Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/31/24


Area Forecast Discussion
National Weather Service Columbia SC
1045 PM EDT Sat Mar 30 2024 .SYNOPSIS... An area of strong high pressure and upper ridging keeps the region dry through the weekend with above normal temperatures into the early part of the week ahead. The next chance for showers and thunderstorms arrives on Tuesday into Wednesday as a cold front crosses the region. Cool, dry weather then follows with temperatures near or below normal through the end of the long term. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... High pressure remains in control through the overnight hours; however, the center drifts south and eastward, causing winds to shift to a more westerly direction late tonight. Some high clouds associated with the low pressure system passing to our north along with the relatively flat ridging continuing to build over the region keeps overnight lows rather mild in the upper 40s to around 50. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... Really quiet and beautiful weather is expected during this period, with high confidence in the pattern evolution. Ridging will continue to build through Monday evening, with surface high pressure settling off to our southeast. As a broad area of low pressure develops across the central Plains both days, a tight pressure gradient will develop across the southeastern US. This should lead to both Sunday and Monday seeing winds gusting 20+ mph during the afternoon. As a result, expecting very warm temperatures and a gradual increase in surface moisture as the week begins. Highs are likely to be in the low to mid 80s both days. Some cumulus is likely Monday afternoon as deeper moisture pushes in & surface dewpoints jump up to near 60. Regardless, both days look great and guidance supports this. Expect lows to moderate into the 60s as low level moisture increases in quality and depth. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Tuesday and Tuesday night looks to be the most active weather of the period. While our ridging takes place the prior two days, what will be driving that is a complex upper trough that is currently pushing into the California coast. This trough is forecast by most ensemble and operational models to continue digging & translating into the southwestern US by Monday morning. As this occurs, a northern stream shortwave is forecast to dive into southeastern Canada, elongating the trough axis and slowing the translation of the trough out of the SW US. This is especially true as the strongest jet streak is forecast to lie downstream of the trough axis by this point, which should lift much of the energy northeastward across the central Plains with some vorticity remaining across the SW. A strong shortwave is then forecast to dig out of central Canada into the northern portion of this elongated trough, phasing the northern & southern streams and yielding a deep, closed low over the OH Valley by Wednesday morning. How quickly this happens is up for significant debate between various guidance, and this could have significant impacts on our sensible weather impacts on Tuesday and Tuesday night. Ensemble guidance has been slowly trending a bit deeper and phasing the mid and upper level troughs a bit quicker, similar to some experimental Machine-Learning guidance from the ECMWF. This is notable because if the quicker phasing solution does verify, there is a higher likelihood that the approaching low and front on Tuesday night could yield severe weather. For now, it looks somewhat lackluster, with better chances likely to our west on Tuesday and east on Wednesday. It is something to keep an eye on, though, as the solution of a faster & deeper phasing over the central Plains could be a problem. In any case, Tuesday looks quite warm again ahead of the approaching front, with winds gusting over 20 mph out of the southwest again. Expect highs in the mid to upper 80s. Showers and thunderstorms are possible Tuesday night with this system, but widespread long duration heavy rainfall looks unlikely at this point. The front should push through on Tuesday night, with temps crashing back below normal for the second half of the week. Look for highs in the low to mid 60s and lows in the upper 30s and low 40s. Dry weather is expected through next weekend behind the front. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... VFR expected through the TAF period. Pressure ridge centered off the east coast of Florida with southwest flow across the area. Southwest winds around 5 kts through the early morning. VAD wind profile from KCAE radar indicating west-southwest winds 1500-2000 ft 35-40 kts. RAP and HRRR Guidance are suggesting wind shear through about 11z at the CAE and CUB terminals. The low-level jet is weaker at other terminals. The pressure gradient tightens again Sunday with weak low moving east across VA. So expect southwest winds to continue through the day with a few gusts around 20 knots mainly after 18z. Some high level clouds will spread across the area late tonight and increase Sunday afternoon. A few cumulus clouds will be possible Sunday afternoon mainly near AGS/DNL. EXTENDED AVIATION OUTLOOK...No significant impacts to aviation through Tuesday morning. Scattered to numerous showers and thunderstorms ahead of a cold front late Tuesday into Wednesday morning may lead to restrictions. Strong gusty winds possible Wednesday afternoon behind the cold front. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$
