Lecture 10Outline of Last Lecture I. Weather of the day (whole lecture today)II. ITCZIII. Force BalancesIV. Coriolis effectV. Surface temperatureVI. Weather Prediction for next weekendOutline of Current Lecture II. Weather of the daya. Knowing that there are different forecast predictions we should look atIII. Geostrophic AdjustmentIV. ModelV. Physic’s ApproachVI. Air ParcelsVII. Gradient Wind Balance…VIII. Wave PatternsCurrent LectureWeather of the day:Still looks like it will be cold next weekend, maybe not as strong as we thought as last week. It is looking a little less intense now; it looked at lot less intense during the weekend. It should be fairly cold next weekend, but probably like the same weather we had a few weeks ago.Now we will look at tropical situation. There are a number of tropical storms right now. Peak period of tropical season is the beginning of September. Prior to September in the summer, warm oceans, but we don’t always have weak winds aloft. Tends to be some wind and weather stuff for the previous winter. It is important for tropical storms to have low upper level winds, very low wind sheer. You can have some wind,but don’t want the wind to change a lot with height. If that happens, different speeds, different height of the wind, that will tear storm apart. This is the biggest factor when water temperature warmer, to have no storm.Atm Ocn 100 1nd EditionMain mechanism for forming storms is that the weather systems will be off of Africa, they will initiate tropical storms or at least waves that move across easterly flow. We talked about raspy waves in westerly flow. Waves will bring across for tropical storm formulation if conditions are right. Sufficient moisture would also be needed. Winter systems starting to build so the moisture right now is less sufficient. Precipitable water: gives an idea of where moisture is. Greens are where the strong moisture is. Band of moisture along inner tropic convergence zone looks weaker and that is because increasing cold air outbreaks that are dry that are pushing moisture out. Removing it from any long fetch in the tropics. Moisture isn’t building as much as it used to. Haven’t seen anything substantial forming here since Edward a couple weeks ago. (warm weekend) A lot of dry air over the US a lot is because of this dry air that is over US and the tropical air has been pushed out. Substantial formation of a tropical cyclone in the Pacific. What is causing this one to form?On tropical convergence zone it is forming. What would cause that initial formation?Pacific is very different from Atlantic, we get surges of westerly wind that come in produced by things in East Asia. The surges pick up cyclones that almost immediately recurve to the north. Typical of typhoons. Weak inner tropical convergence zone in the east. Surges of moisture being compressed in the line by the surges of dry air. We have frontal systems that move off of north America and only go so far south that they stall in the Atlantic. As it stalls produces a convergence line where dry air converging with moist air, lifts the air in tropics and makes region of deep moisture, when storm stops, line of deep moisture will sit there and brew. Sometimes tropical system can start to develop out of this. Tropical cyclones? Yes they are considered this as they get bigger, pretty much identical. In initial systems, there are subtropical cyclones instead of tropical cyclones. Unlike the typhoon they don’t have tropical origin. Origin is frontal system that moves off. Invest area in the east. Invest area associated with previous frontal passage from last week that was stalled in the Atlantic. Something forming here! They don’t have a prognosis for where it is going to go yet. Already swirling band of clouds in the IR. In the visible there is already a nice rotating system. Not even of tropical storm intensity, but it is there. Will it have enough moisture? Not obvious that it will. This may or may not turn into a tropical cyclone or tropical storm in the next couple days. http://moe.met.fsu.edu/tcgengifs/European center… on this model we are looking at. Similar to national weather center we have in the US. Low pressure, associated with subtropical system we just looked at. If we go ahead in time, there is a little bit of development. And then when we go forward a few hours suddenly fairly decent size storm. By Friday reasonable size storm, way out in the Atlantic, doesn’t threaten any land. This is enough intensity that may produce a tropical storm maybe even a hurricane. Hard to tell what is going to happen because not enough resolution to really see strength of the storm. But this is very good model we can look at, this European model.We can now try another model. There is a Canadian model. GFS model also on there. Looking at the GFS model, we can see bloated system or very large not so circular isobars. Isobars have kidney shape to them with a trough in there. The trough is warm and cold fronts. So we can see by the shape of these contours is that the GFS model has taken this system and turned it into an inter-tropical system like snowstorms by the end of the week. By Friday, this storm becomes modern intensity extra tropical cyclone. In the European center one that has higher resolution, argues that it is tropical storm of modern intensity by the end of the week.Different predictions by the two different models!Canadian Model:Its forecast says big extra tropical system too. Agrees with GFS of the storm by the end of the week. The European one says tropical one, like a small hurricane. We will watch it and see what happens by the end of the week. We see this to see different models with different opinions. If you look at just one, don’t see all the possibilitiesthat could occur. All models same data in different ways. Using aircraft observations, ship observations. Up to 2 billion observations goes into all three models, but all a little different in data the way they incorporate it. Coming up with different solutions. All three are possibilities for the forecast. Normally not a good idea to put a forecast to the public based on just one of these models. Have to make a choice of what to say to the public. Expect at any rate storm in the north central Atlantic. Can argue how tropical it will be or how intense it will be based on the difference of these probes.Long term: 850 mb elevation. Global view of temperature at 850 mb. Can see by the