Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/05/21

Area Forecast Discussion
National Weather Service La Crosse WI
651 PM CDT Sun Apr 4 2021 .SHORT TERM...(Today through Monday) Issued at 205 PM CDT Sun Apr 4 2021 Forecast concerns will continue to be the elevated fire weather conditions today and near record high temperatures, the a return to a more active weather pattern this week. Water vapor satellite imagery and heights show a broad mid- tropospheric ridge over the Rockies and the Plains. Visible satellite imagery had some mid and high level cloudiness across the area into northern Wisconsin with a subtle shortwave, mid level warm air advection combined with a weakening low level jet. At the surface, low pressure was centered over northern Minnesota with a warm front lifting north across the region and a trailing cold front that will continue to move into the forecast area this evening. The front stalls across northern Iowa and southern Wisconsin, then lifts north Monday...meanwhile another subtle shortwave trough will track across parts of Minnesota tonight and another wave will push across Iowa Monday. Near critical fire weather conditions continue with the dry conditions today and brisk south winds. Temperatures are warming through the 70s. La Crosse`s record for today is 80 degrees set in 1921, so should get close. The surface winds gusting 20 to 30 mph should relax this evening as the trough approaches. Used the RAP for surface dewpoints yesterday and delayed the onset of the 50`s dewpoints. A look at recent observations show the 50s dewpoints into Nebraska and southern Iowa. The HREF and RAP are handling these well and transport deepening moisture northward across western Iowa and into southern Minnesota. The HREF is a little faster with their arrival after 02Z and north of the IA/MN state line 08Z. The RAP brings them west of the area, but then only the 40s dewpoints spread into the forecast area until Monday morning. These higher dewpoints and a more active shower and thunderstorm pattern will bring an end to low relative humidities and provide some much needed moisture. Monday will be noticeably more humid with a warm front north of the forecast area. There may be something isolated tonight with scattered showers and thunderstorms possible late tonight and Monday morning with the 40kt low level jet to the south. This jet weakens to 25 to 30kts as it spreads into the area Monday. A few stronger storms are possible with MLCAPE values of 800 to 1800 J/kg and 0-6 KM Bulk Shear of 25 to 40 kts. The strongest deep layer shear looks to be over parts of the forecast area around 18Z...then shifts toward northwest Wisconsin later Monday night. Forecast soundings show elevated instability and shear during the morning, the afternoon and evening. The is some significant drying around 850mb during the afternoon and evening and could contribute to gusty winds with any of the showers/tstorms. .LONG TERM...(Monday Night through Sunday) Issued at 205 PM CDT Sun Apr 4 2021 Weak cold front becomes quasi-stationary over southern WI/into IA going into Tuesday as low pressure ramps up over the Plains. Some weak mid-level ridging looks to dry things a bit Tuesday morning (maybe a few lingering light showers) but then increasing push of 850mb moisture transport int/over the front is expected to fuel more showers/embedded storms later in the afternoon. Temperatures remain warm otherwise with readings topping off in the mid-60s to lower 70s. For Tuesday night through Friday morning, that Plains low pressure closes off and slowly lifts northeast into the region. May have to watch Wednesday as we build some small cape while there`s pretty good curvature in the 0-3km hodograph. May be one of those scenarios where we could get a few brief small/weak tornado or two. Otherwise, will see an increase in coverage of showers and isolated storms as the low approaches. Scattered showers expected to continue Wednesday night through Friday morning in cyclonic flow. Look for highs in the mid-50s to mid-60s. A few lingering showers still possible east of the Mississippi River Saturday in cyclonic flow of that closed low lifting toward the UP/Lake Superior. Otherwise, looking continued mild with highs remaining in the mid-50s to lower 60s. Models bring a ridge of high pressure into the area for Sunday but looks like there could be some embedded energy rounding it for the possibility of a few showers. Will keeps chances on the very low side at this point. Remaining mild though with highs in the 60s. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 650 PM CDT Sun Apr 4 2021 VFR conditions expected to continue through this TAF period. A weakening cold front approaching RST will swing winds around to the northwest this evening as wind speeds relax. A surface trough will then settle over the TAF sites overnight, lifting northward Monday morning. This will bring RST winds back to a more southerly direction late tonight into Monday, meanwhile keeping winds southerly at LSE tonight into Monday. Breezy southwest winds are expected Monday afternoon as the pressure gradient strengthens, with gusts of 20 to 25 knots likely. Plenty of mid to high clouds through the period. Models show an increase in instability on Monday, which could lead to isolated showers and perhaps a storm or two during the day, particularly afternoon. Activity would be more favored south of RST/LSE, so did not have enough confidence to include in the TAFs at this time but will continue to monitor this potential for later issuances. && .FIRE WEATHER...Into Early This Evening Issued at 205 PM CDT Sun Apr 4 2021 Very low RH values in the teens/lower 20 percent range and southerly winds of 10 to 15 mph with gusts up to 25 mph will continue to produce near critical fire weather conditions as grasses and other fine fuels remain dry. Moisture starts to increase across the area tonight with RH values climbing into the upper 60s to upper 80s after midnight. Rain chances return on Monday into Monday night, then widespread rains are looking likely Tuesday night into Wednesday. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Zapotocny LONG TERM...DAS AVIATION...Kurz FIRE WEATHER...DAS/Wetenkamp
..Sunday Afternoon Forecast Discussion...

SHORT TERM /Tonight through Monday Night/... High pressure regime continues, need we really say more? Afternoon temperatures continue to increase with each day with low 70s today giving way to highs in the mid to upper 70s tomorrow. Overnight, radiational cooling will once again be strong with clear skies and calm winds but should stay in the low 40s, which mean no more frost or freeze threat. The trickiest part of the forecast continues to be the afternoon dewpoints and relative humidities as guidance continues to struggle with deep atmospheric mixing entraining very dry low-level air into the mixing layer, and eventually reaching the ground. A spread of 10-18 degrees exists between the 12Z runs of the HRRR and the NAM3km, with the NBM and other blends splitting the difference. But day after day, we`ve seen models like the HRRR and ARW perform well under blue sky conditions and so have lowered dewpoints to match resulting in RHs tomorrow afternoon between 20-30 percent. Thiem LONG TERM /Tuesday through Sunday/... Dry conditions will be ongoing to start the forecast period on Tuesday. The center of surface high pressure will be pushing farther off the Florida Atlantic coastline, bringing a return to southerly flow with continued warming temperatures and gradually increasing moisture levels. By Wednesday, a closed upper low will be dropping southeastward through the Central Plains while shortwave ridging will build over the forecast area ahead of it. At the surface, the associated surface low will be occluding over the Plains with the cold front making gradual eastward progress into the Mid South. Wednesday should remain mostly dry locally with temperatures warming near or above 80 degrees across most of the area. While the cold front`s forward progress slows to our west, rain chances will increase appreciably by Wednesday night into Thursday as shortwave energy swings eastward. Instability will be limited as convection approaches Wednesday night into Thursday morning, so intensity may be on a downswing at that time. This activity will push eastward across the area through the day Thursday. By Thursday night into Friday, the forecast begins to become less certain. Additional convection may develop to our west near the surface front in association with another shortwave. At this point, chance PoPs were maintained into Friday given uncertainties on finer details. Forecast uncertainty increases further by the end of the period with general consensus that the upper low will remain lingering in the Great Lakes region but less agreement on frontal placement and subsequent shortwave energy. Therefore, chance PoPs remain the rule on Day 7. RW AVIATION... 18Z Update... VFR under SKC will prevail through the period. Winds are light and generally westerly between 4-10kts, but have some variability and very isolated gusts at different sites around the area. Winds should go mostly calm tonight, and be light out of the WSW, below 7 kts, tomorrow in the late morning and afternoon. //ATL Confidence...18Z Update... High on all elements. Thiem && .AVIATION... 