Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/02/21

Area Forecast Discussion
National Weather Service La Crosse WI
1025 PM CDT Sat May 1 2021 .SHORT TERM...(This evening through Sunday) Issued at 215 PM CDT Sat May 1 2021 Still could see a few showers develop late this afternoon and continue into the early evening in the Interstate 90 corridor across western Wisconsin. The RAP continues to suggest some weak frontogenesis in the 850-500 mb layer across this area combined with some convergence at 850 mb as the moisture transport begins to increase ahead of an approaching short wave trough. These should then move out of the area early this evening with much of the rest of the night expected to be dry. The rain chances will then increase Sunday, especially in the afternoon. The upper level flow will turn to the southwest ahead of an approaching trough in the northern stream. The models have been consistent in showing this to be a rather dirty flow pattern with several smaller embedded short wave troughs versus a single stronger one. As a result, the pv advection in the 500-300 mb layer never looks to be all that impressive, but it will be rather persistent once it starts. A cold front will ever so slowly move into the area and looks to have good low level forcing along it. The RAP suggests there will be 4 to 6 ubar/s of up glide on the 305K surface in the warm air advection right ahead of the front. This lift looks to be augmented by a zone of weak to moderate frontogenesis in the 850-700 mb layer. This should allow showers to develop pretty quickly in the afternoon over the northwest sections of the forecast area. Around 750 J/kg of ML CAPE should be in place in the warm sector to support some rumbles of thunder as well. The chances for any severe storms looks very low as the shear in the baroclinic zone looks to only be around 20 knots or so. .LONG TERM...(Sunday night through Saturday) Issued at 215 PM CDT Sat May 1 2021 Slightly southwest flow aloft with several embedded waves, combined with the sluggishly progressing surface front, will result in periods of showers and storms Sunday night and into late Monday when the front finally exits. Quasi-zonal flow will persist through the middle of the work week, giving way to slightly more amplified northwest flow as we head into next weekend. The next notable chance for rain is Thursday as a weak trough and surface cold front passes by. Otherwise, generally cool temperatures will continue through the extended portion of the forecast. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1025 PM CDT Sat May 1 2021 Cigs: sct-bkn mid level vfr deck persists into Sunday morning, with an increase in low level saturation then expected into Sunday night. MVFR still looks likely, but how soon those lower cigs move in is the big question. NAM/GFS suggest sub 3 kft will build in by 18z now. RAP and SREF would hold off until closer to 00z. For now, will continue to hold with bringing the low cigs in later, with the expected pcpn. Trends will have to be monitored closely. Once the cigs settle in, they will look to hold into Tue morning. WX/vsby: latest RAP/HRRR a bit quicker with pcpn onset at KRST/KLSE, although still mostly tied to the cold/warm fronts. SHRA/TS looking more likely by 00z Mon now, but could be a tad earlier too. Expecting widespread shra/ts for the evening, becoming scattered overnight. Winds: mostly southerly through Sun afternoon, roughly around 10 kts. LLWS a concern for both sites tonight with +40 kts by 2 kft. Should improve by 08-10z. Warm front slated to sag south to around the I-90 corridor. As (if) it does, winds should become a tad lighter and more east/northeast. Going to lean the forecast this way. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...04 LONG TERM...DMD AVIATION...Rieck
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
646 PM CDT Sat May 1 2021 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...A mix of low and mid level clouds and light winds prevail across deep south Texas early this evening. Ceilings are expected to improve somewhat through late this evening as some drier air starts to filter into the area from the W-SW. However, short term guidance continues to suggest ceilings at HRL and BRO may drop to MVFR/IFR levels overnight into Sunday morning. Otherwise, VFR conditions are expected for the next 24 hours. Light and variable winds tonight will increase and become southerly on Sunday. && .PREV DISCUSSION... /issued 256 PM CDT Sat May 1 2021/ SHORT TERM (Now through Sunday Night): The latest KBRO reflectivity indicates that the conv coverage continues to decrease steadily across the region with the bulk of the ongoing conv located offshore over the lower TX Gulf waters. The