LMK issues Area Forecast Discussion (AFD) 838 FXUS63 KLMK 140513 AFDLMK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 113 AM EDT Mon Jul 14 2014 ...Updated Aviation Discussion... ...Forecast Update... Issued 1230 AM EDT Mon Jul 14 2014 Numerous T-storms have developed along the surface trof and progressed to near and just south of the I-64 corridor. Still no organized cold pool but impressive downdraft CAPE south of the line has allowed individual cells to develop fairly impressive velocity signatures. Main threats overnight will be isolated wind damage and excessive rainfall, with amounts exceeding 1 inch in less than an hour. Only saving grace is that the storms have been just progressive enough not to train. Issued 825 PM EDT Sun Jul 13 2014 Just did a quick update to higher-resolution products to reflect lower POPs over most of the area for the next few hours. Thunderstorms over southern Indiana remain disorganized after failing to generate a cold pool, so would not expect this line to march south through Kentucky as previously advertised. Zone Forecast shows most areas under a likely POP for the night, and this still has a good shot at verifying. Next wave upstream is generating convection along the east-west oriented surface trof over SE Missouri, and with this boundary hanging up somewhere over the Ohio Valley, expect precip chances will be on the increase again after midnight. Still a low-end likely, as locations that do not end up close enough to the boundary could well miss the action. Not yet ready to tone down the HWO at the moment, as there is still quite a bit of downdraft CAPE and storms over southern Indiana look quite capable of producing near-severe winds. .SHORT TERM (Now through Monday Night)... Issued at 300 PM EDT Sun July 13 2014 A weak cold front draped across central Indiana will slowly sag south this evening across southern Indiana. It will then stall out overnight across north central Kentucky before finally pushing south towards Tennessee on Monday. This boundary will serve as a focus for repeated episodes of convection this evening and overnight, with a possibility of isolated damaging winds this evening and localized heavy rain through Monday. For the rest of this afternoon and evening, expect that scattered to numerous thunderstorms will congeal into a line of storms by late afternoon or evening, then slowly sag south towards I-64 by mid to late evening. It will be this line that has a potential to produce isolated severe weather, mainly in the form of damaging winds. Farther south across central Kentucky, clusters of scattered thunderstorms will produce brief heavy rainfall and gusty winds through late afternoon. Overnight, a weak upper-level wave will move east and allow showers and storms to continue. High PWATs and possibly training storms, may bring localized excessive rainfall. Indeed, expect an west-east strip along the axis of heaviest rain to average 1 to in excess of 2 inches somewhere across southern Indiana or central Kentucky overnight. Across our southern counties, widespread thunderstorm coverage will likely not develop until after midnight, and may continue in some fashion through the mid-morning hours. Temperatures will stay warm overnight, especially prior to any thunderstorm activity. Lows will likely range from the upper 60s north to the lower 70s south. The focus for any additional thunderstorm development Monday afternoon will be across our southern counties, which will lie under the axis of greatest precipitable water and have the potential for adequate instability. Depending on instability and cloud cover, some storms may become severe across our south during the afternoon. Scattered thunderstorms also have the potential to develop across southern Indiana during the afternoon as well, prompted by an approaching strong cold front. Highs Monday will range from the mid to upper 80s. Showers will end across the south Monday evening. A unseasonably strong cold front will drop south of the Ohio River early Tuesday morning. Cooler temperatures and much lower dewpoints will already be noticeable by dawn Tuesday morning along and north of the Ohio. .LONG TERM (Tuesday through Sunday)... Issued at 254 PM EDT Sun Jul 13 2014 A deep upper low over the Great Lakes at the start of the period will pull off to the northeast but its parent upper trof will remain in place, extending back to the Tennessee Valley. The trof will then get reinforced by a new, weaker, trof coming in from the west, resulting in general upper troffing through the work week. At the surface, high pressure having originated over the Canadian Archipelago will be entering the northern Plains at the start of the long term, build into the Ohio Valley, and then proceed on to the East Coast. This surface high in concert with the upper trof will bring unseasonably cool air into the region. Afternoon readings will peak in the 70s Tuesday and Wednesday, and right around 80 on Thursday. The current forecast highs at the four main climate record sites in central Kentucky are only 0 to 2 degrees warmer than the record cool highs for July 16. Wednesday morning and Thursday morning well enjoy temperatures in the 50s. The Wednesday morning forecast is currently 3 to 6 degrees warmer than the record lows, and on Thursday morning is 2 to 7 degrees warmer than the records. Friday into the weekend the upper troffing will relax and well be on the west side of the Canadian high so well see a moderate return of warmth and moisture. Still, daytime highs will only be in the lower and middle 80s with morning lows in the 60s -- not bad for July. Also, the chances for scattered storms will increase and we could definitely use the rain. The most recent drought analysis shows most of southern Indiana and central Kentucky in the "abnormally dry" category, and local residents have been telling us that things are starting to look dry out there... && .AVIATION (06Z TAF Update)... Issued at 111 AM EDT Mon Jul 14 2014 Showers and storms will continue along a boundary that is stalled across central Kentucky overnight. These storms have are currently in the vicinity of LEX and SDF. A weak upper wave is expected to enhance the storm activity over the next couple of hours. This will allow them to continue to form across north central KY. Therefore SDF and LEX will see thunderstorms with reduced visibilities and gusty winds off an on for much of the night. This activity will slowly sink southward through the morning hours and should move out during the morning hours. As the showers and storms sink southward they will begin to affect BWG. BWG looks to see storms from around sunrise through the morning hours. These storms will move out of the area this afternoon. The actual cold front will move through the region tonight. However, with the stabilized airmass think that there will not be many storms so will keep precip out of the forecast for tonight. With the frontal passage, winds will shift to northwesterly towards the end of the SDF TAF period. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Update.........RAS Short Term.....JSD Long Term......13 Aviation.......EER
Posted on: Mon, 14 Jul 2014 05:13:59 +0000
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