Area Forecast Discussion
National Weather Service Cheyenne WY
920 PM MDT Sat Mar 30 2024 .KEY MESSAGES... - Another band of locally heavy snowfall is expected to develop late this evening across Carbon, Albany, Converse, and Niobrara counties. Expect significant variability in snow totals over fairly small distances. - A final round of snow remains on track for Sunday late afternoon into Monday with banded snowfall expected over portions of the High Plains. The exact location of more significant impacts remains uncertain. && .SHORT TERM /THROUGH MONDAY/... Issued at 400 PM MDT Sat Mar 30 2024 A complex storm system continues to impact our area this afternoon, with several components leading to a somewhat uncertain outcome. Current satellite imagery shows the primary closed low responsible for this weekend`s unsettled weather located off the central California coast, with moisture streaming out ahead of it in southwest flow aloft. Another vort-max has ejected out ahead of the main trough and is moving into the area this afternoon, marked by increased atmospheric water vapor on satellite imagery. While a relative lull in precipitation is in place across the area, this should begin to fill in again soon. The persistent diffluent flow over the Rockies is beginning to produce pressure falls over east central Colorado this afternoon, which should renew isentropic lift in the 850-650 mb layer. This is causing showers to re-develop over the High Plains this afternoon. This activity should continue through about 3AM or so, and wouldn`t be surprised to see a few rumbles of thunder embedded. Most of this activity will remain north of I-80. Further north and west, the presence of the stalled frontal boundary will complicate the forecast somewhat. Isentropic lift combined with modest frontogenesis and the vicinity of the left exit region of a 130-knot upper level jet streak is expected to lead to another round of banded snowfall. Currently, this band is visible as a train of shower activity around the Muddy Gap area towards Casper, but HiRes model guidance generally shows this deteriorating and being replaced by another band slightly further south that will then shift north through Sunday morning. While earlier runs were in pretty good agreement on a position generally from Rawlins to Lusk, later HiRes model runs have abandoned this consensus. Thus, we still don`t have the confidence to say exactly where this band will leave its heaviest snow. However, with the expected southward jog of the frontal boundary tonight, think that temperatures will run on the cooler side north of this, leading to a faster change-over. Therefore, decided to expand the Winter Weather Advisory to include Converse and Niobrara counties. While advisory criteria snowfall is not expected to cover the whole county, a narrow band is likely to drop impactful accumulations of 3-6 inches somewhere in the zone. Warning criteria amounts are likely to show up somewhere in Carbon county, but don`t have the confidence for any upgrades due to the uncertainty in the exact position of the banded snowfall. This band of snow should move mostly north of the area by late morning Sunday, putting another lull in place across the area. This will be fairly short lived though. Cold air advection aloft in advance of the main system will steepen lapse rates, leading to several hundred J/kg of CAPE by Sunday afternoon. Showers should develop by mid afternoon. This should be rain south and east of a Cheyenne to Glendo to Alliance line, with snow mixing in outside of this box. HiRes model guidance shows the surface frontal boundary pushing back south tonight, and with northeast winds in place, expect it to hold stronger on Sunday than it did today. Therefore, cut temperatures down towards the low end of the NBM spread for the US-20 corridor once again. The final phase of this system remains extremely complex and highly uncertain. As the surface low strengthens to our south, it will draw the front back to the south Sunday afternoon and evening, leading to a rapid change-over back to snow for the warmer areas mentioned above. A secondary 500-mb low north of the main trough located over central Wyoming during this period will complicate the typical wrap-around flow. Divergent handling of the transfer of energy from this central WY low to the developing Colorado low is resulting in a very large spread in outcomes for snowfall Sunday night into Monday. The ECMWF/GFS/RAP/HRRR solution keeps the developing low suppressed to the south and keeps the old low stronger for longer. The result of this is that effective wrap-around flow never really develops, leaving us mostly dry Monday during the day and limiting