Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/10/19

Area Forecast Discussion
National Weather Service Bismarck ND
1022 PM CDT Tue Jul 9 2019 .UPDATE... Issued at 1022 PM CDT Tue Jul 9 2019 Only minor changes were made with this update relying on observed trends and recent rapid-refresh guidance, including time-lagged HRRR output which continues to capture precipitation trends well. The stacked low has progressed eastward and rainfall is pivoting southward in line with earlier expectations. Rainfall intensity is still forecast to slowly decrease overnight, and lightning will be at a premium owing to weak instability, especially once convection near the vorticity maximum near McHenry County at 03 UTC weakens. UPDATE Issued at 716 PM CDT Tue Jul 9 2019 A stacked low is centered near Minot as of 00 UTC, and while it is slightly further west than expected at this point, it has recently begun to shift eastward per radar and satellite imagery. Even so, the shield of rain associated with its forcing for ascent has not pivoted southward as quickly as earlier expected, so the primary adjustment with this update cycle was to hourly PoPs through late evening to account for that progression. Time-lagged HRRR guidance captured ongoing trends well and hourly PoPs were weighted to its output, with a ramp-up in probabilities along the Interstate 94 corridor from Dickinson to Bismarck from 03 to 05 UTC. Persistent and strong deformation and continued moisture transport have been and will continue to yield moderate to heavy rainfall through the evening west of the stacked low, with a slow decrease in rainfall intensity overnight concurrent with diminishing moisture transport and weakening deformation. Even so, our NBM-driven QPF forecast includes up to 0.50" inches of rain as far south as Interstate 94. Otherwise, low-level SRH along and north of the warm frontal zone from near Minot to Carrington has diminished and is less than 100 m2/s2 as of 00 UTC per RAP-based objective analysis and the KMBX and KMVX VAD wind profile data. Thus, the potential for low-topped mesocyclones has diminished considerably, and despite a residual corridor with moderate instability characterized by MLCAPE around 1000 J/kg in the James River valley, weak effective shear combined with midlevel lapse rates around 6 C/km suggest the probability of any marginally-severe storms has decreased significantly. We thus have chosen to adjust messaging to take out any mention of severe- storm risk for the rest of the evening. We are maintaining only a slight chance of non-severe thunderstorms in the forecast tonight given expected weak instability and recent observed trends in both GLM and ground-based lightning detection networks. && .SHORT TERM...(This evening through Wednesday) Issued at 230 PM CDT Tue Jul 9 2019 Concerns this period will be rain and possible rural and urban minor flooding across the northwest and north central this afternoon and evening. Have issued a flood advisory for northwest and portions of north central North Dakota through 1045 pm this evening. With abundant low level vorticity and shallow dry adiabatic lapse rates, will get some funnel clouds. Otherwise expect the showers and thunderstorms to diminish tonight and generally end on Wednesday morning. Not as cool on Wednesday with highs in the 70s. .LONG TERM...(Wednesday night through Tuesday) Issued at 230 PM CDT Tue Jul 9 2019 After the upper low exits the region Wednesday, a broad h500 ridge replaces it, bringing warmer temperatures and generally dryer conditions to the region. Although the ridge will be in place across the northern plains, a shortwave trough will pass through the ridge axis bringing a chance for thunderstorms Thursday night. The National Blend of models did not give widespread POPs for this, possibly because an Environmental Mixed Layer (EML) will keep some capping in place. If the capping breaks more widespread thunderstorms, and even severe weather may be possible. Otherwise, widely scattered thunderstorms are possible again Saturday night and Sunday night as the ridge axis shifts east and backing flow aloft allows more shortwave energy to move into the northern plains. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1022 PM CDT Tue Jul 9 2019 Rain and isolated thunderstorms with MVFR to local IFR conditions will impact most of western and central ND overnight as an area of low pressure slowly moves eastward. Northwest wind gusts up to 35 kt are also expected tonight west and central, and over the James River valley Wednesday. Expect improving conditions from west to east along with diminishing winds Wednesday, with VFR conditions area-wide by Wednesday afternoon. && .HYDROLOGY... Issued at 1022 PM CDT Tue Jul 9 2019 Widespread heavy rainfall with observed totals of 2 to 5 inches in northwest and north central ND through this evening will result in rises on small creeks and streams, flooding of rural roads, and is expected to cause the Little Muddy River near Williston to reach minor flood stage on Wednesday. As a result, a Flood Advisory has been extended in those areas through Wednesday evening, as runoff will continue into the day tomorrow even after rainfall diminishes tonight. Otherwise, a Flood Warning remains in effect for Beaver Creek near Linton and a Flood Advisory is in effect for LaMoure County as a response to heavy rain that occurred in those areas Monday night. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CJS SHORT TERM...WAA LONG TERM...WAA AVIATION...CJS HYDROLOGY...CJS
