Jason's Weather Website
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Welcome to Jason's Weather Website
Welcome to my website. This website is run by Jason Godwin, a second-year meteorology graduate student at the University of Miami. On this website, you will find blog articles on various high-impact weather events, weather maps, links, and some of my research projects. All opinions on this website are my own.
NOAA Forecasts for Thursday, December 5 (weather high/low)...Atlanta: 60% chance of rain 70/63...Boston: 70% chance of rain 51/48...Chicago: Mostly cloudy 32/21...Dallas: 90% chance of freezing rain 39/26...Houston: 60% chance of rain 75/46...Los Angeles: Mostly sunny 59/42...Miami: Partly cloudy 81/72...New York City: 70% chance of rain 59/51...Philadelphia: 70% chance of rain 63/52...Seattle: Mostly cloudy 34/26...Washington: 50% chance of rain 68/55...
Synopsis: 13 November 2013A cold front will finish pushing through the southern United States tonight, bringing cooler and drier weather to the region. The next strong storm looks to move onto the coast of California in the late part of this week. On Friday, a large area of high pressure will be anchored over the north-central U.S. As the upper-level low and associated trough over the southwestern U.S. moves south, it will allow the cold air mass over Canada and the northern U.S. to build south, bringing an intense cold front through the southern plains on Friday. Thunderstorms will be possible over eastern Texas, Louisiana, Mississippi, and Alabama ahead of this cold front on Saturday. This cold front will continue to push south and east into the weekend. Following the passage of the cold front, the GFS forecast shows much of the south below freezing pushing as far south as the Interstate 10 corridor.
GFS Forecast sea-level pressure, winds, and temperatures for 24 November 2013 at 7:00 a.m. EST (image source: University of Oklahoma Weather Lab)
Four days of severe weather possible across the Southern Plains
28 October 2013 - 18:40 GMT (2:40 p.m. EDT)
The Storm Prediction Center (SPC) convective outlooks show that there is a slight risk for severe
thunderstorms across portions of the southern plains today (Monday), tomorrow (Tuesday), and the
next day (Wednesday). Additionally, there is a potential for severe thunderstorms on Thursday
across parts of the Lower Mississippi and Lower Ohio Valleys. We will look at each of these setups
one day at a time.
RAP analyzed 500 mb geopotential heights and aboslute vorticity, 28 Oct. 2013 at 17:00 GMT
Monday: modest warm air return is forecast over the Texas/Oklahoma Panhandles and western Kansas, which should bring temperatures into the mid to upper 70s with dewpoints rising into the upper 50s. This, along with steepening mid-level lapse rates, should combine to produce modest instability (CAPE of about 1000-1500 J/kg). Given the forecast 50-knot 0-6 km shear, there should be enough shear and instability to perhaps support a few severe thunderstorms, but with limited large-scale forcing (the stronger lift will arrive on Tuesday), this is a somewhat conditional risk for severe thunderstorms. In other words, there may not be much in the way of thunderstorm development, but any storms that do develop could become severe.
Tuesday: while it appears that the main trough axis/upper-level low will not move very much between Monday and Tuesday, model forecasts do suggest that an embedded shortwave trough will move out of Arizona and into New Mexico during the day Tuesday, which should provide enough ascent over the southern high plains to result in surface cyclogenesis over southeastern Colorado. This cyclogenesis will allow for strong warm air return over the region, ushering in upper 70s to near 80 surface temperatures and dew points in the upper 50s to near 60 over the southeastern Texas Panhandle and western Oklahoma. Equivalent potential temperature (known as theta-e) is the theoretical temperature a parcel of air would have if lifted until all moisture condensed and precipitated out, then lowered to 1000 mb pressure level. This value is a good way to assess both moisture and temperature simultaneously. Figure 2 shows the forecast theta-e values for 4:00 p.m. CDT Tuesday. The NAM forecast is for very warm, moist air to be in place over the southern Texas Panhandle and into southwestern Oklahoma. The main limiting factor appears to be shear where the winds are nearly unidirectional above 800 mb. My forecast for Tuesday is that storms will likely form roughly between Midland, TX and Frederick, OK, with large hail and damaging winds being the main threat, but given a small amount of low-level shear, an isolated tornado cannot be ruled out.
NAM forecast 850 mb geopotential heights, winds, and theta-e
Wednesday: the main trough axis is forecast to be located along a line from roughly Cheyenne (WY) to Durango (CO) to Gallup (NM) to Tucson (AZ). Another surface low is expected to begin forming over the northern plains ahead of the upper-level low located back over eastern Wyoming. This will lead to strong warm, moist air advection over the central United States, transporting 60s dewpoints as far north as Des Moines by Wednesday evening. While the thermodynamic environment is expected to be quite favorable for thunderstorms on Wednesday, the wind shear, while large in magnitude, will be somewhat lacking directionally, which means that while severe thunderstorms will likely develop, the tornado risk appears to be somewhat limited (though a few tornadoes cannot be ruled out).
Thursday: the main trough axis is forecast to be located along a line from near La Crosse, WI to Kansas City, MO to Oklahoma City, OK. This will put the largest vertical ascent over the Lower Mississippi and Ohio River Valleys. Temperatures in the lower 70s along with dewpoints in the lower 60s should result in modest CAPE (around 1000 J/kg) over the region. Additionally, a strong low-level jet with winds of over 50 knots is forecast to be in place over the area (Figure 3). While the winds are somewhat unidirectional, like on the previous two days, the low level jet is so strong, that tornadoes, some strong, will be possible on Thursday, along with damaging winds and large hail. Of the four days in question, Thursday is probably the most likely day for tornadoes.
NAM forecast 850 mb winds and geopotential hieghts
The bottomline right now is that there appears to be potential for severe thunderstorms over west Texas and southwest Oklahoma on Tuesday, central Oklahoma, Kansas, and western Missouri on Wednesday, and western Kentucky, western Tennessee, northern Mississippi, and northern Alabama on Thursday, with the exact details of these setups still somewhat in question at this time. Check back here each day to get updates and discussions on the actual observations (rather than a model discussion) on the day of each potential event. In the mean time, now is not a bad time to review your severe weather safety plans if you live in the southern or central plains, or in the Lower Mississippi, Lower Ohio, and Tennessee Valleys.
Continental U.S. Radar Mosaic
Continental U.S. Infrared Satellite
Atlantic Tracking Chart
Tropical Atlantic Infrared Satellite
Tropical Atlantic & Eastern Pacific Surface Analysis