QPF. However, another solution shown by the NAM and several GEFS members shows a stronger Colorado low closer to our area with potent wrap- around moisture leaving fairly widespread snowfall across the area through the day on Monday. These two solutions result in a very large spread in potential snowfall outcomes for the area, with the HRRR showing little to nothing south of the Pine Ridge, and the 3-km NAM showing a widespread 4-8" over this area. With this little confidence, decided not to do anything with headlines once again (since this also may distract from the more immediate phase of this system discussed above). Overall, leaning towards the drier scenario with the official forecast at this time, but will need to monitor model trends over the next 12-24 hours for the higher end potential. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 400 PM MDT Sat Mar 30 2024 Looking at a speedy warm-up in the long term once the precipitation associated with the Sunday/Monday system moves out. The upper-level trough responsible for the precipitation will push eastward on Tuesday, allowing a strong ridge to build in its place. Temperatures will jump a solid 10 to 15 degrees on Tuesday compared to Monday`s high. This will put highs around average for early April. Temperatures continue to warm on Wednesday with the ridge axis shifting over Wyoming. Highs will jump another 10 to 15 degrees with temperatures in the 60s and low 70s east of the Laramie Range and 50s to the west. Last little push of warmth will happen on Thursday as southerly winds advect warmer air into the CWA. This warmth will continue into Friday with highs both days in the upper 60s and 70s for the plains, and 50s and 60s out west. Currently, high temperatures do not look to be in record warmth territory, however, highs will be about 15 degrees above average. Expect mostly sunny skies Tuesday through Thursday as subsidence under the ridge keeps conditions dry. Heading into Friday evening, both the GFS and ECMWF are in good agreement with a Pacific trough moving into Wyoming. Although this is still a week out, this could be the CWA`s next precipitation maker. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 911 PM MDT Sat Mar 30 2024 Southwest flow aloft will continue with weak disturbances in the flow, and a stationary front draped across the area. Wyoming TAFS...At Rawlins, ceilings will be near 2500 feet until 15Z, with occasional visibilities near 1 mile in snow and fog and ceilings near 500 feet until 10Z, then ceilings will increase to 5000 feet after 15Z. At Laramie, ceilings will range from 2500 to 5000 feet until 00Z, then lower to 1500 feet with visibility 2 miles in light snow and fog. Visibilities will be near 5 miles in light rain from 18Z to 00Z. At Cheyenne, broken ceilings will be near 1200 feet until 08Z, then ceilings will be near 4000 feet until 00Z, then lower to 1500 feet with visibilities near 2 miles in light snow and fog after 00Z. Nebraska TAFS...At Chadron and Alliance, ceilings will range from 1500 to 2500 feet, with occasional visibilities from 2 to 3 miles in light rain, snow and fog. At Scottsbluff and Sidney, ceilings will range from 1500 to 6000 feet, with occasional visibilities near 2 miles in fog until 10Z, and then visibilities near 2 miles in light snow and fog after 00Z. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Weather Advisory until noon MDT Sunday for WYZ101-102. Winter Weather Advisory until 9 AM MDT Sunday for WYZ103>105- 109>111-113. Winter Storm Warning until 6 PM MDT Sunday for WYZ112-114. NE...None. && $$ SHORT TERM...MN LONG TERM...SF AVIATION...RUBIN
Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
610 PM CDT Sat Mar 30 2024 .KEY MESSAGES... - Multiple rounds of showers and storms are expected late tonight through Tuesday morning. There is a marginal (level 1 of 5) risk of severe weather Sunday evening/night. A greater severe risk is apparent on Monday, with all hazards possible, mainly south of I-70. - Storm total rainfall for the event is forecast to range from 0.75 to 2 inches, with the greatest totals east of U.S. Highway 65. - Cooler and drier weather will briefly return for the middle of next week, with a quick warm-up to follow by the end of the week. && .DISCUSSION... Issued at 213 PM CDT Sat Mar 30 2024 Temperatures have struggled to warm this afternoon, with light northerly winds continuing to supply just enough cold advection to inhibit more substantial warming. High clouds have also impeded insolation a little bit, keeping highs a few degrees below what they were expected to be at this time yesterday. Meanwhile, there are signs the long-advertised warm front/baroclinic zone is developing, with winds in Kansas veering to a more east-northeast direction and southerly surface flow nosing northward into far southwest Missouri. Meanwhile, upper-air analysis from 12z reveals low-amplitude but broad ridging encompassing much of the central U.S., with a digging and potent trough near the West Coast. A midlevel zonally- oriented jet streak stretched from the Intermountain West to the Ohio Valley, with subtle