Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/17/20

Area Forecast Discussion
National Weather Service La Crosse WI
1043 PM CDT Sat May 16 2020 .SHORT TERM...(This evening through Sunday) Issued at 300 PM CDT Sat May 16 2020 At 3 PM, easterly winds continue to advect dry air into the region. Surface dew points are mainly in the 40s. This dry air has been limiting the amount of low clouds. As a result, we have been seeing some filtered sunshine through much of the day. This has allowed temperatures to warm into the mid- and upper 60s north of Interstate 94 and into the lower 70s elsewhere. As a strengthening shortwave moves out of the Northern Plains tonight, the 925 and 850 mb moisture transport will gradually increase. With this system slowing as it deepens, the timing of the showers and isolated/scattered storms gets later and later in the RAP and HRRR. At this time, it looks like the precipitation will move into southeast Minnesota and northeast Iowa mainly after 9 PM and for Wisconsin it looks dry until after midnight. While the instability remains mainly less than 200 J/kg, the models continue to show strong isentropic and synoptic lift and precipitable water water values of 1-1.5 inches. This will promote the development of isolated to scattered storms and the potential of heavy rain at times. The heaviest rain continues to shift further north and west with each progressive model run. At this time, 1 to 2 inches is expected from north-central Iowa into east- central Minnesota and near and north Interstate 94 in Wisconsin. The HREF continues to suggest the highest rainfall amounts will be in the 2 to 3 inch range. There are a few outlying models which even suggest 4 to 5 inches. This seems a bit too high considering the limited instability. On Sunday, the closed low pressure area will move slowly east through the region. This will keep the rain over the area. However, with the strongest 925 to 850 mb moisture transport moving east of the area, the rainfall will be on the lighter side (0.25 to 0.75 inches). .LONG TERM...(Sunday night through Saturday) Issued at 300 PM CDT Sat May 16 2020 It continues to look like the low pressure system will be much slower moving out of the region. As a result, carried some small rain chances into Monday morning. In addition with the clouds holding over the area into Tuesday, lowered the temperatures by at least 5 degrees and that may not be enough yet. In the wake of this system, a rex block develops over the eastern US. This will keep a ridge over the area. The warmest air will stay west of the area. Even though this will be the case, we will still see high temperatures from the mid 70s to mid 80s. The warmest temperatures will be late in the week. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1043 PM CDT Sat May 16 2020 VFR conditions are prevalent along and north of I-90 at the moment but that will change overnight and into Sunday as slow-moving low pressure wraps bands of rain into the region. Overall conditions will likely dip to prevailing IFR at RST and mainly MVFR at LSE (with some IFR possible at times), as light to moderate rain comes in waves, with even a brief period of heavy rain expected at RST either side of sunrise. A rumble of thunder is also possible but should be the exception for either site, while easterly winds crank up to 15 to 25 knots with some higher gusts possible late tonight into much of Sunday. If this storm system strengthens a little more than currently forecast, a window of winds gusting up to 35+ knots could occur on Sunday, though at this time, confidence in that occurring remains a bit on the low side. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Boyne LONG TERM...Boyne AVIATION...Lawrence
Area Forecast Discussion
National Weather Service Charleston SC
1053 PM EDT Sat May 16 2020 .SYNOPSIS... Tropical Storm Arthur will remain offshore of the Southeast U.S. coast through Sunday and move near the North Carolina Outer Banks Monday. A cold front will bring unsettled weather to the area Monday and Tuesday before weak high pressure likely returns later in the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Tropical Depression One has been upgraded to Tropical Storm Arthur. The only major change for the late evening update was to introduce locally dense fog across the interior where the latest NARRE-TL probabilities show a 50-70% chance for dense fog in the Ludowici-Glennville to Allendale-Harleyville corridor. The rest of the forecast looks on track. The main forecast concern centers on fog and stratus development. Guidance continues to trend a bit higher with the fog coverage overnight along/west of I-95 where both the RAP and NAM show very low 1000 hPA condensation pressure deficits developing after midnight. Coastal winds look a bit too high to support too much fog, so stratus should prevail there, while farther inland a combination of fog/stratus will dominate. Do not anticipate widespread dense fog issues at this time, but locally dense fog will be possible. "Areas of fog" will be introduced with this update mainly in the Ludowici-Glennville to Allendale-Harleyville corridor. Lows will range from the lower 60s inland to the upper 60s/near 70 at the beaches, Downtown Charleston around the Santee-Cooper lakes. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... Moderate confidence this period. Tropical Depression One well off the northeast Florida coast is expected to move generally northward about 150 to 200 miles off the northern GA/central- southern SC coasts as a deep upper trough approaches from the west, likely as a tropical storm. At this point we are thinking most of the showers will stay offshore but can`t rule out a few into Sunday night as the low moves by, mainly near the central SC coast. Conditions also look favorable for stratus/fog Sunday night. By Monday the aforementioned upper trough will be pushing a cold front toward the area and with some deeper moisture and lift we should see a bit better risk for some showers and thunderstorms into Monday night, possibly even a few isolated severe storms with damaging winds. By Tuesday the deeper moisture will likely have shifted northeast of the area but strong forcing from the upper low and some instability along with the sea breeze should be enough for some more showers and thunderstorms. Temperatures should stay just above normal through the period. