Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/20/20

Area Forecast Discussion
National Weather Service Bismarck ND
945 PM CDT Fri Jun 19 2020 .UPDATE... Issued at 944 PM CDT Fri Jun 19 2020 At 930 PM CDT, a line of showers and isolated embedded thunderstorms was moving east toward the Highway 83 corridor. This activity is tied to a distinct mid level shortwave that can be seen on water vapor imagery rotating through the base of the closed upper low spinning over Manitoba. Meanwhile, scattered showers and isolated thunderstorms continue to regenerate over southwest North Dakota in response to lowering mid level heights along a quasi-stationary surface boundary. Expect these trends to continue for at least the next couple hours. CAMs that have a 0000 UTC or later initialization time are doing a very poor job capturing current conditions, so will only make adjustments to the ongoing forecast based on observed trends. UPDATE Issued at 705 PM CDT Fri Jun 19 2020 Scattered showers and a few thunderstorms have developed from southwest to north central North Dakota early this evening. A stronger storm cannot be ruled out in the southwest given the presence of around 500 J/kg SBCAPE, 30 kts effective bulk shear, relatively low freezing levels, and large surface dewpoint depressions. But the probability for stronger storms remains low, with model soundings suggesting storm tops will barely exceed 20,000 ft. Other than aligning the forecast with current observations and trends, the most notable adjustment for this update was to add more detail to the timing of thunderstorm chances tomorrow. && .SHORT TERM...(This evening through Saturday) Issued at 259 PM CDT Fri Jun 19 2020 Main forecast concerns are shower/thunderstorm potential this afternoon/evening, and potential severe thunderstorms Saturday, mainly southeast. Currently, a broad upper level cut-off low remains over Saskatchewan/Manitoba region with cyclonic flow in place over the Northern Plains. Water vapor shows several embedded shortwaves upstream of ND. Consensus remains good between the CAMS and supported by instability generally less than 500 J/KG, while RAP is coming in on the higher side and a bit more suspect as surface dewpoints appear too high. Mid-level lapse rates are best in the southwest along with right entrance support from a 60kt 500mb jet streak that pushes off to the northeast fairly quickly this evening. A weak surface boundary/wind shift will also support low level convergence and shower/thunderstorm development. Therefore, will continue to carry an area of showers and non-severe thunderstorms spreading from southwest to east late this afternoon and evening. Beginning to see some light radar returns on Bowman radar approaching southwest ND. Will continue to monitor and may need to increase pops there in the near-term. Will also continue to carry low pops across much of our area through the night, with cyclonic flow in place and the shortwaves mentioned earlier. CAMS and global models support this as well, showing another area of showers spreading into western ND around 06Z. Later tonight and Saturday, upper low begins to pivot with shortwave trough axis moving across the state. Return low level flow advects dew points around 60F across the eastern part of the state, coincident with a cold front, 30-40kts of 0-6km bulk shear and CAPE around 500-1000 J/KG. HREF ensemble products and CIPS severe analogs support the severe potential as well, with hail being the biggest threat, with severe wind gust possible as well. SPC has upgraded portions of SE ND to slight risk for severe on Saturday. We will message potential for half-dollar size hail and 60 mph wind gusts. .LONG TERM...(Saturday night through Friday) Issued at 259 PM CDT Fri Jun 19 2020 The upper low remains nearly stationary before slowly moving eastward by early next week. Occasional showers and thunderstorms will continue through Monday, with upper level ridge axis approaching western ND by Wednesday. This will support a brief mid-week warming trend with highs expected in the 80s. Also begin to see some differences in height fields in the global models developing, so greater uncertainty with precip chances. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 705 PM CDT Fri Jun 19 2020 Chances for scattered showers and thunderstorms will continue across much of western and central ND through the forecast period. The best chances this evening are at KDIK, with thunderstorms passing by to the south at the time of this writing. On Saturday, the best chances will be at KJMS, with severe thunderstorms possible, capable of large hail and strong wind gusts. Further mentions of TS may need to be added in future updates, but confidence beyond the aforementioned locations and timing is too low. Other than potential MVFR to IFR visibility restrictions in heavier showers or thunderstorms, VFR conditions are expected through the forecast period, with winds mostly light and variable. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Hollan SHORT TERM...JNS LONG TERM...JNS AVIATION...Hollan