vorticity maxima present on moisture-channel imagery along this axis. Signs of surface cyclogenesis in the lee of the Rockies were present, with increasingly cyclonic surface flow in the central/southern Great Plains. Examination of the 00z ensemble data continues many of the same themes from yesterday: the GEFS has a more potent leading vort max as it lifts northeastward into the central Plains on Monday, with the GEPS (CMCE) considerably more suppressed and delayed. The EPS (ECMWF) remains in between the two extremes. So many of the uncertainties in the forecast for early this coming week remain, though the advent of convection-allowing models through the weekend has permitted some improved confidence regarding convective potential and evolution through Sunday night across the CWA. The first round of convection is expected to develop late tonight as a low-level jet noses northeastward to the lower Missouri Valley atop a tightening baroclinic zone stretching east-to-west across Kansas and Missouri. Surface observations this afternoon suggest a placement somewhere close to the Missouri River, with showers and isolated storms developing near and north of the boundary some time late tonight into the morning hours. HREF timing is consistently around daybreak tomorrow, with initiation in vicinity of (or just east/northeast of) the KC metro area. Isentropic ascent will continue through much of the day as an attendant perturbation progresses through the region, allowing convection to persist for much of the day in a corridor from southern Iowa and northern Missouri eastward. Used HREF-based PoPs for the forecast through this period, with the best chances (40-60 percent) generally along and north of U.S. Highway 36 and east of I-35. HREF deterministic members generally agree on most of the convection moving eastward from the CWA by afternoon, with the warm sector edging northward and remaining unperturbed through the diurnal cycle. By evening, another perturbation will approach the Missouri Valley, with (some) convection-allowing models initiating another round of storms around 00z. The 12z/18z HRRR initiate storms in a northeast-southwest broken line in vicinity of I-35, for example. A look at various HREF member model soundings indicate MLCAPE around 1000 J/kg and 0-6 km bulk shear approaching 60 kt in the pre-convective environment (and 0-1 km SRH exceeding 100 J/kg). This near-storm environment would be favorable for all hazards, though marginal boundary-layer moisture would likely inhibit a more significant tornado threat. However, convective initiation is not guaranteed, with impacts of predecessor morning convection and residual capping inhibiting factors. Should capping hold, another round of elevated convection would be favored farther north of the warm/quasi-stationary front Sunday night, with marginally severe hail the primary hazard. This leads to the question of how Sunday night`s convection influences the severe potential on Monday. GFS-related guidance continues to indicate a strong cyclone with widespread storms in advance in much of the Missouri/Mississippi Valleys Sunday night and Monday. Notably, however, the low track is farther south than yesterday, which makes sense given (1) the strength of the southern-stream dynamics associated with the system and (2) the influence of antecedent precipitation shunting the warm sector farther south with time. This would keep the highest severe potential mostly south of the region. The CMC-related guidance is slower, allowing for somewhat improved recovery in the central Plains and perhaps better timing for more vigorous convection toward the I-70 corridor in the afternoon/evening. Of note, the NAM and NAM Nest solutions are qualitatively similar to the slower/more suppressed guidance. At this stage, it seems reasonable to infer that the greatest severe potential is south of I-70 on Monday, with the northernmost extent contingent upon the prior convective evolution Sunday night and Monday morning. No matter the model suite that verifies best, it appears widespread convection is still in the cards Monday and Monday night. Precipitation would be most welcome, with general QPF of 0.75 to 2 inches (lowest northwest and highest east) for this event by Tuesday afternoon. Models have continued to slow the system as it passes the region, and especially as it continues to strengthen to our east. As such, PoPs linger through at least Tuesday morning in most of the area, with precipitation moving out of the far east CWA during the afternoon/evening. Stout cold advection in the wake of the departing low should bring a sharp cooldown for the middle of next week, with another couple of nights of near-freezing to sub-freezing temperatures to the area. Wednesday night looks to be the coldest night, with a widespread freeze possible (probability of sub-freezing temperatures in much of the area greater than 40 percent). Otherwise, dry weather is expected for the rest of the week, with warming conditions after the midweek cool spell. Highs by Friday will be well above seasonal averages again, with upper 60s and lower 70s progged. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 610 PM CDT Sat Mar 30 2024 Lo conf TAF this cycle with the surface front in the VC of the TAF sites til late in the TAF pd. VFR conds are expected to prevail til 09Z-12Z when MVFR cigs are expected to develop at the TAF sites. Cigs are then expected to further sink to IFR btn 12Z-14Z with the chc for lgt shra in the VC. Cigs are expected to lift back to MVFR around 18Z before becmg VFR aft 20Z. Winds to begin the pd will be out of the NE before becmg easterly aft 05Z. By 13Z winds will veer to the SE before becmg southerly aft 18Z. Winds speed will be generally btn 7-12kts however southerly gusts to 20-25kts are expected at IXD and MKC aft 18Z-20Z. && .EAX WATCHES/WARNINGS/ADVISORIES... MO...None. KS...None. && $$ DISCUSSION...CMS AVIATION...73
Area Forecast Discussion
National Weather Service Green Bay WI
1048 PM CDT Sat Mar 30 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - There is a 50-70% chance of light rain over central and east- central Wisconsin from late Sunday afternoon through late Sunday night. While some snow may mix in with the rain on Sunday night, little to no accumulations are expected. - A second round of wintry precip is expected to impact the forecast area on Monday and Monday night. Rain and snow will both be possible, although there is still uncertainty in the track of the system. - Quiet conditions and near to slightly above average temperatures return mid-week. && .DISCUSSION... Issued at 328 PM CDT Sat Mar 30 2024 Short Term...Tonight and Sunday The latest RAP analysis and satellite/radar imagery show an area of low pressure moving into northeast Ohio while shortwave energy is passing across the northern Great Lakes. Precip associated with the shortwave will be exiting far northeast Wisconsin by issuance time, but there is widespread low overcast upstream getting pushed into northern Wisconsin via northwest winds. Some of this low overcast is eroding on the southern flank as it runs into stronger mixing where there is sunshine over southwest Wisconsin and southeast Minnesota. A cloudy high pressure system resides over the northern Plains, while the next precip maker is currently over the central Rockies with high cloud cover already spreading into the northern Mississippi Valley ahead of it. Besides cloud cover, forecast concerns mainly revolve around light precip on Sunday afternoon from this system. Clouds and Precip Chances: Weak high pressure will be building into Wisconsin tonight. Think some clearing is possible over central and north-central WI later this afternoon and into this evening as thermal troughing is relatively flat. Not as confident over north- central Wisconsin where clouds are relatively solid. But if clouds erode, temps could reach their lows this evening before mid and high clouds quickly return by late evening or overnight. As a warm front aloft moves into Iowa and northern Illinois on Sunday, clouds are expected to thicken through the day. Fgen is expected to increase with the tightening thermal gradient that could lead to sufficient saturation for light precip after about 3-4 pm over central to east-central Wisconsin. Temperatures will be warm enough for only rain to occur. Temps: Even with a slackening pressure gradient and light winds, counting on broken to overcast clouds to prop up temps and prevent them from tanking tonight. Fresh snow cover makes this a dicey proposition, so just went slightly below the NationalBlend over north-central WI. On Sunday, lowered temps a few degrees based on 925mb temps and cloud cover. Highs will range from the low 40s over Vilas county and near the Lakeshore to 50 degrees at the warm spots. Long Term...Sunday Night Through Saturday Main focus from this forecast period revolves around the potential for wintry weather from Sunday night through Wednesday. Models continue to show a southern trend with the precip chances during this time. Therefore, chances for a rain/snow mix have shifted further south, mainly along and south of Highway 29, while the north should be precip-free. Sunday night through Wednesday...F-gen driven moisture/precip flowing along an upper-level zonal flow, spreading from NE to PA, will attempt to lift into WI Sunday evening. While some models have this precip band lifting into the southern portion of the forecast area, others keep the precip south of the CWA due to the presence of mid-level dry air dropping down from the north. Lowered rain and snow chances and kept them along and south of Highway 29 as a result, but did not want to go with a dry forecast across the entire CWA given some CAMs indicate this precip band setting up in this area. If this precip occurs, it would mainly be rain, but snow could mix in along the northern edge. A lull in the precip is anticipated from at least late Sunday night into Monday morning ahead of an approaching Colorado Low. Plenty of uncertainty remains with the timing and placement of this Colorado Low, as there are issues with how the upper-level pattern will evolve with the phasing of two troughs overhead. Models