Windspeed
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The naming of Winter storms has always been controversial due to unwarranted exemplification of ETs/mid-latitudinal storms, their frequency of occurrence, and hype that overwhelmingly isn't required from a human impact and safety standpoint. The naming of Tropical Cyclones, on the other hand, is entirely warranted due to those same phenomenon. We name them because they can be inherently dangerous. Sure, some are just a maritime nuisance. Also, sure, with better RS technology, better satellite resolutions and data gathering, we classify TCs that likely wouldn't even get noticed several decades ago. But sticking to the rules of what gets classified, it would be silly to keep them unclassified merely because they are weak, less substantial/impactful events, or even subtropical. We name TCs for important reasons, hard to argue against that. But we also need to stick to the rules. If a system meets the criteria, it gets classified, period. I realize the tongue-in-cheek on the off-topic here. But it's worth reminding and pointing out why NOAA/NHC handles TC classifications the way they do, and also why private companies naming mid-latitudal ETs is ridiculous and of little credence beyond attention generation and money for their service platforms. It's hardly a matter of public safety and science. Major differences in mission strategy and purpose here.
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Another healthy wave south of the Verdes. Easterlies are still a bit lopsided towards the 700 hPa level. But the wave train continues. Eventually easterly trades are going to better align as Azores ridging takes its seasonal build/shift westward into an ECONUS WAR/SER; we already have ENS support for strong interior CONUS 600 dm heights incoming; and if these waves continue training, ITCZ wave breaking and an axii is inevitably going to close off at the surface and stack. The vigor in the WAM and ITCZ needs to be paid attention. We are mere weeks away from modeled increasing MDR favoribility. If that happens sooner, expect one of these waves to develop into our first MDR TC before August.
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Special Message from NHC Issued 9 Jul 2020 20:17 UTC NHC will initiate advisories on Tropical Storm Fay, located just east of North Carolina, at 5 pm EDT. 000 WTNT31 KNHC 092055 TCPAT1 BULLETIN Tropical Storm Fay Advisory Number 1 NWS National Hurricane Center Miami FL AL062020 500 PM EDT Thu Jul 09 2020 ...RECONNAISSANCE AIRCRAFT FINDS TROPICAL STORM FAY HAS FORMED JUST OFF THE COAST OF NORTH CAROLINA... ...EXPECTED TO BRING HEAVY RAINFALL AND GUSTY WINDS TO PORTIONS OF THE MID-ATLANTIC COAST AND SOUTHERN NEW ENGLAND... SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...35.5N 74.9W ABOUT 40 MI...65 KM ENE OF CAPE HATTERAS NORTH CAROLINA ABOUT 195 MI...310 KM S OF OCEAN CITY MARYLAND MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...N OR 360 DEGREES AT 7 MPH...11 KM/H MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Tropical Storm Warning has been issued from Cape May New Jersey northward to Watch Hill, Rhode Island, including Long Island and Long Island Sound. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Cape May New Jersey to Watch Hill Rhode Island including Long Island and Long Island Sound A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours. For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. DISCUSSION AND OUTLOOK ---------------------- At 500 PM EDT (2100 UTC), the center of Tropical Storm Fay was located near latitude 35.5 North, longitude 74.9 West. Fay is moving toward the north near 7 mph (11 km/h). A northward to north- northeastward motion at a faster forward speed is expected over the next couple of days. On the forecast track, the center of Fay is forecast to move near the mid-Atlantic coast on Friday, and move inland over the northeast United States on Saturday. Data from an Air Force Reserve reconnaissance aircraft indicate that maximum sustained winds are near 45 mph (75 km/h) with higher gusts. Some slight strengthening is forecast tonight and Friday. Weakening should begin after the center moves inland on Saturday. Tropical-storm-force winds extend outward up to 140 miles (220 km) primarily to the east and southeast of the center. The latest minimum central pressure reported by reconnaissance aircraft is 1005 mb (29.68 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Fay can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT1 and WMO header WTNT41 KNHC. RAINFALL: Fay is expected to produce 3 to 5 inches of rain along and near the track of Fay across the mid-Atlantic states into southeast New York and southern New England. These rains may result in flash flooding where the heaviest amounts occur. WIND: Tropical storm conditions are expected to first reach the coast within the warning area on Friday and spread northward through the warning area Friday night. NEXT ADVISORY ------------- Next intermediate advisory at 800 PM EDT. Next complete advisory at 1100 PM EDT. $$ Forecaster Brown
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Good thread on current anomalous upper tropospheric temperature profiles that may persist into the heart of the Atlantic hurricane season. Generally, cooler upper profiles aid in colder cloudtops and more intense convection. May also aid in upper divergence for 400-200 hPa anti-cyclones.
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The wave I posted above when it rolled off Africa is still making its way across the western MDR at a low latitude. It's nothing special, there may be some weak mid-level vorticity. It also isn't the sharpest of wave axii. But it has a favorable upper environment and if convection can coalesce to tighten vorticity or close off a surface low, could be interesting in the southern Antilles and deep Caribbean later this week.
