Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/03/20

Area Forecast Discussion
National Weather Service Gaylord MI
1023 PM EDT Tue Jun 2 2020 .UPDATE... Issued at 1023 PM EDT Tue Jun 2 2020 Earlier thinking still holds up. Very clearly, the strongest convection is inbound to central/southern lower MI. Would still not preclude a strong-ish storm in our far south. A storm due west of MBL over the WI waters of Lake MI spiked up decently within the past 40 min, before weakening. Some adjustments to pop coverage (increasing) and timing (a little faster) have been made. UPDATE Issued at 856 PM EDT Tue Jun 2 2020 Another note...00Z observed APX sounding had circa 1900j/kg of SbCape and 1100j/kg of MlCape. Of course, we were capped at 800mb, with 85j/kg and 145j/kg of SbCin and MlCin, respectively. The winds also have a northerly component thru the entire column, a clear obstacle to activity moving northward. The GRB 00Z sounding does at least have due west winds in a portion of the column, but no where is it outright southerly. (GRB also has a SbCape of 4500j/kg!) UPDATE Issued at 827 PM EDT Tue Jun 2 2020 Early thoughts... Convection upstream is starting to take shape, with svr storms developing due w of Manitowoc WI. That`s also due w of MBL/LDM. Deep convection seems unlikely to migrate northward with time, with a southward-sinking surface cold front and convection- generated cold pool, and essentially zonal mid-level flow. So it seems as though our svr threat is confined to the southernmost sliver of this forecast best. Most of the CAMs I have looked at this evening keep with strong/svr convection primarily near and south of LDM. This includes mainline HRRR and RAP runs, along with the HRRR run at SPC. There are plenty of types of interesting wx possible, even if organized svr wx misses us to the south. Pressure rise and fall couplets, and wake lows, could contribute to gusty winds well behind and otherwise displaced from the parent convection. In addition, the above could result in fluctuations of water levels on Lake MI (seiches and/or meteotsunamis) - a potential problem with very high lake levels. There`s still plenty to keep an eye on tonight. Showers and embedded thunder are north of the svr storms, and a good portion of northern lower MI is still getting wet tonight. But the early returns suggest the svr threat is going to slip by to the south. && .NEAR TERM...(Through Wednesday) Issued at 402 PM EDT Tue Jun 2 2020 ...Round of thunderstorms possible tonight... High Impact Weather Potential: Severe thunderstorms possible later this evening and overnight. Pattern Synopsis/Forecast: Afternoon composite analysis reveals broad ridging/warmth through the central CONUS into the Upper Midwest with strong W/NW mid level flow across the western Great Lakes. Mid-upper level speed max/short-wave trough is pressing into the northern Plains along the North Dakota/Canadian border. At the surface, broad low pressure is across south-central Ontario with a with a cold front that stretches from the central U.P. down through central Wisconsin and across southern Minnesota with a very warm and somewhat humid airmass south of the front across the Midwest into Michigan. Temperatures across northern Lower Michigan have warmed through the 80s...and touching 90 degrees in a few spots with MLCAPE values now in the 1-2K J/KG range. But as anticipated, much of the region remains capped this afternoon with lots of sunshine and only a little bit of Cu across NE Lower Michigan. Primary forecast concern: Convective development/evolution and severe weather threat remains the main forecast concern this through tonight. Still in a wait and see mode for convection over the next several hours. There is a narrow line of post-frontal showers/storms sagging southward across central Minnesota. But as talked about in earlier discussions, still anticipating additional convective development further south along the cold front heading into the evening hours, likely across southern Minnesota and eastward into Wisconsin. Convection still appears likely to continue to grow upscale/propagate eastward as a quasi MCS this evening and into central and southern lower Michigan late this evening and through the overnight hours, clipping the southern part of the CWA. Severe storm parameters remain favorable with strong mid level flow and resulting 0-6KM bulk shear values running 35 to 45 knots through the night, supporting organized storms. Time of day is not the greatest however with decreasing surface based instability and storms will have to cross cold Lake Michigan. But enough there to warrant a severe weather threat for large hail/damaging winds, mainly south of M-72 and mainly during the overnight hours. Convection should exit S/E early Wednesday morning with clearing skies and a little cooler/drier air overspreading northern Michigan. That said, forecast soundings Wednesday afternoon suggest enough surface heating/instability for a few showers and possibly a thunderstorm to fire across the E/SE part of the CWA...where northwesterly flow will intersect the marine layer off Lake Huron. Confidence is not high, but enough so that I`ve introduce some low end pops to the forecast for those areas. && .SHORT TERM...(Wednesday night through Friday) Issued at 402 PM EDT Tue Jun 2 2020 High impact weather potential: Minimal. High pressure builds into the Great Lakes region Wednesday night and will produce precipitation-free weather through at least Thursday afternoon...when a weak disturbance brushes the forecast area from southern Canada. Zonal flow continues over the Great Lakes region along with surface high pressure through Friday. Only some small chances of a stray shower or two with some upper level disturbances and accompanying moisture. Winds will remain fairly light Wednesday night as aforementioned high pressure moves overhead. Winds will become a bit breezy Thursday afternoon and become southwesterly while veering to more northwesterly throughout the day Friday with once again some gusty conditions during the afternoon hours with diurnal mixing. High temperatures will be in the upper 70s to low 80s Thursday and cool down to the low 70s to near 80 Friday...while lows will be in the 50s. .LONG TERM...