00:01 - From the band family studios in the department of

00:04 - meteorology and atmospheric science at penn state

00:08 - this

00:08 - is whether world.

00:23 - Second twenty twenty sucks

00:25 - on your host then the others join alongside by your forecast or burn rubber

00:29 - and then today's certainly the

00:31 - same sticky and muggy day outside Logan

00:33 - almost getting up into the hundreds and lots of places in

00:36 - Pennsylvania

00:37 - but potentially looking to downgrade that just a bit eventually but yes today a

00:42 - couple of records falling for others the hottest day in fifteen years if you're into

00:46 - this sort of thing we're going to do it again tomorrow before those changes certainly

00:50 - sounds like a ban we'll get to that shortly here in your short range forecasts

00:53 - but later here on weather world today we're going to take it back a couple of decades

00:57 - and be looking at the weather during the revolutionary war

00:59 - and the battle of gettysburg but first

01:01 - here's been.

01:03 - Thanks very much land in today yeah just some really

01:05 - nasty stuff out there in fact it's a good time to

01:08 - check in on

01:09 - the last time that we had triple digits at our major sites and thanks to Rob light

01:14 - for doing some data sleuthing today

01:16 - the Pennsylvania one hundred degree day is not a usual thing.

01:20 - Despite Philadelphia doing it last year the next closest to turn was Harrisburg a

01:24 - couple of years ago elsewhere it's been quite a while and hundreds

01:28 - have been wild today southeast of pretty much interstate

01:31 - seventy eight here the temperatures as of four thirty

01:34 - allentown to Harrisburg south and east many

01:36 - thermometers getting above one hundred today

01:39 - and elsewhere

01:40 - well into the nineties and most spots interestingly enough only to record highs

01:44 - officially so far Williams port at ninety nine

01:47 - and the one oh three at reading elsewhere it's just

01:49 - really really hot but not quite rare heard breaking today

01:53 - do points once again

01:54 - that tropical feel out there although I actually have

01:57 - come down a bit today in eastern pa which has helped

02:00 - the temperatures to pop up it's a little bit easier to heat up

02:03 - dry air than it is humid air

02:05 - and I think that's why in central and western Pennsylvania day the temperatures have

02:09 - not been overly impressive at least to a record bro making level

02:12 - or anything like that but nevertheless you combined the temperature with the humidity

02:16 - not feeling good at all heat index values well above one hundred and eastern pa

02:20 - well into the nineties or the low one hundred central and west

02:24 - and we're going to do this over again tomorrow that

02:26 - is why the heat advisory for the higher elevations

02:29 - and the extreme heat warning in eastern and south

02:32 - southwestern Pennsylvania remains in effect through Friday

02:35 - because we are going to basically have a repeat performance of today

02:39 - once again tomorrow before we start to see some more notable changes move in

02:43 - today we were pretty much right underneath the big Ridge of high pressure it features

02:48 - a lot of sinking air very warm air columns from top to bottom really hard to ge

02:52 - generate clouds and certainly any precipitation when you're right underneath the

02:56 - Ridge all of the action forced to rotate around the periphery eventually as this area

03:01 - of high pressure starts to contract and break down we will end up in the periphery

03:05 - and that is going to begin as early as tomorrow but more notably so

03:09 - as we get into independence day itself so the weather map shows that area of high

03:13 - pressure anchored near us or just to our south and

03:15 - west as we get into tomorrow this will slowly begin

03:19 - to break down and move to the south and west that will allow the opportunity for a

03:23 - few thunderstorms and a few spots late tomorrow

03:26 - more notably those we get into Saturday

03:29 - as this front drops in from the north that will act as a fall arcing mechanism as

03:33 - this drops into a hot humid air mass I think Saturday afternoon and evening

03:37 - could start to become fairly active at least for some of us

03:41 - tonight though not active at all it will be mainly clear very little wind

03:46 - many of these overnight lows would be record warm lows some of the big cities not

03:50 - even dropping below eighty degrees to a night so certainly

03:54 - sultry as we head into Friday I'm calling it a dangerous deja vu very similar to

03:59 - Thursday hundred south and east ninety's pretty much everywhere else blazing sunshine

04:04 - couple of thunderstorms could pop up especially east and northeast in the afternoon

04:09 - not many folks see one but if you do it does have the opportunity a

04:13 - to be on the strong side

04:14 - more organized storms I think arrived northern west late

04:17 - that's a sign of things to come for Saturday where changes start to arrive

04:22 - another hot one south and east and then as that front moves in late in the day some

04:26 - thunderstorms and downpours will start to fire up

04:29 - northern west could really shower at any time but it will not be as hot there

04:33 - this is going to lead to a much more unsettled Sunday we think where

04:37 - an area of low pressure could traverse that front showers

04:40 - thunderstorms and downpours could be around at any time

04:43 - temperatures not nearly as hot

04:45 - and we will be back to.

