Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/27/18

Area Forecast Discussion
National Weather Service Albany NY
1024 PM EDT Tue Jun 26 2018 .SYNOPSIS... Expect a pleasant night as high pressure maintains influence of our area. On Wednesday, unsettled weather from the Great Lakes gradually shifts towards the Northeast, bringing the potential for periods of rain and some thunderstorms late Wednesday afternoon into Thursday. Some periods of heavy rain are also possible. Then, we are watching a period of hot and humid weather Friday into the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... As of 1015 PM EDT...Beautiful and tranquil night across the region as ci/cs continues to stream across the night sky. Winds are light and variable as ridge at all levels continues over the region. As dewpoints remain in the 40s, should see a steady drop in temperatures the remainder of tonight. As the upper level ridge axis moves into eastern New England after 06z/Tues, a southwesterly return flow will ensue leading to gradually increasing clouds and weak warm air and moisture advection. This will keep our low temperatures milder than last night, only falling into the mid - upper 50s. The main focus Wednesday continues to be a low pressure system in the Great Lakes that we expect to track up the St. Lawrence River Valley. Clouds increase in coverage and thicken through the day with dew points rising into the 50s. With our high shifting off the coast of RI/MA, southeasterly surface flow could introduce somewhat of a marine influenced airmass to some areas, limiting high temperatures to the low - mid 70s. Noticed signals of a cold air wedge developing near the surface on POU and ALB BUFKIT soundings suggesting that high temperatures will be cooler than today. Warm air advection and cyclonic vorticity advection increases through the day but initial showers may struggle to reach eastern NY/western New England thanks to dry air and influence of the aforementioned high. Latest HRRR guidance shows showers in PA eroding away as they try to progress into NY, adding confidence to this thinking. Thus, kept most areas dry through 15z Wednesday. Gradually increased POPs from west to east through the afternoon before introducing high chance and likely POPs by 21z/Wednesday to 00z/Thursday in the Adirondacks and Mohawk Valley. Kept western New England in slight chance or low end chance thru sunset where the influence of the high off shore could be greater. Showalter indices remain positive through sunset so kept thunder out. Given that Pwat values rise towards 1.50" by late Wednesday afternoon, heavy downpours are possible. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/... Wednesday night into Thursday morning will feature the greatest potential for periods of widespread rain that may also include heavy downpours. Our positively shortwave trough will move into western NY giving way to height falls over eastern NY/western New England and upper level diffluence. As the approaching trough and surface low move closer to the high positioned off the New England coast, we notice a strong low level jet developing overnight ranging from 35-45kts. This will lead to strong moisture and warm advection into our area with Pwat values rising to 1.50 to 2.00 inches or 2-3 standard deviations above normal. Notice tall skinny MLCAPE ranging 500-1000J/kg developing mainly near and after 06z/Thursday and with warm cloud depths ranging from 10k- 12k feet, we should have efficient warm rain processes. Thus, we could see heavy downpours and potential for isolated areas of flooding. Overall rain amounts should range 0.50 - 1.25 inches. See our hydro discussion for more details. Areas of widespread rain could linger into Thursday morning (including the morning rush) as the upper level trough moves into our area and becomes neutrally titled. The better forcing reaches western New England by 15z - 18z before subsidence in the wake of the trough arrives for the afternoon. We could see breaks of sun take place in the afternoon with dew points remaining high in the 60s. Thus, expect a muggy afternoon with highs in the 70s. Our surface cold front will not coincide with the upper level forcing and looks to move through the area between 18z/Thurs and 00z/Fri. Given the potential for breaks of sun and high humidity, instability values look to increase up to 1000-1500 J/kg so isolated to scattered showers and thunderstorms are possible during this period. Again, heavy downpours remain possible as high Pwats remain in place. Severe thunderstorms parameters are not very impressive so thinking any severe threat at this point is low. The front should move through by 00z Friday but we are expecting not much of an air mass change. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Behind the departing shortwave, upper level heights will quickly rise, as ridging translates eastward from the Ohio Valley and Great Lakes towards the Northeast. The upper level ridge axis will be directly over the Northeast for Saturday and just east of the area for Sunday, with 500 hpa heights of 591-594 dm over the area. 850 hpa temps aloft will surge to 20-22 degrees C by the weekend. The result will be some extremely warm temperatures, especially for Sunday, with a southwest flow within the low to mid levels will allow for compressional warming thanks to downslope flow off the Catskills/Helderbergs. Temperatures should reach into the upper 80s for Friday. Although it will be somewhat muggy (dewpoints in the lower 60s), heat index values look to fall short of heat advisory criteria. However, temperatures should reach the low to mid 90s on Saturday and mid to upper 90s for valley areas on Sunday. Valley areas should reach heat advisory criteria on Saturday, with perhaps heat advisory criteria for nearly the entire area on Sunday, and even a few valley areas from the Saratoga Springs region down towards the mid-Hudson Valley reaching Excessive Heat Warning criteria (heat index values of 105+). Dewpoints will be very muggy, with values in the upper 60s to near 70. There won`t be much relief at night either, as overnight lows will only fall to near 70. With the strong ridge in place, a cap will be in place aloft, preventing any showers or thunderstorms from occurring. Will keep it precip-free for Friday through Sunday. Sky cover will generally be mostly sunny, with just some high cirrus passing through (mainly for northern areas). By Monday into Tuesday, there is a little more uncertainty within the forecast. While strong ridging should still be in place nearby, an upper level shortwave over southern Canada will be trying to run into the ridge and a surface cold front will be approaching from the northwest. Although it appears that the front may not cleanly make it across the area, its proximity could allow for some scattered showers or thunderstorms, especially aided by any lake-breeze boundaries or pre-frontal surface troughs that could be in place. As a result, some clouds and any possible precip may keep temps a little cooler than the weekend, but still above normal, with highs in the upper 80s to low 90s for Monday into Tuesday. Heat index values may still reach advisory for Monday, although this will depend on just how warm it does get, which is still somewhat uncertain. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... High pressure will shift offshore tonight. A low pressure system will approach from the Great Lake Region Wednesday with increasing clouds and a threat of showers in the late afternoon and into Thursday. VFR conditions are expected tonight and into Wednesday morning for KGFL/KALB/KPOU/KPSF. The exception maybe be some patchy radiative shallow mist/fog at KPSF. We placed an MVFR 4-hr window in there from 07Z- 11Z/WED. The high clouds will increase in the late morning with perhaps some mid level clouds by the early Wednesday afternoon with the increasing low to mid level warm advection ahead of the sfc wave and warm front. The chance for showers increases as well with PROB30 introduced at all TAF sites. The winds will be light in variable in direction at 6 kts or less the rest of tonight and then will shift to the south at 4-8 kts especially at KALB overnight. The southerly flow will increase late Wednesday morning at around 8-12 kts. Outlook... Wednesday Night: High Operational Impact. Definite SHRA...TSRA. Thursday: High Operational Impact. Definite SHRA...TSRA. Thursday Night: Low Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX. Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... Light southerly flow tonight will lead to increasing clouds and moisture with max RH values near 90% towards sunrise. Dew points continue rising through the day Wednesday thanks to increasing moisture and warm air. Therefore, afternoon minimum RH values should only drop to 50-55%. Showers become possible late Wednesday afternoon, mainly north and west of the Capital District, with periods of widespread rain and some thunderstorms expected overnight into Thursday morning. Heavy downpours are possible during this period. Widespread rain exits by Thursday afternoon with just isolated to scattered showers and thunderstorms possible thru sunset. Then, hot and humid weather is expected Friday into the weekend. && .HYDROLOGY... As of the latest update from the US Drought Monitor last week, most of the entire Hydro Service Area /HSA/ is under abnormally dry conditions. However, many areas did receiving appreciable rainfall over the weekend, with a half inch to one inch of rain common across the area. Dry weather will continue for tonight through tomorrow morning. The next storm system looks to bring some showers and possible thunderstorms to the region between late Wednesday and Thursday evening. With PWAT values rising by Thursday, some locally heavy downpours will be possible within any shower or thunderstorm. Basin average amounts will be around an inch, although point totals may be locally higher due to thunderstorms. This could allow for some minor rises on rivers and streams, but no flooding is anticipated on main stem rivers. With the locally heavy downpours expected, some minor flooding of low lying, poor drainage or urban areas cannot totally be ruled out. Hot and dry weather is then expected to return for Friday into the weekend, with river levels holding steady or slowly falling. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Speciale NEAR TERM...BGM/Speciale SHORT TERM...Speciale LONG TERM...Frugis AVIATION...BGM/Wasula FIRE WEATHER...Speciale HYDROLOGY...Frugis
Area Forecast Discussion
National Weather Service Birmingham AL