big question is whether or not there will be any last minute development as the 500 mb closed low over the Big Bend region starts lifting NE allowing a drier and more subsident flow aloft to spread over the region. The latest vsbl satl imagery shows there is some orographically driven conv firing over the higher terrain in NE Mex. Since some of this may hold together long enough to move into the RGV, will leave some mention of low end pops in place for one more period this evening. However, the latest HRRR and RAP is pretty pessimistic that much more significant rainfall will occur this evening and tonight across the region. The HRRR shuts us out completely from the conv while the RAP13 does try to bring a few cells right over the Cameron County area later tonight. Outside of the shorter range conv models, the NAM/GFS and ECMWF models are all consistent in lifting the Big Bend 500 mb low out to the NE later tonight and Sun moving it into the ARK/LA/TEX area tomorrow. As the 500 mb low moves out of the area and the moisture levels decrease across the region, high temps will be on the increase tomorrow as the daytime heating increases. The short temp guidance reflects this warmup pretty nicely and will opt for a general blend of the model temps throughout the short term. Since the pops will be decreasing this evening and the heavy rain threat appears to be fading, will cancel the FFA for the Coastal areas of Cameron/Willacy and Kenedy Counties. LONG TERM (Monday through Saturday): Weak mid level ridge of high pressure across the Gulf of Mexico gets pushed a bit further south next week by a shortwave as it sweeps through TX on Tuesday. A stronger 500mb high builds through the end of the week. Low pressure across the Plains will strengthen the pressure gradient on Monday, bringing another windy day across the lower Texas coast. A Wind Advisory may be needed. A dryline works into the western CWA on Monday as well, allowing temperatures to spike and humidity values to crash. The lower humidity and higher winds may just miss each other across the CWA, to fall short of any Fire Weather criteria. A weak frontal boundary approaches on Tuesday and stalls just south of the border on Wednesday, before dropping further south through the remainder of the week. Low pressure returns to the Plains next weekend, likely strengthening the PGF and bringing more breezy to windy conditions to the lower Texas coast. The best POP will remain Tuesday evening into Wednesday morning, mainly across the ranchlands and coastal counties. Kept light POPs in along the southern border and offshore into Wednesday afternoon near any remaining frontal boundary convergence. Highs on Monday could range from 81 to 88 along the coast and 97 to 104 across western counties. Expect 90s again on Tuesday before the front brings highs back toward normal or slightly below on Wednesday. The remainder of the week looks close to normal. MARINE (Now through Sunday Night): The PGF will remain pretty weak for tonight and Sun allowing for pretty low winds and seas to persist. Another 500 mb short wave digging across the Southwestern States will result in a pretty strong surface low spinning up over the South Central Plains States Sun Night into Mon morning. This may result in some SCEC conditions for both the Bay and Gulf waters. Monday through Saturday: High pressure across the Gulf edges further eastward as low pressure deepens across the Plains. The pressure gradient strengthens along the coast on Monday, with SCEC conditions on the Gulf and potential SCA on the bay due to winds. Persistent southeasterly swell is expected to build or maintain elevated seas Tuesday into Wednesday as a weak cold front arrives and gradually slows or stalls south of the Rio Grande. SCEC to SCA are possible late Tuesday into Wednesday. High pressure builds through the remainder of the week, allowing marine conditions to improve. As low pressure returns to the Plains, expect another breezy to windy day on Saturday. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 69 88 74 88 / 20 0 0 0 BROWNSVILLE 70 90 76 91 / 20 0 0 0 HARLINGEN 67 92 74 94 / 20 0 0 0 MCALLEN 68 96 74 97 / 20 0 0 0 RIO GRANDE CITY 65 101 73 103 / 20 0 0 0 SOUTH PADRE ISLAND 71 79 74 82 / 20 0 0 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV 63-KC
Area Forecast Discussion...CORRECTED
National Weather Service Cheyenne WY