Area Forecast Discussion
National Weather Service Dodge City KS
1042 PM CDT Fri Jun 19 2020 ...UPDATE TO SYNOPSIS... .SYNOPSIS... Issued at 1040 PM CDT Fri Jun 19 2020 WV imagery indicates a weak upper level shortwave trough of low pressure moving eastward across the Western High Plains. Near the surface, high pressure is drifting eastward out of the Northern Plains into the Upper Midwest. && .SHORT TERM...(This evening through Saturday) Issued at 200 PM CDT Fri Jun 19 2020 Our much needed rainfall this morning is now well east of the FA. Some amounts were over 2", such as here at KDDC. The rest of the afternoon will remain precipitation-free. Attention then turns to late this evening. Terrain/upslope flow induced convection is expected to develop across Colorado. This activity is expected to merge into an MCS and move across the Kansas prairie late tonight through the early morning hours. Much of the models agree in such as storm evolution. As such, have aligned pops in a general consensus of the meso models through the next 24 hours. The main threat with the storms will be heavy rainfall. Would not be surprised for a few locations to see another inch of rain. Right now, the western to central zones (along and west of Highway 283) stand to see the highest chances for storms and heavy rainfall. A secondary threat could be some wind, however, by the time the activity reaches this FA, this may be mitigated somewhat by the decoupling of the boundary layer. Still, near the Colorado border, a strong to perhaps marginally severe outflow may be possible late this evening as the convection begins to cross the state line. For Saturday, the atmosphere will have been worked over. Mesoscale subsidence the wake of the departing MCS will result in a dry forecast for much of the day. Highs in the mid 80s are expected. .LONG TERM...(Saturday night through Friday) Issued at 200 PM CDT Fri Jun 19 2020 Attention then turns to Sunday. An upper level trof will push out across the Northern Plains and over the central United States. A stationary boundary is expected across Kansas. Will have to watch out for the potential a higher severe thunderstorm threat Sunday afternoon and evening. CAPE will be plentiful (which is obvious because it`s Summer). More importantly, bulk shear will increase enough for supercells. Forecast soundings do show an environment that is supportive of large to giant hail. In addition, there is enough directional shear that is a little more concern for a non-zero tornado threat. Two negatives exist Sunday for Sunday... Speed shear is weak and storm evolution is not clear at this point in time. None of the parameters matter if you don`t have supercells in the first place. Convection may congeal into a MCS, in which the threat for hail and tornadoes would be very low. Heavy rainfall and some strong/severe outflows would be the main threats. Regardless, the weather on Sunday is something to monitor in terms of the potential for a high magnitude severe threat and additional heavy rainfall. Beyond Sunday, the EC continues to suggest that the MCS pattern will prevail across southwest Kansas. Nightly thunderstorm complexes may continue Monday and Tuesday. Good news that will we proudly take given the ongoing drought that we are in. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 649 PM CDT Fri Jun 19 2020 Weak upslope surface flow is conducive to thunderstorms persisting into the area this evening, moving in from isolated ongoing activity in eastern Colorado. HRRR model might suggest the best opportunity for storms between 3 and 6 Z between Garden and Liberal and a little later in time around DDC. Hays is a bit more uncertain whether it could be impacted by CB or not. Ceilings should drop into MVFR cat at least for several hours with lower vsbys in locally brief moderate/heavy rain. Any residual lower status will likely rapidly improve beyond 12 UTC in the western areas. The stratus will linger on much longer through late Saturday morning at HYS, but clear up by the early afternoon. && .PRELIMINARY POINT TEMPS/POPS... DDC 60 85 61 92 / 70 20 0 20 GCK 57 85 59 91 / 80 10 0 20 EHA 57 87 60 94 / 80 10 0 10 LBL 58 87 60 93 / 100 10 0 10 HYS 61 84 60 91 / 70 20 0 40 P28 65 87 63 93 / 60 40 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...JJohnson SHORT TERM...Sugden LONG TERM...Sugden AVIATION...Russell
National Weather Service Kansas City/Pleasant Hill MO