00Z Update... VFR conditions continue through the TAF period with SKC. Winds will go variable to calm at most sites tonight. West winds again tomorrow from 4-8 kts, with some slightly higher gusts possible, but not expected to pick up until 16-17Z. //ATL Confidence...00Z Update... High confidence all elements. Lusk && .PRELIMINARY POINT TEMPS/POPS... Athens 43 76 49 79 / 0 0 0 0 Atlanta 45 75 50 76 / 0 0 0 0 Blairsville 40 71 45 73 / 0 0 0 0 Cartersville 40 75 46 77 / 0 0 0 0 Columbus 43 76 48 79 / 0 0 0 0 Gainesville 44 74 50 76 / 0 0 0 0 Macon 41 77 46 81 / 0 0 0 0 Rome 40 75 47 78 / 0 0 0 0 Peachtree City 40 75 46 78 / 0 0 0 0 Vidalia 43 78 50 81 / 0 0 0 0 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Thiem LONG TERM....RW AVIATION...Lusk
Area Forecast Discussion
National Weather Service Gray ME
946 PM EDT Sun Apr 4 2021 .SYNOPSIS... Low pressure south of Nova Scotia will spread some rain and mountain snow showers from east to west tonight into Monday. This low pulls away Tuesday with high pressure building in for the middle of the week. Precipitation chances remain low for the second half of the week with temperatures running above normal. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 940 PM Update...Little change to the going forecast other than to update PoP timing as precipitation moves in from the east. The western ME mountains look to pick up 1 to 3 inches of snow from this which is consistent with our previous update. From the foothills southward to central ME and portions of the interior Midcoast, wetbulbing may change light rain over to snow for periods of time overnight with little or no accumulation expected except for perhaps up to an inch in the hills of northern Waldo County. Winds will continue to be gusty at times, especially on the coastal plain. Evaporational cooling at precip onset may boost winds for awhile as well. They will remain below wind advisory criteria, however. 625 PM Update...Have updated the forecast based on latest observational trends in radar imagery and SFC obs. Have also incorporated the latest few runs of the HRRR PoPs to better define the leading edge of the westward-moving precipitation shield this evening. Vsbys are impressively low in snow in Caribou and Houlton as of this writing. As the band pivots westward it should weaken some, but our Western ME mountain zones should catch some pretty good rates later this evening and possibly see 1-3" of snow, especially above 1200 ft or so. Will continue to watch the progress and strength of the band for areas farther southwest, but outside of the mountains it may be tough to get any accumulating snow other than the hills of Waldo County. Will continue to monitor. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Precip will be showery for most of Monday and any SHSN will be in the mtns, and mostly at elevation by mid-morning. From far nrn NH to SW ME and points E will be mainly cloudy through the day, while clouds will move W into nrn and central NH during the morning. srn NH and the srn CT valley are likely to see the most sun through the day. It will also stay breezy with N-NW winds gusting to 25-30 mph at times. Parts of central and srn NH will once again approach critical fire wx conditions, see Fire Weather section below. Highs range from 40-45 in the mtns to the mid to upper 50s in srn NH. The coastal low will begin to shift back E Monday night, but also will begin interacting with wave passing to the N, so while the threat of showers lovers and moves N, it never really the mtns thru overnight. Also, expecting clouds to linger in all but srn NH thru much of the night as well, with lows around 32 in the mtns and in the mid to upper 30s elsewhere. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Blocking pattern in the North Atlantic will continue through midweek with an upper low spinning well offshore in the vicinity of the Canadian Maritimes. Towards the end of the week the upper low will slowly shift east while the blocking high builds westward over eastern Canada. Precipitation chances will remain low through the end of the week with temperatures running above normal. Showers associated with the offshore low will end by Tuesday morning with a mainly dry day. Skies will be partly to mostly cloudy with highs ranging from the 40s north to near 60F south. Northerly winds will be breezy Tuesday with minimum RH dropping to 35 to 40 percent Tuesday afternoon leading to some fire weather concerns, but widespread Red Flag conditions do not look likely. Upper level heights will build over the area as a narrow upper ridge moves from the Great Lakes to our area for the second half of the week. This will allow for temperatures to creep upwards with highs in the upper 50s to mid 60s. As the upper ridge axis nears overhead Thursday and Friday winds will shift from northerly to onshore leading to cooler conditions near the coast. Going into the weekend forecast confidence drops off as the upper ridge pinches off to our north as an upper low meanders to our west over the Great Lakes. If this upper low is able to progress eastward then chances for widespread precipitation will increase, but at this time global models keep it too far to our west through the weekend. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Short Term...Mainly VFR through Monday night, with exceptions at KAUG/KRKD, which will see MVFR cigs and showers late tonight and Monday, with a chance for a short period of IFR. Long Term...MVFR cigs are possible Tuesday morning from KAUG to the coast. Mainly VFR expected through the end of the week as high pressure builds in. && .MARINE... Short Term...No changes to flags on the waters with increasing N-NW flow thanks to tightening pres grad, will see SCA winds continuing through Monday, with a period of Gales in the east tonight into early Monday. Long Term...Low pressure will spin well offshore southeast of Nova Scotia through the middle of the week. Northerly winds will gust up to 25 kts Tuesday morning with gusts generally below 20 Tuesday afternoon through Wednesday. High pressure builds in Thursday and Friday with winds turning onshore with winds and seas remaining below SCA thresholds. && .FIRE WEATHER... Clouds and showers will work in from the E tonight covering much of ME by morning, and the clouds will move into the nrn half of NH Monday morning. This will limit the fire threat in these areas on Monday, However, the srn half of NH will see sun through much of the day and wind gusts of 25 to 30 mph, which will combine with dry conditions to create elevated fire spread conditions. Winds will subside and low level moisture increase on Tuesday across the whole the CWA which limits the fire threat. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 5 PM EDT Monday for ANZ153-154. Gale Warning until 8 AM EDT Monday for ANZ150>152. && $$ NEAR TERM...Ekster SHORT TERM...Cempa LONG TERM...Schroeter
Area Forecast Discussion
National Weather Service North Platte NE
1054 PM CDT Sun Apr 4 2021 .SHORT TERM...(This evening through Monday night) Issued at 254 PM CDT Sun Apr 4 2021 An upper level disturbance moving through Utah this afternoon will emerge onto the central Plains of ern Colorado and KS this evening. The disturbance, not readily discernable in the models but clearly shown on Satellite might be the basis for isolated showers and thunderstorms across swrn Nebraska this evening, but none of the models suggest anything more than sprinkles-too dry, but it will be close. The NAMnest, the most aggressive model, shows thunderstorms taking off this evening across scntl Nebraska in response to a strengthening low level jet. The forecast will lean on the NAM for an isolated thunderstorm chance across a small portion of southwest Nebraska. The HREF, NAM and to a lesser extent the HRRR show another isolated thunderstorm chance across ncntl Nebraska Monday evening. This storm activity will form on the edge of a nearly stationary dryline. This time, according to the NAM, winds aloft and instability might be sufficient for strong or severe storm activity. CONRAD, courtesy of Bufkit, suggests storm splitting in response to a belt of linear but strong winds aloft. The NAMdng would suggest wind damage would be the primary hazard with any storms which become severe and looking at Bufkit, the very large T-Td spread below h500mb would certainly support that claim. Note, the forecast for an isolated severe storms is speculative for the following reasons: the upper level forcing is weak and the sfc focus for storm development could be east of ncntl Nebraska, across nern Nebraska. The temperature forecast tonight, Monday and Monday night leans on the short term model blend plus bias correction. This suggested highs in the 80s Monday which is very close to the guidance blend plus bias correction but several degrees cooler than the 50 percentile of the model blend which suggested highs around 90 in many areas. .LONG TERM...