959 PM MDT Sat May 1 2021 .UPDATE... Issued at 951 PM MDT Sat May 1 2021 A fairly active late afternoon and early evening as scattered high-based showers and thunderstorms developed and moved east- northeast across the CWA. The primary threat with the showers and storms has been strong and gusty outflow winds. Peak wind gusts were 60 mph at KRWL and 64 mph at KDGW, with numerous 50 to 60 mph gusts along portions of I-80 between Cheyenne and Rawlins. Isolated thunderstorms are still possible until midnight, with scattered rain showers overnight. Precipitation amounts will be light. Adjusted PoP, sky and weather grids to match trends. Updates sent. && .SHORT TERM...(Tonight - Monday) Issued at 215 PM MDT Sat May 1 2021 Scattered to numerous showers & perhaps a weak thunderstorm can be expected across much of southeast Wyoming and the western Nebraska Panhandle through this evening. This activity will be mainly high- based with very limited low-level moisture, so generally expect to see virga showers for most areas. Inverted-V profiles & high DCAPE values around 1000 J/kg will support occasional wind gusts near 50 MPH with some cells. Scattered showers will continue overnight for many areas, but potential for strong wind gusts should diminish by 03z or so. Low-level moisture return becomes more established late tonight and early Sunday as an upper level short wave digs south & and east into the 4 Corners. Increasingly difluent flow aloft will support widespread convective development after 18z on Sunday. Dew points near 50 F, coupled w/ steep mid-level lapse rates may prove supportive of SBCAPEs up to 1200 J/kg. 0 to 6 km shear of 40 to 50 knots may support a few organized updrafts capable of severe hail/ wind along the I-80 corridor east of Cheyenne. The 12z installment of the HRRR did show several helicity tracks in/near the CWA. MRGL Risk from SPC on DY2 looks good. In the meantime, convection along with some orographic support will yield a period of heavy mountain snow especially in the Snowys. Models have trended lower with QPFs over the high country, but the potential does exist for 12+ inches above 10k feet from Sunday afternoon through Monday. Have issued a Winter Storm Watch for the Snowy Range. Advisories could be needed for the Sierra Madres and perhaps the I-80 summit by Sunday night/ early Monday. .LONG TERM...(Monday Night - Saturday) Issued at 215 PM MDT Sat May 1 2021 Unsettled weather continues Monday evening as a shortwave moves east through southeast Wyoming and western Nebraska bringing more rain to lower elevations and snow to the mountains. There`s a brief settling of the weather Tuesday during the day, then by Tuesday night another shortwave disturbance will pass through southeast Wyoming and western Nebraska bringing rain to lower elevation areas and snow to higher elevations and the mountains through Wednesday night. Thunderstorms are possible Wednesday afternoon in far southeast Wyoming and western Nebraska as this disturbance moves east. Thursday, a strong ridge will build in with above normal temperatures and dry conditions through Friday. Possible precipitation returning to western Nebraska Saturday as a brief disturbance passes through, breaking down the ridge. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 520 PM MDT Sat May 1 2021 Latest KCYS radar scanning scattered showers and thunderstorms across southeastern Wyoming. Brief gusts up into the 40s and 50s may be possible in strongest decaying thunderstorms. VFR conditions should return for all sites after 09z in WY with last showers ending late Sunday morning for NE. Models are trending in response to frontal passage and upper trough moving in for lower CIGS after 18z. && .FIRE WEATHER... Issued at 304 AM MDT Sat May 1 2021 Relative humidities will be quite low today across the entire region with values ranging from 10 to 15 percent. It will also be quite breezy over the Wyoming plains, but fuels are not ready in this region yet. East of the Laramie Range wind speeds will be lighter at 10 to 15 mph. This area is leaning a bit towards more critical fire weather conditions. These near critical fire weather conditions will be short-lived after the front moves through the area on Sunday and brings more rain and snow to the region through midweek. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Storm Watch from Sunday afternoon through Monday afternoon for WYZ114. NE...None. && $$ UPDATE...MAJ SHORT TERM...CLH LONG TERM...LK AVIATION...WM FIRE WEATHER...REC
Area Forecast Discussion
National Weather Service Dodge City KS