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... A large closed upper low will meander near the mid-Mississippi Valley mid to late week. Weak surface high pressure is expected to reside over the local area with dry, slightly cooler conditions. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... The risk for IFR-LIFR cigs is the main concern at both KCHS and KSAV overnight. Low clouds are expected to fill in after midnight as winds tip northeast ahead of Tropical Depression One. There looks to be too much wind to support fog, so this stratus development is preferred. KCHS: Expect MVFR cigs to reach KCHS by 07z then drop below alternate minimums by 09z. Cigs look to remain just above airfield minimums at this time. Conditions should rise above airfield minimums by 13-14z with MVFR cigs breaking to VFR during by mid-afternoon. KSAV: The fog risk could be a bit higher here as low clouds could be delayed here by 1-2 hours as winds trend a bit lighter. MVFR cigs are expected by 08-09z with cigs dropping at/just below airfield minimums by 10z with MVFR vsbys. Confidence in prevailing cigs dropping solidly below airfield minimums it not as high at KCHS, so this will be handled with a TEMPO group 10-12z. MVFR cigs will return just after daybreak with MVFR by late morning/early afternoon. Extended Aviation Outlook: High confidence in some restrictions Sunday night due to low clouds/fog, possibly IFR or lower. Additional periodic restrictions later Monday into Tuesday from showers and thunderstorms due to a cold front. Lower confidence for additional restrictions Wednesday and Thursday from more showers/storms depending on how long the cold front and an area of low pressure linger. Breezy conditions likely each afternoon through Tuesday. && .MARINE... Tonight: Tropical Depression One currently east of Florida will slowly lift northward through tonight. Marine users should refer to the latest NHC advisory regarding details of this system. Northeast winds will be 10 to 15 knots much of the night, before increasing to a solid 15 kt towards daybreak. Wind speeds in waters beyond 20 nm will be a bit higher, peaking in the 15-20 kt range. Elevated seas will maintain a Small Craft Advisory in the outer Georgia waters, with the advisory expanding to include the Charleston county waters at 2 AM. Sunday through Thursday: Moderate confidence this period. Low pressure, likely a tropical or sub-tropical cyclone, is expected to shift northward east of the local waters with the main impact being increasing swells which will lead to slightly higher seas Sunday before the low passes by to the northeast into Sunday night. Small Craft Advisory conditions are expected for mainly the Charleston County nearshore waters and offshore Georgia waters, but could be needed for at least the rest of the SC waters Sunday into early Sunday night. Additional marginal Small Craft Advisories may be needed Monday into Tuesday ahead of a cold front for a portion of the area. Rip Currents: Swells from offshore low pressure will continue to impact the waters into early next week leading to an enhanced risk through at least Sunday, possibly even into Monday along parts of the SC coast. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 2 AM EDT Monday for AMZ374. Small Craft Advisory from 2 AM Sunday to midnight EDT Sunday night for AMZ350. && $$
Area Forecast Discussion
National Weather Service Grand Rapids MI
812 PM EDT Sat May 16 2020 LATEST UPDATE... Update .SYNOPSIS... Issued at 322 PM EDT Sat May 16 2020 - Heavy rain and flooding threat Sunday and Sunday night - Trend toward more unsettled weather Monday and Tuesday - Uncertainty from mid to late week && .UPDATE... Issued at 811 PM EDT Sat May 16 2020 I have updated our zone forecast to increase the wind Sunday into Sunday night. I have noted that the NAM is forecasting 20 knot winds at 10000 mb at 8 pm Sunday. I can honestly say that when the 1000 mb wind at GRR on the NAM as observed at 20 knots we have just about always needed to have a wind advisory (I have at least 20 years of data to back that up). Looking at the ECMWF, the HRRR, HREF all of them are showing median wind gusts Sunday evening in the 40 to 50 mph range north of I-96. My update now has wind gusts to 40 mph and for now that should be fine. We may need a wind advisory for this system on top of all the other headlines we now have out. && .DISCUSSION...(This evening through next Saturday) Issued at 322 PM EDT Sat May 16 2020 -- Heavy rain and flooding threat Sunday and Sunday night -- As mentioned in the previous update, an Areal Flood Watch has been issued for the entire area for Sunday through Monday morning. The trend over the last 24 hours with this system has been for heavier rain totals spread across the entire area (vs. just the south), and for convection to be a little further south, keeping any small severe chances limited to the very southern portion of the area, and likely just south of the area. It is looking like we will see the brunt of the two main forcing mechanisms with this rain event over the region. We will see the rain move overhead early Sunday morning and into Sunday with the initial push of warm and rich moisture ahead of this developing system with the 40 knot low level jet nosing in. (I have been forecasting for 40+ year so that is a long time) The sfc low then translates what looks to be just south of the area by Sunday evening. Immediately ahead of this low is when we look to have the best chance of thunder over the southern portion of the area. This low track is a tad