(Tuesday through Sunday) Issued at 254 PM CDT Sun Apr 4 2021 There is not much change in the predicted track and evolution of the storm system currently affecting British Columbia. The models are in good agreement tracking the h700mb low through the Rockies and Wyoming Monday. This low will move east into the Sandhills Tuesday and then be drawn south into KS Tuesday night by heavy convection. There is a chance the system could drop south into nern Colorado and then east into Kansas favoring more of wrn and ncntl Nebraska for rain but this would be dependent on moisture transport into the system. For now, the models are slow to moisten the system up and if this holds true, the system would likely maintain the more easterly track into the Sandhills as shown by the models. The NAM continues show reasonable elevated CAPE of up to 1500J/KG and this will easily support thunderstorms capable of small hail Monday night and Tuesday. The 40kts of bulk shear and CAPE could also support an isolated severe storm capable of large hail. These storms would be most likely to occur across swrn and ncntl Nebraska Monday night. All of these storms should be post frontal. A cold front will sweep into wrn and ncntl Nebraska Monday evening. By Tuesday afternoon, the upper low should be positioned over cntl KS favor that area of severe weather. The storm system will move slowly east Tuesday night and Wednesday. Rain chances will be ending west to east during this time frame. The models are in good agreement developing north and northeast winds of 20 to 25 mph as the storm departs wrn and ncntl Nebraska. The departing storm Wednesday will end rain chances across wrn and nctnl Nebraska for the rest of the week. Northwest flow aloft will take hold Thursday and Friday. A second upper level low may drop through the nrn Plains Friday presenting a rain chance Friday or Saturday but the predictability of this occurring is very low. In fact, the model blended forecast for this time frame is dry. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1051 PM CDT Sun Apr 4 2021 Broken high level cloudiness will persist the rest of tonight into Monday across western and north central Nebraska. Isolated thunderstorms are possible late tomorrow afternoon across all of the area. Winds will be light tonight and generally 15 kts or less Monday. Some localized gusts up to 20 kts are possible Monday afternoon across northern Nebraska. && .FIRE WEATHER... Issued at 254 PM CDT Sun Apr 4 2021 Isolated thunderstorms capable of dry lightning have been observed across southwest Nebraska this afternoon. This storm activity is expected to continue into early evening affecting areas of southwest and south central Nebraska along and south of a line from Imperial to North Platte to Broken Bow. A Pacific cold front moving through the WA-OR this afternoon should move into nrn Nebraska Monday afternoon, perhaps 18z-21z. The models are in fairly good agreement gusting winds to around 25 or 30 mph behind front but not ahead of it. Despite the cooler air behind the front, a few hour period of gusty northwest winds and RH near or below 15 percent should develop. A Fire Weather Watch is in effect Monday afternoon and early evening across the Sandhills, Niobrara region and eastern Nebraska Panhandle. && .LBF WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Monday afternoon through Monday evening for NEZ204-206-208. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Taylor FIRE WEATHER...CDC
Area Forecast Discussion
National Weather Service Riverton WY
225 PM MDT Sun Apr 4 2021 .SHORT TERM...(This evening through Tuesday night) Issued at 119 PM MDT Sun Apr 4 2021 Elevated fire weather conditions across the south and into southeast Fremont and Natrona counties continues to be the primary area of concern for today. Temperatures will be similar to yesterday, with more daily record highs likely to be broken once again. The HRRR and HiRes models continue to show the possibility of some convection firing late this afternoon from eastern Sweetwater County into southern Natrona County. A small line of virga showers has formed south of I-80 on the Sweetwater/Carbon County line, which has produced a raindrop or two on some of the webcams, but most is remaining virga. Surface dewpoints remain in the teens or below, so there is not enough surface moisture to produce rain showers. We will continue to monitor the radar and webcams into the late afternoon and evening. Tonight, mainly quiet weather with increasing cloudiness, especially across the west. Monday morning, some precipitation begins to move into the far northwest associated with an incoming trough. Precipitation will likely start as all rain in the valleys and a rain/snow mix in the higher elevations. Snow levels drop Monday night, and precipiation will make the transition to all snow for areas north and west of the Divide. Currently have advisory amounts in the