625 PM CDT Sat May 1 2021 ...Updated Aviation Discussion... .SHORT TERM...(This afternoon through Sunday night) Issued at 1230 PM CDT Sat May 1 2021 Starting off May with a near perfectly clear sky across all of SW Kansas as of midday. 12z NAM deepens the lee cyclone to near 992 mb near Limon, Colorado by 7 pm, which will act to keep pressure gradients tight for the remainder of the day. South to southwest winds will routinely gust 30-35 mph through sunset, with afternoon temperatures in the 80s. South winds will remain elevated tonight, averaging 10-20 mph, facilitating moisture return and dewpoints climbing back into the 50s. Moisture advection will allow stratus to spread northwestward into at least the eastern half of SW KS tonight, most likely along and east of US 283. Some uncertainty exists on how far west stratus will advance tonight, with some drizzle possible in the deepest moisture across the southeast zones. Most locations will hold in the 50s through sunrise Sunday. Closed low over Texas Saturday afternoon will finally eject to the Mississippi valley Sunday afternoon, as shortwave energy begins to approach from the west. The vast majority of Sunday will be dry, with elevated and gusty S/SE wind in response to strong low pressure developing near the NW panhandles. Models show little if any cooling versus Saturday, so expect lower to mid 80s to again prevail Sunday afternoon. NAM develops CAPE of 2000+ J/kg Sunday afternoon and early evening, east of the dryline, with isolated thunderstorms possible across the western/NW zones toward sunset. 12z NAM and the latest HRRR iterations agree, suggesting an organized thunderstorm complex will develop near the Palmer Divide Sunday evening, and then advance eastward into NW Kansas Sunday night. Current model trends suggest this complex may only graze the northern zones, with a strong capping inversion discouraging convection further south. Inherited likely pops Sunday night, but it is probable these are overdone south of K-96, and pops will likely need to be lowered if trends continue. Damaging winds and marginally severe hail would be a risk from any organized complex, and SPC`s 15% wind/hail probability mainly north of K-96 is warranted. Outflow from any mesoscale convective system in NW KS will help propel a strong cold front through SW KS Sunday night/early Monday, with a period of strong north winds. Trended wind/wind gust grids toward the stronger 12z MET guidance, especially along the preferred US 83 corridor. .LONG TERM...(Monday through Saturday) Issued at 220 PM CDT Sat May 1 2021 A big change to a windy, wet and raw day on Monday behind the cold front. North winds will be quite strong in response to surface low pressure sliding east through Oklahoma, and increased the NBM wind and wind gust grids by several mph. Cold advection will drive 850 mb temperatures down to the 3-5C range by late afternoon, and coupled with an expected overcast, temperatures will struggle through the 50s. Reduced NBM`s max T grid 1-2 degrees, but it may be cooler than that. 12z ECMWF remains consistent spreading the best opportunity for measurable rain into SW KS Monday afternoon, as forcing for ascent ahead of the approaching shortwave increases. Instability is essentially wiped out by Monday, so thunder will be hard to come by. 12z ECMWF suggests 0.25-0.50 inch of rain Monday, with heavier amounts favoring the southern zones adjacent to Oklahoma. Subsidence behind the exiting wave will provide much improved weather Tuesday, although temperatures will still be several degrees below normal. Sunshine, much lighter winds, and afternoon temperatures in the 60s. A shortwave embedded in the NWly flow aloft will pass through the region Wednesday and Wednesday night, providing a chance of showers and thunderstorms in the region. Accepted NBM`s pops for now, but will need to rearrange these as the wave approaches and any instability is ascertained. 12z ECMWF builds a strong ridge axis through the Great Basin on Thursday, and then slides the ridge axis to the spine of the Rockies on Friday. More dry quiet NW flow aloft will result with a warming trend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 615 PM CDT Sat May 1 2021 Gusty south southeast winds at around 15 knots will continue overnight. These winds will draw increasing low level moisture back into southwest Kansas with ceilings falling into the 2000 to 3000ft level in the Dodge City area after 06z Sunday. Ceilings as low as 500 to 1500ft AGL will be possible between 10z and 15z Sunday. Hays will also have a high probability of lowering ceilings overnight with the lowest ceilings occurring between 12z and 18z Sunday. HRRR and NAM late this Saturday evening suggesting these low clouds will stay east of Garden City and Liberal areas but confidence is not high that this will occur so did include a tempo group of low clouds in these locations also. Also overnight the winds in the 1500 to 2000ft AGL level will increase into the 40 to 45 knot range so did include a wind shear group at all four TAF sites late tonight. && .PRELIMINARY POINT TEMPS/POPS... DDC 57 81 52 59 / 0 10 60 70 GCK 53 82 49 57 / 0 30 70 80 EHA 52 88 48 56 / 0 20 20 80 LBL 53 87 49 58 / 0 10 30 70 HYS 58 80 51 62 / 0 20 80 60 P28 59 80 57 68 / 0 0 30 60 && .DDC WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 8 PM CDT /7 PM MDT/ this evening for KSZ061-062-074-084. && $$ SHORT TERM...Turner LONG TERM...Turner AVIATION...Burgert