638 PM CDT Fri Jun 19 2020 .Discussion... Issued at 231 PM CDT FRI JUN 19 2020 As with most June forecasts for our area what happens overnight drives what happens during the day. This is one of those scenarios where convection over central KS overnight will likely be the main factor in what actually happens over our area today. Two MCVs have developed over central and along the KS/MO border currently. CAMs seem to handle this features somewhat well and with little forcing in the low levels this will be the main forcing mechanism to fire up some convection this afternoon. Cloud coverage and cooler air from all the morning convection will limit the amount of instability over eastern KS and western MO. The best place for possible clearing and building instability will be just SE of the KC Metro and into central Missouri and possibly up into north central Missouri. The RAP has ~1500 J/kg building up in that region and the differential heating could help create a discontinuity boundary and extra forcing. A few strong to severe storms have formed up on the eastern edge of the MCV. The main threat would likely be damaging wind and heavy rain, but small hail to isolated 1" hail is possible. This threat would be short lived and off to the east by 5-6PM with the more stable air moving in behind it. Scattered showers and maybe an isolated thunderstorm have started to form up behind this feature over eastern KS and western MO with the second MCV moving over the area, although the impacts will be mostly just isolated heavy rainfall with these storms. A major shortwave trough will exit Colorado this afternoon, likely developing a line of storms over western Kansas this afternoon. This feature and the developing LLJ overnight will be the main driving mechanism for our area overnight. How far north the low level warm air can recover from the cold pool this morning will determine where the focus will be after sunset. Most guidance has this occurring south of HWY 50, and maybe even towards Clinton, with a SW to NE oriented line that may merge with the incoming MCS moving east over Kansas. The SW to NE oriented line could cause flooding concerns as training thunderstorms look favorable with the LLJ and MBE vectors less than 10kts. With PWAT values near 1.75" these storms will be efficient and 2-4" could drop rather quickly if this set up occurs. How the MCS and stalled boundary to our south play out Saturday morning will have major implications for what happens Saturday afternoon. A shortwave trough and associated cold front will push through the area Saturday afternoon, so forcing will not be an issue. The question will be how quick we can recover and how much instability will be available by the afternoon. The most likely area to have time to recover would be east of I-35 and north of the Missouri River. Guidance does seem to hint that this occurring as does the Day 2 SPC convective outlook. With all the uncertainty on how Saturday morning plays out there is low to medium confidence on things playing as our forecast and guidance suggests. The shear profiles are much more favorable for severe weather with bulk shear 0-6km 30-40kts, so if instability can develop then severe weather will be in play with damaging wind and large hail the main threats. The cold front Saturday will bring in some cooler air, but it will be short-lived as strong southerly flow and WAA build quickly into the front range Sunday morning and continues east into the afternoon. This develops a dryline from western KS up into Nebraska with a warm front over eastern Nebraska. This boundary will be the primary forcing mechanism with 3000 J/kg to work with. A digging shortwave trough and associated strong LLJ will set up the possibility of a substantial MCS moving through our region Sunday evening into the overnight hours. Damaging winds will be the main factor with forward propagation vectors showing 70-80kts. Steep lapse rates may also allow some large hail, but it would be more isolated than the wind threat would be. Monday another shortwave will enter the Northern Plains helping to enhance boundary from OK up into IA. This boundary will move into our area as a cold front Monday afternoon and if we can recover from the morning MCS, may cause another round of scattered storms Monday afternoon over central Missouri. Tuesday and Wednesday look mostly dry with cooler high temperatures in the lower 80s. A developing boundary Thursday evening may bring back some showers to the area as the warmer air starts to return with southerly flow. This boundary will move slightly to the north and be another possible focus mechanism for showers and storms over northern Missouri Friday. && .Aviation...(For the 00Z TAFS through 00Z Saturday Evening) Issued at 636 PM CDT FRI JUN 19 2020 Light showers will persist for the next few hours, but coverage will be minimal and impacts will be largely negligible. Overnight tonight there will be some pockets of low clouds, but at this time coverage doesn`t look like it will be widespread enought to warrant prevailing flight category changes. Likewise, while the showery activity will pick up again on Saturday, aerial coverage appears to be rather small at this time, and hi-res models indicate a better chance for showers east of the terminals. Will update that thinking with upcoming forecasts. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...Barham Aviation...Leighton
Area Forecast Discussion
National Weather Service Louisville KY