Area Forecast Discussion
National Weather Service Birmingham AL
708 PM CDT Tue Jul 9 2019 .UPDATE... For 00Z Aviation. && .SHORT TERM... Through tonight. The heat is on for most locations as of noon, with temperatures in the low to mid 90s and very humid dewpoints in the low to mid 70s. Heat indices have already risen above Heat Advisory criteria in Tuscaloosa and Montgomery, hitting 106 and 107 degrees. At this time, we`re not planning on extending the area of the Heat Advisory, and will remain across roughly the western half of Central Alabama through 7pm. Meanwhile, convection is developing along the NW periphery of the trough/area of low pressure centered over southern Georgia and the Florida Panhandle. This is the same area of low pressure that the National Hurricane Center will be monitoring as it moves into the Gulf of Mexico. The convection is developing within a convergence zone as was mentioned in the previous discussion this morning. The 12Z KBMX sounding this morning indicated much warmer conditions aloft today than yesterday due to the upper height rises and 592 decameter upper ridge centered over much of the southeast. Even though mid-level lapse rates are weak due to the higher temperatures aloft, conditions at the surface are very unstable. RAP analysis indicates SBCAPE values of 4000-4500 J/KG across our southern tier of counties where the most showers and storms are expected to develop. In addition, microburst composite parameters are higher today than they have been over the past several days mostly due to drier air aloft. Therefore, we`ll have to keep a close watch on these storms this afternoon, as Troy measured a wind gust of 37 knots with a storm that wasn`t able to get very tall or organized on radar. In addition, torrential downpours could lead to some localized flooding and ponding in isolated locations as some storms will be training at times as they move from northeast to southwest this afternoon. We`ll expect at least scattered storms to persist in areas along and south of the I-85 corridor through late this evening. 56/GDG .LONG TERM... /Updated at 0348 AM CDT Tue Jul 09 2019/ Wednesday through Tuesday. By Wednesday the low pressure system is situated to our south and has just entered the Gulf of Mexico. As the low drifts southwestward into the western Gulf, upper level ridging will amplify over our area. Afternoon thunderstorm activity won`t be quite as prominent as we have seen in previous days. The best chances will be in our southeast counties due to more of an influence from the exiting low pressure. Temperatures will are expected to reach the mid 90`s Wednesday afternoon. Heat indices have the potential to reach at or above 105 degrees particularly in areas of southern and southwest Central Alabama. An upper level trough and associated surface low pressure system will move into the Great Lakes region on Wednesday afternoon. A frontal boundary associated with this upper level system will push southeast into the northern Mississippi Valley region Wednesday night. By Thursday, the surface front will have entered the northern part of our CWA increasing rain chances. While temperatures are still expected to be in the low/mid 90`s with mid 70-degree dewpoints, cloud cover from increasing rain chances could prevent heat advisory criteria from being met. I will continue to mention heating impacts in the HWO as there is still some uncertainty. The low pressure system in the Gulf is expected to become a tropical disturbance by the end of this week. There is still plenty of uncertainty with regards to timing and track. Guidance has struggled with the handling of the frontal boundary approaching from the north and the interaction with the low in the Gulf. At this point, most guidance seems to be tracking the low more westward. Either way, an increase in tropical moisture from this system will allow for an increase in shower and thunderstorm activity for much of Thursday, Friday and Saturday. The forecast for the remainder of the period solely depends on the evolution of this low pressure system. At this time I have capped PoPs at 30% for Sunday afternoon and gradually trending down to the end of the period. && .AVIATION... 00Z TAF Discussion. Outflow-driven convection continues from near EET southward to Selma. This activity will continue to shift westward over the next couple of hours before hopefully diminishing. Storms in SW Georgia may enter Barbour County, but do not anticipate them reaching TOI at this time. No widespread fog expected overnight, but will continue to mention some MVFR visibilities at TOI due to the rain observed there earlier today. More scattered storms on tap for Wednesday, best chances across the south. 