further south than expected yesterday. Right now, it seems that with the low staying just south of the area, sfc based instability would also stay just south of the area, and thus the best chance of severe weather Sunday afternoon and evening. The thing to watch with this, is if the low and front comes a little further north than expected. Then a better severe threat would sneak into the southern counties. The convective nature of the rain will allow for some decent local bands of rainfall. -- Trend toward more unsettled weather Monday and Tuesday -- The sfc low and low level moisture feed were expected to clear the area to the east early Monday morning. The latest trend now is for the upper low to close off a little sooner, and keep the surface low and moisture feed nearby into Monday. In addition, we will see the band of rain associated with the deformation of the upper low hold in, and affect the northern part of the area as the upper low becomes nearly stationary. This is why the heavier amounts are now also expected across the north. Right now, this is forecast to move out by Tuesday morning. The heavier rains would diminish to more scattered showers for Tuesday with the upper low nearby. The movement of upper lows are difficult to forecast, and the trend has been for this one to linger longer over the past couple of days, so this is still subject to change. -- Uncertainty from mid to late week -- It looks like a highly amplified pattern upstream over the western and central portions of North America should help to push this low out of the area, at least temporarily by Wednesday. Another strong upper low coming on to the Pacific Coast will push the ridge over the area, and the upper low south. This is not certain, and the upper low could easily rotate back to the north later in the week. This would bring back shower chances, and keep the area a bit cooler, instead of being warmer under the possible upper ridge. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 745 PM EDT Sat May 16 2020 Expect IFR conditions with very strong winds by Sunday afternoon at our TAF sites. Currently at 2330z VFR conditions prevail at all of our TAF sites. There is an area of VFR cig clouds over central lower Michigan that look like they will drift to the west and mix out by 03z. I did not to much with them in the TAF since I expected VFR to prevail. The main issue is the storm moving into our TAF sites Sunday, during the daylight hours. The system has slowed down in the models as to how fast it moves through the area. It looks to bring a prolonged period of rain, heavy at times, and strong east winds by mid afternoon Sunday. Expect showers to move in by mid morning from the south and southwest spreading across the area by late morning. Isolated thunderstorms are more than possible south of I-96 in the afternoon and evening. I put VCTS for that in the southern and eastern TAF sites. Another aspect to this storm is very strong east winds. The ECMWF and our high resolution models like the HREF as well as the HRRR and NAMNEST show winds sustaining 20 to 25 knots with gusts in the 40 knot range west of Lansing and near and north of I-96. Wind is likely to be a real issue with this storm Sunday afternoon. && .MARINE... Issued at 322 PM EDT Sat May 16 2020 We have a couple of marine related hazards expected for Sunday and Sunday night. The first will be winds picking up with the incoming system. The other concern will be additional lakeshore flooding and beach erosion also for Sunday and Sunday night. We will be issuing headlines for each of these with this afternoon`s package. Winds will increase late tonight, and more so on Sunday. We are looking at a solid Small Craft Advisory event for our nearshore waters. The gale conditions and higher waves will be over mid-lake due to the offshore component of the wind. The other hazard expected is the lakeshore flooding and beach erosion. Even with the expected offshore winds, lakeshore flooding and erosion looks likely. This is the result of strong easterly winds over the region pushing water from Lake Huron, to Lake Michigan through the Straits of Mackinac. This will result in a increase of water levels over the already record high levels. This will affect the rivers near Lake Michigan, with levels rising to over docks, nearby roads, and approaching buildings near the rivers and inland lakes, immediately adjacent to Lake Michigan. The worst conditions are expected over the southern lakeshore, where the water will pile up the most. && .HYDROLOGY... Issued at 1224 PM EDT Sat May 16 2020 (I have been forecasting for 40+ year so that is a long time) We are looking at an increased risk for potential areal flooding, and flooding on area rivers as a result of the rainfall that is expected from late tonight through Monday morning. While the details have to be worked out yet with exact placement of heaviest rain, it appears that 1 to 2 inches of rain should fall at most locations through this period. This is going to start to cause issues over the south where the ground is already quite saturated from the Wed night/Thu rains. Also, the Grand and Kalamazoo River basins will be most affected. Right now, contingency forecasts with up to 2 inches of rain have many sites on the Kalamazoo and Grand River basins approaching flood stage, with a couple of sites exceeding flood stage (Comstock Park and Robinson Twp). If we start to see amounts approaching 3+ inches of rainfall, much more significant impacts will be felt with many sites going above flood stage, and even some sites on the downstream portions of the Muskegon River. Some locations on the Grand would be looking at Moderate flooding with 3 inches of rain. We will continue to monitor the latest trends. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Lakeshore Flood Warning from 5 PM Sunday to 8 PM EDT Monday for MIZ056-064-071. Flood Watch from 8 AM EDT Sunday through Monday morning for MIZ037>040-043>046-050>052-056>059-064>067-071>074. Lakeshore Flood Advisory from 5 PM Sunday to 8 PM EDT Monday for MIZ037-043-050. LM...Small Craft Advisory from 6 AM Sunday to 2 AM EDT Monday for LMZ844>849. && $$ UPDATE...WDM SYNOPSIS...NJJ DISCUSSION...NJJ AVIATION...WDM HYDROLOGY...NJJ MARINE...NJJ