941 PM EDT Fri Jun 19 2020 .Forecast Update... Issued at 942 PM Fri Jun 19 2020 Convection has all but died off this evening minus a decaying storm in NE Nelson county and one on the Russell/Clinton line. This should give way to a quiet overnight as an upper ridge axis slowly builds in from the west. Given mostly clear skies, relatively calm winds, and some low level moisture expect there could be some fog around by sunrise. Best chance is east of I-65 and especially in the river valleys and areas that saw recent rainfall. Otherwise, expect a quiet night. Updated products already out. && .Short Term...(This evening through Saturday) Issued at 305 PM EDT Fri Jun 19 2020 Popcorn-like showers are starting to fire up across parts of central KY and southern Indiana again this afternoon. So far the only cells producing lightning were in the Bluegrass region, where SPC RAP CAPES were over 2000 j/kg, though anticipate a few of the others will generate thunder as well. On the plus side, the convection remains short-lived and disorganized, with no training of cells like last evening. On the down side, motion is relatively slow - only 10- 15 mph to the SSE, so if a N-S oriented line develops along some as of yet unseen boundary, isolated flooding can`t be completely ruled out, though is not anticipated. The convection and clouds should dissipate quickly this evening, with only scattered clouds overnight. The diurnal cloud cycle will return with 20 pops by afternoon. Weak southwesterly surface flow will help inch dewpoints upward tonight and tomorrow, resulting in overnight lows about in the mid 60s to low 70s - a few degrees warmer than this morning and just above climatology. Daytime highs will be 85 to 90 for most - also at or slightly above the seasonal norms. .Long Term...(Saturday night through Friday) Issued at 305 PM EDT Fri Jun 19 2020 To start the period, we will continue to be under the influence of some slight ridging Sunday as a trough associated with an upper level low over Manitoba Canada stretches south through the upper Midwest and the Mississippi River Valley. This will keep us hot and humid and bring back unsettled weather for Father`s Day and into early next week. Highs Sunday and Monday will be in the upper 80s to near 90 and dew points in the upper 60s and low 70s. With the trough just off to our west, multiple shortwaves will move in the SW flow keeping the threat of scattered showers and storms. CAPE values Sunday and Monday will range from 1000 to 2000 J/Kg with limited shear, so while storms are possible the severe threat looks limited. Upper level low over Canada slowly slides ESE over the Great Lakes by the middle of the week, dragging a surface cold front through the region Tuesday night into Wednesday afternoon. Increasing our chances of more widespread rain and thunderstorms Tuesday and Wednesday. Temperatures remain warm both day in the low to mid 80s. Through the end of the week, while there remains a chance of showers and storms we see a slight drying trend near the end of the week with 20-30% PoP for Thursday and Friday. && .Aviation...(00Z TAF Issuance) Issued at 7:56 PM EDT Fri Jun 19 2020 Scattered showers and thunderstorms across the CWA are not currently impacting any TAF sites, and conditions should quiet down once diurnal heating diminishes this evening. Crossover Temp method does indicate some fog potential for BWG and LEX overnight. Another round of isolated showers and storms will be possible tomorrow afternoon, especially for the Bluegrass. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...BJS Short Term...JBS Long Term...BTN Aviation...BJS/CJP
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
700 PM CDT Fri Jun 19 2020 .SHORT TERM... 238 PM CDT Through Saturday night... Our recent dry spell looks like it`ll be coming to an end over the next 24-36 hours as the persistent mid-level ridging that we`ve had overhead will finally be giving way to eastward- advancing troughing which has been incrementally shifting closer each day this week. In the meantime, anticipating largely precipitation-free conditions through the rest of the afternoon. Have noted a few blips on radar out of the bubbling cumulus field in northwest Indiana, but the effects of both ongoing mixing (holding dewpoints into the mid 50s) and lingering large scale subsidence should keep any precipitation production to a minimum and too low to warrant a mention in the gridded forecast. Farther to the west, surface-based instability continues to struggle to work much farther east than the river, as mostly sunny skies have once again allowed PBL mixing to drop dewpoints into the mid and upper 50s across our I-39 locales. Have pared back PoPs into the evening there and have limited things to just a mention of showers at this point with the expectation that any of the more robust convection remain tied to the front across central and eastern Iowa. Upstream, we`re monitoring a nicely defined MCV (Mesoscale Convective