19 && .FIRE WEATHER... Expect lower chances for showers and storms across the north and west through Wednesday. However, scattered to numerous showers and storms can be expected in the south and east during mainly the afternoon hours. Relative humidity values should bottom out in the 40 to 50 percent range during the afternoon hours before the overnight recovery. Showers and storms will remain in the forecast for good portion of the forecast period. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 73 92 73 91 72 / 30 30 20 60 50 Anniston 74 91 74 90 73 / 30 30 20 60 40 Birmingham 76 94 75 93 74 / 30 30 20 60 40 Tuscaloosa 77 96 76 94 74 / 20 30 20 60 40 Calera 74 93 74 92 73 / 30 40 20 60 40 Auburn 75 90 74 88 73 / 30 50 30 70 40 Montgomery 76 94 76 92 74 / 20 50 30 70 30 Troy 75 92 74 90 73 / 20 60 30 70 30 && .BMX WATCHES/WARNINGS/ADVISORIES/... Heat Advisory until 7 PM CDT this evening for the following counties: Autauga...Bibb...Blount...Chilton...Coosa...Dallas... Elmore...Fayette...Greene...Hale...Jefferson...Lamar...Lowndes... Marengo...Marion...Montgomery...Perry...Pickens...Shelby...St. Clair...Sumter...Talladega...Tuscaloosa...Walker...Winston. Heat Advisory from noon to 7 PM CDT Wednesday for the following counties: Autauga...Bibb...Blount...Chilton...Coosa...Dallas... Elmore...Fayette...Greene...Hale...Jefferson...Lamar...Lowndes... Marengo...Marion...Montgomery...Perry...Pickens...Shelby...St. Clair...Sumter...Talladega...Tuscaloosa...Walker...Winston. && $$
Area Forecast Discussion
National Weather Service Cheyenne WY
223 PM MDT Tue Jul 9 2019 .SHORT TERM...(This evening through Wednesday) Issued at 225 PM MDT Tue Jul 9 2019 Forecast concerns deal primarily with severe thunderstorm chances this afternoon and early evening. Currently...Cold front moving through the area this afternoon. Upper shortwave moving through northeast Wyoming into western South Dakota this afternoon. Seeing a pretty strong jet max of roughly 100kts rounding the base of that shortwave into Converse/Niobrara and the northern Nebraska Panhandle this afternoon. 500mb temperatures down to -13 to -15C this afternoon...aiding in steeper lapse rates across our northern counties. SPCs Mesoanalysis page showing surface based CAPES around 2000 to 2500 J/KG this afternoon for that area. Radar showing some convection over northern Converse and Niobrara Counties this afternoon. Strongest storms up over northeastern Wyoming in Rapid City`s area so far. Latest HRRR showing a few thunderstorms becoming strong after 22Z this afternoon across our northern counties with all convection coming to an end after 01Z/02Z. Current Watch runs to that looks pretty good. For Wednesday...Much drier and more stable conditions for Wednesday as upper ridge begins to build across our western CWA. Have PoPs pretty much zeroed out for Wednesday afternoon. .LONG TERM...(Wednesday night through Tuesday) Issued at 225 PM MDT Tue Jul 9 2019 Dry and warm weather continues through Thursday as 700mb temperatures climb to +15 to +16C. Pretty warm surface temperatures with mid 90s in the Panhandle to the I-25 Corridor and upper 80s out west. Backdoor cold front still on track for Friday afternoon. Showers and thunderstorms expected to develop along this front Friday afternoon/evening. This front looks to stay with us through the weekend into next week. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1135 AM MDT Tue Jul 9 2019 VFR conditions expected through the forecast period with gusty winds posing the main threat through 02Z this evening. Strongest winds will be seen near KLAR and KRWL with westerly winds gusting near 30 kts at times this afternoon. Will need to monitor the TAF near KCDR for timing and location of thunderstorms late Tuesday afternoon which may result in brief periods of reduced visibility in heavy rainfall and stronger winds. Additionally, a cold front will push through the area turning wind directions northerly for NE Panhandle terminals after 00Z. && .FIRE WEATHER... Issued at 225 PM MDT Tue Jul 9 2019 Cold front moving through the northern Nebraska Panhandle as well as Converse and Niobrara Counties could produce a few severe thunderstorms this afternoon. These storms expected to end early...before sunset today as the front moves east. Drier weather for Wednesday and Thursday with afternoon humidity falling to critical levels...especially along and west of the Laramie Range. Fortunately...fuels are still being reported green and winds are not expected to be too strong over the upcoming days. So fire weather concerns are minor. Next chance for wetting rains and thunderstorms return Friday afternoon as a cold front moves in from the north. Areas along and east of the Laramie Range stand the best chances for seeing these wetting rains. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...GCC LONG TERM...GCC AVIATION...MB FIRE WEATHER...GCC
National Weather Service Kansas City/Pleasant Hill MO