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
956 PM CDT Sat May 16 2020 .UPDATE... Issued at 956 PM CDT Sat May 16 2020 Have issued a flash flood watch through mid morning on Sunday for the potential for additional heavy rainfall tonight. Showers and a few thunderstorms continue to move northeast across the area late this evening. Latest surface analysis is showing a surface front stalled across the region with the water vapor analysis showing a upper trough over the Central Plains. Latest runs of the RAP/NAM are showing increasing low level moisture convergence increasing and becoming aligned beneath this weak ascent in the watch area late tonight. RAP soundings are very favorable for heavy rainfall given PWATS near 1.7" and deep warm cloud layers. Expect additional showers and scattered thunderstorms to move across eastern Missouri and southwest Illinois overnight into Sunday morning with some areas receive 1-2" of rainfall with locally heavier amounts. These amounts falling on already saturated ground will likely result in flash flooding. Britt && .SHORT TERM... (Through Late Sunday Afternoon) Issued at 314 PM CDT Sat May 16 2020 Unsettled weather will continue through the weekend as an upper level trough passes through the central CONUS. Two features of note were analyzed within the broad upper trough this afternoon; a weak negatively tilted shortwave extending from the central Plains into Louisiana and a closed low moving ESE through the northern Plains. A surface low was analyzed in the vicinity of the Arklatex, with a warm front extending north and east into southern SE MO and southern IL. Several areas of showers and storms have developed in the mid- Mississippi Valley along the elevated portion of the front. The most vigorous convection is along and east of the Mississippi River, where limited clouds have allowed for MUCAPE to build to around 2,000 J/kg. Effective bulk shear in this area is rather limited, so individual updrafts have been fairly short-lived. Nonetheless, at least one storm has pushed up to near severe levels and I couldn`t rule out another storm or two following suit. These storms have also been very efficient rainfall producers. With PWs in the upper quartile of seasonal climatology and a tendency for new updrafts to develop in the immediate wake of dying convection, we`ve had reports of 1-1.5" per hour beneath the heaviest cores, resulting in flash flooding in a few areas. Fortunately there does not appear to be any sort of anchoring feature to focus these storms over a particular area, so I think additional flash flooding will be rather isolated. As we move into the evening hours, storm coverage will wane with the instability. Meanwhile, the previously mentioned negatively- tilted wave will continue to the ENE, drawing the surface low and associated warm front north into the Mid-Mississippi Valley around midnight. The surface low will then deepen and push to our NE tomorrow morning as it interacts with the northern upper low, before eventually dragging a cold front through the area tomorrow afternoon. As larger scale forcing intensifies in the early morning hours, CAMs are in good agreement increasing precip coverage after roughly midnight. Scattered to widespread storms are then expected to continue until the cold front sweeps through the area during the day tomorrow. Instability is expected to build to around 1,000 J/kg ahead of the ahead of the front tomorrow, supporting yet another round of thunderstorms. Much like today, effective bulk shear looks fairly limited, with SREF guidance showing a less than 50 percent chance of us topping even 30 kts. Nonetheless this CAPE/shear parameter space coupled with the frontal forcing would support a limited severe threat in southern Illinois tomorrow afternoon. BSH .LONG TERM... (Monday through Next Saturday) Issued at 427 PM CDT Sat May 16 2020 Large scale omega block still on track to take hold at the beginning of the week while a closed low sits and spins over the eastern third of the CONUS. Surface ridging will develop beneath the block, kicking off an extended period of quiet weather in the mid-Mississippi Valley. Our proximity to the eastern CONUS low will keep things on the cloudy and cool side for the early portion of the week. The deep moisture associated with that low will wane as we move through the week, resulting in less overcast to broken stratus and more broken to scattered cu. This will allow temperatures to gradually build through the week. Some guidance is showing a chance for diurnal showers toward the end of the week, through the signal for this is quite weak, so have omitted it from the forecast at this point. BSH && .AVIATION... (For the 00z TAFs through 00z Sunday Evening) Issued at 611 PM CDT Sat May 16 2020 Showers and storms across the region will continue to decrease in intensity and coverage this evening before picking back up around 06z as low pressure moves through the region. I think we`ll only see isolated to perhaps scattered thunder in the overnight hours, so have left thunder out of the TAFs until storms become more likely after sunrise. Scattered to widespread showers and storms will then persist until a cold front moves through the region in the afternoon, ushering the precip out of the area. Given questions around exact timing and coverage of tomorrow`s storms, have just gone with VCTS and will update as details become more clear. Guidance in good agreement showing cigs quickly falling in the early morning hours as ample low level moisture moves into the region with the previously mentioned low. I`m not very confident on exactly how low cigs will drop, but at this point much of the guidance has all terminals dropping below 1,000 ft, so ended up going IFR at all terminals. BSH && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Flash Flood Watch through Sunday morning for Crawford MO- Franklin MO-Iron MO-Jefferson MO-Lincoln MO-Madison MO- Reynolds MO-Saint Charles MO-Saint Francois MO-Saint Louis City MO-Saint Louis MO-Sainte Genevieve MO-Warren MO- Washington MO. IL...Flash Flood Watch through Sunday morning for Bond IL-Calhoun IL- Clinton IL-Fayette IL-Greene IL-Jersey IL-Macoupin IL- Madison IL-Marion IL-Monroe IL-Montgomery IL-Randolph IL- Saint Clair IL-Washington IL. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