613 PM CDT Tue Jun 26 2018 .UPDATE... For 00Z Aviation. && .SHORT TERM... Today and Tonight. We continue with much of a status quo in our weather pattern, at least through tonight. Convection from yesterday did lower readings in the east, with lower dew points into the upper 60s. However, dew points are expected to recover quickly this morning as more moist low level flow off of the Gulf of Mexico returns into Central Alabama around the still present Atlantic ridge. In the upper levels, we continue to have a somewhat flat ridge across Southern Conus. We are again expecting very warm temperatures today. The highest readings should be in the west today. Readings may be a tad lower in the east as the airmass recovers from yesterday. The current heat advisory for the southwest half of Central Alabama looks to be good, and we are not planning on adding any more counties at this time. Convection should again be heat induced this afternoon with scattered thunderstorms possible once again as precipitable H2O values remain up. Not expecting any organized severe today, but we will get too hot not to expect some development maybe even a few strong storms. 08 .LONG TERM... Wednesday through Tuesday. The ridge that has been in place over Central AL the past few days finally breaks down slightly as a trough and low pressure system move through the Upper Midwest and into the Great Lakes Region. The GFS tries to stretch a weak cold front down through the TN Valley and through Central AL Wednesday afternoon, but don`t get too excited because temps only drop 3-4 degrees. The NAM and ECMWF don`t have this discernible cold front and instead keep the system as more of an upper level trough axis passage rather than anything meaningful at the surface. Either way, expect some extra synoptic forcing with the trough axis moving through, so we could see extra cloud cover and higher coverage of afternoon showers/thunderstorms on Wednesday. The NAM keeps the area dry, but the GFS, ECMWF, and higher resolution CAMs develop the afternoon precip, especially in the North and East. Therefore, will increase PoPs for those areas. 1000-850mb thickness values decrease slightly with the trough passage as well, so afternoon highs could be slightly lower than the previous couple of days, but overall, still expect borderline heat advisory criteria in the heat indices. Will continue mention in the HWO for heat impacts on Wednesday, but will hold off on any expansion of the heat advisory because of the uncertainty with the "cold" front. I wish I could say that the forecast gets easier for the second half of the week, but it doesn`t. The GFS tries to cut off a weak upper level low from the base of the passing trough axis and retrograde is back over Central AL on Thursday as the ridging at 850mb strengthens. This would lead to an increase in 1000-850mb thickness values, supporting afternoon high temps in the mid 90s or above and continued heat advisory conditions. However, with the weak upper level low, we could see increase synoptic lift allowing higher coverage of afternoon convective storms, which depending on time and location of initiation could limit the afternoon temps. Meanwhile, the ECMWF and Canadian are more progressive and don`t have the cut- off upper level low development until the system is off the Atlantic Coast. This would bring in the amplified ridge across Central AL again, leading to more typical afternoon convection with heat indices in the 100-105 range through the end of the week. Will continue edging the forecast more towards the ECMWF and Canadian, which meshes well with the National Blend Model for high temps through the end of the week. Will also go closer to climo on diurnal precipitation patterns and maintain low confidence mentions for heat impacts in the HWO through Saturday. The determining factor for the heat advisories for this week will likely be coverage and timing of afternoon convection, which unfortunately will require more of a day- to-day reassessment. For later part of the weekend and into early next week, the GFS and ECMWF are in decent agreement with the ridging pattern remaining in place across the Eastern CONUS with typical summertime diurnal thunderstorm activity. However, the center of the 850mb ridge should shift more over the East Coast and into the Atlantic, allowing our 1000-850mb thickness values to decrease, returning Central AL to afternoon highs in the upper 80s to near 90 degree mark. This pattern change towards the extended is supported by NAEFS, GEFS, and ENS, which are all showing near or above max values for mean temps and mean geopotential heights over the Northeastern CONUS. Therefore, will not go past Saturday for heat impacts in the HWO and will adjust temps back towards the typical model blends. 25/Owen && .AVIATION... 00Z TAF Discussion. Afternoon convection has been confined to mainly the eastern and southern portions of Central Alabama. The air mass at KMGM and KTOI has already been worked over from earlier convection, so sea-breeze initiated line of storms currently south of these sites should weaken as it tracks southward. KMGM will likely have the best chance of getting additional tstms since surface temperatures are still warmer than other surrounding locations. The HRRR model has been forecasting convective development along the I-59 corridor between 02z and 03z as an outflow boundary pushes into the area from the south. Went ahead and added VCTS at KBHM, KEET, KASN, KANB for a few hours this evening for this possibility. Expect rain free conditions by 04z. More development likely again after 18z Wednesday, with better chances across the northeast counties as a boundary slides southward out of Tennessee. 58/rose && .FIRE WEATHER... Isolated to scattered afternoon storms are possible with daytime heating for the next few days. Very warm temperatures with triple digit heat indices will be the biggest issue for crews. Humidity values remain high, and there are no fire weather concerns at this time. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 71 91 74 93 74 / 40 50 20 40 20 Anniston 72 91 74 92 75 / 40 50 20 40 20 Birmingham 74 93 76 93 76 / 30 40 20 40 20 Tuscaloosa 75 95 76 96 76 / 30 20 20 40 20 Calera 73 92 75 92 75 / 30 30 20 40 20 Auburn 74 91 74 91 75 / 40 30 20 40 20 Montgomery 75 94 75 93 77 / 30 30 10 40 20 Troy 74 93 74 92 75 / 30 30 10 40 20 && .BMX WATCHES/WARNINGS/ADVISORIES/... Heat Advisory from 10 AM to 8 PM CDT Wednesday for the following counties: Autauga...Barbour...Bibb...Bullock...Chilton... Dallas...Elmore...Fayette...Greene...Hale...Lamar...Lowndes... Macon...Marengo...Marion...Montgomery...Perry...Pickens...Pike... Russell...Sumter...Tuscaloosa. Heat Advisory until 8 PM CDT this evening for the following counties: Bibb...Chilton...Fayette...Greene...Hale...Lamar... Marengo...Perry...Pickens...Sumter...Tuscaloosa. && $$
Area Forecast Discussion
National Weather Service Charleston SC
959 PM EDT Tue Jun 26 2018 .SYNOPSIS... A stationary front will dissipate over the area into Wednesday. Weak low pressure will then linger over or near the area into early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 10 PM: Leading edge of the gust front sourced from Midlands convection has entered northern Dorchester and Berkeley Counties. The outflow boundary was arching NW and intersecting with a storm over the Savannah River Site (SRS). The SRS storm will likely surge eastward along the outflow, gradually weakening. However, it appears that coverage and lightning activity will increase over Screven, Allendale, and Hampton Counties late this evening. To the north, the outflow will likely trigger some new updrafts around Moncks Corner. I will update PoPs to cover the latest thunderstorm trends. As of 8 PM: Very latest KCAE images indicate that the gust front is starting to pull ahead of the deep convection. To the east, NW bound sea breeze was located on KCLX along a line from Claxton to Walterboro. I would expect the convection over the Midlands to gradually weaken through the rest of the evening. However, the storms over the middle Savannah River Valley may continue to remain strong to severe into late tonight. Recent 0Z KCHS sounding indicated CIN in the wake of the sea breeze was already between 15-35 J/kg. Storms will certainly gradually dissipate east of the sea breeze. As of 615 PM: A well organized band of thunderstorms was pushing from the SC Upstate into the Midlands. Radar data indicates that the convection was located very close to the leading edge of the cool pool. However, recent KCAE scans indicate that the gust front will slightly outpacing the convection over Newberry and Fairfield Counties. Given the new updrafts developing ahead of the convection, it appears that instability will likely maintain the MCS across the Midlands of SC. Given the recent runs of the HRRR, I would expect the convection to weaken significantly, but showers and thunderstorms should not total dissipate before reaching the Coastal Plain. I will reduce PoPs, keeping higher chc values across the inland counties of SC/GA. Previous Discussion: Temperatures have been slow to warm today with a weak stationary front lingering over the area. This has had an impact on instability with early afternoon GOES-E visible satellite imagery showing mostly flat cumulus inland from the beaches. Some enhancement to the cumulus field has been ongoing over the past 1-2 hours in the vicinity of the sea breeze where instability is being augmented by a pool of slightly higher dewpoints, so at least initially, the risk for isolated convection will remain confined to the coastal counties as the sea breeze moves inland. This risk will slowly expand inland as temperatures reach around 90 and convective outflows begin to interact with the inland moving sea breeze circulation. Attention shifts to later this evening as several CAM members suggest convection currently developing south of Asheville tries to organize into a mesoscale convective system (MCS) over the Upstate and Midlands as shortwave energy along the southern Appalachians propagates southeast along the backside of the upper ridge. How far to the southeast this feature will get is still unclear as much will deep on how unstable inland areas can get over the next few hours and how well developed any potential cold pool upstream will become. Some of the more reliable CAMs such as the NSSL-WRF are quite aggressive in dropping the MCS all the way offshore of the southern South Carolina coast, while the RAP and H3R weaken the system as it approaches the southern Midlands. Current instability trends suggest the RAP and H3R are probably trending in the right direction, but plan on a compromise solution to construct overnight pops given northwest flow events are notoriously difficult to forecast. Pops will range from 40-50% across Southeast South Carolina to 20-40% across Southeast Georgia. Still can not rule out an isolated severe tstm or two with damaging winds being the primary hazard. Lows will bottom out in the lower-mid 70s inland with upper 70s/near 80 at the beaches. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... The weak front draped over southern SC is expected to dissipate on Wednesday. Meanwhile, a building upper ridge over the central United States will gradually push east. High temps will be back into the middle 90s by Thursday and Friday, along with dewpoints in the low to mid 70s. Heat Advisories are likely Thursday and Friday due to heat indices of 105-108F during a few hours each afternoon. Isolated to scattered convection is expected each day, mainly during the daytime hours in association with the greatest instability. However, some showers and/or thunderstorms could affect the area at nighttime due to a series of weak shortwaves dropping southeast through SC/GA during the period. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... The latest medium range model guidance suggests weak troughing will persist over or near the area into early next week as upper ridging remains centered over Ohio Valley and Mid Atlantic. Temperatures will remain above normal with rain chances mainly near normal. A Heat Advisory is possible Saturday but not thereafter as our Advisory criteria changes to 110 degrees beginning July 1. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... KCAE radar images around 0Z indicated that the gust front is starting to pull ahead of the deep convection over the Midlands. The sea breeze has advanced well inland of KCHS and KSAV. The environment in the wake of the sea breeze should result steady weakening of convection across the Coastal Plain. Remnant convection and gust front should pass over KCHS tonight, highlighted with a TEMPO from 1Z-4Z. KSAV may see a VCTS between 4Z-6Z. Otherwise, conditions should remain VFR. Scattered convection is forecast to develop around the sea breeze again tomorrow afternoon, with a PROB30 at KCHS and KSAV from 17Z-22Z. Extended Aviation Outlook: Brief flight restrictions in scattered afternoon/evening thunderstorms. && .MARINE... Tonight: East to southwest winds will veer to the southwest overnight and increase to 10-15 kt. Seas will average 1-2 ft, highest over the Georgia offshore leg. There is a chance a line of showers/tstms could move into mainly the lower South Carolina waters later this evening and bring a risk for winds 35 kt or greater, cloud-to-water lightning and low vsbys. Wednesday through Sunday: Weak low pressure will linger just inland with mainly southerly winds prevailing. However, the lack of strong pressure gradients outside of brief afternoon/evening sea breeze enhancement will mean conditions should stay below advisory levels. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM...JRL LONG TERM... AVIATION...NED MARINE...