636 PM CDT Tue Jul 9 2019 .Discussion... Issued at 254 PM CDT TUE JUL 9 2019 For the rest of this afternoon, the chances for new convection look fairly low. The best chances look to be across the northeastern quadrant of the forecast area, where there`s taller/cooler CU noted on visible/IR combo imagery. There may also be weak low level convergence in this area that trails southwestward to the eastern portions of the KC metro. Have maintained low PoPs, 15-20% in this area to capture this potential. While CAPE is ample, shear is weak and as such, no severe weather is expected. For tonight through tomorrow, a cold front will move through the area tomorrow morning. This may bring a chance for storms tomorrow morning from northeastern Kansas through west central Missouri. The 12Z HRRR shows this potential, while most other models hold off until later in the day, when the front is further south. Since confidence is fairly low at this point, have kept PoPs below mentioning any weather. But during the afternoon, when heating is near its peak in the southern third of the forecast area, chances will increase. Have added chance PoPs to the forecast to capture this. Again, the threat of severe weather looks low due to weak shear. But there is ample instability so a few strong storms are possible. Much cooler dewpoints will fill into the area behind the front leading to a much more comfortable feel to temperatures. Highs on Thursday should be in the middle 80s with lower 60s dewpoints. Temperatures may warm a few degrees Friday, but with dewpoints still in the mid 60s, it`s still just typical summer warmth. Even over the weekend, as temperatures climb into the low to middle 90s dewpoints look to be in the middle to upper 60s, perhaps touching 70 degrees. So our next round of heat, shouldn`t feel as hot as a few weekends ago with a bit cooler dewpoints in the region. Next week, the progress of whatever is leftover from a possible tropical system will need to be monitored. The remnants of that system may begin to impact the area late Tuesday. The impacts will be from heavy rain but, with the exception of northern Missouri, which may not see much from this system anyway, much of the area doesn`t need to have tropical enhanced rainfall. && .Aviation...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 636 PM CDT TUE JUL 9 2019 VFR conditions largely expected through the fcst period, although predawn fog cannot totally be ruled out at STJ after the 09z time frame. In any event, will continue to monitor model trends before possibly inserting a mention with the 06z package. The other concern will be for possible morning convection after 13z as a cold front moves through the region. For now, feel the prospects are handled accordingly with a VCTS mention, however models continue to indicate very widely scattered coverage. If this trend continues, we may have to consider removing mention with the next fcst issuance. SW winds this evening and overnight will veer to the northwest after 13z before increasing to 10-15 kts during the late morning and afternoon hours. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...CDB Aviation...32
Area Forecast Discussion
National Weather Service Wilmington NC
1145 PM EDT Tue Jul 9 2019 .SYNOPSIS... A cold front will be stalled nearby through Wednesday keeping the weather unsettled. This front will lift north by Thursday bringing an even more humid airmass still very prone to thunderstorms. Late week storm coverage will increase as a cold front approaches from the northwest. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... As of 1145 PM Tuesday...Convection late this evening has organized along an east-west line just off the Brunswick County coast. Environmental winds below 400 mb are generally southeasterly, and many models show this convective line pushing inland from Myrtle Beach and Southport north into Wilmington overnight. The 02z HRRR did not initialize well with this line, but its wind profiles agree with a slow northward drift of anything offshore. New PoP/Wx/QPF grids show a half inch of rain possible for Oak Island, Southport, and Bald Head Island, with lesser amounts spreading inland. Discussion from 300 PM follows... Essentially more of the same for the next 24-36 hours. The front that continues to bisect the area will continue to wobble around and eventually dissipate. There isn`t much thermal definition to the front (if any) but you can still see northeast storm motions north and more sea breeze east to west across southern zones. The convection should be more confined to coastal areas this afternoon although all areas are somewhat fair game. We should see a minimum tonight and do it all over Wednesday. Lows tonight and Thursday morning will be in the steamy 70s, yes the windows are quite fogged up in the mornings with daytime highs, modulated by convection and possibly low clouds again in the middle to upper 80s. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... As of 330 PM Tuesday...The frontal boundary staying off to the north and SSW low-level flow will lead to warm and humid conditions across the fa...highs in the upr 80s to lwr 90s with heat indices peaking around 100. The high humidity will also lead to low LCLs and thus thunderstorms will form readily on any and all mesoscale boundaries while weak mid-level shortwaves lead to larger scale lift. The end result will be a higher than normal distribution of storms that will wane but not to zero coverage Thursday night. PoPs 40-60% daytime Thursday, 30-40% Thursday night. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 330 PM Tuesday...A weakening cold front drops into the area late Friday, as a thermal trough of low pressure persists over the weekend into early next week. Precip Chances: Highest Friday (50-60%) as the front drops into the area. Still 40-50% Saturday, then down to just 20% at most Sunday and Monday as deep layer moisture profiles decrease. Temps: Near to slightly above normal through the period...highs in the upr 80s to mid 90s with lows ranging through the 70s. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 00Z...Stationary front hanging on along the coast has created widespread thunder and shower activity that has pushed into the inland counties. Expect precip to end from east to west over the next 3-6 hours. With not much changing in the patter, have gone with a persistence forecast of fog and stratus inland with mainly stratus along the coast. A few showers possible along the front near sunrise tomorrow with increasing chances of storms as the day progresses. Best chance of a shower will be along the coast. Extended Outlook...Early morning fog and stratus possible, with scattered convection in the afternoon and evening throughout the period. && .MARINE... As of 1145 PM Tuesday...Buoy reports in the Cape Fear area show synoptic winds near 15 knots from the east even well outside of the convection off the Brunswick County coast. This is 5-10 kt stronger than our previous forecast, and a new Coastal Waters Forecast has been issued. Seas reported from CORMP and NDBC buoys show 3 foot seas inside 20 miles from shore. The CORMP Lejeune offshore buoy has 4 foot seas currently, but I am hopeful these higher seas remain outside of the coastal waters through the night. Widespread showers and thunderstorms just off the Brunswick County coast are slowly drifting northward, but may redevelop and expand overnight given the presence of the front and a very warm and unstable airmass. Discussion from 300 PM follows... Modest east to northeast winds continue across the waters but should continue or begin to turn more southeast through the evening and overnight hours. The directions could be quite erratic for the next few hours due to convection however. The synoptic southeast flow will continue Wednesday and turn more southwest into Thursday morning. Speeds should be 10-15 knots leaning heavily toward the lower end of the range. Significant seas should hang around 2-3 feet. For Friday through the weekend...winds continue out of the S/SW at 10-15 kt on average, occasionally at 15-20 kt during the evening hours. Significant seas of 3-4 ft will fall to 2-3 ft by Sunday. This will consist of a persistent SSWly 5-6 second wave and a weak SEly 8-10 second swell. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...MAS NEAR TERM...TRA/SHK SHORT TERM...MAS LONG TERM...MAS AVIATION...21
Area Forecast Discussion
National Weather Service Indianapolis IN
1129 PM EDT Tue Jul 9 2019 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 400 PM EDT Tue Jul 9 2019 Expect largely dry weather tonight into early Wednesday under the influence of a gradually weakening ridge aloft. An upper level low pressure system will push into the upper Midwest overnight into Wednesday, which will likely spark some organized convection to our northwest. This activity appears likely to move into central Indiana late tomorrow into tomorrow evening, and may produce some severe weather. In the wake of this system, another fairly dry period is expected, with a largely dry forecast much of the rest of the period, as the ridge reasserts control and temperatures begin to climb again late in the weekend into early next week. && .NEAR TERM /Overnight/... Issued at 1007 PM EDT Tue Jul 9 2019 A warm July evening in progress with mainly clear skies across central Indiana. 02Z temperatures ranged from the mid 70s to the lower 80s. Surface high pressure off to the east of the region and ridging aloft will keep dry conditions across much of the area through the overnight. The only big change to the overnight forecast was to add in a very low threat for a stray shower or storm in the predawn hours focused over the northern Wabash Valley. While confidence is low...cannot entirely rule out that ongoing convection over northwest Illinois may be able to sneak into far northwest portions of the forecast area late tonight prior to completely dissipating. HRRR continues to advertise this possibility as well. Overall airmass will remain capped with little to no instability and any impacts from convection will be isolated and brief. Zone and grid updates out. && .SHORT TERM /Wednesday through Friday/... Issued at 400 PM EDT Tue Jul 9 2019 Will maximize pops late Wednesday afternoon into the evening, as it appears likely that convection will fire to our northwest during the day Wednesday and push east/southeastward as the cold front moves into the area. For collaboration`s sake will keep a slight chance earlier in the day, but impact should be quite limited. Pops will taper off late Wednesday night into early Thursday morning with passage of the cold front, and the remainder of the short term will be dry. Severe weather will be possible tomorrow, mainly northwest as the system may be weakening with loss of heating as it moves into the central and southeastern area. Looks like a