714 PM CDT Sat May 16 2020 .SHORT TERM...(This evening through Sunday night) Issued at 228 PM CDT Sat May 16 2020 The overall forecast scenario hasn`t changed much, but a persistent dry easterly flow is working to delay the arrival of precipitation across much of the area. So, slowed progression of PoPs a bit in line with HRRR and other CAMs. That being said, we should still see precipitation overspread the area from late afternoon through the evening hours. Visible imagery shows the effect of dry air, with plenty of sunshine filtering through high clouds from southeast Minnesota into west central Wisconsin this afternoon. However, the upper shortwave trough is evident on water vapor imagery across the northern high Plains, and we`ll see the precipitation spread eastward as this feature moves south and east through tonight. A baroclinic wave can be seen in the long wave infrared imagery, from eastern Nebraska through northern Minnesota and surface low development is taking place near its inflection point near the Nebraska/Iowa border. This low will deepen some as it lifts northeast tonight, with precipitation maximizing across our area near the inverted trough that will extend northward from it. It still looks like we`ll have some elevated instability in place across the southern/eastern portion of the area, so maintained a thunder chance. Precipitation amounts will be heaviest where convection enhances things, but widespread amounts in excess of an inch still appear likely. The activity will slowly move out from west to east late Sunday afternoon and Sunday evening. .LONG TERM...(Monday through Saturday) Issued at 228 PM CDT Sat May 16 2020 The large scale pattern looks to amplify in the wake of this weekend`s system, with ridging developing across the central and eastern US as a deep upper trough sets up over the west. Our current system looks to cutoff beneath the upper ridge and loiter across the Ohio and Tennessee valleys for much of the week. With the upper ridging, we`ll see a prolonged period of dry weather from Monday through Thursday, with temperatures warming through the 70s to around 80 by Wednesday and Thursday. After that we`ll start to see chances for showers and thunderstorms work into the region from the west as impulses are ejected from the western trough. At this point, have low PoPs for much of the period from Thursday night through Saturday, but given the amplified pattern would expect a somewhat slower progression of PoPs eastward, so as we get a bit closer in time wouldn`t be surprised to see dry weather persist a bit longer, and PoPs be more focused from late Friday into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 714 PM CDT Sat May 16 2020 Conditions were still VFR in many locations early this evening, with MVFR ceilings or visibilities in just a few spots over central into southwest MN. But this will be changing to widespread MVFR as rain persists and intensifies later this evening and overnight over much of southern MN and spreads more into west central WI. Main question revolves around whether IFR will develop, and it probably will Sunday morning from south central MN into west central WI where the heavier rain persists the longest. IFR is possible to develop elsewhere, and this is something that will be watched closely. Finally, northeast winds will strengthen somewhat tonight as surface low moving across Iowa intensifies a bit. Gusts over 30 knots may occur over south central MN into WI. KMSP... Main issue will be northeast winds. Ridge to our north will weaken and surface low near Omaha at 00Z will move east, allowing winds to shift from the current nne to more ne. Winds will also intensify somewhat as low moves east due to a tighter gradient later tonight and Sunday morning. Therefore gusts will likely be 25-30 knots Sunday morning, with sustained of 15-20 knots. MVFR conditions will arrive with the heavier rain late tonight and Sunday morning. There is some chance for IFR ceilings and visibilities in the heaviest rain, and if that happens, it would most likely occur in the 12Z-18Z time frame. But not confident enough to include that right now. /OUTLOOK FOR KMSP/ MON...VFR. Wind NE 10-25 kts. TUE...VFR. Wind SE 5-10 kts. WED...VFR. Wind S 5-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ SHORT TERM... LONG TERM... AVIATION...TDK
Area Forecast Discussion
National Weather Service Marquette MI
715 PM EDT Sat May 16 2020 .SHORT TERM...(This evening through Sunday) Issued at 418 PM EDT SAT MAY 16 2020 WV imagery and RAP analysis indicated a mainly zonal pattern through the northern CONUS with a vigorous upstream shortwave trough over Southwest South Dakota. At the surface, high pressure extended from James Bay and northern Ontario into the northern Great Lakes resulting in easterly winds over Upper Michigan along with local lake breeze components. Mid level fgen and isentropic lift associated with upper level div from the right entrance of a 300 jet stream through northern Ontario supported a band of light rain and sprinkles over eastern MN. However, with the dry air in place over Upper Michigan, mainly just virga into northwest WI. Tonight, since the strongest 700-300 qvector conv, isentropic lift and moisture advection ahead of the shrtwv remain well to the southwest through se MN into wrn WI, expect little if any pcpn into Upper Michigan. Increasing and thickening clouds will keep min temps in the lower 40s. Sunday, the models have trended significantly drier over most of Upper Michigan as the fgen/def supported heavier rain and strongest isentropic lift and moisture inflow will remain over WI. So, dry weather is expected across the north half. However, rainfall amounts along south of US-2 could still reach 0.25 inch with amounts over 0.50 inch near MNM. With less rain over the area, highs should be able to reach the mid 50s with readings even to around 60 east. Readings near lake Superior where brisk northeast winds prevail will keep temps in the 40s. .LONG TERM...