(Friday night through Tuesday) Issued at 402 PM EDT Tue Jun 2 2020 High Impact Weather Potential: Minimal. Extended range features an increase in amplitude in the overall pattern compared to the mostly zonal flow expected through the rest of this week. Deepening Pacific trough will push heights upward over central North America to start the weekend...along with subsequent downstream troughing over the northeast U.S. Evolution of this downstream trough will have potentially bigger impacts on the upper Great Lakes heading into next week...specifically with regard to the position of central North American ridge axis and impacts on at least temperatures. Looks like the weekend starts with surface ridging building into the upper Midwest and upper Great Lakes Saturday with some northerly component boundary layer flow. Short wave trough is forecast to pass by Michigan in the Friday night through Saturday time frame which could kick off a shower threat. Surface ridge axis forecast to lie across the Great Lakes Sunday...and potential for stronger warm advection upstream between the upper level ridge axis and the trough over the northeast U.S. Some signal for an increased precipitation threat by Monday as strong warm advection begins to impinge upon the upper Great Lakes. But right now looks like the forecast trend should be warmer heading into midweek. Will be interesting to see what the remnants of T.C. "Cristobal" end up doing as they get pulled into the Gulf coast region early next week with a deep upper level trough over western North America. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 718 PM EDT Tue Jun 2 2020 SHRA/TSRA late evening and overnight. A cold front continues to slowly settle across the northern Great Lakes, running into warm/muggy air. Our wx is presently quiet, but SHRA/TSRA are rapidly developing in central/northern WI. These will move e to ese-ward, targeting central lower MI in particular. MBL has the best chance to see strong/svr TSRA, toward and after midnight. Chances for thunder will decrease as one heads further north. Substantial cig/vsbys restrictions are of course possible as active wx moves thru. Conditions will be mainly VFR and quiet again during the day Wednesday. Gusty westerly breezes will diminish this evening. A light nw to n breeze on Wednesday. && .MARINE... Issued at 402 PM EDT Tue Jun 2 2020 No marine headlines anticipated through the middle part of the week. Some gustiness will be found in the nearshore areas into early evening. Winds veer northwesterly on Wednesday likely with some gustiness again through the afternoon. But winds/waves are expected to remain below small craft advisory criteria. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...JZ NEAR TERM...BA SHORT TERM...TL LONG TERM...JPB AVIATION...JZ MARINE...BA
Area Forecast Discussion
National Weather Service Binghamton NY
1052 PM EDT Tue Jun 2 2020 .SYNOPSIS... Severe thunderstorms possible late tonight and again tomorrow across the Twin Tiers as a couple fast moving disturbance cross the region. Weak high pressure builds back in on Thursday with mainly dry weather, but another front may pass Friday. && .NEAR TERM /THROUGH WEDNESDAY/... 1045 PM Update Strong supercell thunderstorms are developing across the Niagara Frontier and coming off of western Lake Ontario. SPC has indicated a 40 percent chance for a severe thunderstorm watch mainly across Yates and Steuben Counties. These storms could approach the far western portion of our CWA over the next few hours and will need to monitor closely. Instability, mainly elevated is trying to advect east and south into our area. 800 PM Update Still watching closely the potential for strong to severe thunderstorms across the western Finger Lakes, Central Southern Tier and into NE PA between about 11 PM and 4AM tonight into Wednesday morning. Uncertainties remain, and thus am in agreement with SPC`s slight risk. For much of our area the convection looks to remain elevated overnight, generally being lifted from around the 850mb level...however it could be closer to surface based across Steuben and Bradford counties. Also, current radar and satellite trends are showing storms popping up near Georgian Bay and are heading SE...but if their direction remains consistent these storms may end up a bit further north/east than earlier forecast. So with this update PoPs and chances of thunder were increased further north/east across CNY overnight. Also added in a mention of isolated large hail, gusty winds and heavy rain overnight in the area where SPC has outlined in a marginal and slight risk. Otherwise, temperatures hold rather steady tonight and may even rise late as dew points also surge into the 60s after midnight. WPC does have a stripe along and SW of a line from Penn Yan--Owego and Scranton included in the marginal excessive rainfall outlook. With PWATs surging to around 1.3 inches we could certainly see some localized torrential downpours and plenty of lightning overnight. Most CAMs are in good agreement that much of our CWA will see a break in the shower/storm activity from about 4-5AM until 9-10AM...during this time it should just be partly to mostly cloudy with perhaps some patchy fog around. Then, the Mesoscale convective complex which is currently over Wisconsin and Minnesota is forecast to quickly race east overnight...potentially reaching our western zones by 10-11am then racing across the Twin Tiers and NE PA midday. A final line of thunderstorms then looks to develop across western NY midday, and push east- southeast quickly across the same region (Twin Tiers/NE PA) during the afternoon hours Wednesday. Ample surface based instability is forecast to builds across NE PA and perhaps the far southern tier or NY during this timeframe. Parameters support strong gusty winds and hail once again with these storms Wednesday afternoon. Adjusted chance for thunderstorms up, and expanded the coverage northward a bit; as much of CNY has at least a chance for a thunderstorm Wednesday. High temperatures range from the low to mid-70s across CNY, with mid-70s to lower 80s expected across NE PA. Dew points reach the mid to upper 60s so it will be quite humid out there. Severe storms possible late tonight and tomorrow... 320 PM Update... Confidence is growing for severe thunderstorms to impact the region late tonight and again tomorrow. 