04:53 - And

05:12 - and.

05:19 - Today we celebrate the end of the revolutionary war

05:23 - it was on October eighteenth seventeen eighty one

05:26 - that the British general cornwallis surrendered

05:28 - to George Washington at yorktown Virginia.

05:31 - For sale seven long years the war had raged

05:34 - but at long last it ended

05:36 - and at least for the colonists the weather proved to be a faithful ally

05:40 - in their fight for freedom.

05:43 - From the early days of the war the weather aided america's battle against British

05:47 - dominance a quick moving cold front on April eighteenth seventeenth seventy five

05:52 - permitted Paul revere to see the warning lights

05:55 - in the old north church

05:56 - on what would normally have been a cloudy foggy new England.

06:00 - The next summer and unseasonable fog in new York city

06:03 - permitted Washington and his defeated troops

06:06 - to escape a British massacre.

06:08 - Later that year a snowstorm on Christmas night

06:11 - was the perfect camouflage for the Americans

06:14 - to take a hessian Garrison

06:16 - in Trenton new Jersey

06:17 - giving the newborn nation a much needed lifting morale.

06:21 - Even the trying winters at valley forge strengthen the will and determination

06:25 - of the continental forces to win.

06:28 - Finally in the fall of seventeen eighty one

06:31 - the British hemmed into southeastern Virginia.

06:34 - Washington's troops and the weather dealt the fo one final blow

06:38 - weather historian David ludlow described what took place in

06:42 - the final battle down and the yorktown

06:44 - area the.

06:47 - The first

06:48 - phase of that was a seat battle

06:50 - which was.

06:52 - Inconclusive.

06:54 - She

06:54 - on an area in

06:56 - September when often hurricanes come

06:58 - through there

06:59 - there had been

07:00 - to the revolutionary war so

07:02 - are hurricanes at that time

07:04 - but there was

07:05 - lack of hurricane

07:06 - and a lack of wind enable the battle to be a stalemate

07:10 - and the French took the British fleet so far offshore that

07:15 - another French

07:16 - lady came down from Newport and brought in

07:18 - all the siege supplies that Washington aided.

07:21 - Without siege

07:22 - material why

07:24 - they were able to circle the British and eventually

07:27 - force them to surrender.

07:29 - Even there I guess the British tried to

07:32 - an escape

07:32 - yeah they tried an escape

07:35 - and

07:36 - one of the last days

07:38 - to take their best troops

07:40 - and leave the worst groups

07:41 - and ferry them across the York

07:43 - river Chile

07:44 - for other potential I guess it's a York peninsula on the other side

07:48 - but.

07:49 - They do didn't have a weather forecast or they're down

07:52 - the York river that night came a

07:54 - severe

07:55 - cold front or

07:57 - line of thunderstorms

07:58 - and after I'd gotten half the troops on one side of the river.

08:03 - The

08:03 - storm hit

08:04 - blew a lot of the poach led

08:06 - learning to use the

08:08 - river

08:09 - with a few boats that are left cornwallis

08:11 - half of his troops on one side of the river have

08:14 - had to bring them back

08:15 - in order to he'd have a fortunate being.

08:18 - That discouraged

08:19 - him so much that surrender

08:22 - took place the next day

08:24 - and.

08:27 - We won the war.

08:29 - That battle the British.

08:32 - Gave up after that when

08:33 - the news got to lord north.

08:36 - Prime minister and then.

08:38 - He heard the news and they said

08:40 - oh god oh god it's all over.

08:44 - From beginning to end the American revolution was fought with great courage

08:48 - endurance and purpose

08:50 - on a stage where at times providential weather events

08:53 - made an important difference

08:55 - in the outcome

08:56 - and.

09:12 - We've come here to gettysburg national military park to explore the weather

09:15 - conditions for the great battle of gettysburg

09:18 - and it's surprisingly know as much as we do because weather observations were

09:21 - disrupted during the civil war but over at gettysburg college

09:25 - one professor Michael Jacobs was hard at work taking his usual weather observations

09:30 - even during the battle

09:32 - and combat finding those with a few other is it's

09:33 - possible to piece together the story of how the weather

09:36 - affected the battle of gettysburg.