(Sunday night through Saturday) Issued at 342 PM EDT SAT MAY 16 2020 Overall confidence in the forecast as we head through much of next week is not high as we see a number of blocking features (cutoff low, weak omega block, rex name it, it seems to make an appearance) progged to set up across the CONUS. This has cause some fairly big changes in expectations for Monday, but also has introduced some added uncertainty in how temperatures will play out later this week. While slightly above-normal temperatures still look to develop this week, whether we see any locations reach that 80 degree mark looks less clear. Sunday night/Monday, shortwave energy tracking east across southern Lake Michigan will gradually slow and keep Upper Michigan on the northern edge of theta-e advection and deeper moisture transport wrapping around the system. There is still some uncertainty in how far north precipitation will be, but overall the best chance for rain during this time period will be across the south-central. Still doesn`t look like any instability will make it this far north, so no mentions of thunder. The combination of the main surface low tracking south and the Hudson Bay High starting to nudge in from the north will create an enhanced pressure gradient, mostly across northern parts of Lake Michigan allowing gusty east-northeast winds to develop and persist. Models seem to be in good agreement with these stronger winds impacting the Bay of Green Bay, but waves heights right now look to fall right along the 5-6 foot threshold. Thus have opted to continue to messaging the minor lakeshore flooding concerns in the HWO. If winds/waves look to come in higher, an advisory may be needed for Menominee County. Monday afternoon, the above mentioned area of high pressure will gradually introduce increasing subsidence and much drier air, favoring a dry day across much of western and north-central Upper Michigan and a drying trend across the south-central. Will need to keep an eye on RHs and winds across the west half Monday afternoon for some potential fire weather concerns, especially if no precipitation develops over the next 24-hours makes it that far north and west. Tuesday through Thursday, upper-level ridging builds across the central CONUS and up in the Upper Mississippi Valley, with the shortwave discussed above becoming cutoff and parking over Kentucky/Tennessee. This will favor easterly flow dominating the low to mid levels, gradually becoming southerly by mid-late week. This pattern will still favor warm air advection moving into the region, but not as warm as yesterday`s southwest flow showed. The forecast could end up seeing more clouds added in as well, with a few pushes of moisture under the east to south flow. Not expecting any precipitation through as the western extend of high pressure continues to impact the Upper Peninsula. RHs could end up being lower than currently forecast later on in the week, but given the pattern and the above mentions of low-level moisture looking to return opted to leave the blend as is for now until confidence in the pattern grows. Friday into next weekend, a kicker wave looks to dig south across the Pacific Northwest disrupting the cutoff low parked over the western CONUS. This will help break down upper-level ridging, across the central CONUS, but it does look like the upper-level pattern will remain stacked up across the central and eastern CONUS, with hints of a rex block developing. Based on the current model depiction of where this next blocking pattern sets up, this looks to leave us mostly dry. NBM did paint some slight/chance PoPs Friday/Saturday, but right now confidence is very low in regards to that panning out. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 714 PM EDT SAT MAY 16 2020 Dry air will likely persist in the low-levels thru Sun. Thus, VFR conditions are expected at KIWD/KCMX/KSAW thru this fcst period. A low pres system will be tracking e, well s of Upper MI. Although bulk of associated rain will remain well s, some -shra may pass near KIWD. Otherwise, main affect will be thickening mid-level clouds at all terminals. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 418 PM EDT SAT MAY 16 2020 Low pressure passing by well to the south of Lake Superior is expected to boost northeast winds to around 20 kts Sunday with stronger winds (25 kts) again possible in the western arm. Otherwise, winds of 15 kts or less are expected through at least the middle of next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...Ritzman AVIATION...Rolfson MARINE...JLB
Area Forecast Discussion
National Weather Service San Francisco Bay Area