Area Forecast Discussion
National Weather Service Cleveland OH
941 PM EDT Tue Jun 26 2018 .SYNOPSIS... Low pressure will track across the Great Lakes tonight through Wednesday, bringing a warm front north through the area overnight followed quickly by a cold front on Wednesday. High pressure will build across the region Thursday and Friday, with a warm front lifting north through the area Friday into Saturday. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... Update...With evening convection gone have lowered pops down to slight chance to begin the overnight period. From there followed HRRR trends of developing a few showers into nern OH/nwrn PA after midnight. Then after about 08Z models suggest an increasing chance of showers/tstms developing on/near the advancing warm front approaching from the southwest. So brought pops to chance nern OH/nwrn PA after 06Z and up to chance from the southwest after about 08Z and interpolating into the high chance pop everywhere at 12Z. Original...Somewhat lower confidence forecast tonight and Wednesday. Ongoing MCS over west central Ohio has tracked south of the area and weakened, with some lingering showers possible, maybe a rumble of thunder, over the next couple of hours. Isolated showers have formed in a corridor of 1000 j/kg MLCAPE near Akron/Canton, and may persist for a couple of hours before weakening/diminishing. The storms may get a bit of a boost as the outflow from the aforementioned MCS reaches the area over the next few hours. Once 00Z arrives, much of the convection will end with a few hours of dry conditions expected for most of the area. Attention turns to overnight convection potential as a surface warm front lifts through the area, and a weak/fragmented low level jet tracks northeast into the area. Hi-res guidance is all over the place with overnight thunderstorm development, and confidence is overall low with coverage and specific area of development, so have opted to keep pops in the chance range overnight. Have generally ramped up pops on Wednesday with the cold front approaching the area, the low passing just to the north of Lake Erie. Hi-res guidance keeps convection quite scattered, however with some decent forcing and a chance for marginal destabilization ahead of the cold front, with some deep layer shear as well, opted to ramp up to likely/low cat pops for tomorrow afternoon, especially along/east of I-77 corridor. SPC Day 2 marginal risk for this area seem on track, but conditional on destabilization given poor mid level lapse rates and deep layer shear near 30 kts. Pops ramp down from west to east across the area Wednesday night with the passage of the cold front. Aside from lows only dropping into the upper 60s tonight, temps will be seasonable Wednesday and Wednesday night. No big changes to the temperatures from previous forecast. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Upper level trough will shift east of the area on Thursday. This may allow for a few lingering showers across northeast OH into NW PA through Thursday morning. We then will start a warming trend Friday that will continue into Saturday. This occurring as high pressure takes control at the surface and aloft. So with this strong of a ridge aloft we typically are dry. The humidity will be on the increase Thursday night through Saturday. Heat index values will definitely be on the increase on Saturday with western areas of the County Warning Area likely around 100 degrees. We will need to monitor this closely for possible heat headlines. Temperatures will get warmer each day of the short term. Highs Thursday ranging from the mid 70s across NW PA to mid 80s NW OH. Warmer on Friday with highs mid 80s to lower 90s. Hot on Saturday with all locations into the 90s, upper 90s across NW OH. && .LONG TERM /SATURDAY THROUGH TUESDAY/... Upper level high pressure will begin to shift to the east over the Mid Atlantic states as an upper level trough begins to shift east into the western Great Lakes region. This will also shift the strong subsidence to the east as well by Saturday evening. However, surface high pressure will be present over the Ohio Valley Saturday and then weaken by Sunday. An upper level trough will settle in over the great Lakes as weak surface low pressure moves east across the southern Ontario Canada. A cold front will slide east into the local area Sunday night and it appears to stall over the forecast area for Monday. Moisture associated with the front will be very limited but the threat for showers and thunderstorms exists during this period. High pressure will build south out of Ontario and nudge a ridge into the local area through Tuesday. Albeit a dirty ridge as another shortwave trough and associated moisture and low pressure system approach the area. Holding on to temperatures in the lower 90s across the area Sunday but cooling down into the upper 80s for Monday and middle 80s for Tuesday as the high pressure builds south. Overnight lows in the 70s cooling into the upper 60s to around 70 by Tuesday. && .AVIATION /00Z Wednesday THROUGH Sunday/... Low pressure in IA will track east across the lower Great Lakes on Wednesday. A warm front will move north across the region in advance of the low overnight into early Wednesday. A trailing cold front will follow. VFR conditions to start the evening across northern OH and Erie PA. however as the low approaches from the west expect CIGS to lower with scattered showers and thunderstorms overnight and then more so on Wednesday. Will continue VFR through the first half of the night. Cigs will likely lower to MVFR CAK ERI and YNG 09-11Z where low level moisture will be best in advance of the warm front. Wednesday expecting more widespread coverage of showers and thunderstorms with MVFR conditions more prevalent with the cold front moving through the area and the low just north of Lake Erie. OUTLOOK...Non-VFR conditions possible through Wednesday night in showers and thunderstorms. && .MARINE... Warm front near the Ohio River Valley will lift northward to the lake tonight. This should help to shift winds from an easterly direction to a southerly direction by sunrise on Wednesday. As low pressure moves across the central Great Lakes Wednesday evening it will drag a cold front eastward with it. Winds in the wake of the front will become westerly and may become just strong enough for a small craft advisory Wednesday evening into the overnight for locations east of Cleveland up to Ripley. High pressure will then take control of the region at the surface and aloft Thursday through Saturday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Greenawalt NEAR TERM...Greenawalt/TK SHORT TERM...Mullen LONG TERM...Lombardy AVIATION...TK MARINE...Mullen
Area Forecast Discussion...UPDATED
National Weather Service Peachtree City GA
831 PM EDT Tue Jun 26 2018 .UPDATE... Near term forecast in pretty good shape. Convective complex in eastern TN still chugging along and just now moving into far north GA. Decent cold pool behind this line with temps around 70F. Not seeing many svr reports in last hour or so but will keep a close eye on it. Another smaller area of showers/storms over westcentral GA but cloud tops warming and radar trends also decreasing quickly. Hires models again of little value. Appears only recent HRRR runs have decent handle on observed trends and very near term so far. Should see convection dissipate by 11p to midnight. SNELSON && .PREV DISCUSSION... /Issued 315 PM EDT Tue Jun 26 2018/ SHORT TERM /Tonight through Wednesday Night/... Upper level ridge still building in place over the gulf states, keeping our area generally in west to northwest flow through the short term period. A perturbation moving through the flow in addition to diurnal heating will bring us showers and thunderstorms this afternoon with another round of showers and thunderstorms possible this evening, mainly across northern Georgia. Have kept slight chance to chance pops across the area for isolated to scattered coverage of showers/storms this afternoon and evening. A few severe storms are not out of the question, especially across northern Georgia. For Wednesday, diurnal showers and thunderstorms are expected again in the afternoon/evening. Later on Wednesday afternoon, a short wave trough will push through the area and with it a focus for showers and thunderstorms in conjunction with diurnal heating. These showers/storms may linger into the evening as well. The best chances for the strongest storms will be across northern Georgia. A few storms may become severe with the main hazard being damaging winds. High temperatures today and Wednesday are in the 80s and 90s. Max heat index values are around 100-103 in central Georgia for both today and Wednesday. Trends will continue to be monitored as this is just below heat advisory criteria. Reaves LONG TERM /Thursday through Tuesday/... The forecast is on track with little changes needed at this update. A trough and associated front will move through later Wednesday through the overnight which should be the axis by which we see most convection during this time. Expecting linear development of showers and thunderstorms to move through from north to central GA. The boundary will sag south of the area and will be the catalysis for thunderstorms develop during Thursday and Friday afternoons. By the weekend into next week, strong high pressure will build overhead with ample ridging aloft. This will result in widespread diurnal convection each afternoon/evening. Temperatures will be AOA normal through the period. 26 PREV DISCUSSION... /Issued 424 AM EDT Tue Jun 26 2018/ LONG TERM /Wednesday Night through Monday/... As the long term portion begins, a shortwave trough will be pushing through the region late Wed evening into Wed night. Although guidance is not really emphasizing this feature, fell combination of this enhanced lift and residual instability will be enough to keep convection going into the first half of the overnight period. Will continue in a NW flow type pattern through the end of the week so will be difficult to time individual impulses within the flow. May be less of a diurnal trend to pops during this time period but for now have continued to indicate highest pops during the afternoon hours. Some indications of perhaps some drier air working into the NE corner of the forecast area Fri but may not be enough to shut down convection completely given aforementioned lift. Mid and upper level high moves over the NE states for the weekend into early next week. Deep layer moisture will traverse the southern extent of this to bring higher rain chances back to the area. Precipitable water increases to 2 inches by late Sat and continues into Sun. Some notable dry air to move in from the east by early next week with PW values falling to at or slightly below seasonal norms. Deese && .AVIATION... 00Z Update... Main concern is TSRA likelihood this evening. Isold SHRA and TSRA east of ATL has dissipated but watching area about 50nm to the southwest of ATL. Have kept TEMPO TS going until 02Z. With rain and cool air in NE GA, could see some IFR cigs near KAHN but otherwise VFR elsewhere tonight and Wed morning. Another round of TSRA likely Wed afternoon after 22Z but not much confidence in coverage. Have used PROB30 for now in most areas. Sfc winds light SW becoming W 5-8kts after 15Z Wed. //ATL Confidence...00Z Update... Low-Medium confidence on TSRA likelihood tonight and Wed afternoon. High confidence in all other elements. SNELSON && .PRELIMINARY POINT TEMPS/POPS... Athens 71 90 72 93 / 50 50 40 30 Atlanta 74 90 75 91 / 30 40 40 40 Blairsville 66 84 67 86 / 50 60 50 30 Cartersville 71 90 72 91 / 40 50 40 40 Columbus 76 93 76 93 / 20 30 30 50 Gainesville 71 88 72 90 / 50 50 40 30 Macon 74 93 74 94 / 20 40 30 50 Rome 71 90 72 92 / 30 50 40 30 Peachtree City 72 91 73 91 / 30 40 30 50 Vidalia 75 94 76 94 / 20 40 30 50 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...SNELSON LONG TERM....22 AVIATION...SNELSON