fairly typical mid summer setup with ample instability and minimally adequate shear. Significant dry air aloft and climatology suggests damaging winds will be the primary threat. There is significant instability in the hail growth zone, but in the absence of significant rotating updrafts it is difficult to get much beyond marginally severe hail this time of year. Window for severe weather potential looks to be the 4 to 10 PM time frame. Temperatures will drop back closer to seasonal normals for a couple of days through the end of the short term before creeping back toward the 90 degree mark in the long term period. && .LONG TERM /Saturday night through Tuesday/... Issued at 248 PM EDT Tue Jul 9 2019 Ensembles continue to be in good agreement with the broad ridging across the Southern Plains beginning to expand north and east throughout the extended periods. This suggests a slow warming trend for late weekend into early next week. Guidance presently indicates a rather quiet stretch of weather; however, there may be a slight chance of thunderstorms from a system skirting the region Mon into Tue. Otherwise a rather quiet stretch coming up with temps slowly warming into the lower 90s and overnight lows in the mid to upper 60s. && .AVIATION /Discussion for 100600Z TAF Issuance/... Issued at 1129 PM EDT Tue Jul 9 2019 VFR conditions expected throughout the forecast period. The Ohio Valley will remain under the influence of surface high pressure and ridging aloft tonight. Isolated convection over northern Illinois may slip into the northern Wabash Valley late tonight before diminishing...but cirrus blowoff will likely drift across the terminals during the predawn hours. Winds will be light and variable. On Wednesday a frontal boundary will approach the region from the northwest by late day. Model soundings show a more favorable scenario for cu formation during the afternoon...and a growing threat for isolated to scattered convection during the mid and late afternoon continuing into the evening. Confidence remains far too low regarding expected coverage and direct impacts to terminals to include any precip mention at this point...but a VCTS will likely be needed with a future TAF issuance. Southwest winds generally less than 10kts are expected Wednesday. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...Nield NEAR TERM...Ryan SHORT TERM...Nield LONG TERM...Beach AVIATION...Ryan
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
917 PM CDT Tue Jul 9 2019 .UPDATE... Issued at 909 PM CDT Tue Jul 9 2019 Scattered showers and thunderstorms are getting ready to exit the far southern part of the CWA. Have gone with mainly dry weather the rest of the night as latest RAP runs are showing little in the way of forcing for additional convective development. Going forecast temperatures look good for tonight with lows staying in the 70s. Britt && .SHORT TERM... (Through Late Wednesday Night) Issued at 325 PM CDT Tue Jul 9 2019 Isolated to scattered thunderstorms this afternoon should weaken and dissipate by late this evening. The rest of the overnight period should be dry or mostly dry, but did keep slight chance PoPs across northeast Missouri and west-central Illinois after midnight tonight as a prefrontal trough approaches from southeast Iowa. This prefrontal trough may attempt to serve as a focus for showers and storms into early Wednesday, but weak/nebulous forcing for ascent along it suggests any activity would be isolated in nature. The late morning and early afternoon hours should be dry, but the expectation is for additional showers and thunderstorms to develop along the trailing cold front. The atmosphere will be very unstable (MLCAPE values 2500-4000 J/kg) with sufficient shear for organized convection (20-25 knots). Damaging winds should be the primary threat with multicellular clusters in an environment characterized by high DCAPE values. Large hail may also be a threat aided by steep midlevel lapse rates, but freezing levels around 14,000 feet AGL will likely make it difficult to get severe criteria hail down to the surface in the absence of a rotating updraft. The best chance of storms appears to be from late afternoon through the early evening hours for parts of west-central and south-central Illinois where the low-level convergence and forcing for ascent associated with the shortwave trough will be strongest. More capping will exist across far southwestern portions of the CWA which may also help limit the coverage of storms. The threat for thunderstorms should diminish behind the cold front across southeast Missouri and southwest Illinois by midnight. Decreasing cloudiness is then likely for the remainder of the Wednesday night period. The other main focus continues to be on heat/humidity on Wednesday afternoon/early evening. With the expectation of little to no convection during the morning and early afternoon hours, confidence has increased for temperatures to reach the low to mid 90s across parts of the area. Warmest conditions should be across the urban heat island of St. Louis where mid 90s are forecast. These temperatures combined with dewpoints in the mid 70s should yield maximum heat index values around 105F Wednesday afternoon/early