857 PM PDT Sat May 16 2020 .SYNOPSIS...Rain showers will spread from north to south across much of our forecast area from Saturday evening through Sunday morning. Shower activity will likely decrease Sunday afternoon, before another round of widespread shower activity develops Sunday night and continues into Monday. There is also a slight chance of thunderstorms on Monday. Drier conditions will develop Tuesday, although a few showers may linger. High pressure builds Wednesday into the Memorial Day weekend, with dry and seasonable temperatures expected. && .DISCUSSION...As of 8:55 PM PDT Saturday...Dry weather prevailed across our area for most of today as precipitation with the incoming system did not arrive on the North Bay Coast until early evening. Increasing clouds in the North Bay today resulted in slightly cooler temperatures there. Plenty of sun elsewhere allowed for warming most everywhere else, with the most robust warming occurring over interior Monterey and San Benito Counties, where a few locations, such as Pinnacles National Park, warmed into the upper 80s this afternoon. Current satellite and radar data shows a cold frontal boundary spreading showers across northern California. The boundary has thus far been pressing very slowly to the south. Rain showers began in northwest Sonoma County at about 5 pm and by 8 pm showers had finally reach northern Marin County. Rainfall so far has been light, with amounts less than a tenth of an inch in Sonoma County. The greatest rain total thus far is 0.16" in Venado. Short-term model data from the 00Z NAM and 00Z HRRR indicate showers will continue to spread across the North Bay through about midnight and then develop from San Francisco southward late tonight and Sunday morning. While the 00Z NAM forecasts the frontal boundary and associated precipitation to become steadily more fragmented with time as the boundary moves south, the 00Z HRRR forecasts a couple of bursts of heavier and more widespread shower activity developing across the central and southern SF Bay Area on Sunday morning and over the Santa Cruz, southern Diablo, and Santa Lucia Mountain Ranges on Sunday afternoon. Precipitation associated with the frontal boundary tonight and Sunday will be most significant in the coastal hills due to orographic enhancement, while lower elevation locations, including most urban areas, will probably see only light amounts, or none at all in rain-shadowed interior valleys like the Santa Clara Valley. Both the NAM and GFS forecast decreasing shower activity Sunday afternoon as the front stalls and dissipates over the southern portion of our area. Shower activity will then increase Sunday evening through Sunday night as the cold core of the upper low approaches the northern California Coast. Scattered showers will continue through Monday when isolated thunderstorms are possible as 500 mb temperatures drop to an unseasonably cool -25 deg C. Inland temperatures from Sunday through Tuesday are forecast to be as much as ten degrees cooler than seasonal averages. Coastal temps will remain near normal or be only slightly cooler than normal. Shower activity is expected to decrease Monday night and mostly end by Tuesday as the upper trough axis shifts to our east. However, isolated showers may linger into Tuesday. Dry weather should return to nearly all areas by Wednesday, but inland temperatures will remain cooler than normal. Forecast rain totals through early next week are expected to be a tenth to a half inch in most urban and lower elevation locations, except up to an inch in the North Bay Valleys, and less than a tenth of an inch in southern rain-shadowed valleys. In the hills, forecast rain totals generally range from 0.5 to 1.5 inches, with locally up to 2 inches possible along southwest-facing coastal slopes. Modest warming is forecast for Thursday as a weak shortwave ridge builds temporarily over California. A trough over the Pac NW is forecast to drop into northeast CA on Friday, which will temporarily halt any warming trend. Precipitation with that trough is forecast to stay to our northeast. Although details vary between the longer range models, the general idea for the Memorial Day Weekend is for dry weather along with a gradual warming trend. && of 4:50 PM PDT Saturday...Frontal system over the northern California coast is spreading mid level clouds into the North Bay this afternoon. Models show rain showers into the North Bay after 03Z spreading into the SFO Bay Area during the night with cigs gradually lowering into MVFR range. Front will weaken and slow down as it moves through the SFO Bay Area so rain will be mostly light and intermittent through Sunday morning. Approaching upper level trough will push the front into the MRY Bay Area Sunday afternoon with improving conditions in the SFO Bay Area. West to southwest winds 15 kt gusting to 20 kt decreasing and switching to southerly after midnight. Vicinity of KSFO...VFR with gradually lowering cigs tonight. Bases lowering to 5000 ft after 03Z and 2500 ft after 06Z. Occasional light rain begins after 09Z and continues through Sunday morning. Onshore winds this afternoon around 15 kt will switch to southerly after 06Z. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...A few low clouds are lingering along the immediate coast. This is expected to expand over the MRY Bay Area tonight. Scattered clouds at MRY and SNS after 03Z becoming MVFR cigs after 06Z. Rain showers will remain north of the area through Sunday morning before finally moving in Sunday afternoon. Onshore winds decreasing and switching to southerly after 06Z. && .MARINE...As of 8:45 PM PDT Saturday...A frontal system will bring light southerly winds to the area tonight and Sunday. Winds will increase over the southern waters and Monterey Bay Sunday as the passing front enhances. Winds will switch back to west to northwest on Monday. Mixed seas will persist with a longer period west to northwest swell arriving Sunday along with a longer period southwest swell. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...NONE. && $$ PUBLIC FORECAST: Dykema AVIATION: W Pi MARINE: W Pi Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Paducah KY