Area Forecast Discussion
National Weather Service Hastings NE
941 PM CDT Tue Jun 26 2018 .UPDATE... Issued at 941 PM CDT Tue Jun 26 2018 A few comments regarding the next 12 hours or so: 1) Although the official forecast has been kept dry (meaning PoPs less than 15 percent) through the night/Wed AM, a few mainly higher res models such as RAP13/HRRR are suggesting that our far northern/northeast counties could have a somewhat "close call" with convection developing southward out of SD, with some of this activity perhaps getting within 50 miles of our CWA mainly during the 6-9 AM time frame. Something for next few shifts to watch. 2) Although not currently expecting widespread dense fog issues, maintained a formal mention of "patchy fog" for mainly our far south/southwest counties a few hours either side of sunrise, as this area remains most supported for fog development per latest RAP/HRRR trends. However, given the light winds/lingering wet ground in many areas, would not be surprised to see at least hit- and-miss patchy fog elsewhere in the CWA as well. 3) Nudged up low temps 1-2 degrees most areas, with the majority of the CWA expected to bottom out in the 63-67 range. && .SHORT TERM...(This evening through Wednesday night) Issued at 330 PM CDT Tue Jun 26 2018 After a few thunderstorms developed across north central Kansas this morning...skies cleared and a beautiful day matured across the region as winds relaxed and temperatures climbed back near and above 80 in most locations. Expect this mild early summer afternoon to give way to a beautiful evening with clear skies and continued mild temperatures. While winds will remain light overnight...they should slowly shift and become southeasterly by early Wednesday morning in the wake of the departing area of low pressure. These light southeasterly combination with clear skies and temperatures forecast to fall to near dewpoint values...should aid in the formation of at least some patchy radiational fog across north central Kansas during the early morning hours Wednesday. The SREF guidance hinted at this earlier in the day...and the latest HRRR is now coming in with some dense fog near our southwestern border towards morning. Given all this...decided to add the mention of some patchy fog across our south to the forecast...and will recommend the evening shift monitor for potential more widespread or dense development tonight. Otherwise...expect temperatures to return to the 90s tomorrow... with heat index values soaring to near 100 in spots...especially across portions of north central Kansas. While dry weather is expected during the afternoon hours tomorrow...confidence is increasing on some convection rotating around the ridge to our southwest and impacting areas north of interstate 80 Wednesday night. While there is no official mention in the forecast...given the significant amount of available instability tomorrow night...would not be surprised to see some strong to near severe thunderstorms impact the area if they do hold together and impact portions of south central Nebraska. .LONG TERM...(Thursday through Tuesday) Issued at 330 PM CDT Tue Jun 26 2018 Dry and hot weather is expected to start the extended periods as the area will be under a transitory upper level ridge Thursday afternoon with breezy southerly winds advecting a warmer and more moist airmass across the local area. This should result in well above normal temperatures during the afternoon hours...with most locations topping out near or above 100 degrees. In combination with the increasing dewpoint values...expect heat index values to exceed 100 degrees across nearly the entire forecast area Thursday...likely marking the warmest day of the extended periods. While the upper ridge will be shifting east on Friday in advance of a west coast trough...temperatures will remain on the toasty side Friday as well as some adiabatic compression ahead of the approaching cold front will likely be realized. Under this scenario...Friday could actually end up just as warm or a few degrees warmer than Thursday...but given increasing cloud cover and uncertainty in the position of the front...kept Fridays highs a couple of degrees below Thursday afternoon and in line with blended model guidance. Once the aforementioned trough and associated cold front reach the local area...expect increasing chances of precipitation over the upcoming weekend as temperatures return back closer to normal and multiple disturbances make their way across the region. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday) Issued at 658 PM CDT Tue Jun 26 2018 PLEASE NOTE: As of this writing, KEAR has been reporting an errant/bogus 200 ft. ceiling since approximately 1630Z. In reality, skies there are currently clear, and no sub-VFR ceiling is currently anticipated through the valid period. General overview: Confidence is fairly high in VFR ceiling/visibility and rain /thunder-free conditions through the valid period. Cloud-wise, expecting really no more than perhaps few-scattered diurnal cumulus during the day Wednesday. Winds should not be big factor either, with generally light/variable breezes this evening becoming light southeasterly overnight, and then picking up a bit during the day Wednesday, but still largely at-or-below 10KT. About the only possible "catch" to this VFR forecast could be some patchy/light fog around sunrise Wednesday, but better potential for this currently looks to focus at least a few counties off to the south-southwest, so will not include at this time. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ UPDATE...Pfannkuch SHORT TERM...Rossi LONG TERM...Rossi AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Goodland KS
629 PM MDT Tue Jun 26 2018 .SHORT TERM...(This evening through Wednesday) Issued at 111 PM MDT Tue Jun 26 2018 19Z Water vapor imagery/RAP analysis indicated short wave ridging building over the area with trough moving across northern Montana. At the sfc, some reflection of this trough apparent with sfc trough across northern Wyoming extending into North Dakota. Sfc low was developing near KTRB with stationary front extending eastward towards KSLN. Main forecast concerns will primarily be temperatures and limited fog potential tonight. Weak easterly flow will persist across eastern CWA tonight with airmass changing little from last night, with moisture profiles increasing with height just off the ground. This seems to be confirmed by diurnal pattern in sfc dewpoints, with values staying steady or increasing a bit with afternoon heating. If winds were to remain easterly across the entire area, could see fairly widespread fog development. However expect to see much of CWA winds shift to the west overnight in response to northern plains system, which would limit westward extent. Right now, it looks extreme eastern part of CWA will have potential for a period of fog around 12z, but things should clear up after that. For precipitation chances, strong CINH associated with warm temperatures aloft will limit convective chances through the period. While easterly flow will advect higher dewpoints into eastern Colorado tomorrow which will destabilize things, cap remains strong through the day. Do not think it is unreasonable that a storm may fire along higher terrain and drift into area, but it would likely be very late in the afternoon and early evening before even this small threat would occur. .LONG TERM...(Wednesday night through Tuesday) Issued at 229 PM MDT Tue Jun 26 2018 For Thursday, a ridge with embedded shortwaves is expected to move over the southern and central Plains leading to temperatures reaching 100 degrees and above. From Thursday through next Tuesday, above average temperatures are expected. By Friday evening, a trough begins to enter the central Plains bringing some slight thunderstorm chances. The trough as well as shortwaves is expected to bring thunderstorms Saturday evening through Sunday night with the greatest chance for thunderstorms Sunday night. By Monday, a ridge begins to build over the central CONUS with temperatures increasing and drier conditions returning. A slight chance of thunderstorms exists Tuesday evening. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 608 PM MDT Tue Jun 26 2018 VFR conditions expected at MCK and GLD through the 00Z TAF period. Mostly clear skies and light winds will prevail across the central high plains region over the next 24 hours as a result of a region of higher pressure remaining over the area. There is a possibility of fog developing in the vicinity of MCK between 10-14Z. However with most of the models and current public forecast indicating a lack of fog and only the HRRR model showing the possibility of fog developing, confidence in fog actually developing is low and have decided to leave it out of the MCK TAF at this time. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...JRM LONG TERM...BLN AVIATION...LOCKHART
Area Forecast Discussion
National Weather Service Grand Rapids MI