evening, and as a result have issued a heat advisory. Behind the cold front, seasonable temperatures will begin to infiltrate the area with lows Wednesday night/Thursday morning dropping back into the mid 60s to near 70 degrees. Gosselin .LONG TERM... (Thursday through Next Tuesday) Issued at 325 PM CDT Tue Jul 9 2019 Seasonably cool temperatures are likely on Thursday behind the cold front as 850-hPa temperatures drop into the mid teens. All in all it should be a fairly comfortable day for mid July with highs generally in the mid 80s, lower humidity, and plenty of sunshine. Dry weather is likely to continue through this weekend as a seasonably strong surface high pressure slowly moves southeastward across the area. Temperatures will moderate a bit each day, with highs on Saturday back above normal into the low 90s. Seasonably hot/humid weather should return on Sunday heading into early next week as the mid/upper level ridge builds back into the area and 850-hPa temperatures once again near 20C. Dry weather is favored to continue into Monday, and then focus will shift toward the remnants of a tropical cyclone and its path. Lots of uncertainty with its path, but based on climatology, a further west landfall along the Gulf Coast (SE TX/SW LA) would have the potential to pose a threat across the mid-Mississippi Valley. Speaking of climatology, a track this early in the season through the area would be extremely rare. In fact, dating back to 1950, only one storm (Claudette 1979) passed within 100 nautical miles of St. Louis within the month of July. At this very early juncture, kept PoPs in the slight chance category. Gosselin && .AVIATION... (For the 00z TAFs through 00z Wednesday Evening) Issued at 617 PM CDT Tue Jul 9 2019 Isolated showers and thunderstorms across eastern Missouri into southwest Illinois are expected to diminish this evening. The chance for showers and thunderstorms will increase on Wednesday afternoon as a cold front moves southeast across the area. The strongest storms will have potential to produce MVFR/possible IFR ceilings and visibilities in heavy rain. SPECIFICS FOR KSTL: Isolated showers and thunderstorms will move away from the vicinity of the terminal before 01Z. Then mainly dry and VFR conditions are expected through Wednesday afternoon before a cold front moves into eastern Missouri bringing a chance of thunderstorms to the terminal late on Wednesday afternoon into Wednesday evening. The strongest storms will have the potential to produce MVFR/possible IFR ceilings and visibilities in heavy rain. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Heat Advisory from 11 AM to 8 PM CDT Wednesday for Jefferson MO- Saint Charles MO-Saint Louis City MO-Saint Louis MO. IL...Heat Advisory from 11 AM to 8 PM CDT Wednesday for Madison IL- Monroe IL-Saint Clair IL. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
800 PM EDT Tue Jul 9 2019 .SHORT TERM...(This evening through Wednesday night) Issued at 358 PM EDT TUE JUL 9 2019 ...STRONG TO POTENTIALLY SEVERE THUNDERSTORMS POSSIBLE WEDNESDAY AFTERNOON AND EVENING... Quiet weather will continue across Upper Michigan into the early evening, with lingering smoke over the east half remaining in place until southerlies can gradually push it out tonight. This has kept temperatures cooler there than out west (70s vs low 80s). Upper level clouds will begin to increase from the west through this evening out ahead of an upper level trough out in the Dakotas and associated sfc low. An area of warm frontal showers, with at least some embedded thunder likely, will move in from the west late this evening into the overnight. This round will gradually decrease in intensity and coverage through the morning hours of Wednesday. The trough and sfc low will skirt the MN/Canada border Wednesday morning. Strong southwesterlies are expected to traverse the Upper Peninsula, and there is a distinct possibility that enough of a dry slot works it`s way into Upper Michigan to allow for brief midday clearing in spots. Warm, moist air will continue to pour in ahead of the sfc cold front, with dew points into the mid to possibly upper 60s in the morning and afternoon temperatures climbing into the lower 80s. It will feel quite sticky during the day, but relief will come by Thursday. Most CAMS continue to indicate redevelopment beginning over the western UP generally around 18Z (WRF-ARW is an outlier with a line of storms running from IMT to ERY 17Z-21Z). Coverage is expected to increase though the afternoon from west to east, exiting by about midnight tomorrow night. General model consensus is that SBCAPE will maximize over the central UP in the 1500-2000 J/kg range, though again if more sunshine is able to break through the potential is there for a brief period of 2500-3000 J/kg. Deep layer shear should be in the neighborhood of 40 kts though the lower resolution models place that number closer to 50-55 kts. Regardless, initial development will have the potential to become supercellular with all weather hazards including hail up to 1.5 inches, strong winds, frequent lightning, and heavy to perhaps torrential rainfall. Climatologically tornados are very rare here. Nonetheless, a brief spin-up is not out