Vortex) pivoting northeastward into north-central Missouri. This feature--a result of overnight and morning convection and associated mid-level latent heat release--has produced a core of enhanced mid-level vorticity which should spread northeast towards Dubuque late tonight/very early Saturday morning. This initial wave by itself may remain just far enough to our north and west to pass by more or less sans fanfare, but it appears there may be a secondary vort lobe trailing this first feature which may make a close enough approach to our I-39 county areas towards daybreak to support at least scattered showers and some embedded thunderstorms. As is often the case with these remnant MCVs, the mid-levels will have warmed within the mid-level thickness bump, and forecast soundings near the Rockford area reveal that this mid-level warming may act as a CAPE robber on Saturday morning with MUCAPE values generally in the 250-750 J/kg range and may mute the degree of thunder potential with this activity. Have generally confined the morning precipitation chances closer to these expected vort maxes, north and west of I-55, and have nudged PoPs up a bit more than recent hires guidance such as the HRRR and 12z 3 km NAM would indicate. With the potential for morning convection and increased cloud cover--especially across our northwest--did make some downward adjustments to the high temperatures across north-central Illinois areas. 850 mb temperatures do still look to rise into the +17 to +19 C range, so this still may very well support high temperatures jumping into the lower 90s south and east of I-57 where precipitation chances appear lowest and insolation potential may remain maximized. The effects of the morning convection cast some uncertainty on the storm chances later on Saturday afternoon. Brief mesoscale subsidence behind these departing waves may make for a relatively quiet late-morning and early-mid afternoon. However, guidance does show instability growing diurnally as temperatures warm. The lower 70 degree dewpoints forecast by the GFS, NAM, and RAP still appear a bit overdone through mid-afternoon Saturday, but even the somewhat drier ECMWF does still support MLCAPE values building into the 750-1500 J/kg range. We`ll be in the right location in the right entrance region of a strengthening jet to support increasing jet divergence through the afternoon as the main shortwave of interest--currently across the Rockies--makes its closest approach to our region. Both mid-level kinematics and lapse rates will be somewhat lacking tomorrow afternoon, with generally 25-30 kts of effective bulk shear available which would point towards multicell convection and loosely-organized clusters as the favored storm mode. This, combined with the lack of a steeper mid-level lapse rate environment to augment mid-level updrafts suggests the hail potential may be on the lower end of things, with isolated strong to possibly severe downbursts the main threats with any activity that manages to develop through the late afternoon and evening hours. At this point, we`re favoring a roughly 4 pm - 8 pm window for any main strong-severe weather risk with storm intensity gradually waning thereafter. Shower and storm chances may linger through Saturday evening as upper divergence and broad warm advection continue. The airmass will remain quite moist, with PWATS still likely pushing 1.75". As a result, the threat for locally heavy rainfall will certainly continue, some some localized corridors of 1-2.5" of rain possible before things wind down late Saturday night. Think the threat for widespread flooding remains low, but we`ll continue to message the potential for some isolated bouts of flooding through Saturday night. Carlaw && .LONG TERM... 330 PM CDT Sunday through Friday... For most of the area, Father`s Day appears it will be a decent summer day. The highest coverage and concern for thunderstorms during the long term is on Monday through Monday evening. This may include some risk for strong to severe thunderstorms, along with heavy downpours and localized flooding. In the wake of Saturday night`s convection, associated weak cold front will push into southeast 1/3 or so CWA by 12z Sunday. Best chance for any lingering convection (widely scattered showers and isolated TS) Sunday morning will be southeast of I-57. While the air mass behind the front will only be marginally drier with respect to surface dew points, models remain in good agreement in advection of much drier air in the 700-500 mb layer. The front will slow it`s forward progress, so in the afternoon, the area that appears will have any chance at a couple showers/storms will be east-central Illinois and northwest Indiana, where modest destabilization will occur. This will be the exception to the rule of what will be a warm and fairly plesant summer day for most with increasing afternoon sunshine. Highs should top out well into the 80s, aside from an afternoon lake breeze that should slip into IL shoreline