Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/13/21

Area Forecast Discussion
National Weather Service La Crosse WI
1020 PM CDT Mon Apr 12 2021 .SHORT TERM...(This evening through Tuesday) Issued at 205 PM CDT Mon Apr 12 2021 An upper low spiraling over Minnesota through Tuesday will continue to bring occasional shower chances as pieces of energy rotate around it. This afternoon, we`ve already seen showers blossom across north- central Wisconsin where not only is upper forcing strongest, but a little frontogenesis and diurnal instability is also present. Earlier runs of the RAP had suggested up to 200 J/kg of CAPE in this area, which might have been enough for an isolated rumble of thunder, but so far things have stayed tame. Elsewhere, mainly dry conditions are expected this afternoon with perhaps an isolated shower here and there. Overnight, would expect isolated showers at times, especially across our northwest closer to the upper low. Even with clouds tonight, an additional push of cold air advection should allow temperatures to drop into the 30s. We could start to see some snowflakes mixing in late tonight and on Tuesday, as that reinforcing shot of cold air drops 925 mb temperatures into the 0C to -3C range for the day. Have lowered highs again for tomorrow as a result, keeping things in the upper 30s to lower 40s. Some guidance does show a few tenths of an inch of snowfall across the area tomorrow, although with a warm ground, would expect most of this to be on grassy/elevated surfaces where it occurs. With surface low pressure hanging out just to our northwest, west winds will once again be gusty (in the 25 to 30 mph range), making it feel like a raw April day. .LONG TERM...(Tuesday night through Monday) Issued at 205 PM CDT Mon Apr 12 2021 Through Wednesday night, an upper level low will slowly move east across the Upper Mississippi River Valley. This system will provide a chance of showers mainly along and north of Interstate 90. Temperatures will be cold enough aloft for scattered snow showers on Tuesday night and Wednesday morning. Little snowfall is expected. With mostly cloudy skies and 850 mb temperatures around -6C, NBM high temperatures looked too warm on Wednesday. This was likely due to the unseasonably warm temperatures earlier in the month. As a result, lowered them down to the 25th NBM percentile. More seasonable temperatures return for Friday and Saturday and then another colder-than-normal air mass returns for Sunday and Monday. How much cooler is still uncertain due to a large spread in the temperature guidance. Currently have the forecast dry from Saturday through Monday. However, may have to add some small precipitation chances depending on the track of yet another upper level low through the region. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1020 PM CDT Mon Apr 12 2021 Clouds with the occasional shower will be the rule through Wed as the area remains under the influence of multiple upper level lows. Cigs: With the TAF sites mostly on the southern flanks of the main cloud mass, will bounce between VFR/MVFR cigs tonight/Tue, although low VFR more favored at this time. MVFR should become more widespread Tue night. WX/vsby: low level instability and the upper level trough should result in scattered/numerous afternoon showers Tue. Temps will support rain and snow, although no snow accum is expected. Winds: holding west and generally a few ticks above 10 kts. Some gustiness also expected - in the low/mid 20s. However, enhanced gusts (30kts) will be possible/probable with any shower Tue afternoon. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Lee LONG TERM...Boyne AVIATION....Rieck
East Central Florida Forecast Discussion
National Weather Service Melbourne FL
823 PM EDT Mon Apr 12 2021 .DISCUSSION... Overnight...Drier air with light NNW flow wl occur overnight after the loss of the seabreeze. A cool night is expected with overnight lows in the M-U50s for most but a few normally cooler spots could see L50s. Barrier islands should realize L-M60s for mins. HRRR suggests some patchy fog before and through daybreak across Lake Okeechobee to Martin and Saint Lucie inland locations. prev disc... Tuesday...Weak high pressure continues overhead with weak pressure gradient in place. Light early morning winds becoming NNE/NE/ENE in the late morning and afternoon with speeds mainly light across the interior and perhaps 10-15 mph along the Space/Treasure coasts. After a cool start to the morning, temps will quickly warm into the U80s over the interior and L80s at the coast. Tuesday