Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/29/19

Area Forecast Discussion
National Weather Service Cleveland OH
955 PM EDT Tue May 28 2019 .SYNOPSIS... Low pressure over the region will drift northeast tonight driving a weak cold front south into the area this evening. The front will stall in the area tonight and Wednesday as waves of low pressure move east along the boundary. The front will finally drop south of the area behind low pressure Thursday. High pressure will build in for Friday. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... Convection has become limited to some scattered showers with isolated thunder late this evening and all severe thunderstorm watches and warnings have expired. Some minor flooding is still noted in the Cleveland and Youngstown metro areas and the appropriate flood products remain in effect for those areas. As current rain moves east out of the area, a relative lull in convection will occur for a few hours before activity enters the area for daybreak Wednesday morning. With that, have low chance to slight chance PoPs for the overnight with just a slight chance of thunder. Original Discussion... Low pressure just north of Lake Erie will move east this evening and in its wake, a cold front will move south into the area. The front is currently in sern lwr MI into central Indiana. There is however, convergence set up across the inland counties from near the FDY area ene, enhanced across nern OH and nwrn PA by the lake breeze. Thunderstorms have developed along this convergence zone. Currently surface based CAPES are around 3500j/kg. Thermodynamics support large hail and strong downburst winds. Shear support steady state, rotating storms especially east half of the area. Expect strong to severe thunderstorms to continue to spread east across the area into early evening. Overnight convection should tend to drift sse and weaken through the late evening. After midnight the HRRR shows convection moving back toward the area from the west along the stalled out boundary. The HRRR takes most of this north more across the lake and possibly affecting some of the northwestern counties. Towards morning another wave will be moving east through northern Indiana toward northwestern OH. Wednesday this stalled front will be across the area and models show another weak impulse moving east along the front during the day. Would expect redevelopment with the more favored area across the southern and eastern counties. Will need to keep chance pops going through Wednesday night. Towards morning Thursday however will increase pops back to likely in the west as another low approaches from the west. Highs Wednesday from north 70 north to near 80 far south. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Thursday will likely be another active weather day over the forecast area. A shortwave trough over the central CONUS will propagate east into the Great Lakes region and get absorbed into a larger trough over the eastern CONUS. At the surface a low will enter Ohio and move east across the forecast area. With good forcing expected over the region along with decent instability and moisture and some good jet dynamics, showers and thunderstorms are likely on Thursday and some severe storms may be possible. Have continued with the high likely PoPs, but have not gone to categorical as there are coverage concerns at this time. There are some timing issues still at this time, but Thursday will be yet another day to watch in what is an active weather week. High pressure will emerge over the eastern Great Lakes on Friday behind Thursday`s low. Light northerly flow, some slight cold air advection, and sinking air entering the region will keep temperatures near to perhaps a couple degrees below normal. && .LONG TERM /SATURDAY THROUGH TUESDAY/... Will continue with a fairly generic forecast for the weekend. Northwest flow sets up over the region with the best energy aloft on Saturday and again on Monday afternoon. Have the highest PoPs during those time periods, but nothing more than scattered showers and thunderstorms. While northwest flow will persist over the region, not too much appears to be in place to alter temperatures to far above or below normal. && .AVIATION /00Z Wednesday THROUGH Sunday/... Update...At 00Z significant wx will be quickly moving east out of the area. At this time most terminals are VFR with the exception of TOL ERI YNG. Expect conditions to bounce between VFR and MVFR through the balance of the evening and then likely drop to MVFR for the overnight with a cold front stalling in the area. Wednesday expect continued numerous showers/thunderstorms as the front remains in place and weak waves of low pressure move through the area along the boundary. Expect widespread MVFR conditions Wednesday with IFR likely in wx. OUTLOOK...Non-VFR possible for periods of time through Thursday. && .MARINE... A cold front will push south of the lake tonight and flow will shift winds around to the north and then northeast. The front then lingers over the area on Wednesday and may try to move back north to the southern lakeshore, but flow will likely remain light out of the northeast. The front remains over the area on Thursday and low pressure will move northeast towards the lake on Thursday night. Winds will flip around to the southwest and then west with this system moving through the region. High pressure emerges over the area on Friday and light northerly flow and dry weather on the lake will allow for Friday to be the best marine weather day of the period. A weak front enters the basin for Saturday and winds may shift around to the northwest by Saturday night. At this time, not expecting any marine headlines on the lake. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...TK NEAR TERM...TK/Sefcovic SHORT TERM...Sefcovic LONG TERM...Sefcovic AVIATION...TK MARINE...Sefcovic
National Weather Service Sioux Falls SD