12Z guidance is now in good agreement with timing of shortwave arriving late tonight around 3Z in Western NY and exiting region by 8Z or 9Z tomorrow morning. Forecast sounding across the Southern Tier of NY and in NE PA, show a low level stable layer, but strong elevated instability exists above this shallow stable layer. RAP soundings highlighting elevated CAPE values over 1000 J/kg (NAM is likely overdone with over 2000 J/kg) and steep mid level lapse rates in the 700 - 500mb layer near 8C/km. Warm air/moisture advection surges in near the 850mb level with an approaching warm front this evening. Storms late tonight should ride along this boundary as short wave dives SE out of Ontario. Strong 0-6km bulk shear of 50 to 55 knots with winds veering from SE in the low levels to NW`rly aloft support rotating storm updrafts and possibly a few right moving supercells overnight. With strong shear and impressive mid level lapse rates, but stable low levels, storms will be elevated, so thinking is that large hail will be most likely severe risk tonight. However, depending on the strength of the low level inversion in place, can`t rule out at least a possibility for some damaging wind gusts. For now, have mentioned the possibility of at least some small hail in the forecast with gusty winds, and if confidence continues to grow later this evening, then more enhanced wording can be added to the forecast. Again, the greatest chance to see any severe storms late tonight will be from the Southern Tier of NY into NE PA. After a brief lull in the action from the storms overnight, we will see more storms enter the region from the west around mid to late tomorrow morning as a cold front approaches. The best threat for severe storms tomorrow looks to be from the NY/PA border on southward. Because of the timing, uncertainty still exists on the amount of instability, as there will likely be little time to destabilize before storms move into our western counties, with the greatest destabilization likely to occur across our NE PA counties. Strong to severe storms will exit the area early tomorrow afternoon, but can`t rule some lingering showers into tomorrow evening. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... 330 PM UPDATE... Not much change to the short term with this mornings guidance. The front is trending a little further south so PoPs were adjusted as well as temperatures increased as clouds may try and clear, especially for our northern zones. Previous Discussion... Cold front stalls over southern PA and becomes the focal point for showers and thunderstorms in the period, but mainly south of the area. Some showers and storms are possible Wednesday evening as an upper wave and the front trigger convection, but they should taper off after midnight. Dry weather continues into Thursday, however isolated showers are possible Thursday afternoon over NEPA as the front sneaks northward a bit and afternoon heating aids in convection. Short wave passing through on Friday will once again work with afternoon heating to fore convection, mainly in the afternoon, scattered over much of the area. && .LONG TERM /FRIDAY THROUGH TUESDAY/... 230 AM UPDATE... A cold front will sweep through the area Friday night into Saturday triggering showers and thunderstorms over much of the area. Long wave trough behind the front will allow for isolated showers and storms Saturday with the cold pool aloft. Upper heights begin to build in Sunday as the trough axis slides east of New England and drier sir builds into the forecast area. The dry weather will continue into Monday as a large ridge builds into the Great Lakes by the end of the period. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Thunderstorms will pass over the KELM and KAVP terminals overnight, first arriving at KELM around 03z, then at KAVP by 05z. Thunderstorms will contain hail, gusty winds, and MVFR restrictions. Brief IFR restrictions are possible. After showers move through the KBGM terminal overnight, ceilings will fall to between 500 and 900 feet in low stratus. Another round of thunderstorms could affect the KAVP, KBGM, and KELM terminals Wednesday afternoon. We will continue to monitor the situation. Outlook... Wednesday night through Thursday night...Mainly VFR. Friday through Friday night...Chance of showers and thunderstorms with associated restrictions as front passes. Saturday...Small chance of showers/restrictions, otherwise VFR. Sunday...VFR expected at this time. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...MPK NEAR TERM...MPK/MJM SHORT TERM...AJG/DGM LONG TERM...DGM AVIATION...DJP
Area Forecast Discussion
National Weather Service Des Moines IA
1058 PM CDT Tue Jun 2 2020 .DISCUSSION.../Tonight through Tuesday/ Issued at 301 PM CDT Tue Jun 2 2020 Synoptic Overview: Broad ridge spreads across most of the central U.S. with the axis sliding across the Missouri River Valley this afternoon. Sharp short- wave trough is moving through the Dakotas this morning with surface thermal boundary placed across the Interstate 90 corridor through the northern Plains into the upper Midwest. This feature will be the focus for a severe weather threat later today. Today: On the south side of the boundary, H85 WAA will be strong today, which along with mostly clear skies will allow temperatures to jump into the lower to mid 90s through most of the CWA. Northern Iowa may actually see warmer temperatures than southern Iowa this afternoon. Expect to see moisture pooling just ahead of the boundary, which will keep dewpoints in the mid to upper 60s across northern portions of the forecast area later this afternoon. The amplified ridge across the central CONUS will begin to flatten as CVA ramps up ahead ahead of the short-wave, promoting H5 height falls across the northern Plains and upper Midwest. This will also force the surface boundary southward throughout the afternoon. This will be the feature to watch with respect to the convection and severe weather potential later this afternoon and into the evening. CAM guidance has not been providing the best consistency for convection and severe weather potential across the northern portions of the forecast area for later this afternoon through the evening. The last few cycles of the operational HRRR have backed off of intense convection over the forecast area, focusing the threat mainly in SE Minnesota and western Wisconsin this evening. However, not completely sold on this operational HRRR trend. 