Area Forecast Discussion
National Weather Service Grand Forks ND
956 PM CDT Sat May 1 2021 .UPDATE... Issued at 956 PM CDT Sat May 1 2021 Frontal boundary pushing through Fargo area, with wind shift to the north northeast. The front will continue to move south through the rest of the evening. Adjusted winds as well as the sky cover a bit for mid-level clouds near the front. Temps still seem on track to slowly fall into the 40s overnight. UPDATE Issued at 640 PM CDT Sat May 1 2021 Still very warm across the region with temps in the 80s across much of our central and southern counties. Cold front pushing into the Highway 2 corridor has shifted wind to the north-northeast and started to drop temps back into the 70s. Used HRRR for wind shift position as it seems closest to reality this evening. Decreasing temps and lower winds should allow us to drop the Red Flag when it expires at 8 PM. Cold front will continue to push southward this evening. && .SHORT TERM...(This evening through Sunday night) Issued at 232 PM CDT Sat May 1 2021 Fire weather remains the main concern in the short term, and that will be discussed in the fire weather section below. Although there are some bands of cloud cover across the FA, it remains mostly sunny this afternoon. Temperatures have risen into the upper 70s and 80s, as expected. At Fargo and Grand Forks, this is the first 80 degree day since late last September. Winds are from a variety of different directions and speeds, and they will stay that way into the evening. Speeds should decrease somewhat overnight, but it will stay relatively mild. Another decent temperature day is anticipated for Sunday, although cooler than today. It does look to be cooler across the Devils Lake region and warmer elsewhere. Winds also look breezy again, especially along and west of the Red River Valley. However, rain should begin to spread into the FA, especially by the afternoon, which will decrease the fire weather threat. Rain chances continue into Sunday night as well. .LONG TERM...(Monday through Saturday) Issued at 232 PM CDT Sat May 1 2021 Impactful weather during the extended forecast period is not easy to find, with chances for mainly light rain presenting during midweek and perhaps at some point next weekend. Pcpn will be heading out of or have completely cleared the area as Mon dawns, with brisk north winds sustaining at 20 to 25 mph. The best opportunity for QPF comes Wed/early Thu with a transient wave. Colder early AM temps would make some snowflakes possible, offering insignificant impacts, except to one`s psyche! The amplified upper structure during the mid week period is likely to see the ridge begin to break down with the flow becoming flatter and more zonal heading toward the weekend. This would allow for some Northern Rockies moisture to move toward our area. The likely result would be surface high pressure in place Thu/Fri yielding to pcpn chances over weekend, although the lion`s share would appear to remain south of the forecast area. The temperature regime will remain below normal during the upcoming week, as 850 mb temps stick close to 0 C translating to overnight lows around freezing with daytime highs only in the 50s. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 640 PM CDT Sat May 1 2021 Winds will be the main issue with VFR conditions for most of the period. Cold front coming down has shifted winds to the north- northeast for all but KFAR which is still northwesterly and gusting to around 20 kts. The cold front will continue to drop down this evening, and winds will decrease overnight. Some picking up again during the day tomorrow to the 10 to 15 kt range with gusts to 20 kts, still mostly from the northeast. Showers and possibly some MVFR ceilings will be possible in the KDVL area towards the end of the period. For now kept just VCSH and lower VFR as most model solutions are not consistent on bringing ceilings down below 3000 ft. && .FIRE WEATHER... Issued at 232 PM CDT Sat May 1 2021 Interesting fire weather day to say the least. The gustiest winds (from the west-northwest) have generally been south of the highway 2 corridor so far. The driest dew points have west and southwest of Jamestown ND. A thin corridor of fairly light winds yet have stretched from Langdon to Grand Forks to just north of Bemidji. Just to the north of this, north winds at 15 to 25 mph are occurring. Temperatures have risen quite nicely, with most locations closing in on the 80s. So critical fire weather conditions will continue into the early evening, when the Red Flag Warning is set to expire at 8 pm. Rain should begin to move into the area Sunday, lessening the fire weather threat. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...JR SHORT TERM...Godon LONG TERM...WJB AVIATION...JR FIRE WEATHER...Godon