1056 PM CDT Tue May 28 2019 .SHORT TERM...(This Evening through Wednesday) Issued at 332 PM CDT Tue May 28 2019 Main upper level low currently noted on WV imagery noted over northeast CO will provide for our next chance of showers and thunderstorms this evening and overnight. Initial round of thunderstorms has already begun from northeast KS into central IA. It is across this area that the main severe threat will stay with the warm front still well south of our area near the KS/MO/IA/NE borders. MUCAPE values over our far southern counties are only a couple/few hundred Joules so we will likely struggle to get any storm to approach the strong category. The main forecast challenge and concern for tonight into tomorrow revolves around the additional rain amounts on already very soggy soils. The surface low will eventually pull into eastern Nebraska and western Iowa into early Wednesday. Where exactly this tracks and what mid level boundary the precipitation forms on will have implication the pivot point for the heavier rain amounts. The 12z GFS/NAM/WRFs and previous model consensus generally had the highest across our west near the James River valley. Meanwhile, the last couple ECMWF runs along with trends in the HRRR have tried to pull this heavier axis to the south and a bit east, likely due to the ongoing convection to our south hanging up the various features further south as well. This is notable as this could potentially shift some of the higher rain totals closer to the area that was harder hit with Sunday night/Monday`s event. Tried to show this trend in the latest QPF which would put a stripe of 1 to 2 inches from Lake Andes further east/northeast toward the Sioux Falls area and perhaps NW IA, with a broad area of 0.25 to 0.75 inch amounts buffering this. While these rain amounts would normally not be much concern, trends will need to be monitored into the evening as the moist antecedent conditions could lead to further impacts on rivers. WPC has continued the Marginal Risk for excessive rainfall for areas south of I-90. Fairly healthy rain chances are still expected for the morning hours Wednesday across portions of SE SD into SW MN eventually fading by the afternoon and shifting south as the upper level low meanders slowly overhead. Could even see some thunderstorm activity over NW IA with some lingering instability and shear, with the GFS the most aggressive with these values. Temperatures for most locations will be stuck in the 60s. .LONG TERM...(Wednesday Night through Tuesday) Issued at 332 PM CDT Tue May 28 2019 By Thursday, region will sit in between the northern and southern stream jets with only the fading forcing left from the decaying upper level low providing for some small precip chances. Overall, expect improving conditions from Thursday into the weekend with no significant systems noted. This won`t necessarily mean a completely dry forecast but the chance for widespread, impactful weather appears low at this time. Also expect temperatures to be on a warming trend thru the rest of the week with 70s expected by Thursday and 70s and even lower 80s expected thru the rest of the extended. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1052 PM CDT Tue May 28 2019 Forecast precipitation chances and amounts have continued to trend downward this evening; however, scattered showers and isolated thunderstorms are still possible overnight at sites south of south of I-90, such as KSUX. Ceilings will vary, with mid-level clouds north of I-90 and low cloud decks south of the interstate. Light northeast and north winds overnight will change to northerly and northwesterly through the evening hours Wednesday. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...Kalin LONG TERM...Kalin AVIATION...VandenBoogart
Area Forecast Discussion
National Weather Service Hastings NE
635 PM CDT Tue May 28 2019 .SHORT TERM...(This evening through Wednesday) Issued at 351 PM CDT Tue May 28 2019 Main concern is potential for severe thunderstorms this aftn into eve as well as ongoing flooding. Objective and subjective sfc analysis indicates a sfc low/triple point just S of RSL at 20Z. This is further S than expected 24hrs ago, and also further S than what earlier runs of the HRRR this morning were showing. A stationary bndry extends to the NE to near STJ with a cold front extending SW from the sfc low into SW KS and into TX/OK Panhandles. These sfc features will be key to determining greatest risk areas for severe wx later this aftn/eve. Sfc obs in the warm sector show temps in the upper 70s and dew points in the upper 60s to near 70. Water vapor analysis reveals a strong closed low over E CO, with an associated strong mid-upper level jet streak across the Central Plains as sampled by the KAMA 12Z sounding to be around 60kt at H5. Morning soundings also sampled very steep mid-level lapse rates on the order of 7.5-8 C/km. The steep lapse rates, combined with high theta-e airmass in the warm sector, is leading to moderate to strong instability with MLCAPE of 2000-3000 J/kg near far S CWA per latest SPC Mesoanalysis. An EML at the base of the steep lapse rates is keeping this instability capped, for now. 1-min GOES vis sat imagery has shown some persistent clearing across north central Kansas counties. Thick, low stratus continues to the N, in an area of moist, easterly upslope flow, and even some drizzle and fog too. Additional insolation as well as cooling mid-level temps should lead to continued destabilization and eventually erode the cap 22-23Z. Large scale forcing for ascent is sufficient for tstm development, as hinted at by persistent band of cirrus (on vis sat) and moist plume (on WV channel) over central KS, and there are several triggers at the sfc. The main question is when and where storms develop. This is mostly tied to location of sfc low/boundaries and what areas see some clearing. Agree with latest SPC outlook that the highest severe probabilities (locally) likely extend a little further W/SW than expected 24 hrs ago. Areas from near Arapahoe to Hastings, to York and points SE have the greatest risk for severe storms given overlap of 0-6km bulk shear 55-65kt