night-Thursday..High pressure will continue to sit over the southeast through Thursday morning with a weak upper-level ridge stretching into the Northeast. Winds will become more southerly on Wednesday and Thursday as high pressure moves downstream with east-central Florida on the back side of high pressure. This will allow dry conditions to continue, in addition to warmer temperatures. Highs will reach the low-to-mid 80s along the coast with warmer temperatures further inland with highs in the upper 80s to low 90s. Slightly cooler temperatures are expected north of I-4 on Thursday as clouds and precipitation move in ahead of our next frontal system. Lows will drop down into the upper 50s to mid 60s during the overnight hours. The upper-level ridge will flatten by Thursday afternoon as an upper-level trough digs southeast across eastern CONUS. This will be the beginning of an unsettled and active weather pattern across the southeast as a zonal upper-level longwave pattern sets up over the country. The upper-level jet will set-up just north of east- central Florida which will make things tricky as models appear to be having a difficult time handling the pattern - producing disagreement of where and when precipitation will occur. With that said, there is some uncertainty with the forecast beyond midweek. Thursday afternoon-Sunday (modified previous)...Broad upper troughing over the northern CONUS will keep a fast westerly flow aloft across the area. This will allow a cold front to push into the area on Thursday, but it should become parallel to the mean flow and stall over south Florida. We`re getting into that time of year when cold fronts have a harder time pushing cleanly through the area. The front is forecast to remain nearly stationary across north/central FL late week and into the weekend which should produce unsettled weather conditions. Details remain uncertain due to timing of ejecting southern stream impulses but have forecast isolated to scattered showers each day from Thursday onward. At this time, the best rain chances look to be across northern sections on Thursday and areawide on Sunday but confidence decreases the further out in time. Temperatures will largely depend on how much cloud cover and precipitation we end up seeing. Expect highs in the upper 70s to low 80s mainly north and west of Cape Canaveral and highs in the low-to-upper 80s further south. Lows are forecast to reach the upper 50s to upper 60s. && .AVIATION... VFR conditions through Tue. && .MARINE... Overnight-Tue...High pressure builds into the area tonight and on Tue. Northerly winds may become variable for a bit in the evening, eventually settling on an offshore (NW) component later in the night due to drainage. NLY winds may gradually veer a bit more NERLY with speeds 6-12 kts. Initial seas of around 2 ft near shore and 3-4 ft offshore will subside to 1-2 ft near shore and 3 ft Gulf Stream by around daybreak Tue morning. && .FIRE WEATHER... Tuesday...Dry air in place with high pressure overhead. Aftn RH values will fall to 30-35pct for the interior and 40-45pct along the coast. Winds will be light, increasing up to 15 mph along the coast behind the sea breeze. && .PRELIMINARY POINT TEMPS/POPS... DAB 56 82 62 85 / 0 0 0 10 MCO 57 88 64 90 / 0 0 0 10 MLB 58 83 65 83 / 0 0 0 10 VRB 56 83 64 84 / 0 0 0 10 LEE 58 88 64 88 / 0 0 0 10 SFB 58 87 64 88 / 0 0 0 10 ORL 60 88 66 88 / 0 0 0 10 FPR 56 85 64 84 / 0 0 0 10 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ JP/MW
Area Forecast Discussion
National Weather Service Mobile AL
1104 PM CDT Mon Apr 12 2021 .NEAR TERM /Now Through Wednesday/...Shortwave ridging aloft will continue to build across the north central Gulf Coast region tonight into Tuesday morning, resulting in continued mostly clear and dry conditions across our area during this time. Surface high pressure will shift eastward toward the FL Big Bend region and adjacent eastern Gulf overnight into Tuesday, allowing for continued light southerly flow across our area. A zonal flow pattern aloft returns by Tuesday afternoon. Shortwave impulses embedded within this flow regime will translate across southern portions of LA/MS during the day Tuesday. Deep layer moisture will become enhanced mainly to the west of our forecast area across southern/southeast LA and southwestern MS, where coverage of showers and thunderstorms are forecast to be most numerous by Tuesday afternoon. However, precipitable water values do improve to around 1.2-1.3" across portions of southeast MS by the late afternoon hours as the shortwave impulses