730 PM EDT Tue Jun 26 2018 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 330 PM EDT Tue Jun 26 2018 A low pressure system will move through lower Michigan tonight and Wednesday with periods of showers and thunderstorms. An upper- level ridge will then build into the area providing the means for much warmer temperatures and more humid conditions across lower Michigan. At this time, highs in the 90s with heat indices at or above 100 are possible starting Friday and lasting through the weekend. A cold front is then expected to swing through early next week bringing an end to the heat. && .SHORT TERM...(This evening through Wednesday) Issued at 330 PM EDT Tue Jun 26 2018 Bottom line: Showers and thunderstorms are expected to increase in coverage early Wednesday morning across much of the area with locally heavy rainfall possible. While the potential for severe weather is low, the threat for flooding (possibly "flashy") is elevated at least through Wednesday morning. The heaviest rain is expected between midnight tonight and 10 AM tomorrow morning. The Details: First thing is first--we continue to monitor a somewhat pesky area of showers and weak thunderstorms across west central Michigan located along the nose of an elevated front pushing northeast across lower Michigan. The activity has been ever so slowly diminishing with time, though there are still occasional pulses of stronger cores and associated short-term increases in lightning. With PWAT increasing to 1.5-1.8 inches, brief heavy rainfall is the main concern. As the showers become more removed from what is left of an 850 mb low-level jet, the activity is expect wane by late evening. Attention then turns to the potential for heavy rain overnight. Various GOES-East satellite channels depict a tightly wound low pressure system centered over central Iowa with developing convection across northern Illinois and southern Wisconsin. A warm front extends from roughly Lima, OH to Madison, WI, south of which dew points are in the upper 60s to lower 70s. As the aforementioned low tracks eastward over the Wisconsin/Illinois border this evening, the warm front will move northward into lower Michigan. Along and just north of the front, increasing isentropic ascent will promote widespread showers and thunderstorms across northern Illinois and southern Wisconsin. As the low then moves into lower Michigan tonight, the expectation is for associated convection to increase area wide, as well. Short-term high resolution model guidance is somewhat all over the place on potential convection evolution this evening and overnight. For one, the NAM and WRFs depict a few thunderstorms developing along the warm front between 00-05Z tonight across the southern two tiers of counties in lower Michigan before any activity arrives overnight. Given low-level directional shear along the front, such a scenario is somewhat concerning. However, widespread convective debris cloud cover from activity across the Ohio River Valley lends me to think that we won`t see much until after dark when the synoptic forcing associated with the low arrives. However, should a thunderstorm or two develop this evening along the front, the favored area for perhaps a very localized strong storm threat would across Van Buren and Kalamazoo counties. As for tonight... Model guidance continues to signal the potential for a swath of heavy rainfall associated with elevation convection along and north of the aforementioned front. Several CAMS denote the potential for 2-3" of rain in spots, with the HREF max 24-hour rainfall showing areas potentially of 4" or more. As previously mentioned, the CAMs are struggling with potential convective evolution this evening, though they do seem to be shifting southward in forecast heaviest precipitation as well as later. While I am not going to sound the alarms just yet for flash flooding, I am certainly concerned that some areas may pick up several inches of rain in a short amount of time, mainly between midnight tonight and 10 AM tomorrow morning. At this point in time, the area with greatest risk for heavy rainfall looks to be bounded by I-196, US- 131, and US-10. However, it is worth noting the last few runs of the HRRR have been showing the heaviest rain falling over the Grand Rapids and Lancing metropolitan areas right around sunrise tomorrow morning. Shower and storms are expected to push northeast out of our area tomorrow morning as the low shifts eastward. Depending on how much clearing we see, it is feasible we may see a regeneration of showers and a few thunderstorms across the southeastern half of lower Michigan as a secondary cold front swings through mid-morning. However, coverage is expected to be much greater across Ohio and southern Ontario. .LONG TERM...(Wednesday night through Tuesday) Issued at 330 PM EDT Tue Jun 26 2018 The upper low will be exiting the eastern CWA to begin the long term period, with any lingering showers quickly coming to an end in the evening. Focus then shifts to the building heat for late in the work week and into the weekend. Models are still on board with heat especially in the Friday to Saturday time frame. 850mb temps are forecast to peak around +25C Friday night. On Thursday we begin to ramp up the heat with highs topping out in the middle 80s. Friday we surge past the 90 degree mark in most areas with dew points that will be in the 70s. Saturday we may hit the mid 90s with high humidity continuing. The hottest, most humid conditions will be on Friday and Saturday which is when we will likely need to consider heat headlines going forward. Heat index values will be in the 100-105 range it appears which straddles Heat Advisory and Excessive Heat Warning criteria, which are 100F and 105F respectively. On Sunday, it appears the ECMWF is going to win out which has been more progressive with the northern stream all along. A wave in the northern stream will push a cold front through our area on Sunday. Therefore, Sunday which once looked like another hot day may be tempered a bit by clouds and showers/thunderstorms. 80s are still expected on Sunday. We will need to keep an eye on Sunday for severe weather chances as moderate to possibly high instability will be present given the heat and humidity. Bulk shear is not all that strong though in the afternoon on the order of 20-30 knots. Monday and Tuesday high pressure looks to briefly build in behind the cold front with 850mb temps cooling to more seasonable middle teens C. Highs will likely be in the middle 80s with mainly dry weather. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 730 PM EDT Tue Jun 26 2018 VFR conditions early this evening will deteriorate to IFR after midnight as an area of showers and thunderstorms moves into Lower Michigan. Thunderstorms in northern Illinois and southern Wisconsin will cross Lake Michigan and reach MKG by 04Z. These storms will spread east and affect GRR and AZO by 06Z then LAN and JXN by 09Z. Low clouds and showers, along with isolated thunderstorms, will persist through much of Wednesday morning with ceilings AOB 1000 ft AGL. && .MARINE... Issued at 330 PM EDT Tue Jun 26 2018 Winds and waves are expected to remain below 21 knots and 4 feet, respectively, through the forecast period. However, southerly winds of 15-20 kts are possible Friday through Sunday. && .HYDROLOGY... Issued at 330 PM EDT Tue Jun 26 2018 Area rivers and streams are expected to handle the anticipated rainfall through Wednesday with little issue (based on NCRFC 95th percentile rainfall amounts) but where the heaviest rains persist it is possible that small rivers and streams could see rises above bankfull. This would mainly be a concern if a few inches of rain fall within a short amount of time over a basin. Currently this is expected to be a low risk and localized in nature, but something we will monitor. The next risk for rain on Sunday is not expected to be && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ SYNOPSIS...Borchardt SHORT TERM...Borchardt LONG TERM...Duke AVIATION...Ostuno/McCormick HYDROLOGY...Hoving MARINE...Borchardt
Area Forecast Discussion
National Weather Service Huntsville AL
922 PM CDT Tue Jun 26 2018 .NEAR TERM...(Tonight) Issued at 922 PM CDT Tue Jun 26 2018 Generally quiet conditions formerly over the forecast area in the latter afternoon and very early evening have come to an end, as isolated to scattered showers and thunderstorms affected parts of the region. Within the last hour or so, a few of the thunderstorms were very electrically active via GLM and surface lightning plots. With rather unstable atmosphere with surface CAPE nearing 4000 J/kg and boundary interaction, that convection had fired and/or moved over the region. However, further night time cooling and a more stable atmosphere should result in a downward trend regarding storm coverage and intensity within the next few hours. Very recent rains from this convection again raises a potential for late night fog development. Looks like in similar area to last night, (east of Interstate 65) patchy fog will be introduced in the forthcoming update. Will also expand area of shower coverage somewhat further to the south for the (maintaining isolated rain chances into the late night) given output from HRRR and older ARW runs. Convection now moving across the Mid Mississippi and Ohio Valley regions should wind down - and for the most part remain north of this area. .SHORT TERM...(Wednesday through Thursday) Issued at 225 PM CDT Tue Jun 26 2018 Another seasonably hot and humid day is xpcted on Wed, as afternoon highs again climb mainly into the lower 90s. Heat indices may also climb just above the 100F mark for a couple of hrs, especially in areas which do not receive any rainfall. The upper shrtwv to the north will continue to translate ewd and may actually dig a bit further to the south closer to the mid TN Valley. This may in fact increase rain chances just a bit on Wed, as slightly better mid/upper forcing spreads into the area from the NW. Showers/tstms may in fact linger into the late evening period Wed night before diminishing, leaving partly/mostly cloudy skies in place. Temps early Thu morning will again be rather mild, with lows predom in the lower/mid 70s. Upper ridging out of the Plains states then begins to build ewd into much of the region starting Thu. This should result in slightly less chances for showers/tstms while afternoon highs increase a degree or two. Afternoon highs Thu may climb as high as 93-94F in some spots, while associated heat indices reach 105-107F in some locations, especially in NW/N cntrl AL. A Heat Advisory may be warranted on Thu. .LONG TERM...(Thursday night through Monday) Issued at 225 PM CDT Tue Jun 26 2018 An upper-level ridge will continue to remain the dominant weather feature across the region, promoting hot and humid conditions across the Tennessee Valley late this week into the weekend. There are some subtle differences between the longer range models regarding the intensity of the ridge and subsequent warming, with the ECMWF and Canadian solutions favoring a slightly stronger/warmer solution. The GFS hints at the possibility of a very weak Gulf low moving north into Central Alabama on Friday -- perhaps resulting in more cloud cover and diurnal convection Friday and Saturday. Regardless, it will feel quite toasty outside, with highs peaking in the low to mid 90s across the Valley. A light SW flow will maintain this very moist, tropical air mass in place across the region, as dewpoints will remains close to the mid 70s. As a result, progged Heat index values on Friday may once again reach or exceed Advisory criteria, peaking in the 105-108 degree range. Will need to continue to monitor this trend in the coming days. The center of the upper ridge will gradually shift to the north and east over the Carolinas. While SW flow will remain in place, temperatures should be a degree or two cooler, placing Heat Index values in the 100-105 degree range, just below Advisory criteria. With the deep moisture in place, the threat for scattered thunderstorms (a few strong) will be possible each day, mainly in the afternoon and evening hours. Will have to watch very late in the period (early next week) should the ridge flatten slightly, allowing a few shortwaves to propagate into the Ohio Valley (and, thus, for any MCS activity to approach the region from the north and west). For this reason, have trended slightly higher with PoPs on Monday and Monday Night, with the higher values favoring the northern zones. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 648 PM CDT Tue Jun 26 2018 For the start of the TAF, isolated showers were in the vicinity of the KHSV terminal. An outflow boundary was also moving southward towards far northern Alabama, east of I-65. This boundary may help with the formation of new convection, mainly east of the MSL/HSV terminals through ~27/0200Z. VFR weather otherwise is expected for the TAF. S-SW winds around 5kt should become light/variable after dusk. Light winds at daybreak should become SW and increase in the 10-15 kt range by noon. Another system approaching from the NW could bring more shower chances to the region Wed afternoon. Given uncertainties, went with VCSH for the afternoon hours. Prob30 and/or prevailing showers and t-storms could be added in later TAFs if better model agreement is realized. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...09 LONG TERM...AMP.24 AVIATION...RSB For more information please visit our website at