and MUCAPE 2500-3500 J/kg. Both of these parameters are more than sufficient for supercell structures. Large hail up to at least golf ball size and damaging wind gusts up to 70mph are the main threats. A couple tornadoes can`t be ruled out immediately near and E/NE of the sfc low, near the boundary, which will likely extend from near Stockton to Hebron. Storms in these areas have best potential to be sfc based, whereas storms a county or two to the north will be elevated above the near-sfc stable layer. As far as timing goes, I suspect to see some CI between 21-23Z over our far S, and last several runs of the HRRR show activity arriving from the W along and S of the state line in the 00Z-02Z time frame. Later tonight, some CAMs suggest some decent cores over the N CWA, generally N of I-80. Forecast soundings show MUCAPE of 1000-2000 J/kg and mid-level lapse rates around 7.5 C/km. However, effective shear is rather weak around 20-25kt. Think these areas could see a few strong to perhaps marginally severe storms, but the weak effective shear should keep this threat limited. The SPC marginal-slight risk areas cover this potential well. Perhaps of greater concern would be the rain that is produced in northern areas as they will be closest to the wrap-around moisture. Models have been fairly inconsistent in QPF amounts in these areas, but latest trends of EC and HRRR are a bit concerning. Current forecast calls for around 0.5" N of the Tri-Cities, but as always, locally higher amounts are possible. Wednesday: Lowered highs by 2-3 deg as models show persistent cold air advection on NW winds along with broken stratocu. This is typically not a good setup for much warming, thus went with some cooler CONSRAW data. Areas along and N of I-80 continue to have best potential for rain shwrs, but amounts should be light, and not expecting anything too convective. .LONG TERM...(Wednesday night through Tuesday) Issued at 351 PM CDT Tue May 28 2019 Will continue to see some lingering influences from the departing upper wave on Thu. The biggest impact will be continued cld cover and cool temps, but some lt pcpn also possible so have maintained low POPs. Model variability is quite high with location and amplitude of several mid level perturbations Friday into the weekend, so confidence on timing and location of pcpn chances is very low. Latest global deterministic models and ensembles for early next week show a deep trough over the NE CONUS and a weaker, somewhat cut-off, trough over/near SW CA. This leaves us in quasi-zonal flow and relatively low day-to-day pcpn predictability. Overall, though, the pattern supports near-normal temps and more dry time than not. This is welcome news for those that need some time to dry out. Temperatures: Expect low 70s on Thu then warmer temps near 80 for the weekend. Mid 80s are possible early next week. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday) Issued at 627 PM CDT Tue May 28 2019 IFR ceilings expected through most of the Fcst period. Dropped mention of VCTS for now, will monitor and amend if TSRA look to impact TAF sites. The winds will start off NE and will become NW as the SFC low tracks to the east later tonight. && .HYDROLOGY... Issued at 351 PM CDT Tue May 28 2019 Will once again be monitoring the hydro situation very closely through tonight as much of the area remains very saturated. Two areas of most concern with be from near Phillipsburg to York (generally S/E of Tri-Cities) as well as areas N of Hwy 92 (generally N of the Tri-Cities). Convection this eve should be rather iso-scat and quick moving, which should keep rain amounts from becoming too excessive. However, some heavy downpours are a concern. The northern area of concern will be driven mainly by wrap-around shwrs and weaker tstms. Rain rates here should be less, but the rain duration could be longer. Model QPF varies from less than 0.25" to as much as 1.25" in isolated spots on some of the hi-res data. Will be watching these areas closely over next 12-18hrs. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Thies LONG TERM...Thies AVIATION...Beda HYDROLOGY...Thies
Area Forecast Discussion
National Weather Service Grand Rapids MI
944 PM EDT Tue May 28 2019 LATEST UPDATE... Update .SYNOPSIS... Issued at 214 PM EDT Tue May 28 2019 - Showers and thunderstorms arriving tonight, mainly south of I-96 - Additional showers and storms possible Wednesday night/Thursday mainly south of I-96 - Thunderstorms possible over the weekend && .UPDATE... Issued at 945 PM EDT Tue May 28 2019 Really there is little change in our thinking as to how the upstream convection will impact our CWA. Seems to me the best convection will stay south of our CWA overnight. Even so, we will get an area of showers with a few thunderstorms crossing our CWA between 11 pm and about 5 am. The thunderstorms should for the most part stay near and south of I-94 with the strong storms closer to I-80. The latest RAP model(8pm) shows a west to east low level jet from RDF to AZO. Over time this feature moves east so by midnight the cores of this jet is near TOL. That puts southwest Michigan in the speed divergence area of this low level jet. That is a major negative to strong thunderstorms. Also the nose of the best 1000/850 moisture transport does not get north of I-80. There is some elevated instability to work with through. the area with MU cape greater than 500 j/kg stays south of I-94 through the night. The bottom line is we will see showers overnight near and south of I-96, a few thunderstorms near and south of I-94 but the storms do not look they would have any significant severe potential due to the fairly strong frontal inversion over our CWA (RAP soundiSo we may ng at midnight shows nearly a 10 degree rise in the air temperature 1400 ft above the ground and 2000 ft above the ground). && .DISCUSSION...