areas and keep temps slightly cooler there. Attention then turns to what could be a pretty messy day convection wise on Monday. Most of Sunday night will be dry and mild. The quasi-stationary boundary that will have stalled over far southern or southeast CWA later Sunday will lift back north as a warm front on Monday in response to surface low pressure tracking northeast into Wisconsin. There is fairly substantial uncertainty on the important details on Monday, including: coverage and magnitude of potential morning to mid day convection and associated effects on how the rest of the day and evening plays out; exact track and timing of surface low which will affect northward progress of warm front. Some of the guidance has a pretty strong convectively modified/enhanced mid-level short-wave moving across the area from late morning west to mid to late afternoon east, while other guidance is a bit weaker and disjointed with the large scale forcing. Mid-level lapse rates are progged to remain modest at generally under 6.5 C/km. Depending on the timing and evolution of the above described details and how much destabilization can occur in the seasonably high moisture (dew points 65-70) amidst temps well into the 80s to possibly near 90, there may be some threat for strong to severe thunderstorms in the area. This would especially be the case if wind fields can be strengthened by stronger mid-level wave/possible MCV. Otherwise, it could be another messy multi-cell episode with isolated strong to perhaps severe downburst potential into the evening. Cold front will sweep across the area late in the evening and overnight, likely bringing an end to the convection. Thereafter, the pattern will trend cooler through Thursday with many dry hours, though with occasional lower end chances for diurnal instability driven showers and perhaps a few thunderstorms. This will take place as an upper trough centered over eastern Canada gyrates slowly eastward, with subtle short-waves traversing the local region. Tuesday is modeled to have stout low and mid- level dry advection behind the front by more reliable ECMWF guidance, so appears to have a sub-mentionable chance for any isolated thunderstorms. It`s possible if trends hold, we may be able to remove Tuesday`s PoPs, followed by a bit better signal for diurnal showers Wednesday PM. Signs point toward mid and upper ridging returning by Friday, so temps should return to near or above normal levels. Castro && .AVIATION... For the 00Z TAFs... The Lake Michigan lake breeze is (slowly) drifting across the ORD airfield, but has stalled over or within a mile to the east of MDW. With weakening SW gradient flow as daytime mixing diminishes, the lake breeze should push through MDW in the next hour. Light and variable winds generally in the SE quadrant are expected into mid- morning Saturday before SSW winds in excess of 10 knots with gusts around 20 knots become common late Saturday morning through the evening. A TS complex over northeast Missouri is expected to shift NNE while slowly weakening through the early overnight hours. This activity should remain well west of the Chicago terminals, but may briefly clip RFD as a few -SHRA in the 03-06Z window. Another weak wave ejecting from Kansas will again brush RFD but not the Chicago terminals after daybreak. Finally, a more pronounced wave from ongoing convection in Oklahoma should be an impetus for TS develop Saturday afternoon and early evening. Confidence in occurrence has increased enough to introduce a TEMPO TS in the 21-01Z window for ORD/MDW/DPA, and 19-23Z at RFD. Briefly heavy rain and gusty winds are possible with any convection. Widely isolated development may occur prior to 21Z over the Chicago metro, but coverage should remain rather low. Kluber && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1047 PM CDT Fri Jun 19 2020 .UPDATE... Issued at 934 PM CDT Fri Jun 19 2020 Showers and thunderstorms have moved out of the area temporarily. Latest radar mosaic is showing some new activity starting to develop over central Missouri where the RAP is showing some weak low level moisture convergence. Water vapor imagery is showing a weak shortwave trough moving into western Kansas that the RAP shows weakening as it moves northeast across the area later tonight. There will continue to be some weak moisture convergence as the 30KT low level jet veers late tonight, so will maintain the low chances for showers and thunderstorms into Saturday morning over the northwest half of the CWA. Going lows still look good, so made only minor adjustments based on the latest observations. Britt && .SHORT TERM... (Through Late Saturday Night) Issued at 331 PM CDT Fri Jun 19 2020 Widely scattered thunderstorms have developed this afternoon across parts of Missouri as expected, and a cluster of storms is moving toward central Missouri from the west. The SPC mesoanalysis page is showing 1500 to 2000 J/Kg of MLCAPE over central Missouri ahead of the cluster which quickly