western mountains, especially the Absarokas and Wind Rivers, but will hold off on issuing Advisories for now due to uncertainty in temperatures and precipiation type. Precipitation will begin to spill over east of the Divide late Monday afternoon and Monday night. Precip should remain all rain for the basins with the exception of the Bighorn Basin and northern Johnson county which may see enough cold air to get some accumulating snow Monday night into Tuesday morning. A brief transition to snow could also occur across parts of Fremont County and Casper Mountain. The Bighorn Mountains may see some Advisory worthy snowfall mainly Monday night and Tuesday morning. East of the Divide, precipiation will depend on the track of the low. Our other concern with this event will be the potential for convection. SPC Day 2 continues with a general t-storm risk across most of the CWA. Our concern would mainly be for strong downdraft winds from convective showers. We will continue to monitor this over the next couple shifts as the trough pushes closer to our region. Precipiation will be mainly out of the region by Tuesday night. Tuesday will see much cooler temperatures than the past several days behind the cold front that will pass over the region Monday. Highs Tuesday will be 20 to 30 degrees colder than Monday, especially across the basins east of the Divide. Tuesday night will see skies begin to clear out as the system moves out of the region. .LONG TERM...(Wednesday through Sunday) The ECMWF and GFS models are both in agreement that any remaining showers will be out of the forecast area by around 12Z Wednesday. A weak ridge of high pressure will quickly shift east across the region between Wednesday and Thursday with dry and milder conditions expected by Thursday. A progressive upper level pattern will continue through the extended forecast period. A couple of short waves at 500 millibars will be expected to move through the region between Thursday and Friday and again next Saturday night and into Sunday. At this point, it still appears that the best chance for any scattered showers will be across the northwest and into northern sections of the state through Thursday and Friday and again on Saturday night and into Sunday. The model differences between the ECMWF and GFS models increase during the extended forecast periods with the ECMWF model indicating a wetter solution, compared to the more drier GFS model solution with both of the systems. For now, have only gone with mainly slight chance pops through the extended forecast periods. Temperatures for the Thursday through Sunday time period should remain between 10 and 15 degrees above normal through the end of the extended forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Expect VFR conditions to continue throughout the forecast period for the TAF sites. Have added in an increase in southwest to west winds for the area mainly after 19Z on Monday for expected sustained winds above 10 knots at several locations and some gusts expected, also. Have added in a VCSH for KJAC after 22Z Monday, as some scattered showers will be possible across the west toward the end of the forecast period. && .FIRE WEATHER... Issued AT 119 PM MDT Sun Apr 4 2021 Continuing with elevated fire weather conditions today, similarly to the past several days. Winds also are similar to the past few days and are not expected to increase much late this afternoon. Come convective virga showers continue to be possible, mainly across far eastern Sweetwater county and into southeast Fremont and Natrona Counties late this afternoon and early this evening, however, precipiation is not expected to reach the ground due to very dry surface RH. A brief gusty outflow wind would be the only hazard with these showers. Widespread precipiation begins to move into the west Monday morning and spread east of the Divide Monday afternoon and Monday night. Higher elevations will see snow with rain turning to a rain-snow mix and eventually to all snow West of the Divide in the valleys. East of the Divide, basins will remain all rain with snow mixing in late Monday night and early Tuesday morning. 6 to 8 inches of snow is possible in higher elevations across the west and the Bighorns, with minimal to no snow accumulations in the basins. Gusty outflow winds from thunderstorms are possible Monday afternoon across the region, mainly across the west and south. Precipiation will exit the region by Tuesday night and the rest of the week looks to see mainly tranquil weather. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Fisher LONG TERM...Troutman AVIATION...Troutman FIRE WEATHER...Fisher