(This evening through next Tuesday) Issued at 214 PM EDT Tue May 28 2019 Challenging forecast for the next couple of days given the potential for organized thunderstorms to form upstream of the region. Tonight...southern parts of the CWA should see showers and thunderstorms rolling in around midnight. These storms are currently organizing into a complex around Kansas City. The warm air advection wing of this developing complex is suggested to impact mainly southern parts of the CWA. The convection should be fairly elevated limiting the overall severe risk. They main hazards look to be locally heavy rain and frequent lightning. If the deeper instability ends up further north...we could end up with some severe weather. We will need to monitor trends closely through the evening. A mid level wave rounds the base of the trough/low in the Southwest U.S. Wednesday and heads towards the CWA for later Wed night into Thu. There is some uncertainty as to whether this feature makes it into CWA. The latest run of the High Res Euro keeps it south while the GFS clips the far south with heavier rain. We will highlight the I-94 corridor with a higher potential for rain. Once again the main instability axis is forecasted to remain south of the CWA. This should overall limit the severe weather risk. If the GFS is right we could see an increased potential for flooding. Going forward...high pressure moves in for Friday. It will not stay long as guidance is showing a stronger front pushing down from the northwest Friday night into Saturday. High pressure then moves in for Sunday drying the weather out. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 737 PM EDT Tue May 28 2019 The I-96 TAF sites are on the edge of going from MVFR cigs to IFR cigs, as of 2330z, GRR is IFR and LAN are IFR while MKG is MVFR. I expect MKG will go IFR due the easterly prevailing low level wind. The I-94 TAF sites are VFR but I believe they too will become MVFR if not IFR within the next few hours. There is a wave on the front to our south that has convection assoicated with it. It would seem most of the thunderstorms will miss our TAF sites to the south in the 05z to 09z time frame as the wave passes just south of this area. If the showers get this far north, the cigs will improve to MVFR due to better mixing assoicated with the convection. Once the convection is to our east I would think IFR should become widespread at all TAF sites by sunrise. This is from both fog and low cigs. Since there is not a strong push of dry air it may be hard to break those low clouds up during the day. I would think the fog should lift by midday. && .MARINE... Issued at 214 PM EDT Tue May 28 2019 North winds may briefly top 20 knots this evening across northern zones but overall the pressure gradient will be relatively weak through Saturday. Near any thunderstorms winds and waves could be higher so mariners will need to monitor the weather closely. && .HYDROLOGY... Issued at 214 PM EDT Tue May 28 2019 The rivers near Vicksburg and Maple Rapids remain above bankfull, with only low lying areas near the river under any water. With rain and possibly a storm in southern Michigan overnight, totals of a quarter to half inch are possible. These totals would not overwhelm the rivers, but may halt the downward trend of the Portage River near Vicksburg for another day or two. The Portage River is only several inches shy of creating relatively greater flood impacts to buildings, but at this time it is not expected to climb that high. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...WDM SYNOPSIS...MJS DISCUSSION...MJS AVIATION...WDM HYDROLOGY...CAS MARINE...MJS
Area Forecast Discussion
National Weather Service Louisville KY
1002 PM EDT Tue May 28 2019 .Forecast Update... Issued at 1000 PM EDT Tue May 28 2019 Other than some very minor tweaks to forecast products in the short term, forecast remains largely on track. CAMs continue to indicate a potential broken line of showers and storms could arrive to portions of southern Indiana by sunrise tomorrow, and slowly push into the rest of the region throughout the day. The latest (00z) HRRR is perhaps the most aggressive CAM with storms tomorrow, and would imply strong/severe storms starting shortly after sunrise and continuing through much of the day. The parameters will certainly be in place to support severe storms, even during the morning hours, so this will be something that will continue to be monitored closely. && .Short Term...(This evening through Wednesday) Issued at 255 PM EDT Tue May 28 2019 ...Severe Storms Possible over Southern Indiana/North Central Kentucky Tomorrow... Expect gusty southwest winds to continue through this evening with a strong cap under upper level ridging keeping the area dry this evening and through much of the overnight hours. Wind gusts will decline shortly after sunset. Tonight the upper level ridge will begin to break down allowing the sfc front to our north to drop south into the region and end up somewhere over central or southern Indiana by sunrise tomorrow. This will allow showers and storms to enter southern Indiana and north central Kentucky late tonight after midnight into tomorrow morning. Soundings at 12Z reveal a weak cap near the sfc which is quickly broken between 12-15Z. Plenty of CAPE (1500-2000 j/kg) will be available for morning storms along with 45-55 kts of 0-6 km bulk shear. Those values will increase as we head into the afternoon hours with max CAPE expected to reach the 2500-3000 j/kg range and 0- 6 km bulk shear in the 50-55 kt range. The boundary nearby and shortwaves along it should produce discrete cells and bowing segments with the main svr wx threats being damaging winds and large hail. There is a small chance for a tornado but unidirectional wind profiles and limited windows of better effective SRH may limit that threat overall. Still strong to severe storms are expected throughout the day tomorrow with the best location being southern Indiana and north central Kentucky in the best moisture/instability axis. Only isolated chances for a storm exists over southern KY tomorrow where the ridge and capping will be stronger. Temperatures tonight will be in the upper 60s to lower 70s for lows. Highs tomorrow will range through the mid 80s to low 90s. Southwest winds will be gusty again tomorrow 20-25 mph outside of any convection. .Long Term...