:06 - Pennsylvania mid 60s to low 70s are average high temperature.

08:09 - So Monday not too far from average Tuesday ahead of that cold front

08:13 - we actually bump up.

08:14 - It's going to be the warmest day of the week,

08:15 - despite the fact the cloud cover

08:17 - is going to be moving in late Tuesday into early Wednesday.

08:20 - Best chance for widespread rain, maybe even some thunderstorms.

08:23 - Temperatures begin to fall on Wednesday, but we really notice

08:26 - that temperature plunge as we go into the end of the week,

08:29 - with highs about 10 to 15 degrees below average.

08:33 - Chance for some scattered showers, maybe even some mixed precipitation

08:37 - across some of the high

08:38 - ground of the north and by Friday, winds are going to be quite chilly

08:41 - throughout the day.

08:42 - We'll be back with week two trends coming up next.

08:57 - The last

08:57 - forecast segment every week on Weather World is called week two trends.

09:00 - The idea here is to look beyond the extended forecast into the period 8

09:04 - to 14 days out.

09:06 - This would start next Saturday and extend through two weeks from today

09:09 - and try to identify trends.

09:10 - For example, will temperatures be above or below average?

09:14 - I think in this week two period.

09:16 - The overall pattern simply does not favor temperatures

09:19 - being above average, at least not for any long stretch of time.

09:23 - If we're going to assess whether temperatures are above

09:26 - or below average, it helps to know what those averages are.

09:28 - And here's what they're where they will be in the middle of the week two period.

09:32 - The rate at which the averages are increasing

09:34 - has now dropped to about a degree and a half a week.

09:37 - As we're,

09:39 - slowly gaining daylight, but not as quickly as we once did.

09:42 - By this time, we'll be gaining daylight at the rate of about two minutes per week.

09:46 - Notice by this time,

09:47 - if the temperature gets to 70 in central Pennsylvania, that would be average.

09:52 - By that time, we're going to use something called ensemble forecasting.

09:55 - We're going to show you the solutions from about 30 different simulations.

09:59 - These are pressure lines up around 20,000ft.

10:01 - We use these in a couple of ways.

10:03 - First of all, the wind tends to follow these lines from west to east.

10:06 - And where these lines dip to the south,

10:08 - these are areas of relatively cold air at high altitudes.

10:11 - This can sponsor chilly air at the surface as well as storminess

10:15 - and where they bulge to the north.

10:17 - We call these ridges relatively warm air at high altitudes that often translates

10:21 - down to the surface and often sponsors, dry weather as we go through time.

10:26 - Notice a pool of cold air over the northeast.

10:28 - By the time we get to Wednesday that will have actually rotated around

10:32 - and now be poised to our west so that by the time we get to next Saturday,

10:36 - the upper air pattern doesn't look all that different than it does today.

10:40 - And so I do think next weekend, notice

10:42 - how some of these blue lines are sneaking into Pennsylvania next Saturday.

10:46 - Most likely below average temperature wise next Sunday.

10:49 - Same thing, although I think temperatures will moderate just a bit

10:53 - now. By this time the lines are really starting

10:56 - to overlap each other, so I'm just going to average all the solutions together.

11:00 - And what that shows us is that the dip in the pattern

11:03 - still resides over the eastern United States at the beginning of week two,

11:08 - and I think there will probably be some sort of significant disturbance

11:11 - that goes through the eastern United States.

11:14 - The timing is always difficult this far out,

11:16 - but perhaps Monday or Tuesday of week two, bringing the best chance

11:19 - of getting some rain.

11:20 - And after that,

11:22 - although the blue colors here representing the chill, migrate

11:26 - a bit off to the northeast, we're still not into the amber colors, the warmth.

11:30 - And so I think it will be a challenge to get temperatures

11:33 - to go back above average, at least for any long period of time.

11:37 - And so the temperature line in the week two trends chart here is speckled

11:41 - with light blue, representing, that I am leaning toward below average temperatures.

11:47 - The overall pattern simply does not favor above average temperatures,

11:51 - and I just have one area of rain here indicated, say most likely in the Monday

11:55 - to Tuesday range timing, precipitation systems

11:58 - this far out is always challenging, but that one looks like it has the potential

12:02 - to at least provide a decent rain to the Commonwealth.

12:06 - That's it for week two trends.

12:07 - We will be back in a moment with more.

12:21 - We've got another night with some frost freeze conditions on the way,

12:24 - especially in western and central Pennsylvania for some evening showers.

12:28 - Clear out.

12:29 - We'll see those clouds

12:30 - also dissipate before more drips and flakes are possible by dawn.

12:34 - In between, I think we'll see those temperatures

12:35 - drop below freezing all the way down to the Laurel Highlands.

12:38 - So cover any plants that you don't want to get a nipped by the frost tonight.

12:42 - Meanwhile, clouds hang tough off to the southeast, temperatures in the 40s there.

12:45 - Any showers northeast will taper off overnight

12:48 - as we go into the day on Saturday.

12:50 - Not much in terms of sunshine.

12:51 - Some spotty showers, but not a washout by any means.

12:54 - The best chance for rain will be during the afternoon

12:56 - in the central part of the state.

12:58 - Sprinkles arriving late in the day off to the east.

13:00 - Temperatures about 8 to 15 degrees below average for this time of year.

13:04 - Another frost freeze as we begin the day on Sunday,

13:07 - but it's going to be the pick of the weekend.

13:08 - More sunshine after that chilly start.

13:10 - Temperatures mainly in the 50s to lower 60s, clouds not hanging tough.

13:14 - We'll see more sunshine likely.

13:15 - More clouds actually do begin to arrive, though.

13:17 - In the afternoon in the west, with some scattered rain possible

13:20 - north and west overnight.

13:21 - But really no big rain chances this weekend.

13:23 - Marissa okay, well, we don't have the rain,

13:26 - but we have the cool air in place as we start the month of May for sure.

13:30 - All right. Well, thank you so much, Rob, and thank you for joining us.

13:32 - Come back next week.

13:33 - It's a bittersweet week here on Weather World

13:35 - when we say goodbye to some of our seniors. We'll see you then.