falls off to less than 500 J/Kg in east central Missouri. There`s not much in the way of shear from in central and eastern Missouri, so the most likely organized storms will only be clusters like the one moving into central Missouri. There is 700-900 J/Kg downdraft CAPE back toward central Missouri which intersects with the areas of higher MLCAPE, so we`ll have to watch for the possibility of strong gusty winds with the storms in central Missouri. The storms should weaken and largely dissipate by 03-04Z this evening due to loss of heating/instability. Additional thunderstorm activity may move into the forecast area from the west overnight as a 20-30kt low level jet associated with a shortwave moves into Missouri. Think best chance for overnight storms will stick to central and northeast Missouri. Another short wave will move out of the Plains and into the Midwest on Saturday. This wave will finally give the front draped over northwest Missouri the push it needs to get it moving southeast. Showers and thunderstorms still look likely to develop ahead of the front, and while there is a chance that convection could develop at any time Saturday, the period when storms will be most likely will be between 300 PM and 1000 PM. 2000 J/Kg MLCAPE once again, but probably a bit more shear in the 20-30kt range will produce a marginal severe wind/hail threat, but that threat should diminish fairly quickly as daytime heating and instability decreases. Carney .LONG TERM... (Sunday through Next Friday) Issued at 331 PM CDT Fri Jun 19 2020 Guidance has the flow aloft becoming quasi-zonal in the wake of the short wave and the front stalls over southern Missouri. The front will continue to be a focus for thunderstorm development on Sunday across southern Missouri and Illinois. The pattern them becomes highly amplified Monday into Wednesday as a strong upper level low drifts down across the U.S./Canada border in the Great Lakes Region. The flow aloft over the Mid Mississippi Valley turns to the northwest and this should finally give the front the push it needs to clear the area on Tuesday. Cooler and less humid air is expected to filter into the mid Mississippi Valley behind the front. Medium range guidance shows a few short waves moving through in the northwest flow which could produce some scattered showers or thunderstorms Wednesday or Thursday, but it doesn`t look like anything strong at this time. Interestingly, the mean and spread of ensemble temperature guidance for Tuesday through Thursday seems to be much tighter than in previous runs, so confidence is increasing in at least a short stretch of below normal temperatures next week. Medium range guidance diverges by the end of the week though with the GFS turning quasi-zonal aloft, and the ECMWF beginning to build an upper level ridge. Either way, we should see temperatures back to near or above normal and potentially another uptick in thunderstorm activity. Carney && .AVIATION... (For the 06z TAFs through 06z Saturday Night) Issued at 1026 PM CDT Fri Jun 19 2020 Showers have recently developed southwest of KCOU and will possibly affect that terminal through 09Z, so have included VCTS in the TAF. Showers and thunderstorms will move northeast and affect KUIN between 09-12Z. Additional showers and thunderstorms will possible during the afternoon and evening at all of the terminals. Any thunderstorms will have the potential produce MVFR/possible IFR visibilities and ceilings. Winds will remain under 10KTS outside of thunderstorms. SPECIFICS FOR KSTL: Dry and VFR conditions are expected through at least early afternoon on Saturday. Then thunderstorms chances will increase during through the afternoon and evening hours and have included VCTS during the late afternoon and early evening hours. Any thunderstorms will have the potential produce MVFR/possible IFR visibilities and ceilings. Winds will remain out of the southwest through the period. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
757 PM EDT Fri Jun 19 2020 .UPDATE... Deep and persistent westerly flow as seen in evening TBW sounding has pushed robust afternoon convection well east of the local area with only a few isolated storms left on old boundaries early this evening. Dry air aloft continues to wrap from the Gulf into the area and expect rain to end shortly with clear skies overnight. Have updated grids and forecasts based on satellite and radar trends. && .AVIATION... Thunderstorm have waned and moved east with VFR conditions and light winds tonight into Saturday morning. && .Prev Discussion... /issued 1151 AM EDT Fri Jun 19 2020/ SHORT TERM (Rest of Today through Saturday)... The weather pattern is setting up to be an active one this afternoon and at least early this evening across central and eastern southern portions of the peninsula. A mid/upper level trough continues to pivot across the deep south accompanied by significant upper jet energy for this part of the country late into June. The central and southern parts of