(Wednesday night through Tuesday) Issued at 315 PM EDT Tue May 28 2019 Wednesday Night - Thursday Night... Diurnally driven convection from Wednesday PM will likely be dying off late Wednesday evening with the loss of heating. However, convection is supposed to redevelop to our SW and move into the region toward dawn on Thursday. The Ohio River Valley will be in the broad SW flow between the weakening upper ridge over the SE CONUS and a central CONUS shortwave trough Wednesday night into Thursday. Ahead of the shortwave trough, a surface low will strengthen a bit over the Wabash River Valley and into the lower Great Lakes by early Thursday evening. Given the weakening of the upper ridge and the steady strengthening of mid to upper level flow ahead of the central CONUS trough, expect to see isolated to scattered showers and storms across our northern CWA early Thursday morning, and scattered to numerous shower and storm coverage by later Thursday ahead of the sagging cold front behind the surface low passing north of the region. Still being on the periphery of the upper ridge, expect modest buoyancy (~1000-1750 J/KG ML CAPE) to develop in the presence of strengthening deep layer shear (~40-50 knots). A few of the storms could become strong to severe, especially across the NW half of the CWA. Right now, we are only in a general thunderstorm risk from SPC, however expect we could be upgraded to Marginal or Slight with coming updates, assuming we are able to realize the modest buoyancy. The cold front passes through later Thursday evening and we will return to mostly dry conditions. However, a few post-frontal showers could linger around. After mild Wednesday night lows in the upper 60s and low 70s, look for Thursday highs in the low to mid 80s. Thursday night lows drop off nicely behind the cold front with mins finding their way back down to the low 60s by Friday morning. Friday - Tuesday... The remainder of the long term forecast will seem like more of a pattern flip as the upper ridge will become established across the western CONUS and shallow troughing takes hold of the eastern CONUS. This will result in a persistent NW flow pattern across our CWA, with several disturbances dropping through that flow. Overall, high and low temps will average about 10 degrees cooler than what we had been seeing in our upper ridge/summer-like pattern. Now we will be much nearer climatological norms with highs mostly in the low 80s and lows mostly in the upper 50s and low 60s. After lingering showers and a few storms on Friday with a passing shortwave, Friday night and most of Saturday should be dry. By Saturday evening through Sunday, another round of showers and storms is expected as a frontal boundary and secondary shortwave drop through the NW flow aloft into our region. Will continue with sct to num pops for this time. Sunday night through Tuesday then look mostly dry as Canadian high pressure at the surface and dry NW flow aloft hold over the area behind the cold front. Some convective activity could come close to our western CWA fringes, but overall think we will stay mostly dry. Temps will be quite pleasing with highs topping out on either side of 80s and lows in the upper 50s and low 60s. && .Aviation...(00Z TAF Issuance) Updated at 720 PM EDT Tue May 28 2019 VFR conditions expected most of the overnight hours. Isolated to scattered showers/storms may move in or develop over parts of the region after 09z, with additional showers/storms arriving after sunrise tomorrow morning. Confidence is very low in the timing and placement of precipitation, as much of it will be influenced by how convection evolves this evening over the Plains. Outside of brief storms, VFR conditions are expected for the duration of the forecast period. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...DM Short Term...AMS Long Term...BJS Aviation...DM
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
814 PM CDT Tue May 28 2019 .MESOSCALE DISCUSSION... 814 PM CDT A large shield of rain with embedded thunderstorms is spreading across northern Illinois this evening, with the likelihood of stronger to possibly severe storms in western Illinois tracking into the southern CWA after 930 p.m. The concerns for flash flooding are increasing as well, which brought about the expansion of the Flash Flood Watch a couple hours ago. Area of rain and embedded storms spreading into north central Illinois is driven by a few features...1.) the far northern area by a remnant MCV and 2.) much of the area by returning moist and warm advection aloft of 35 kt as seen on the 00Z ILX sounding. Much of the region is also under quickly increasing larger scale forcing for ascent ahead of a stronger short wave, likely convectively enhanced, in southwest/south central Iowa. Cloud tops also continue to cool on satellite, with values of -70C to -77C in eastern and southern Iowa. All of this, with the support of convection allowing models, indicate rain and embedded convection having upscale growth over the area through midnight. High absolute moisture values...including 850 mb dew points of 14-15C as noted on upstream ILX and SGF soundings and precipitable water at or above 1.50 heavy rainfall rates. Also the nose of the 35 kt moisture-replenishing low-level jet is positioned into the southern and central CWA ahead of this ongoing convection. So we are concerned with a several hour (3+) period of heavy rain rates, and the far southern CWA could have multiple waves of these into overnight / early Wednesday morning. So flash flooding could easily become realized, and may need to consider expanding the watch into a portion of northwest Indiana. While some of the upper forcing is moving north of east, the convective focus for the heaviest rain rates will likely hang near the 850-925 mb baroclinic zone, and this is slightly south of the greater Chicago area. Will need to continue