National Weather Service Sioux Falls SD
717 PM CDT Sat May 1 2021 .SHORT TERM...(This Evening through Sunday) Issued at 229 PM CDT Sat May 1 2021 As of mid afternoon, surface observations show temperatures have skyrocketed into the upper 80s to mid 90s. Humidity levels have dropped to the teens and 20s, with fire danger being exacerbated across northwest Iowa where warm air advection ahead of the stationary front has combined with deep boundary layer mixing to produce gusts up to 40 mph. Scattered cirrus and cumulus may help taper high temperatures a bit, but overall hot and dry as expected. Cloud cover will increase across the region tonight, in advance of an approaching mid level shortwave. In response to the resident dry air and height falls aloft associated with the departing upper ridge, temperatures will drop dramatically overnight, reaching the 50s by early Sunday morning. A mid level shortwave brings scattered showers and maybe a brief rumble of thunder to areas in south central and southeast SD late tonight and through Sunday. Rain chances will spread east of I-29 in southwest MN early Sunday morning. Model soundings suggest it may take up to a few hours for lower levels to saturate with this weaker disturbance so expect meager rainfall amounts only up to a few hundredths of an inch at most sites. Up to a tenth of an inch of rain is possible along and west of the James River Valley. There`s a prolonged period of rain chances given lower confidence in location of off/on showers scattered across the region on Sunday, but the majority of Sunday should be dry for most. Cooling aloft combined with cloudiness and the lingering stationary front bisecting the region will mean Sunday`s highs should be 10 to 20 degrees cooler than Saturday`s. Increased dew points will make for higher humidity levels Sunday, and highs should still reach the 70s, cooler further north behind the stationary front. .LONG TERM...(Sunday Night through Saturday) Issued at 229 PM CDT Sat May 1 2021 Showers and storms are likely to develop Sunday late afternoon and night as a stronger mid level trough tracks through in southwest flow aloft and interacts with the stationary boundary draped across northwest IA and eastern NE. There is disagreement on timing the mid level wave and cap erosion, but most guidance supports a line of storms popping up along the front in western IA. A second area of scattered showers and isolated weaker storms is possible further west across the rest of the forecast area Sunday night, prompted by the approaching upper longwave trough. In northwest IA along and ahead of the front, HREF guidance of SBCAPE 1000-1750 J/kg and mid level lapse rates 7-8 C/km are supportive of storm development and small hail, but deep layer effective shear is weak at 20-25 kts and the overall wind profile remains unimpressive. Although today`s 12z HRRR paints a robust picture of a line of storms from SPW to SUX and southwest, the severe threat is quite low unless the front stalls further west than currently expected and is able to interact with stronger deep layer shear. The more likely scenario is to see scattered storms initiate in northwest IA Sunday night with perhaps a stronger storm or two with gusty winds and small hail. Cooler, near normal air moves back in for Monday and Tuesday as highs return to the 50s and 60s in the vicinity of a passing upper longwave trough. Most of the region will see lingering cloud cover and rain chances continues for parts of northwest IA on Monday. A breezy north wind will make Monday feel even cooler as the Northern Plains remains squeezed between the departing sfc low and approaching high. Drier air and weaker winds spread in with sfc high pressure Tuesday. Widespread rain chances and breezy conditions develop for Wednesday through Thursday as a strong clipper system tracks through the Northern Plains in northwest flow aloft. At this point, there is low confidence regarding the exact track and how much rain we could see, but the latest guidance does still support the better chance of rain being Wednesday afternoon and evening. Beyond this system, late week looks mainly dry with near seasonal average temperatures continuing through Thursday - highs in the 50s to 60s and lows in the 30s to 40s. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 715 PM CDT Sat May 1 2021 Frontal boundary sagging through KFSD at time, but most winds are starting to decouple pretty well in the vicinity of the boundary. As winds weaken toward/after sunset, low-level wind shear conditions will develop again during the overnight ahead of the front, including the KSUX area. This front will focus the better chances for precipitation by late in the TAF period, but hard to mention much in the way of chances past a couple hours at this point. There may also be some weakening showers moving through KHON after 09z. Otherwise, there is a non-zero threat that some stratus could move north and get close to KSUX toward 12z, but the focus at this point seems far enough eastward to not mention more than a hint with a few/sct layer for the morning. && .FIRE WEATHER... Issued at 229 PM CDT Sat May 1 2021 As of mid afternoon, temperatures have risen in the mid 80s to mid 90s. With dew points in the 30s and 40s, this has fueled very dry conditions with humidity levels dropping as low as the teens across northwest Iowa. The area in the Red Flag Warning is also seeing gusts above 20 mph, occasionally as high as 40 mph, making for extreme fire danger. Elsewhere, fire danger remains very high due to dry conditions and hot weather. We strongly encourage avoiding burning if possible through tonight, even if your location is not included in critical conditions due to having lighter winds. Low humidity levels combined with dry fuels may still support rapid spread of wildfires. After sunset, falling temperatures and weakening winds will reduce fire danger. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...BP LONG TERM...BP AVIATION...Chapman FIRE WEATHER...BP
Area Forecast Discussion
National Weather Service Reno NV
151 PM PDT Sat May 1 2021 .SYNOPSIS... A cold front will bring a few showers and thunderstorms to the region late this afternoon and tonight. Breezy winds and cooler temperatures Sunday, will be followed by another warmup through mid week as high pressure overspreads the west. Pacific low pressure will bring increased winds Thursday and Friday along with cooler temperatures into next weekend, but unfortunately little to no precipitation. && .DISCUSSION... * Cold front dropping through the Great Basin will bring breezy winds through tomorrow along with isolated-scattered showers and thunderstorms this afternoon and tonight. No significant changes to the ongoing forecast with respect to these items. Latest NAM3 and HREF guidance shows sufficient instability along and north of a SVE-RNO-NFL line to produce a few t-storms but nothing overly strong with basically zero updraft helicity noted in HREF. HRRR produces outflow gusts in model convection to about 30-40 mph, so that coupled with brief heavy rains and lightning are the main hazards. * Breezy W/NW winds today will transition to more N/NE tomorrow in the post-frontal airmass. Not an overly impressive wind scenario but gradient is sufficient for winds to remain gusty even overnight tonight, with some stronger N winds possible along Hwy 95 and the Eastern Sierra valleys tomorrow. Typical travel and recreation impacts expected. Localized fire weather concern in lower elevation areas with dry fine fuels and limited greenup. * After a cooler and more seasonable day Sunday, temperatures warm well above normal by Wednesday. Small chance, but not zero, we approach record highs at least at RNO on Wednesday with NBM 75th percentile max temp of 87 - a record tie. * Ensemble guidance from both GEFS and ECMWF showing a decent Pacific trough working towards the west coast late week. This one unfortunately does not have much if any moisture to work with. There does look to be potential for another couple breezy days Thursday-Friday per latest NBM and ECMWF EPS guidance. Most EPS members show 30-40 mph type stuff with 1 in 4 chance of seeing widespread winds 40-50 mph with more appreciable travel and fire weather impacts. For Thursday the latest Hot Dry Windy Index based off the GEFS is up into the 95th percentile for this time of year. * Upper low settles into the Great Basin next weekend and that could be enough to generate a few instability showers. Ensemble guidance is quite noisy so there`s low confidence on those shower prospects. Week two outlook has potential for some showers if that upper low lingers around, but only a small fraction of ensemble members produce any meaningful precipitation. Drought continues. -Chris && .AVIATION... Southwest wind gusts generally in the 20-30 kt range will continue for area terminals through this evening. Showers and thunderstorms will develop north of I-80 this afternoon and evening with some small hail possible. These showers weaken and move south overnight, with showers chances south of I-80 and east of highway-95 through Sunday morning. Winds will shift to the north Sunday with afternoon gusts again in the 20-30 kts range. Expect