12z NSSL-WRF and NMM attempt to develop a cluster of multi-cells across northern Iowa after 2z this evening (and the 18z HRRRv4 has done this as well). A look at CAM soundings across the northern forecast area shows decent capping, which could potentially limit updraft development. However, these CAM soundings are generally under estimating dewpoint temperatures, by 8-10F in some of the extreme cases. Further, the boundary layer across the north has had plenty of time to destabilize. Given that several of the CAMs are coming in too low with dewpoint temperatures, the surface based CAPE values are likely closer to the maximum of the HREF members rather than the mean, which would place values closer to 4000 J/kg this afternoon. Adjusting the dewpoints in CAM soundings also yields similar CAPE values. Thus, the capping inversion noted in these soundings may not be as much of an issue if this instability continues to develop this afternoon, especially in the presence of strong convergence with the synoptic boundary in place and an outflow boundary noted on GOES satellite imagery moving southeastward from the remnant convection over the Dakotas this morning. As for the severe threat, the more favorable shear environment for Iowa does not come into play until after 01z, where 0-6 km bulk shear will be around 35-40 kts. Coupled with rather steep low and mid-level lapse rates (assuming mixing remains robust this afternoon), updrafts may be sustained over a considerable depth, thus looking for hail to be the primary threat with storms over Iowa. Damaging wind gusts up to 70 MPH could come into play, with DCAPE values between 1000-1500 J/kg. Lapse rates look to remain near dry adiabatic up to around 800 mb. If a rogue supercell thunderstorm is able to develop, an isolated tornado could be possible. But throughout this afternoon, the low-level shear environment just does not seem to be materializing for it. HREF mean 0-1 km SRH values barely touch 100 m^2 s^-2 close to time of CI. This may be very reliant on storm scale processes sharply modifying the near storm environment. Additionally, LCLs at their lowest will be around 1500 m, with several point soundings showing over 2000 m. Thus, will be looking mainly at a hail and wind threat. Due to the cap that is in place, bust potential still remains medium on the severe threat this afternoon. SE Minnesota and and western Wisconsin will have the environment with slightly less uncertainty. Should deep convection be inhibited late this afternoon, can still expect some elevated showers on the backside of the boundary, with the short-wave moving in from the Northern Plains providing enough convergence to get things going. Wednesday and Beyond: Mid-level flow becomes more zonal through the middle and end of this week. However, several small perturbations will result in modest height falls, providing chances for light showers Wednesday and early Thursday. Temperatures will remain warmer throughout the week as H85 flow quickly returns southerly, leaving the forecast area in in an area of moderate WAA. If precipitation or cloud shield remains expansive, this will limit insolation and high temperatures some throughout the week. Late Thursday into Friday morning, another short-wave trough moves across the Missouri River Valley. This short- wave will be tied better with a surface cyclone and boundary that may bring convection to the forecast area. Ahead of the surface boundary, GFS/NAM attempts paint an area in the western forecast area with surface CAPE over 3000 J/kg, along with around 40 kts of 0- 6 bulk shear, may support a severe threat. This threat is currently highlighted by the SPC Day 3 Slight Risk for severe weather. This instability will be conditional on clearing from previous shower activity. Into the weekend, the synoptic picture becomes interesting. At 500 mb, a closed 5910 m contour high begins to move northeastward off the Mexican Plateau into the southern Plains. Meanwhile, a closed low sits off the Baja Peninsula. The high off the Plateau will act as a block to the closed to low. GFS and ECMWF solutions diverge. GFS depicts a short-wave at H5 that kicks off from the Rockies over the weekend, while the ECMWF amplifies the ridge across central CONUS. Thus for the weekend, will keep limited POPs in the forecast to account for possible action within mid-level southwesterly flow. Temperatures at this time for the weekend will also be kept closed to the mean of the possible solutions, and will pinpoint better as guidance converges to a more consistent solution. && .AVIATION.../For the 06Z TAFS through 06Z Wednesday night/ Issued at 1058 PM CDT Tue Jun 2 2020 Sct SHRA/TSRA will sink south through the TAF sites overnight but VFR conditions are forecast to prevail. Front stalls near southern Iowa Wednesday but latest models have precip all south of the state thorugh the fcst pd. VFR with light and variable wind on Wednesday/Wednesday evening. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Krull AVIATION...FAB
Area Forecast Discussion
National Weather Service Green Bay WI
1047 PM CDT Tue Jun 2 2020 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Wednesday Issued at 324 PM CDT Tue Jun 2 2020 Focus is on thunderstorms development and severe potential late this afternoon and tonight. At 20Z surface cold front was draped from west to east across the center of the CWA, roughly from Wausaukee to Marshfield, as evident by the wind shift to the W/NW. Seeing a few cu trying to develop near the front, while some higher clouds from the convection across MN also started to stream into northern and central WI. Further west, the main line of thunderstorms has persisted across central MN and continues to track E/SE. CAMs today have continually been slowing down the arrival of the convection into the WI and the GRB CWA. Latest (18Z and 19Z) HRRR shows a few storms getting into far northern WI around 22-23Z, but the bulk of the thunderstorms do not arrive until 01-02Z or so, across central and east- central WI. The 19Z sounding from GRB shows MUCAPE of 4000 J/kg, MLCAPE of 1700 J/kg, DCAPE of 1300 J/kg, and mid level lapse rates around 8.0 C/km. This is in line with the RAP analysis showing similar values across the southern two-thirds of WI or so. Once thunderstorms arrive there is more than sufficient instability for storms to produce