monitoring trends though to ensure flooding threat is indeed west/south of the city. As for the severe thunderstorm threat...a well-defined bowing segment approaching the Peoria area has shown better organization and is riding the instability gradient around 925 mb eastward. The stable layer is shallow there, and this has enough structure to continue a wind threat eastward possibly into the southern CWA. Rainfall rates within this are very heavy too (2+" per hour). Mid-level lapse rates as noted on the ILX sounding as well as analyzed by the SPC RAP mesoanalysis are steep (8C per km 800-500mb) and could support a hail threat given 50 kt of deep layer shear, especially in any developing stronger cells ahead of this area. In addition, any west-to-east convection in a pseudo- warm advection wing, would further enhance the training convection threat for possible flash flooding. If any flash flooding were to develop -- and again the trends are increasing that at least some flooding will likely occur in/near the CWA -- this could continue into Wednesday morning. MTF && .SHORT TERM... 245 PM CDT Through Wednesday night... Showers, thunderstorms and associated heavy rainfall are the main focus once again. Complex of storms crossing the area this afternoon will continue eastward and exit to the east in the next few hours. Frontal boundary hung up to the south will continue to be the focus for new and potentially severe development through late afternoon. Attention then turns to the wave that is moving from northeast Kansas into NE/IA/MO and generating thunderstorms. Thinking continues to be that this will congeal into an organized complex and track eastward into the area from mid evening into the early overnight. Guidance has struggled with the current complex crossing the area so there is some question on how this may impact the next complex this evening. However, given that there is larger scale forcing at play, have somewhat better confidence in the trends that had things been more mesoscale driven. That said, placement of the heaviest axis of precipitation and its eastward extent is still somewhat uncertain. Provided the expected complex arrives from the west, low/mid level ascent will be increasing out ahead of it this evening and should support the development of elevated convection on more of an east-west axis across central or northern parts of the area. Am leaning towards central areas being the more likely location for this to occur vs. northern areas given the current complex crossing the area perhaps limiting any northward push of features that earlier guidance had anticipated to occur without the complex occurring. The heart of the expected MCS would likely track a bit to the south as the lower level instability gradient is likely shunted a bit south thanks to the current afternoon convection. Have opted to keep the previously issued flash flood watch as-is. With uncertainty in how the next complex will shape up and any developing impact the afternoon activity will have going forward do not have any additional confidence over what the earlier shift had on any expansion. So far, the current activity has generally produced a half inch or less of precipitation. Moisture transport should increase into the evening but the activity also looks to be rather progressive. Certainly cannot rule out isolated flash flooding outside of the current watch though. Will pass concern onto evening shift. May see lingering showers and thunderstorms in the southern or southeastern CWA Wednesday morning but expect a break in additional activity through most of the afternoon. Another series of troughs is expected to eject eastward across the plains and Mississippi River Valley Wednesday bringing more chances for showers and storms Wednesday evening/night. MDB && .LONG TERM... 244 AM CDT Wednesday night through Monday... The frontal boundary which appears poised to push its way south of the forecast area Wednesday afternoon, and perhaps very briefly dry things out, begins to lift back north Wednesday night into Thursday morning at the same time models show height falls aloft associated with the ejection of a cluster of shortwaves from the upper trough still sitting to our west. Considerable moisture convergence at low levels along with continued high PWAT values through this period would support yet another chance of heavy rain. Precip chances appear to diminish somewhat by Thursday afternoon and evening as low level support becomes less favorable, but the passage of an upper level trough axis along with the southward departure of the frontal boundary could still support some scattered showers. By later Thursday night into Friday precip chances diminish further as drier northerly flow develops at low levels and the upper trough has passed to our south. Presently Friday is looking like a good day to dry out from all the recent and upcoming rainfall. Confidence for the weekend and beyond becomes much lower as the upper pattern transitions at least briefly to a more subtle quasi- zonal to weakly cyclonic flow with embedded disturbances across the eastern CONUS, downstream from the next deep trough digging into the Pacific coast. Models are suggesting one of those disturbances could traverse the area sometime on Saturday, though timing is a question. There is better agreement that Sunday and Monday will be dry with rising heights aloft and drier air under a Great Lakes ridge at the surface. Lenning && .AVIATION... For the 00Z TAFs... Main concerns are the thunderstorms marching east toward the terminals this evening... and increased NE flow again behind the convection overnight enabling an onshore flow and hence pockets of IFR and possibly even LIFR through daybreak and into the mid morning Wednesday. Extrapolated timing of ongoing leading rain edge crossing the Mississippi River and in northwest Illinois has showers and embedded thunder arriving at ORD and MDW from 02-03 UTC. Strong moisture transport north into this large area of rain and thunder suggests a period of many hours of rain (~6-10) possible at the terminals. Embedded thunder within the larger rain area is expected to diminish however as the night transitions into morning. Reinforced northeast/onshore flow becomes well established again as the larger convective area moves off to the east and south... hence expect cigs to lower back to IFR conditions around 09-10 UTC with rain cooled air and cold marine layer undercutting very moist air aloft. Ed F && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Flash Flood Watch...ILZ003-ILZ008-ILZ010-ILZ019-ILZ032 until 7 AM Wednesday. Flash Flood Watch...ILZ011-ILZ020-ILZ021-ILZ022-ILZ023-ILZ033- ILZ039 until 7 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...UPDATED