of the question with RAP soundings indicating the potential for 0-1km shear of ~15 kts and 0-3km shear nearing 30 kts. There is some minor discrepancy between models on whether LL flow will be unidirectional or have a slight backed component. In all likelihood, storms should grow upscale into a multicell, or more likely linear configuration owing to boundary parallel flow and strong linear forcing along the front. A much more comfortable air mass will begin to move in Wednesday night with dew points back down into the 50s across the region by 12Z Thursday. Models are heavily hinting at some upslope fog/ drizzle/light rain over the northern tier of counties overnight. Low level moisture is likely still overdone in the NAM as usual, so while I have included this in the forecast, confidence is not very high in this solution at this time. .LONG TERM...(Thursday through Tuesday) Issued at 242 PM EDT TUE JUL 9 2019 The end of the week into early next week, we`re looking at fluctuating day-time temperatures in the 70s and 80s as we remain on the norther periphery of upper-level ridging building across the southern Rockies and Plains. While we will see periods of drier weather at times, we should still see periods of active weather with shortwaves ridging the northern edge of ridging to our southwest. Thursday will be a cool day across the area, especially near Lake Superior as we remain under the influence of north to northwest winds behind the system exiting to out east. It certainly is not out of the question that we could see some marine fog/drizzle along the shoreline and inland early-on during the day Thursday. As high pressure starts to drop south, drier and and subsidence should help dry things out Thursday afternoon and night. Thursday night/Friday morning, high pressure quickly drops south as another shortwave tracks southeast across the region, bringing a cold front into western parts of Upper Michigan. This will bring back chances for showers and thunderstorms out west Friday morning. As the front continues to push east across the Upper Peninsula, the rest of the area will a chance for showers and thunderstorms Friday/Friday night. Based on the NAM and GFS, with around 30-40 knots of deep-layer shear and an axis of MUCAPE between 1000-2000 J/kg we could see a few strong to severe storms along the cold front. Forecast soundings do show ample dry mid-level air in place with a skinny CAPE profile, so coverage may end up being more scattered in nature, especially given the subtle nature of the shortwave. Therefore, not expecting any widespread impacts at this time. The upcoming weekend looks nice as another area of high pressure drops south across the area. Will need to keep an eye on how smoke may evolve across the area with active wildfires to our northwest in Canada. However, temperatures should warm a couple degrees above- normal with a gradual warming trend into early next week. By early next week, models are in fairly good agreement with surface high pressure sliding well southeast of the region, placing us back under warm/humid moisture return. With this moisture return, depending on when we see additional shortwave/fronts move across the area we certainly look like we will be getting back into an active weather pattern. Right now there is quite a bit of uncertainty as to when the better chance for precipitation will arrive. Given the uncertainly, didn`t make any changes to the PoPs that far out, but they certainly could be overdone at times early in the week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 747 PM EDT TUE JUL 9 2019 Showers with perhaps some rumbles of thunder will eventually make their way into the KIWD and KCMX areas, but them making it to KSAW overnight is highly questionable. However, storms tomorrow afternoon are expected to reignite, which may very well impact all three terminals. As that time inches closer, look for refined details in timing in subsequent TAF issuances. VFR conditions should otherwise predominately prevail. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 242 PM EDT TUE JUL 9 2019 Winds will remain between 10 and 20 knots, with the strongest winds expected over the eastern half of Lake Superior this evening through tonight. As a cold front passes over the lake tomorrow, winds will become light from west to east throughout the day. As this front passes through, thunderstorms are possible along with the development of fog as humidity levels increase, and especially so if heavier precipitation develops. Behind the front, winds will become westerly late in the day Wednesday, and then northwesterly overnight into Thursday. As winds become northwesterly, expect speeds to increase to between 20 and 25 knots. Not out of the question that a few higher platforms over the eastern half of the lake could gusts closer to 30 knots due to the elevated wind just off the surface. However, based on the stability of thermal profiles, confidence is low that these winds will reach the lake`s surface. Winds will then relax for the end of the week/weekend, with speeds expected to remain below 20 knots. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...KCW LONG TERM...Ritzman AVIATION...lg MARINE...Ritzman