damaging winds and large hail. While an isolated tornado cannot be ruled out completely, with marginal shear around 20 to 25 knots, SRH less than 100 m2/s2, and LCL heights ranging from 1500 to 2000m do not expect tornadoes to be a main concern. Of course, heavy downpours and frequently lightning can be expected within any storms. With storms arriving a couple hours later than the previous forecasts, also expecting storms to end a couple hours later, ending between 06-09Z from NW to SE across the area. Once storms and lingering showers clear out, clouds will also clear out by early to mid-morning on Wednesday. Wednesday is looking very summer-like. As sfc high builds into the area expecting dry weather and mostly sunny skies. Afternoon highs will range from the upper 70s in the Northwoods and along Lake Michigan, and from 80-85 degrees across central WI and the Fox Valley. Humidity will also fall with Tds in the mid 40s to mid 50s with light winds. .LONG TERM...Wednesday Night Through Tuesday Issued at 324 PM CDT Tue Jun 2 2020 Flattened, zonal flow remains expected to be in place across the northern tier of the CONUS through Friday. Then as a deep trough develops over the west coast, a building ridge across the western Great Lakes will lead to a warmer and more humid trend this weekend into early next week. Wednesday night through Thursday night...Relatively quiet weather remains expected to occur on Wednesday night as the cold front will linger across the far southern Great Lakes. Clear skies and light winds will lead to a relatively calm and pleasant night. The next shortwave trough is then expected to move across south-central Canada in the Thursday to Thursday night time period. It will push a weak front across the region during the same time frame. Although moisture and instability will be increasing ahead of the front, convergence along the front looks relatively weak and upper support will remain well to the north. So even though some thunderstorms will be possible, severe weather is looking unlikely at this time. Rest of the forecast...The chance of storms may continue into Friday if the front cannot sag far enough south on Thursday night. Also seeing evidence of a tail of a more potent shortwave moving across the northern Great Lakes, which could provide large scale lift. But for now, precip chances will remain low. Once this shortwave passes, the first half of the weekend is looking quiet as high pressure settles over the area. Then the arrival of more humid/unstable air will lead to increasing chances of storms late in the weekend into early next week. && .AVIATION...for 06Z TAF Issuance Issued at 1047 PM CDT Tue Jun 2 2020 Showers will linger across far southern central and east-central Wisconsin for a few more hours before dissipating during the overnight hours. Clouds will clear behind the showers with mainly clear conditions by mid Wednesday morning and lasting into Wednesday evening. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....KLJ LONG TERM......MPC AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
901 PM CDT Tue Jun 2 2020 .UPDATE... 901 PM CDT The main focus this evening has been on the convective trends with the MCS across WI. THe southeastward propagation has by far out passed forecast guidance. The current timing of this convective activity would put it at the IL state line just prior to 10 PM and into the northern suburbs of Chicago by 11 PM. Fortunately the threat for severe wind gusts looks to be dropping off as the storms are becoming outflow dominate. Nevertheless, expect some gusty winds of 30 to 40 mph over the next 1 to 2 hours over far northern IL as the gust front and storms approach. The main update to the forecast was to move up the time of precipitation by 3 to 4 hours to account for the observational trends over the past couple hours. KJB && .SHORT TERM... 212 PM CDT Through Wednesday night... Summer like warmth is upon the region this afternoon with nearly cloudless skies and a 850-925 thermal ridge (and associated elevated mixed layer) nosing over the area from the west. Still 3 degrees away from 92 record high at ORD as of this writing, MDW has already tagged 90. The nearest forcing mechanism aloft a decent wave/500 mb speed max across north central Minnesota on the southern flanks of the upper level jet across the Borderland. This wave is moving along the northern periphery of the stout CAP. The surface front is currently draped across southern MN and extending northeast toward Lake Superior. Concerns center around how much of the activity associated with this wave will make it into our area tonight, and where the effective boundary will be tomorrow when convective initiation occurs again. The speed max does appear to take a more W-E track which should also keep the effective front north of the local area. MCS maintenance parameters/as alluded to in the earlier AFD, are not super favorable for keeping a robust MCS occurring into northern IL tonight as 850- 300 mb wind vectors/thickness fields remain oriented W-E, and forward propogating vectors also keep a similar orientation, and actually have somewhat of a SW-NE component. SPC has expanded the Enhanced Risk into lower MI with more of this idea of a forward propagating system following this W-E track. CAM depiction of some clusters of storms upstream with potential outflow advecting into the region tonight seems reasonable, but with a weakening trend as any showers/storms make their way in. Forecasted DCAPE values do support cold pool sustainability which could act as a driver for additional storm development from elevated and conditionally unstable parcels. It would surmise that convection, if it were to occur, would be on the leading edge of this outflow and favored very late evening/early overnight. Shear profiles with this arrival time are on the lower end of the severe spectrum in N IL which is why the severe risk, while not zero, is focused in WI. We will retain a healthy MUCAPE corridor overhead tomorrow which eventually will manifest itself toward the surface given a weaker CAP. The next upper wave across WY will make headway across the plains and then toward our area midday into early afternoon while the effective frontal boundary continues to nose southward across NE IL/NW IN. We could still have some scattered storms with the MUCAPE axis around, though