Area Forecast Discussion
National Weather Service Lincoln IL
659 PM CDT Tue Jun 26 2018 .SHORT TERM...(This evening through Wednesday) ISSUED AT 315 PM CDT Tue Jun 26 2018 Main forecast concern for the short term will be the redevelopment of any convection in central/southeast IL this evening into early tonight. The latest surface analysis at 19z indicated an occluded low in north central IA with a warm front extending into NE and east central IL and a cold front into east central IA and NW MO. Thus, the whole forecast area is in the warm sector. However, a 17z sounding at KDVN and the latest SPC mesoanalysis shows that much of the area has stabilized from the convection earlier today and the associated cloudiness. Some destabilization may occur this evening across the forecast area, with the highest CAPE expected in areas south of I-70...and near the warm front in northern IL. The most recently updated SPC convective outlook bears this out with a Marginal risk for severe storms now extending from Henry thru Bloomington/Normal to Paris for this evening. A majority of the short range CAMs are way over done with their depiction of thunderstorms late this afternoon and this evening. Prefer the NAM and RAP depiction of periods of showers and t-storms, so will maintain the likely PoPs up to midnight, and then only keep chance PoPs in for extreme eastern IL overnight. A partly sunny and seasonable day will be in store Wednesday as the cold front sinks into far southern IL and weak high pressure takes over. .LONG TERM...(Wednesday night through Tuesday) ISSUED AT 315 PM CDT Tue Jun 26 2018 The main story for the long term period continues to be increasing heat and humidity for late in the week. There is model agreement in transitioning an upper level ridge toward the MS Valley on Thursday. Where there is quite a bit of disagreement is in the strength of a short wave trough overtopping the ridge later in the day Thursday and its potential to provide support for convection. Will go with only slight chance PoPs for now due to the model uncertainty and since most of the convection is expected to stay just to the southwest of the forecast area. The upper ridge axis is expected over our region on Friday, and then it will progress to our east Saturday. The models have been consistent in increasing our dew points into the mid-upper 70s, with temperatures in the lower-middle 90s. Resulting heat index values ranging from 105 to 110 degrees will be common across the area early this weekend, as a result. The extreme heat, fortunately, appears that it will be short lived as the upper ridge heads to the east coast by Sunday, with a southwest flow developing on the backside of the ridge. This will allow for the development of showers and thunderstorms Saturday night mainly in the vicinity of the I-74 corridor where the upper cap will be weakest, and across the whole forecast area Sunday. Once again, our summertime pattern of fronts dropping into central IL and then stalling out appears to be in store for us Monday into Tuesday. The GFS and Canadian models are preferred as it appears the European model tries to rebuild upper ridging too quick into the Midwest. The resulting blended solutions give us at least a chance for showers and few t-storms Monday and Tuesday and temps in the mid-upper 80s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 655 PM CDT Tue Jun 26 2018 Predominantly VFR conditions expected across the central Illinois terminals through the 00Z TAF valid time. A weak cold front will push across the region tonight, possibly accompanied by a shower or thunderstorm. However, the bulk of the precipitation is expected to stay north or south of the area. Moisture wrapping in behind the front may bring a period of MVFR CIGS later tonight or early Wednesday. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Miller LONG TERM...Miller AVIATION...Bak
National Weather Service Jackson KY
1046 PM EDT Tue Jun 26 2018 .UPDATE... Issued at 1042 PM EDT TUE JUN 26 2018 Several updates have been made since the last discussion. The first was to drop the ongoing Flash Flood Watch during the 9 pm hour (set to expire at 10pm). Rains have dissipated and exited east KY leaving dry conditions across the CWA late this evening, with no further flash flooding expected during this time. That being said, we are continuing to track a MCS moving across western and now central Kentucky. This system is moving quickly, but has shown rapid weakening as it pushes nearer this side of the state. The latest CAMs continue to get a better handle on the system, showing it making it eastward into the CWA by 6Z. However, they are all in agreement that it will have weakened substantially by the time it gets here, and will likely not add to the ongoing flooding concerns. Furthermore, there is good agreement that the best pops/qpf will be across the northern CWA, which was not substantially impacted by heavy rains earlier today. Updated the pops and weather to account for the ongoing dry conditions across the CWA, as well as timing in the shower/thunderstorm chances during the second half of the overnight. Also made sure the near term grids were on track with the ongoing conditions by loading in the latest observations. All updates have been sent to NDFD/web. A new forecast package was sent out to reflect changes to the weather and also to remove the flood watch wording. This included sending a new HWO as well. && UPDATE Issued at 830 PM EDT TUE JUN 26 2018 Revamped much of the short term forecast to better line up with the current radar trends and the hi-res model data. Heavy showers and thunderstorms that plagued much of eastern KY late this afternoon have dissipated significantly and are almost SE of the state. Expect all shower activity to be out of the CWA over the next hour or two. Meanwhile, a small MCS is currently making its way across western KY. There is the potential that this can continue to progress eastward as we head into the overnight, and lead to some convection late tonight and through dawn tomorrow. Hi-res models are still showing quite a bit of variation with this. If the HRRR pans out, much of the system will have dissipated by the time it gets to us. If the NAM, ARW, or NMM pan out, we could see some convection moving across generally between 9 and 14Z. This will bring us into the daytime hours for Wednesday. A cold front is forecast to drop southward and become stationary along the Ohio River throughout the day. Kentucky`s location just south of this boundary will result in deep southerly flow and the advection of warm and moist, unstable air into the region. This, plus the nearby boundary, will spawn scattered to numerous convection throughout the afternoon. Shear, both directional and speed shear, look a bit better for tomorrow afternoon compared to previous days. And given the strong influx of moisture, expect that any storms that do develop could once again result in some heavy downpours, heavy lightning, and the potential for flooding concerns. As for the rest of this evening, adjusted the grids based on the current conditions, and loaded the latest observations for temps, dew points, and winds into the near term grids. All updates have been published and sent to NDFD/web. A new forecast package was also sent out. A new HWO will follow shortly. && .SHORT TERM...(This evening through Wednesday night) Issued at 345 PM EDT TUE JUN 26 2018 Scattered to numerous showers and thunderstorms will move across eastern Kentucky this afternoon into early this evening. The stronger storms will be capable of producing damaging wind gusts and locally heavy rainfall that could cause isolated instances of flash flooding. Scattered showers and isolated thunderstorms will be possible overnight as well. Another round of showers and storms will be possible on Wednesday, as a frontal boundary meanders about the area. Some of the storms on Wednesday may produce small hail, damaging wind gusts, and locally heavy rainfall that could lead to flooding. The best chance for storms on Wednesday will be from the late morning through late afternoon hours. The precipitation should gradually taper off and begin moving out of the area Wednesday night. Temperatures on Wednesday should be slightly below normal, due to widespread cloud cover and precipitation. Low temperatures the next two nights will be in the upper 60s for most locations, which is slightly above normal for the time of year. .LONG TERM...(Thursday through Tuesday) Issued at 345 PM EDT TUE JUN 26 2018 Isolated to scattered showers and storms will likely linger across the area on Thursday, as a frontal boundary remains in place just to our south. This activity should be exiting the area by late Thursday afternoon, as the front drifts southward. Showers and storms will then be possible from Friday through Sunday, mainly during the afternoon and early evening hours. More persistent showers and storms are expected across the area from Sunday night through Monday night, as another frontal boundary moves slowly across the area. Temperatures in the extended look to be quite warm, with daily highs topping out in the upper 80s and lower 90s, with nightly lows only falling into the upper 60s and lower 70s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) ISSUED AT 841 PM EDT TUE JUN 26 2018 Heavy to torrential rainfalls that swept across eastern KY throughout the day are now dissipating and exiting east of the state. Expect mostly dry conditions in its wake through the first half of the night. Large amounts of lingering llvl moisture will likely lead to some fog development, despite ongoing cloud cover. However, much like last night, the impacts will be variable from location to location, and will fluctuate throughout the night. Trended towards predominately MVFR or IFR VIS and LIFR CIGS or lower. Another round of convection may pass through from late tonight through dawn. The extent of this convection is still uncertain, but it may be enough to mix things up a bit and help to deter best fog. As a result, have some improving conditions (MVFR) generally after 9Z, along with introducing VCSH. Isolated thunderstorms can`t be ruled out, however. Things will ramp up again during the day tomorrow, with scattered to widespread showers and thunderstorms throughout the day, especially in the afternoon and evening. Any storms will result in significant lowering of VIS, as well as some variability to the CIGS. Winds will generally be light and variable throughout the period, outside of any thunderstorms. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...AR LONG TERM...AR AVIATION...JMW