National Weather Service Los Angeles/Oxnard CA
504 PM PDT Tue May 28 2019 updated aviation discussion .SYNOPSIS...28/700 AM. Afternoon temperatures will be notably warmer this week with only a slight chance of afternoon and evening thunderstorms in the mountains. Overnight and morning coastal low clouds will persist through the week. && .SHORT TERM (TDY-FRI)...28/121 PM. An upper level trof currently extends southward through California. It will fill over the next few days, and then an area of closed circulation aloft will slowly work from central California through the CWA and then south of our area during the extended period. A weak impulse associated with the trof will move over the area this afternoon. Afternoon heating will help the clouds build over mountain areas this afternoon. Already seeing some cumulus over the San Gabriel mountains and north of the Ventura County mountains. Watching the LIs drop by the hour, so some rain is looking likely, with a slight chance of thunder. Expecting 3 to 5 degrees of warming today in the coast and valley locations with higher amounts at higher elevations. Max temps will stay below normal today, but this should be the last cool day for the next few days. The HRRR and our local WRF are indicating elevated winds along the western Santa Barbara south coast this evening from roughly 7 pm to 11 pm with sustained winds of 30 mph. Will keep to monitor the area for a possible low-end wind advisory. Increasing onshore flow will help develop marine layer stratus and bring it to the coasts and the lower valleys tonight and into Wednesday norming. The trof fills in a bit Wednesday and the dry and slightly cyclonic flow will persist of the area. Skies should clear by late morning. NAM and the ensembles agree there will be a chance of showers and slight chance of TSTMs over the higher mountains again. The atmosphere will continue to warm under the high sun, and afternoon high temperatures will rise another couple of degrees. Less warming along the immediate coast where the return of stratus will drop the starting point. The marine layer will repeat Wednesday night and it will likely arrive a little sooner since the onshore flow is stronger. A weak upper low moves out of Oregon on Thursday and slides southward down the state. By afternoon the stratus will have pulled off the coast, but the mountain areas will begin to cloud up as the upper low provides both lift and instability. Still looks like Thursday will be the best day for TSTM development, especially over the Ventura County mountains. Thursday will be the warmest day of the week. The upper low moves moves closer on Friday and it will be not too different than Thursday. Heights drop a few DM, so afternoon temperatures will cool back to Wednesday levels. Onshore flow should keep the marine layer stratus as a morning feature. Again a chance of afternoon showers and possibly thunder in mountainous areas. .LONG TERM (SAT-TUE)...28/128 PM. Very little day-to-day change in the extended forecast as the upper level low migrates over us and then to our south. Moderate onshore flow will keep the night through morning low clouds going through the period. Expecting little change in high temperatures until next Tuesday when heights have climbed to 584 DM. While there will be some afternoon cumulus over the mountains each day, there will likely be insufficient moisture and instability to create a risk of thunderstorms. && .AVIATION...29/0003Z. At 2330Z at KLAX...there was a weak inversion at 1600 ft deep. The top of the inversion was near 4000 ft with a temperature of 15 deg C. Moderate confidence overall in the 00Z TAFs. Low clouds and IFR/MVFR cigs are forecast to develop tonight and move into the coastal and vly airfields, with the onset ranging from about 06Z at KSMX to about 14Z at KSBA, KCMA, KBUR and KVNY. The low clouds are then expected to clear to VFR by late Wed morning to early Wed afternoon. The timing of the onset and dissipation of the low clouds may be off +/- an hour or two. There is also a 30%-40% chance the low clouds may not affect KBUR and KVNY at all during the period. For KPMD and KWJF, there is hi confidence in VFR conditions through Wed afternoon. Gusty W winds are expected this evening. KLAX...Moderate confidence overall in the 00Z TAF. Low clouds and MVFR cigs are forecast to affect the airfield from about 12Z-19Z Wed and again aft 03Z Wed evening. Otherwise, VFR conditions can be expected for most of the TAF period. The timing of the onset and dissipation of the low clouds may be off +/- an hour or two. KBUR...Moderate to hi confidence overall in the 00Z TAF. Low clouds and MVFR cigs are forecast to affect the airfield from about 14Z-17Z Wed. There is a 30%-40% chance the low clouds may not affect the airfield at all during the period. Otherwise, VFR conditions can be expected for most of the TAF period. The timing of the onset and dissipation of any low clouds may be off +/- an hour or two. && .MARINE...28/144 PM. For the outer waters, high confidence in forecast. NW winds will remain at Small Craft Advisory (SCA) levels much of the time thru Wed night. There is a 30% chance of SCA level winds Thu thru Fri. For the inner waters north of Pt. Sal, moderate confidence in forecast. Winds are expected to reach SCA levels this afternoon and evening, then SCA conds are not expected thru Sat. However, there is a 20% chance of SCA level winds during the afternoon and evening hours Wed, and a 30-40% chance during the afternoon and evening hours Thu. For the inner waters south of Pt. Conception, moderate to high confidence in forecast. Winds are expected to reach SCA levels this afternoon and evening across western portions of the SBA Channel. Otherwise, SCA conds are not expected thru Sat. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 9 PM PDT this evening for zones 645-650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zones 670-673-676. (See LAXMWWLOX). && .HAZARD POTENTIAL OUTLOOK (FRI-TUE). Showers and thunderstorms are possible each afternoon and evening in the mountains through at least Friday. There is a small chance for heavy rainfall and isolated flash flooding accordingly. && $$ PUBLIC...jld AVIATION...Sirard MARINE...Sweet SYNOPSIS...Kj
Area Forecast Discussion
National Weather Service Paducah KY
858 PM CDT Tue May 28 2019 .UPDATE... Issued at 858 PM CDT Tue May 28 2019 Based on radar observations to our west and north, and the latest CAM data, have updated the forecast to limit PoPs late tonight primarily to southern Illinois and southeast Missouri after 4 AM. Strong to severe storms do not seem very likely in this scenario, but will keep the mention of a stray strong storm in the HWO. Locally heavy rainfall and lightning will be the most likely impacts late tonight. UPDATE Issued at 700 PM CDT Tue May 28 2019 Updated aviation discussion for 00Z TAFs. && .SHORT TERM...(Tonight through Thursday night) Issued at 330 PM CDT Tue May 28 2019 Upper ridge shifts east tonight and Wednesday, leading to more of a general southwest flow regime aloft, with a sfc frontal boundary draped north of the region. This boundary will make an attempt to settle southward toward the forecast area Wednesday night, but will likely hold off reaching us until Thursday. Latest HREF CAMS tend to suggest some sct thunderstorms later tonight/Wed morning, mainly over se MO and sw IL as an MCS (or weakening MCS) tries to spill southeast from MO/IL. Climatology would dictate a weakening trend at that time frame, but will need to monitor its progress. Chance of severe seems low but not zero. Becoming a bit more concerned with the severe storm risk Wednesday, especially for the later afternoon and evening hours. 12Z CAMS now are hinting at another area of convection to get going Wed AM out over the southern Plains. This round of thunderstorms would try to build east toward se MO/sw IL Wed afternoon. Instability will likely be moderate to strong (SBCAPES AOA 3000 J/KG) in wake of any morning convection. In addition, AM convection may actually serve to leave a sfc boundary draped e-w across the middle of the forecast area, which could interact with the afternoon storms. Both 12z NAM and RAP sounding now introduce a greater amount of wind shear late in the day into the early evening, esp over se MO/srn IL/sw IN. O-6 KM bulk shear is significantly higher than advertised yesterday, with values closer to 40-45 kts over those areas. In fact, SPC has now upgraded the day 2 Outlook to a slight risk over all of that 3 state region. In addition, locally heavy rainfall, generally over southeast MO and southwest IL could become an issue Wed/Wed night if storms manage to undergo training within the moist warm sector. Will hold off on any headlines for now. Will be interesting to see if any precursor heavy rains develop late tonight in that region. If so, flash flood watches may be required later tonight or Wednesday AM. Short wave energy and sfc cold front are still expected to cross the region Thursday. However, extensive cloud debris and weakened instability should preclude much of a strong to severe risk. .LONG TERM...(Friday through Tuesday) Issued at 330 PM CDT Tue May 28 2019 Medium confidence in the extended with the ECMWF having the most stable solution. The Canadian has similar timing but very stingy with the qpf leading up to the extended. The GFS stalls the front over us through Friday. This is yet another flip flop in its solution. With this in mind will weight the ECMWF heavier with the extended. The overall synoptic scale features remain similar with the upper level high sinking southward into the Gulf. We expect two closed upper level over the west coast and the other near Hudson Bay. This will place us in a near zonal flow aloft starting Friday then becoming northwest as we head into the weekend. Upper level ridging will take place over plains. This northwest flow will allow for minor perturbations in the flow rotating around the upper low in Canada. This will allow for low chance pops as we head through the weekend. There will also be a weak cold front which should approach the area mainly Saturday night and move through Sunday. This will enhance rain chances but still relatively low pops and qpf. It may drop temperatures and dew points a couple of degrees but thats about it. The best chance of encountering a thunderstorm through the extended will be in the peak heating of the day. However these spokes of energy are difficult to time that far out and relatively weak. Temperatures will be lower than it has been averaging between 80 and 85 for highs through the extended. && .AVIATION... Issued at 700 PM CDT Tue May 28 2019 VFR conditions are expected through most of the period. A decaying line of showers and perhaps some thunderstorms is expected to move into portions of southeast Missouri and southern Illinois late tonight and early Wednesday morning, likely dissipating as it pushes further east into the area. Much of the afternoon should be dry as cumulus develops in the recovering atmosphere ahead of a second round of showers and storms Wednesday evening. South to southwest winds will diminish to 5 to 10 knots tonight, then increase to around 10 knots with some gusts of 15 to 20 knots by Wednesday afternoon. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...DRS SHORT TERM...GM LONG TERM...KH AVIATION...RJP