the forcing initially may be weak and we could have some capping in play. This is where guidance is initially mixed with many of the CAMS showing weak forcing, but the HRRR/raw NAM12/RAP are a bit more aggressive, potentially with the low level convergence fields. The remainder of the HREF CAM suite is muted. We are not surprised on the mixed signal as we will need to await what the expected storm complex across WI will do tonight. There are mixed signals with the guidance has to how quick the convective initiation will be and therefore how far north this will occur. Lake breeze convergence could be in play too depending on initiation time -- so plenty of complicating factors. During the afternoon this composite boundary should be along/south of I-80 as most guidance members show. The cap will be appreciably weaker than today with mixed layer CAPE forecast upward of 1500-2500 J/kg near the boundary. Scattered mature convective development seems probable and given effective shear of 25-30 kt and the lapse rates aloft, hail and wind would be threats with the strongest storms. If this setup indeed pans out, there will likely be a localized area of flooding potential near and just south of the boundary with slower and training storm motions. The boundary will stall Wendesday night, and thus will maintain some lower end PoPs for any westerly waves to incite some low level jet response -- but confidence is low. KMD && .LONG TERM... 320 PM CDT Thursday through Tuesday... The large scale pattern will generally favor above normal temperatures through the period, though the signal continues to point toward pronounced lake cooling over the weekend and possibly into Monday. In addition, it appears that humidity levels will be fairly comfortable area wide over the weekend and possibly into Monday. The main time window for a chance of isolated to widely scattered showers and thunderstorms is Friday afternoon. On Thursday, dry air aloft through much of the column and fairly weak lapse rates aloft could keep destabilization more muted and the atmosphere capped. Also, there`s not much of an apparent mid and upper level trigger mechanism. Much of the guidance favors a drier look, but held onto some low PoPs from NBM south of I-80 where instability could be a bit higher and capping a bit weaker. There should be a fairly early lake breeze push inland, keeping lakeside areas mainly in the 70s. The rest of the area should be in the mid to upper 80s and can`t rule out a few 90 degree readings. Most convective activity Thursday night should be off to the northwest, with a preference for the NAM and ECMWF, so the low NBM PoPs may be generous. On Friday during peak heating, the forcing is again pretty nebulous, with strongest mid and upper level forcing generally well north of the area. Temperatures in mid to upper 80s and dew points of 65-70 will likely yield moderate to strong instability at peak heating and models suggest weak capping at most. Therefore, convective temp may be reached fairly early, with any subtle low level convergence aiding in lift for thunderstorms. Lake breeze may be one of these sources of low level convergence during the afternoon. With the weaker overall forcing, NBM PoPs in lower chance range appear reasonable at this vantage point. A belt of 35-40 kt 500 mb flow on northeast periphery of ridging centered over the Plains could yield effective deep layer bulk shear of 30-40 kt. Thus there is a conditional risk for a strong to severe thunderstorms (wind/hail risk), though coverage may be low for reasons described above. The core of the mid and upper level ridging will gradually push east through the weekend. Any additional convective threats later Friday evening and overnight and shifting south. There remains good agreement on a backdoor cold front passage by Saturday that will bring mainly a lower humidity air mass to the region, along with more pronounced lake cooling due to persistent onshore winds. On Monday-Monday night, the surface high pressure that will bring the fair weekend weather will be slowly sliding east, so inland areas could warm a few degrees Monday PM and lake cooling confined to the Illinois shore. There`s uncertainty on whether convective chances will return Tuesday or primarily beyond day 7, though humidity should be on the rise. Castro && .AVIATION... For the 00Z TAFs... Aviation forecast concerns... * Fairly low confidence in timing of potential thunderstorms late tonight into Wednesday morning, and wind shift to north- northeast with convective outflow. * Chance of another period of thunderstorms mid-late Wednesday AM. * Chance of MVFR ceilings Wednesday morning. * Lake breezy for Chicago terminals Wednesday afternoon. Somewhat messy, low confidence forecast with respect to thunderstorm chances and timing late tonight into midday Wednesday. Very but strongly capped air mass is in place across the terminals early this evening. Thunderstorms have developed to the northwest of the area across southern MN and into western WI during the afternoon, along a combination of a cold front and a pre-frontal surface trough, and within a region of weaker capping in association with an approaching mid-level disturbance. While individual cell movement is expected to be generally easterly, the 850-300 mb thickness field does suggest the potential for a gradual east-southeastward movement to the developing convective complex, which could impact parts of far northern/northeast IL later tonight. Convective allowing models (CAMs) have quite a bit of spread in solutions of timing and coverage of storms moving southeast along outflow from WI storms as they attempt to spread into the more strongly-capped air mass across our area. This leads to somewhat low confidence in the evolution of convection into the terminal areas. The 4km WRF appears to be doing the best in the near term with storms building from southern MN into northern IA, and this model depicts outflow-generated convection developing into far northern IL in the 06-08Z time frame, though weakening or struggling against the capping inversion south of the IL/WI border. Operational and experimental versions of the HRRR are much slower (though are not handling ongoing storms well), and develop convection more notably along the cold front as it pushes across the terminals Wednesday morning. Have generally relied on the 4km WRF solution with the 00Z TAFs. A brief period of MVFR ceilings is possible in/after precipitation early Wednesday. In addition to timing complexities of storms, organized outflow would likely disturb the wind field across the area into Wednesday morning, with a northerly component to the surface winds for a time, and then more firmly northerly with the passage of the cold front by midday. Chicago terminals would likely see a lake breeze induced northeast wind during the afternoon. Ratzer && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