536 PM CDT Sat May 16 2020 .UPDATE... Issued at 533 PM CDT Sat May 16 2020 Updated Aviation discussion for 00Z TAF Issuance. && .SHORT TERM...(Tonight through Monday night) Issued at 353 PM CDT Sat May 16 2020 The 18Z HRRR has a good handle on the convective evolution through tonight. Current convection will continue its northward movement out of the area in the early evening. Haven`t seen any gusts over 30 mph so far and would not expect much more. From late evening on through Sunday morning the focus shift over southeast Missouri and southern Illinois. Mainly showers are expected, but a few thunderstorms cannot be ruled out. The cold front will move eastward across the region Sunday afternoon and evening, and this should provide a focus for convection. Clouds will likely limit instability, and the better shear will likely lag behind the front, so organized severe weather is not likely. That said, a few stronger cells with gusty winds and small hail cannot be ruled out. The convection should be east of the area by 12Z Monday, but as the upper low slides south toward the area, scattered mainly light showers will be possible at least in the east through the day, and possibly into Monday night. .LONG TERM...(Tuesday through Saturday) Issued at 353 PM CDT Sat May 16 2020 Upper level low is forecast to be over Indiana at the start of the period. Models typically have a difficult time with these, so confidence level is low until it finally exits the area well to the east on Friday. In general, the GFS and GEFS keep the upper low over east Kentucky/Tennessee during the midweek period. The ECMWF meanders the low around and even puts it over west Nashville at times. The question is then how far west will the showers be Tuesday, Wednesday, and Thursday. Deep moisture is forecast to extend to at least the MS river through the period. Right now going with the best chance for precipitation on Tuesday and Wednesday in the east and will keep it dry Thursday and Friday. Looks like a build up of clouds each day with dissipation during the evening. On Friday a small ridge builds over the lower Ohio Valley. There are some indications this will be transient and we may be on the west side of the ridge Saturday which would allow for a small chance of storms for the start of the Memorial Day Weekend. && .AVIATION... Issued at 533 PM CDT Sat May 16 2020 Scattered showers/storms should mostly diminish near term with the setting sun, with variable VFR clouds offering scattered to broken bases the first half of the night. As the Low(s) drift closer with time, we`ll see lowering bases again, and another uptick in showers/coverage. This will begin late tonight but be most active tmrw with diurnal assistance, with widespread restrictions to both cigs/vsbys in showers and storms. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday) Issued at 243 PM CDT Sat May 16 2020 Small chances for showers or a storm or two this afternoon before a cold front pushes through bringing very pleasant conditions to the area. The upper pattern as sampled by the 12Z RAOB network shows a mid to upper level trough over the deep south which is in response to the MCV over the deep south from yesterday and overnight periods. Meanwhile, the northern stream trough - in the process of closing off - from the northern Plains has translated into the northern Plains with the southern flank digging into Nebraska. Mid level speed max and upper jet lag behind currently streaming out of WY into portions of western NE. A sharp mid level ridge resides over to the west over the intermountain west. The surface baroclinic zone has been sharpening through the day with the cold frontal portion now stretched from south central NE into north central portions of KS then back into the DDC area. This afternoon have had to lower high temps a bit due to persistent mid to high level clouds streaming from south to north into the area in response to the overall sharp meridional flow helping to draw convective debris over the area. Where clearing on the backside of these clouds has taken place, temperatures through portions of north central KS has been rising and with mid 50s dewpoints, MLCAPE across the area has risen to around 500 J/kg. Per SPC mesoanalysis, the shear is below 25kts through the 0-6km layer. With overall minimal shear and instability as well as a fairly weak cold front with weak overall surface convergence moving into the area, it makes sense that any showers that have tried to develop have quickly fell apart. Most short-term CAMs have continued to trend down the threat of storms developing with the most recent run of the HRRR backing off even more from this mornings runs. I`ve tried to lower POPs also as a result keeping in mind that there may be some opportunity into this evening for some showers to develop along the cold front. However, these POPs may still be a bit high over the area. In short, the confidence in showers or storms developing on any meaningful scale is low. Into the overnight, the upper low in the northern Plains will deepen and dig into the upper MS Valley region as the cold front tracks through and east of the area. some wrap around stratus may linger into part of Sunday. But, overall a breezy but pleasant day is in store with high temperatures topping out in the low 70s. .LONG TERM...(Sunday night through Saturday) Issued at 243 PM CDT Sat May 16 2020 Into next week, mostly dry and pleasant weather will reign across the central Plains with a steep mid level ridge in place. Temperatures rise a little more each day into the 80s by Wednesday. Perhaps as soon as Thursday and into Friday some shower and storm chances return to the area as the ridge breaks down. A more full return to southwest flow aloft appears to be shaping up into next weekend with storm chances increasing again. Could see some near 90 temps if strong WAA can be established for a few days. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 631 PM CDT Sat May 16 2020 Winds gradually become west and northwest through 04Z as a weak frontal boundary moves through. Chances have diminished for tsra and may only see a brief shower through 04Z. Some lower mvfr cigs may move south into the terminals after 10Z or so as the mid level low tracks into Missouri. Cigs are forecast to recover to vfr by 17Z. Winds increase from the northwest to near 15 kts with gusts to 24 kts after 15Z. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Drake LONG TERM...Drake AVIATION...53