move over this portion of the region. Scattered showers and storms could develop and clip across parts of southeast MS, far southwest AL, and our adjacent western Gulf zones during the afternoon and evening. We will carry a chance (30-40%) of showers and a few thunderstorms mainly along and to the southwest of a Richton, Lucedale, Dauphin Island/Gulf Shores line late in the afternoon through the mid- evening hours Tuesday. Forecast soundings indicate that instability should be very weak and elevated across this portion of the region, so severe weather is currently not anticipated. Highs Tuesday are forecast to range in the lower 80s across southeast MS and adjacent southwest AL where cloud cover gradually increases through the day, while warmer temperatures in the mid to upper 80s are expected into the interior northwest Florida panhandle and adjacent south central AL. A few additional light rain showers or possibly an isolated thunderstorm could develop across southeast MS and adjacent southwest AL late Tuesday night, where moisture and ascent increases slightly ahead of another shortwave trough moving into LA and western MS. Patchy fog may otherwise develop again in a few spots across southern portions of the area late Tuesday night. Lows are forecast to range in the upper 50s to lower 60s inland and in the mid 60s along the coast. A more complex forecast unfolds on Wednesday. The slightly more amplified shortwave trough over LA/western MS early Wednesday morning is expected to translate eastward across our forecast area late Wednesday morning into Wednesday afternoon. A surface cold front will also be pushing southward into central portions of MS and northwest AL through Wednesday afternoon. A moist S-SW surface flow ahead of this boundary will advect increased moisture into much of our CWA through the day Wednesday, with dewpoints rising into the lower to mid 60s over all but perhaps interior south central AL where dewpoints will be a bit lower in the mid to upper 50s. There is still some uncertainty on where the strongest ascent will become focused across our forecast area during the day Wednesday. The 12Z ECMWF, 00Z NAM, and 00Z WRF-ARW show rather strong lift spreading across much of our CWA ahead of the approaching front late Wednesday morning into Wednesday afternoon, while the 00Z GFS and HRRR extended runs suggest ascent will be more focused across southeast MS and into southern portions of southwest AL and the western FL panhandle, keeping lesser coverage over our northeast zones. There is enough indication in multiple guidance members to support high POPs across our entire CWA during the day Wednesday with potential for an organized complex of showers and thunderstorms to advance from northwest to southeast across our region. With PWATs increasing to as high 1.6-1.8 inches and the signal for increased ascent, this looks like a favorable set up for heavy rainfall across portions of our CWA during the day Wednesday. Rainfall amounts could exceed 2-3" in a short period of time within the convective complex, which could result in localized flash flooding Wednesday. There also remains some variability in the guidance on the available amount of instability Wednesday. There are indications that MLCAPE values between 800-1500 J/KG could advect into southern portions of our CWA Wednesday afternoon, along with increased westerly low level flow, which could bring potential for localized strong to severe storms with localized damaging winds and hail and possibly a tornado. This will be something to monitor closely over the next couple of forecast periods. Highs Wednesday should otherwise range from 70-75 over northwestern portions of the area, to the upper 70s to lower 80s over our southeastern zones. /21 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at:
Area Forecast Discussion
National Weather Service Tulsa OK
927 PM CDT Mon Apr 12 2021 .DISCUSSION... Scattered showers and thunderstorms have developed this evening in the vicinity of an elevated frontal zone. Storms remain ongoing as of mid evening across west central Arkansas. Last few runs of the HRRR have initialized quite poorly wrt to ongoing convection. However, this and other CAM solutions indicate additional development later this evening and overnight. That said, will keep pops going in the vicinity of the elevated boundary overnight, with highest pops across NW AR. Temperatures look reasonable for the overnight period, so will leave those as they are. Updated ZFP/PFM/AFM out shortly. && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...23