09:39 - Actually the part the weatherman played was important even before the battle started

09:43 - because it was from an old guard up near gettysburg

09:46 - college which is just about a mile from here

09:48 - where professor Jacobs helped out some officers of the union signal corps

09:52 - to choose this site

09:54 - cemetery hill

09:55 - as the best place to set up a defense.

09:58 - As for the battle itself

10:00 - professor Jacob's records show it was fought under

10:02 - conditions of a strengthening Bermuda high situation

10:05 - that typical summertime feature

10:07 - led to increasing heat and humidity during the days of the battle.

10:12 - With the conflict there was no rain

10:14 - so no doubt these fields were solid for the movement

10:17 - of artillery and cavalry but the heat was a problem

10:20 - at the so called high tide of the confederacy

10:23 - pickett's charge which came right up this hill

10:25 - at that time temperatures were near ninety degrees in the shade

10:29 - and out in the bright sunshine

10:30 - it was much much hotter.

10:32 - Can consider also that at the time battle clothing

10:34 - consisted of rather heavy shirts and trousers

10:37 - more suitable for cold weather campaigning

10:40 - it really isn't known how many casualties on these battlefields

10:43 - were caused directly or indirectly by this stifling heat.

10:48 - Of course well entrenched on the high ground the forces

10:51 - of the north repulse the ill fated confederate attack

10:54 - generally ordered a full scale retreat

10:57 - and for Lee the weather became both an enemy

10:59 - and an ally.

11:00 - Weather records from Harrisburg show that over eleven inches of rain fell during the

11:04 - ten days of the confederate retreat

11:07 - often the beaten were slog ageing through knee deep mud

11:11 - but at the same time union general Meade apparently just wasn't up to pursuing the

11:15 - southern forces through the frequent rains and thunderstorms

11:19 - and ultimately

11:20 - Lee was able to preserve his army

11:22 - and retreated into Virginia.

11:24 - When the commander in chief of the union forces president Abraham Lincoln.

11:28 - Learned

11:29 - the beaten confederates

11:30 - had been allowed to retreat.

11:32 - He apparently became quite angry

11:34 - this led to a shake-up of the union generals

11:36 - which eventually led to putting ulysses Grant in charge.

11:41 - When you put it all in perspective there are definite web connections to the great

11:45 - battle of gettysburg but the weather doesn't

11:47 - appear to have been crucial to the outcome

11:50 - and really president Abraham Lincoln but it did very well in perspective

11:53 - in his famous address commemorating this battle

11:56 - he said

11:57 - the world will little note

11:59 - more long remember what we say here

12:01 - but it can never forget

12:02 - what they did here.

12:04 - I.

12:11 - Hmm.

12:21 - Thunderstorms will become increasingly

12:24 - persistent or prominent as we get deeper into the

12:26 - holiday weekend but not tonight just a sultry slumber

12:29 - seventies for most of us in the big city south and east having a hard time falling

12:34 - below eighty degrees a record warm night

12:36 - for many

12:37 - as we head into Friday dangerous heat once again for all of us especially south and

12:42 - east where those feels like values will be between one

12:44 - hundred and five and one hundred and fifteen once again

12:47 - air temperature tours near or above one hundred

12:49 - nineties for the rest of us a couple of isolated

12:52 - thunderstorms east and northeast in the afternoon

12:54 - and then more organized storms arriving late north and west overnight

12:58 - Saturday in northern pa it could really shower at any time

13:01 - there will be more clouds around so therefore not as hot

13:04 - as a front slides into the heat once again though some scattered thunders too arms

13:08 - and downpours in the afternoon some of those could be on the strong side

13:12 - I think there will be some interrupted

13:13 - fireworks displays

13:15 - late on the fourth Sunday an area of low pressure could ride that front and at the

13:19 - moment that's starting to look like

13:21 - a bit of a rainier day land and by then I think we could certainly use it by the way

13:25 - you got that Sunday map as a bonus tonight because

13:28 - we will not have a show on tomorrow

13:30 - that is correct that robs us of this week here on world

13:32 - world next week we will have our weekly segment of.

13:35 - Guidelines than

13:36 - water watch performs here whether all

13:38 - have a safe and fun weekend.