the state will sit under the RRQ of this jet this afternoon...within a favorable upper divergence/diffluence pattern to promote lift. In Florida, we look for reasons why it will not rain during the summer, and anything extra in terms of atmospheric lift...generally seems to seal the deal for widespread convection. Well north of I-4, we run into less column moisture, and there the convective activity may be somewhat more limited in nature. However, along and south of the I-4 corridor, moisture is abundant, with PW values at or above 2" today. Greatest weather concern will exist in the form of locally heavy rain and localized flooding over roughly Highlands, central/southern Polk, and parts of Hardee/DeSoto counties. Give this general area a little spread in nothing is weather is a sharp line. 1000-700mb layer flow is from the SW...but generally still on the light side. This should allow the east coast seabreeze to migrate inland with time early this afternoon. All indications from the ensemble guidance are that we will have a decent convergence zone setting up across the aforementioned area to support robust convection. Given the focus for storms in this area, once they develop, updrafts will feed on a fairly moist column and upper support. RAP runs continue to indicated 20-30kts of deep layer bulk shear in this region for the afternoon/early evening, which suggests a slow-moving multicellular convective mode. A bit concerned about an NW to SE band organizing and not moving much off the convergence zone. Ensemble probabilities off the HREF for >1" are 90% or higher across this entire area. That is a fairly significant signal of agreement among the members. Given this, localized amounts in the 2-4" range should be considered as a reasonable worst case scenario through 02Z. Thereafter convection should fade rather quickly. SPC has also outlooked inland areas in a marginal risk for severe weather. Given the robust convection expected, a few damaging wind gusts and/or quarter sized hailstones can not be ruled out with the strongest and/or most precipitation loaded cells. Saturday... A more typical summer type pattern begins to return for the weekend as the upper level energy/troughing pivots away from the region early in the day. Surface ridge will lie across the south- central peninsula, generally to the south of the I-4 corridor. The flow around this ridge axis will favor a scattering of storms around Lee county and southward where layer winds are weak or from the SE. Further north, a SW wind will push any convection fairly quickly away from the coast into the interior zones. However, there are some indications that some drier air will arrive aloft from I-4 northward and keep the overall convective extent more limited, especially compared to today. Outside of the summer storms, expect partly cloudy skies, and temperatures generally peaking in the lower 90s. LONG TERM (Sunday through next Thursday)... The second half of the weekend into much of next week looks like a typical late June weather pattern. The subtropical ridge will lie across the Florida peninsula, with some minor migration north and south on a daily basis. The exact pattern of storms will depend on this migration, but we see no day with a well-defined either westerly or easterly flow to say that the favored area will be here vs there. As we get closer, these more detail about the ridges possible will emerge and some finer tuning can be done to daily spatial and timing aspects of the rainfall probability forecast, but for now, near normal temps and rain chances is sufficient and appropriate to message. MARINE... Thunderstorms are increasing in coverage over the coastal waters early this afternoon to the south of Anna Maria Island and Siesta Key. Mariners are urged to check local forecasts and radar before heading out on the water this afternoon. Further north, storm coverage looks to be more isolated in nature. High pressure will remain in place over the eastern Gulf of Mexico through the upcoming weekend, leading to mostly benign conditions, outside of typical scattered showers and storms. The storms will be most common during the late night and morning hours. Mariners can expect light east to southeast winds over the Gulf waters, with the flow along the coast turning onshore each afternoon as the sea breeze develops. FIRE WEATHER... High pressure and abundant moisture over the state expected to keep minimum RH values comfortably above critical thresholds through the period with no fire weather hazards expected. Greatest shower and thunderstorm chances likely over interior and southern locations. && .Preliminary Point Temps/PoPs... TPA 75 90 76 92 / 20 30 10 30 FMY 74 91 75 91 / 20 60 30 50 GIF 72 92 74 93 / 40 50 10 50 SRQ 74 90 76 92 / 10 30 10 40 BKV 70 92 72 93 / 20 30 10 30 SPG 77 90 78 92 / 10 20 10 30 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...None. Gulf waters...None. && $$ UPDATE/AVIATION/MARINE...25/Davis UPPER AIR...99 DECISION SUPPORT...99