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
658 PM CDT Tue Jun 26 2018 .MESOSCALE DISCUSSION... 317 PM CDT Couple rounds of convection still on track late this afternoon into the evening. As of 300 PM CST, upper low is noted on water vapor imagery centered near DBQ while axis of greatest height falls is beginning to overspread northern Illinois which has helped to kick off scattered thunderstorms early this afternoon. At the surface, broad and ill-defined warm front stretches from near DBQ through DKB towards RZL in northwest Indiana. Within this corridor, dew points have pooled into the low 70s and flow becomes slightly backed with northward extent. Dew points combined with temperatures in the low 80s is contributing to moderate instability with MLCAPE in the 1000- 1500 range per recent RAP analysis. Additional modest destabilization is expected as we continue to thin some of the cloud cover that has been in place much of the day. Increasing forcing for ascent and instability will continue to support thunderstorm development over the next several hours. Shear appears to be a limiting factor with respect to a more organized severe threat today. Mid level flow has been slightly weaker than anticipated. Special 17Z raob from DVN indicated only 34kt of flow at 500mb and deep unidirectional flow is resulting in 0-6km shear of only 25kt. Lower level shear is a little better, though still not impressive. 0-1km SRH does approach 100 m2/s2 near the low track and within the frontal zone over far north central Illinois, though values quickly drop off farther southeast. A couple storms so far today have shown weak rotation and supercellular characteristics, so not completely out of the woods despite the limiting factors. Any supercell storms that are able to tap into the better low level helicity may be able to produce a tornado. Deubelbeiss && .SHORT TERM... Tonight... 247 pm...Convective trends remain a bit uncertain this evening with additional scattered thunderstorms possible mid/late this evening perhaps slowly dissipating to showers after midnight... though exact end time will need refinement. As the surface low moves across the northern cwa overnight...expected low clouds to develop and the potential for patchy fog mainly along/north of I-80 but not expecting anything dense at this time. Any patchy fog that does develop may begin to improve by early morning as winds turn west/northwest on the back side of the departing low. Dewpoints stay in the 60s through the night thus lows only dropping to mid/upper 60s by morning. cms && .LONG TERM... 333 PM CDT Wednesday through Tuesday... The primary concern for the extended period is the two-day stretch of heat and humidity expected Friday and Saturday. Tomorrow should be dry and cooler in the post frontal northerly flow behind the departing low and ahead of an approaching surface ridge axis. Thursday will be a bit warmer as the ridge shifts east and allows southerly flow to develop locally. The upper level ridge trails its surface counterpart and moves overhead early Friday ahead of an upstream longwave trough over the western CONUS. In the strong southwesterly flow ahead of the slowly progressing longwave trough, multiple surface lows develop over the Plains and lift northeast through the end of the week into the weekend. The first of these lows stays upstream but pushes a warm front across the area early Friday and ushers in a very warm and humid airmass for Friday afternoon. Late Thursday night there is a chance that the combination of a low level jet, the warm front, and associated midlevel shortwave energy could support early morning thunderstorms Friday that could delay the onset of warming and perhaps inhibit the eventual afternoon highs. Still thinking the most likely scenario is for this activity to clear out early enough to allow for mid 90s in most locations Friday afternoon. With the combination of mid to upper 70s, especially in southern and western portions of the forecast area, this would lead to heat index values in the 100 to 110 range with a few locations possibly a bit warmer. Friday night heat indices only drop to the mid 70s and then Saturday appears to be a near repeat of Friday. Confidence is fairly high that headlines for heat advisories or watches/warnings will need to be considered for later shifts but it is still a bit early to hoist anything at this time. By Saturday night the longwave tough has moved close enough to the area to allow one of the surface lows to push into the western Great Lakes and drag a trailing cold front into the area early Sunday. In fact the corresponding upper shortwave takes a bit of a negative tilt which could also support a period of severe storms sometime during the weekend after the heat breaks. Timing at this range is far from certain, but current trends suggest that Sunday will be wetter and cooler than the preceding days. Again, with much less certainty, the early part of next week looks cooler and drier under the influence of a surface ridge sitting to our north and Gulf moisture shunted off to our west. Lenning && .CLIMATE... Record Temps For the Chicago area... Record High Max Temp June 29: 97F (1954) June 30: 99F (1913, 1953) Record High Min Temp June 29: 80F (1931) June 30: 80F (1931) For the Rockford area... Record High Max Temp June 29: 103F (1931) June 30: 102F (1931) Record High Min Temp June 29: 75F (1931) June 30: 74F (1913, 1931) && .HYDROLOGY... 328 AM CDT Chose to issue a Flash Flood watch as multiple rounds of thunderstorms are expected this afternoon and evening. Guidance suggests that precipitable water values will increase to 1.5-1.75. Moisture convergence vectors converge on northern IL signaling pooling of moisture. Storm motion will also play a factor as the surface low moves over northern IL. Storms currently over Iowa are training signaling flash flooding may be possible. Storms are moving toward the north at 25 MPH, but as more storms form to the south, rain continues to fall over the same areas. Expecting this same trend over the Flash Flood Watch area this afternoon and evening. Given recent heavy rainfall across much of the region, saturated ground will lead to mostly runoff also suggesting flood potential. JEE && .AVIATION... For the 00Z TAFs... Multiple concerns for the terminals for the period. Initially, tsra and winds will be the concern and then transitioning over to cigs/vis overnight. At issuance time, scattered thunderstorms were occurring invof or at the terminals. An outflow boundary from earlier convection has turned winds at ORD/DPA to nwly, while MDW/GYY remain more sly and RFD is vrbl and convectively altered. Expect that the lake breeze boundary will no longer be a concern for the terminals and will be disrupted by ongoing and upcoming thunderstorms. Still expect periods of thunderstorms at the Chicago area terminals until arnd 04-05Z with a short period of lingering shra. The initial storms could produce very heavy rainfall rates, so will continue the mention of 1sm +TSRA through 01z, but TS strength should weaken through the evening. Winds will be low confidence in speed and direction for the period of the main thunderstorm activity. The main low pressure center, initially over swrn WI, will track ewd through the evening, with winds gradually veering through swly to wly overnight. Also, as the low passes across the region, latest guidance is lending higher confidence in cigs lowering to ifr levels durg the early morning hours, with some potential for cigs as low as 300 ft possible at some locations. Will limit cigs at ORD/MDW to 800 ft for now and go with 300 ft in a tempo for DPA/RFD. However, there is a chance that ORD/MDW/GYY could see a period of lifr cigs as well. Cigs should be slow to improve through the day tomorrow as the region will remain under the wraparound cloud cover from the exiting low as well as cyclonic flow aloft. Latest guidance suggests that conditions should improve to vfr by late tomorrow afternoon. && .MARINE... 333 PM CDT Low pressure and a cold front crossing the southern lake tonight will bring a period of unsettled weather through early morning. Northerly flow tomorrow backs to westerly for Thursday, then continues backing to southerly for Friday and Saturday as the gradient tightens and supports stronger winds especially across the north half. The next cold front appears to pass sometime over the weekend. Lenning && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Flash Flood Watch...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010- ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020 until 1 AM Wednesday. IN...None. LM...None. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1040 PM EDT Tue Jun 26 2018 .SYNOPSIS... A frontal boundary will be stalled just south of the area through Wednesday with an area of low pressure moving along it. The low and front will move northeast Thursday, and then another cold front will move in from the northwest Friday. High pressure will build in over the weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 1020 PM Tuesday...Minor adjustments to POPs/weather next few hours but did leave in higher chance POPs along coast late tonight. Front is still stalled south of area with weak waves on along it but latest NAM and HRRR continue to indicate slightly stronger low development south of Cape Lookout near morning resulting in additional shower/tstm development mainly near coast. Temps on track for lows 70-74. /Previous discussion/ As of 3 PM Tue...Latest sfc analysis shows cold front lingering across the southern tier this afternoon, which is becoming the focus for convective development. Latest radar imagery shows scattered moderate to heavy showers and isolated storms developing across the southern tier this afternoon. Instability has been limited today with widespread cloud cover. Mesoanalysis shows sfc based CAPE values 1000-2000 J/kg, highest near the boundary, with 0-6km shear around 20 kt. Isolated strong wind gusts will be possible across the very southern areas this afternoon and evening near area of higher instab. but think the main threat will be locally heavy rainfall. PWATs currently just over 2 inches, combined with the observed rainfall over the last several days, some areas could see minor flooding. Precip could continue into the late evening, before shifting off the coast late tonight. Front is expected to push slightly further southward tonight as weak low develops along it. Overnight lows in the upper 60s to low 70s. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... As of 3 PM Tue...Front will remain stalled just south of the area Wednesday, as areas of low pressure strengthens along it and moves along the NC coast. Upper level flow becomes a little more zonal ahead of next approaching shortwave. Not expecting as much precip coverage, with best chances along the coast early then shifting more inland during the afternoon. Expect coverage to remain fairly scattered and will keep low chance pops. Isolated stronger storms possible, but with PWATs still around 2 inches. Low level thickness values support highs in the mid to upper 80s. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... As of 310 am Tue...Unsettled pattern continues into Thu night. An approaching upper level shortwave with several embedded vort waves will pass through Wed night into Thu, with scattered showers and thunderstorms. A drier pattern develops for Fri into Sat with a weak front passing through Fri morning and a surface ridge behind it passing by to the north. Isolated showers possible in southwest counties Friday then dry throughout for Saturday. The typical summertime pattern redevelops Monday with the mid- state surface trof and offshore high and mainly diurnal convection. Highs Wed will range in the mid to upper 80s, with lower 80s OBX, then upper 80s coast to lower/mid 90s inland for the remainder of the period. Lows will be in the lower/mid 70s. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Short Term /through 00Z Thursday/... As of 745 PM Tuesday...Showers lingering near frontal boundary over southern sections will keep mainly MVFR CIGs at KEWN and KOAJ this evening while northern sites remain VFR. Showers expected to diminish overnight but easterly low level flow will result in lowering CIGs with periods of IFR likely all sites 06Z-13Z with some MVFR VSBYs in light fog as well. Conditions improving to MVFR by 16Z and VFR by 18Z with shower/tstm threat mainly near coast. Long Term /Wednesday night through Sunday/... As of 310 am Tue...Sub-VFR Wed-Thu in scattered thunderstorms. VFR/dry Fri and Sat, except isolated storms possible Fri at EWN and OAJ. && .MARINE... Short Term /through Wednesday/... As of 645 PM changes to winds/seas with update. Tighter pressure gradient producing E-SE winds 15-20 KT north of Ocracoke Inlet with buoy obs indicating seas 4-6 ft, thus no changes to SCA. /Previous discussion/ As of 3 PM Tue...Latest obs show NE to SE winds 5-15 kt, with gusts to 20 kt north of Lookout, and seas 2-4 ft. Expect mainly E/ESE winds 10-20 kt through tonight, strongest north of Ocracoke. Will go with a SCA for the waters north of Ocracoke beginning this evening into early Wed morning, with persistent E/ESE winds 15-20 kt building seas to 4-6 ft. NWPS and Wavewatch show seas building up to 6 ft. Front will likely remain stalled just south or near the southern waters late tonight and Wed as weak low pressure strengthens along it and lifts along/near the NC coast.Challenging wind forecast for Wed, with variable winds. Expect mainly light NW across the southern waters becoming S 10 kt or less during the afternoon, and then remaining ESE 10-20 kt north of Ocracoke. Seas subsiding to 3-5 ft north of Ocracoke, and remaining 2-4 ft south. Long Term /Wednesday night through Sunday/... As of 310 am Tue...Winds go southwest for Thu and Thu night. A weak front will pass through Friday with high pressure passing to the north this weekend. Seas north of Ocracoke will average 3-5 feet through Thu night and 2-3 Fri and Sat. Seas south of Ocracoke will average 2-4 through the period. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...Beach Hazards Statement from 8 AM EDT Wednesday through Wednesday evening for NCZ103. MARINE...Small Craft Advisory until 8 AM EDT Wednesday for AMZ154. Small Craft Advisory until 8 AM EDT Wednesday for AMZ150-152. && $$ SYNOPSIS...CTC/CQD NEAR TERM...JBM/CQD SHORT TERM...CQD LONG TERM...HSA AVIATION...JBM/HSA MARINE...JBM/CQD/HSA
Area Forecast Discussion
National Weather Service Nashville TN
755 PM CDT Tue Jun 26 2018 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Only a few weak storms remain in Middle Tennessee at the moment. A line of severe storms is currently moving across western Kentucky and may clip our northern zones. An even more widespread convective system over southern Illinois and southeast Missouri will likely affect the mid state afterwards, but the HRRR shows these storms dissipating rapidly as they enter Middle Tennessee later this evening. The 00Z sounding from OHX does show some instability in place (lifted index of -4, surface-based CAPE of 751 J/kg), but also the boundary layer has become stable owing to afternoon storms. Have lowered overnight lows on the Cumberland Plateau a few degrees since the rain-cooled air has already dropped early evening readings to or below previously forecast lows. Will keep scattered POP`s in the forecast through the overnight period, tapering off further south. No other changes are planned for now. && .AVIATION... 00Z TAF DISCUSSION. Difficult forecast for this TAF period as rounds of showers and thunderstorms will be possible overnight and into the day Wednesday. Consensus has the evening TS more isolated, but another line of showers and storms looks to move in later this evening into the overnight hours from the northwest. Timing is hard to nail down with short term models having little agreement, so have VCTS mention for now. Should showers and storms impact terminals, periods of MVFR and even IFR vis will be possible with heavier rain. There looks to be a brief drier period just before sunrise, and another round of showers and isolated storms will move in mainly during the morning and early afternoon. Cigs look to remain VFR, with southeasterly winds around 10 knots becoming southwesterly by tomorrow afternoon. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......08 AVIATION........Barnwell
Area Forecast Discussion
National Weather Service Paducah KY
709 PM CDT Tue Jun 26 2018 .UPDATE... Issued at 709 PM CDT Tue Jun 26 2018 Updated Aviation Discussion for 00z TAFs. && .SHORT TERM...(Tonight through Thursday night) Issued at 509 PM CDT Tue Jun 26 2018 Much delayed this discussion this afternoon due to convective watches, warnings, and potential for other headlines during the next few days. In coordination with SPC, extended Severe Thunderstorm Watch Number 224 east-southeast to southern Illinois as atmosphere has recovered sufficiently for severe potential into that area. High Resolution, Convection Allowing Models (CAM), such as the ESRL HRRR and RAP guidance are having some spatial issues dealing with the detection of cold pool expansion and upshear thunderstorm development along and behind the series of MCS (Mesoscale Convective Systems) moving through the WFO PAH forecast area. The trend is to develop convection (showers and thunderstorms) and resultant higher QPF (rainfall amounts) much further south than has been actually occurring. This seems to be the bias the last couple of days. Adjusted forecast PoP grids northward to reflect the better rainfall potential for the remainder of this afternoon and this evening. Once the small MCS (currently over southern IL and southeast Missouri) moves east, the expectation is for a third MCS to move through overnight and into Wednesday morning. There continues to be some uncertainty on coverage of severe weather further to the south and east this evening and overnight, so will have to monitor and adapt, as needed. With the frontal boundary moving south on Wednesday, kept a prolonged period of chance PoPs matching closely to the stalling boundary through the area and reflecting the instability along and south of the front (as highlighted by the SPC Day 2 Severe Weather Outlook). Most of the convection should be capped to the west going into Thursday from the west, but there may be enough insolation and weak shear for a slight chance/chance of thunderstorms during the afternoon on Thursday. Have been strongly considering an excessive heat watch or heat advisory from Thursday afternoon through Saturday afternoon (and possibly into Sunday). The likelihood for issuing a heat advisory or better headline continues to be greater than 70 percent. However, due to the potential for convective activity near the start time of an advisory on Thursday, combined with procedural implications of issuing an advisory at or beyond 48 hours, will just continue a mention of elevated heat index values in a hazardous weather outlook and a strongly worded special weather special statement. Regardless, it will be quite warm for the latter part of this week. .LONG TERM...(Friday through Tuesday) Issued at 509 PM CDT Tue Jun 26 2018 Hot and humid conditions will be the primary weather story in the long term. The main forecast challenge is convective coverage and resulting impacts on heat indices. The models have slowed the arrival of the 500 mb high by a day. Therefore, Friday now appears to be the hottest day as the 594 dm high center passes over the lower Ohio Valley. A few isolated storms are possible. Afternoon heat indices will peak above 105 degrees, which is well advertised in the HWO and social media messaging. The 500 mb high will move northeastward over the weekend, which means our region will be under the southwest periphery of the anticyclonic circulation. The main challenge is how much convection will occur around the high center. Highs will be in the lower to mid 90s with heat indices topping 100 each day. Isolated convection could provide some local relief both Sat and Sun afternoon. Early next week, a broad weak 500 mb ridge will extend from the Plains to the Northeast. Most of the model guidance shows a weakness in the ridge over our region, permitting some convective development Monday and Tuesday. Although it will remain hot and humid, the convection could limit heat indices to mainly sub-advisory thresholds. && .AVIATION... Issued at 709 PM CDT Tue Jun 26 2018 Multiple lines of thunderstorms with trailing stratiform rain moving through the area this evening. The complex of thunderstorms moving in from southeast Missouri should rapidly spread eastward and be ending from west to east by 03-05z timeframe. Some gusty winds expected, perhaps severe up to around 50kts in some places, as the main line moves through this evening. Should be a gradual lull in activity by late evening/midnight. Some short term models tending to redevelop some convection later in the overnight period lasting into the morning hours. Went with vicinity mention for now as unsure of the placement and overall coverage. Breezy WSW winds expected tmrw with some gusts up around 20 kts. Overall VFR cigs and vsbys should dominate the period, but may be some temporary reductions with the stronger storms down to mainly MVFR. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...SP SHORT TERM...Smith LONG TERM...MY AVIATION...SP