National Weather Service Morristown TN
914 PM EDT Tue Jun 2 2020 .UPDATE... EVENING UPDATE. && .DISCUSSION... Forecast for the remainder of tonight looks to be on track, with a mostly clear sky and low temperatures a bit above normal. Will just make a few minor tweaks mainly to temps and dew points with this update. && .AVIATION... 00Z TAF DISCUSSION. There will be some mainly scattered clouds around at times, but VFR conditions are expected for the period all sites. Winds will become lighter overnight, but will increase again closer to 10 kts from the southwest during the day Wednesday. LW && .PREV DISCUSSION... /ISSUED 301 PM EDT Tue Jun 2 2020/ SHORT TERM...(Tonight and Wednesday) Key Messages: 1. Warm and humid with very spotty afternoon/evening thunderstorms, especially in the Plateau and mountains. Discussion: The clouds have mixed out as expected this afternoon with full sunshine and continued WAA allowing temps to reach the upper 70`s to low 80`s as of 18Z. The warmest spots were in the southern valley with 84 at CHA. A very pleasant evening is on tap, although continued southerly flow will bring dew points into the mid/upper 60`s leading to a muggy evening and overnight. For tonight, the mid/upper ridge over much of the southern CONUS will begin to flatten as shortwave energy moves through the lower Great Lakes pushing a cold front gradually southward. At the same time, a southern stream upper low, currently analyzed over N TX, will begin to slide eastward into AR. With warm 700 mb temps between 8 and 10 C and associated strong mid level capping scene in the RAP soundings, as well as strong Bermuda high pressure remaining in control of the SE, the upper low to the W will only result in a gradual increase in high clouds. Reflected a gradual increase in clouds in the sky grids from SW to NE after 07Z. Lows will stay in the mid/upper 60`s. For tomorrow, the aforementioned Great Lakes mid/upper shortwave and associated surface low will progress through the NE U.S. and SE Ontario with its trailing cold front slowly continuing a southward jog into the OH Valley. This will set up NW flow over the NE U.S. while the southern CONUS ridge tries to hold on in a more suppressed state. This will cause the front`s progression south to be very slow, however, this system will begin to phase with the old southern stream upper low over AR and pull it east toward our area. Subtle cooling aloft from the lowering heights (slightly weaker cap), continued SSW flow of warm, humid air, and added moisture from the approaching upper low will cause spotty convection to initiate in the Plateau and eastern mountains from late morning through the evening. Some of this activity could move into the valley, so added slight chance to chance PoPs for most areas except for far NE TN and SW VA. Confidence is low on how much convection we will see due to the aforementioned capping, but if anything does develop, an isolated severe storm could occur. Steep mid level lapse rates above 7 C/Km will allow for MUCAPE values over 3000 J/Kg by late morning with LI`s of -6 to -8. This combined with PWATs increasing to over 1.5 inches will cause locally heavy rainfall, as well as the potential for isolated wet microburst, if any cells develop. Any microburst will be very localized. Highs will reach the upper 80`s areawide. RG LONG TERM...(Wednesday night through Tuesday) The long-term period of the forecast continues to be an active with good chances for afternoon showers/storms with increasing moisture on Thursday into Saturday. A cold front with drier conditions forecast Sunday into Monday and then some decent uncertainty at the end of the forecast with the Tropical Storm Cristobal. Upper level heights will begin to fall Wednesday night into Thursday as an upper level trough passes to the north across the Great Lakes into the New England. Cyclonic flow associated trough will extend southward into the Southern Appalachians even into the northern Gulf of Mexico. Additionally, a 80-100 kt jet will extend across eastern Great Lakes into New England putting the forecast area in the right entrance region of this jet. At the surface, the high will be to the east with generally southwesterly flow. All of these variables will add up to produce above normal PW values in the 1.5-1.7 inch range. These values are near the 75th-90th percentile for early June. The synoptic lift is weak but have higher confidence in precipitation occurring than during a typical summer time pattern. Better chances will continua to be over the higher elevations. Some precipitation may linger into the overnight hours with the saturated atmosphere and weak lift but expect most activity will come to an end with the loss of daytime heating. Much of the same will continue into the day on Friday. The troughing aloft looks a bit weaker and have slightly lower PoPs. Surface dewpoints will be back to typical summer time values on Thursday and Friday into the mid and upper 60s. A strong to marginally severe storm will be possible during this timeframe. Better chances for an isolated severe storm or two appears to be on Thursday. SBCAPE values will be near 1000-2000 J/Kg with 0-6 km bulk shear of 15-25 kts. The main threat with these storms would be isolated damaging wind gusts. The pattern begins to amplify going into the weekend. A trough will race out of the Great Lakes to the southeast into the Mid-Atlantic. To the west, a ridge will amplify across the Mississippi River Valley and Great Plains. The aforementioned trough will bring a cold front into the forecast area with showers and storms developing along this boundary on Saturday. Models indicate the surface boundary will stall just to the south or over southern portions of the area with a few showers continuing across this area. This is still several days away and the models will continue to vary on how far south the front makes it. Precipitation chances increase some on Tuesday as showers around the periphery of the Tropical System could impact the area. MA && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 66 89 69 85 68 / 0 20 30 60 40 Knoxville McGhee Tyson Airport, TN 67 89 69 85 67 / 0 20 30 50 40 Oak Ridge, TN 65 89 68 84 67 / 0 20 30 50 40 Tri Cities Airport, TN 61 86 65 83 64 / 0 10 30 50 40 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$