lighter winds Monday through Wednesday but strong winds, mtn wave turbulence and LLWS are possible for the Thursday through Saturday period. JCM && .FIRE WEATHER... Dry and breezy conditions will continue through this evening with critical conditions for wind prone areas, especially in the Lahontan Basin, Sierra Front, Southern Sierra Front, and Southern Mono County. Breezy north winds to follow tomorrow, but RH will trend a bit higher than today (likely 15-20% tomorrow afternoon). Showers and thunderstorms north of I-80 could bring some spotty wetting rains this afternoon, and outflow wind gusts up to around 40 mph. These showers may shift south overnight, reaching Mono and Mineral Counties by tomorrow morning. There could also be some buildups and isolated showers over the Sierra crest tomorrow afternoon. A low-pressure system forecast for the second half of next week looks to be fairly dry and windy. The timing is uncertain, but at this point Thursday through Saturday are the days with potential for critical conditions due to gusty winds and low RH. JCM && .REV Watches/Warnings/Advisories... NV...Lake Wind Advisory until 11 PM PDT this evening for Pyramid Lake in NVZ004. CA...None. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Topeka KS
1107 PM CDT Sat May 1 2021 ...AVIATION UPDATE... .DISCUSSION... Issued at 349 PM CDT Sat May 1 2021 1. Increasing Clouds--Still a Pleasant Weekend: Another gorgeous, albeit breezy day was in progress this afternoon as the pressure gradient gradually tightens on the backside of our departing ridge. A southern stream cutoff low is slowly working eastward across Texas this evening and will start to eject northeastward tonight ahead of the next main shortwave moving into the Pacific NW. High cirrus were already overspreading the forecast area ahead of this low and clouds should continue to thicken through the afternoon and evening. Lower clouds spread northward overnight and may linger through the morning on Sunday based on a number of shorter range solutions. We may see some breaks in the afternoon, but expect more clouds than sun. Highs will be tempered a bit by the clouds, but with a similar lower-tropospheric airmass in place, readings will still be above average for this time of year. The threat for showers and storms has decreased for the day on Sunday with forcing still weak and increasing inhibition noted on forecast soundings. Trimmed PoPs for the daytime hours to just the far east/SE forecast area. 2. Unsettled Start to the Week Medium range solutions have slowed the eastward advance of a cold front Sunday night into Monday, bringing it through mainly after 06Z. Convection developing off the High Plains may congeal into an MCS and propagate eastward within a corridor of higher theta-e air resulting in 1500-2000 J/kg of MLCAPE/MUCAPE. The lack of deep shear may keep the system from maintaining severe winds for long (cold pool quickly working ahead of the line) and this idea is well- reflected in the 12Z members of the HREF. There still remains some uncertainty in how far eastward the cold front and resultant severe weather threat will push before peak heating on Monday. The general concensus is that the boundary and warm sector will be nearly completely out of the forecast area by this time. The evolution of the Southern Plains lee cyclone during this time will also drive the potential for precipitation in the warm conveyor belt region of the system for Monday night into Tuesday. The EC ensemble members remain slower and wetter than their GEFS counterparts and in general have kept with the NBM PoPs for that timeframe. 3. Pleasant Middle to End to the Week Broad cyclonic flow will persist in the wake of our early week convection, which will keep temperatures seasonal with periods of sun and clouds. The medium to longer range guidance shows one disturbance working through on Thursday, thus have maintained some slight chance PoPs for that period. && .AVIATION...(For the 06Z TAFS through 06Z Monday) Issued at 1107 PM CDT Sat May 1 2021 It appears the stratus may be slower than models earlier progged. The stratus has developed over western KS and the 02Z RAP appears to have the better depiction of this. And the RAP is slower to advect the low clouds into the terminals. But there remains a consensus for the low clouds to move in with CIGS hanging in across eastern KS well into the afternoon. They should improve to VFR as the boundary layer deepens Sunday afternoon. Otherwise the terminals look to remain between the upper low lifting across the Ozarks and the frontal system moving in from the northwest late Sunday night so will keep the forecast free of precip. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Skow AVIATION...Wolters