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The MCV accociated with the old boundary draped off the ECONUS might be forming an LLC under the current MCS complex that went up this evening. Note the circular pattern of the lightning near the highest cloud tops. Possible curved banding forming might be the beginnings of an LLC and we may get a named system out of this sooner than later if it holds together.
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Fairly healthy wave axis with an MCS mid-level vort max south of the Verdes. Who knows if it will persist long with the SAL locked in to its NW. But interesting nonetheless. 12Z ECMWF does have a solution or two that closes off a surface low but there's negligible model support beyond that.
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TN valley heavy rain/flooding week of whenever
Windspeed replied to janetjanet998's topic in Tennessee Valley
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Classic La Niña taking shape. Questions remain on strength and coverage, especially in 3.4, but it is no doubt kicking in at this point. I suspect even a moderate La Niña would be a safe call, but still can't rule out a --ENSO either.
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That particular model animation shows Azore's ridging below the 700 hPa layer of the atmosphere backing down over the eastern subtropical Atlantic. Surface-to-mid level pressures weaken slightly, retreating poleward. This eases low-level easterlies off Africa, which, in turn, limits SAL propagation westward off Africa. Additionally the ITCZ would become less suppressed south and gain some latitude within that pressure regime. This would help increase instability along the MDR, with better low-level convergence for convection, especially if the MJO is in a favorable phase aloft. Tropical wave tracks would also gain some latitude with the decrease in pressure heights, and be able to tap into moisture feed from the ITCZ. We generally see this pattern of strong Azores ridging back down in August, not early July. Typically a beefy late Spring to middle Summer eastern Atlantic Azores ridge is why we generally see SAL and too amped a low-level easterly jet to favor any MDR development. That, and upper level shear and vorticity is not yet favorable. At any rate, the pattern in the animation above may coincide with a favorable MJO [see below] and a relaxation of upper level wind shear across the Caribbean and lower MDR as well.
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If SAL plumes continue to be lifted and break away into the easterly jet during the potential favorable MJO phase over the Atlantic, I am sure it would still have a negative effect on environmental conditions for cyclogenesis. But we have seen cyclogenesis occur with waves that were interacting with SAL in the past. It really just depends on location of a hypothetical wave axis versus the most hostile dry airmass and propagation of moisture flux out of the ITCZ. That's a remains to be seen kind of thing. Who knows...
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Plumes of SAL dry airmass and aerosols riding the easterly jet should suppress activity for a few weeks at least. It will moderate with time as the ITCZ and individual waves begin to gain some latitude July-August.
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Looks like AOML's OHC and TCHP maps are ingesting RS data correctly now. Still a vast spread of TCHP for mid-June, but way more realistic.
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Loving it!
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Notice in long-range modeling, the region of above median precipitation shifts from interior western Africa to off of the western coastal region of Africa, just south of the Cape Verdes, into the Atlantic MDR. The ITCZ and WAM becomes focused there. As such, this suggests that easterly intertropical waves that continue forming over deep interior and eastern Africa, if their energy holds together, will move off the African coast, and should reach a favorable environment for tropical development somewhere within the MDR:
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That precip anomaly map only matters to show that the pattern from the Indian Ocean to West Africa has favored stronger intertropical frontal troughs to support wave formation in the interior of central Africa. This has coincided with an amped West African Monsoon, resulting in a much wetter pattern than normal the past few months. The pattern could, of course, change. At any rate, the N. African anticyclone / SAL typically breaks off aerosol-laden dry airmasses during this stretch of Summer when typical strong Azores ridging below the 700 hpa layer begins cranking the ENE and easterly jet off of NW Africa. But by mid-July to mid-August, the Azores SPHP generally shifts west into a SER/WAR regime, especially during a +AMO/+NAO/-ENSO setup, allowing WAM to expand west of the Cape Verdes and ITCZ to gain latitude. If that occurs, increased numbers of tropical waves and MCSs exiting Africa into the Atlantic MDR would seem to favor the MDR being active this year. I believe it will even be hyperactive based on earlier discussions in this thread, but we shall see.
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The dust is coming from the Saharan and portions of the sub-Saharan that is not within the above normal precipitation regions discussed earlier. Yes, Morocco and Northern Algeria has seen above normal precipitation due to cutoffs and the previous -NAO pattern, which tracked extra tropical cyclones into the Mediterranean off of the Eastern Atlantic. This had little influence on the main desert regions though. In the image below, the two red Xs have remained normal (dry, low precip) over Saharan and sub-Saharan. The blue X has seen above normal, but that is still mostly an arid region. The point of the original post above was to show the extreme above normal precipitation amounts for already generally moist grasslands and forest regions of the interior and west-central African continent, south of the sub-Saharan region. This suggests increased numbers of multi-convective systems and tropical waves advancing through the West African Monsoon (WAM), which should increase activity out into the Atlantic ITCZ and MDR through the heart of the Cape Verde stretch of the season. As for the dust, the Azores ridge is cranking below the 700 hpa level of the atmosphere seen in purple below. This is inducing strong easterly trades off the Sub-Saharan region pulling desert dust along with it. The low-level easterly jet burst will push all the way across the Atlantic over the next 10 days.
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