Area Forecast Discussion
National Weather Service Pueblo CO
251 PM MDT Tue Jun 2 2020 .SHORT TERM...(This evening through Wednesday) Issued at 250 PM MDT Tue Jun 2 2020 Currently...radar indicates scattered showers and thunderstorms across the region. Storms are moving very slowly to the south. A surface boundary is stretching from near Trinidad, northeast to Haswell, with winds north of the to the north, while surface winds are southerly ahead of the boundary. Temperatures have warmed into the 80s and 90s across the Plains, while the San Luis Valley is in the 70s and 80s. Rest of today and tonight...high pressure is currently sitting over the Desert Southwest, with northerly flow aloft across much of Colorado. 500 mb vorticity fields indicate an upper disturbance dropping south across the Plains. This will continue to spark showers and thunderstorms over the area. The HRRR and ARW are consistently developing activity, mainly along I-25 and south of Highway 50 through this evening. Modest instability will allow for gusty winds to near 45 mph, and possibly dime size hail with stronger storms. Given the slow storm movements, locally heavy rainfall will be possible. If one of these storms happens to move over a burn scar, flash flooding will be possible. Models in good agreement moving this activity south and dissipating around midnight. After midnight, clearing skies are expected. Overnight lows will fall into the 50s and 60s by Wednesday morning. Wednesday...the upper level high pressure looks to remain stationary over the Desert Southwest, with broad northwesterly flow aloft. Models have an upper disturbance across Wyoming, moving into northeastern Colorado by the afternoon, and into western Kansas by evening. Southeasterly flow at the surface will keep moisture pooled across the Plains. This will help boost instability with CAPE values around 1500 j/kg. Expect scattered showers and thunderstorms to develop, initially over the Mountains, and spread east into the I-25 corridor by afternoon. Coverage is not anticipated to be as widespread as previous days. If any spot was going to see the potential for a couple of strong to severe storms, it would be out of Kiowa and Prowers Counties during the afternoon, where instability is forecast to be highest, and nearer the upper level energy. Otherwise, main threats from thunderstorms will be lightning, gusty outflow winds and small hail. Again, if a storm should move over a burn scar, flash flooding will remain possible. Afternoon highs will once again be warm with lower 90s across the Plains. Mozley .LONG TERM...(Wednesday night through Tuesday) Issued at 250 PM MDT Tue Jun 2 2020 .Wednesday night...Shortwave will continue moving eastward during the evening. Threat for severe weather is greater over northeast Colorado with severe weather threat extending into southeast Colorado. Bufkit and models show around 1500 J/kg or higher of CAPE in the evening with bulk shears around 30 to 40 knots. SPC Day 2 outlook has the area defined well. LCL look to be fairly high so the main threat from the storms will be some large hail and strong winds. By later in the evening, the activity will move into Kansas. Elsewhere, storms should end my mid evening. .Thursday...Shortwave ridge remains over the region with stronger mid level winds mostly staying to the north of the region. Mid level moisture decreases slight, but there is still enough moisture for some diurnal convection over the mountains. Mid level winds remain at around 20 to 25 knots at 500mb which will allow storms to be progressive. Low level moisture is greater near the Kansas border, east of a dry line. SPC has marginal risk extending southward along the Kansas/Colorado border. Increased PoPs over the plains Thursday evening to have thunder mentioned in the forecast for possibility of a strong to severe storm. Otherwise, continued hot on the plains with some highs around 100F. .Friday and Saturday...Upper low off the California coast starts to move northeast as an open wave. Looks as if most of Friday, during the day, will be warm and dry with best lift staying southwest of the forecast area. By later in the afternoon, the system may start affecting the Eastern San Juans and move northeast during the night. The models and ensembles are continuing to indicate the best lift and most of the convection will be over the mountains with best chances over and near the Continental Divide region. NBM has mostly silent PoPs over the Interstate 25 corridor and eastern plains through midday Saturday. By later in the afternoon Saturday, some modest convection may develop over the plains and Interstate 25 corridor. Increased wind speeds on Saturday as NBM under does gusty winds on the plains. There is the potential for critical fire weather conditions in the San Luis Valley on Friday. Threat for critical fire weather conditons spreads eastward on Saturday with increasing winds on the plains. .Sunday through Tuesday...Dry and warm southwest flow aloft continues over the region with fire weather concerns each day. On Tuesday, a weak cold front on the plains may be cooler weather and a modest chance for some diurnal convection on the plains. --PGW-- && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 250 PM MDT Tue Jun 2 2020 VFR conditions at all three terminals through the next 24 hours outside of thunderstorms. Thunderstorms will remain possible at all three terminals through 06z/wed this evening. Reduced CIGS and VIS along with gusty outflow winds to near 45 mph will be possible should a storm hit a terminal. Mid and high level clouds will spread across the region overnight. Another round of afternoon showers and thunderstorms is anticipated on Wednesday afternoon. Mozley && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...MOZLEY LONG TERM...PGW AVIATION...MOZLEY