continue to keep the bulk of the moisture associated with the Colorado Low to the south of the region Monday into Monday night due to the continued presence of mid-level dry air. But, there are still some ensemble members indicating precip lifting into the southern portions of the forecast area, mainly south of Highway 29. Kept chances for rain and snow in these areas mainly during Monday afternoon and evening. Uncertainty continues with where the Colorado Low will track Monday night into Tuesday as this is when the upper-level troughs finally phase together. If the low has a more northeasterly track across northern IL, as some ensemble members are depicting, there will be a higher chance for portions east- central WI to see accumulating snow Monday night into Tuesday. However, this solution is trending drier. If the track is further south along the Ohio River Valley, like many other ensemble members are depicting, the forecast area may remain precip-free. Given the large model spread, kept the blend of models solution during this time with chances for rain and snow staying along and south of Highway 29. Late Tuesday into Wednesday, guidance indicates a large upper-level closed low developing overhead, causing the surface low to potentially retrograde over the eastern Great Lakes region. Depending on how far west it retrogrades, portions of eastern WI may see continued chances for rain and snow during this time. Rest of the extended...The upper-level closed low will gradually shift eastward on Thursday and make way for an upper-level ridge building towards the region. This ridging will set up over the region through at least the first half of the weekend, keeping conditions dry and allowing temperatures to rise above normal into the 50s. && .AVIATION...for 06Z TAF Issuance Issued at 1048 PM CDT Sat Mar 30 2024 Widespread MVFR to low-end VFR stratus will prevail across the region into Sunday. Some breaks may try to develop in the low clouds late tonight into Sunday morning, though it is uncertain where that will occur. The next chance for light rain (VFR visibility) arrives at the very end of the TAF period, but only across the southern portion of the forecast area. Besides ceilings, aviation impacts will be low. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....MPC/Kruk AVIATION.......JLA
Area Forecast Discussion
National Weather Service Grand Rapids MI
737 PM EDT Sat Mar 30 2024 .KEY MESSAGES... - Rain Returns Sunday Afternoon - Active Weather Monday Night Through Wednesday && .UPDATE... Issued at 450 PM EDT Sat Mar 30 2024 Based off of local webcams, the fog has thickened up along the lakeshore. The HRRR suggests is could last for a few hours. I updated to grids to reflect this and amended the nearshore and zone forecasts. && .DISCUSSION... Issued at 330 PM EDT Sat Mar 30 2024 - Rain Returns Sunday Afternoon Deeper moisture is peeling off to the east by this evening with showers ending but low stratus clouds and possibly patchy drizzle persisting for several hours this evening. The low clouds should start to break up by sunrise as RH profiles show moisture becoming shallow by 12Z although mid and high clouds remain. The break in the rain is brief with the next wave moving east along a very active baroclinic zone aligned from the Plains through the Ohio Valley. Rain showers will be forming in an area of isentropic ascent across southern and central Lower Michigan on Sunday afternoon with increasing frontogenetic forcing Sunday night. There could be p-type issues across our northern zones Sunday night as colder air filters south and GFS and NAM model soundings show a mix with or change to snow can be expected before the precip ends late Sunday night. - Active Weather Monday Night Through Wednesday Persistent upper-level zonal flow pattern finally begins to break apart late Monday into Tuesday as several upper waves merge and deepen over the Great Lakes. Given the complex interactions between these upper waves there still remains a good deal of uncertainty on forecast details at this point. Low chance for precip (likely in the form of rain) Monday evening across Southern Michigan as a stationary front sets up south of the state line. Tuesday morning/afternoon sees better precip chances as a surface low approaches from the southwest and travels into the Ohio Valley. The flow will begin to shift northerly and a deformation band will set up across Lower Michigan. By Tuesday night to early Wednesday the upper level waves merge and deepen into a cutoff low. In response, the surface low deepens and retrogrades into Eastern Lower MI and Southern Ontario. Lower Michigan becomes socked into the cold sector with 850mb temps dropping towards -5C to -7C. At this point northerly winds will turn gusty due to the deep surface low to the east and snow will begin to mix in. Important details such as the track of the low, timing, and precipitation amounts remain uncertain, but there does seem to be good ensemble consensus that some amount of accumulating snow will be likely late Tuesday through Wednesday. Can`t rule out travel impacts Wednesday due to snow, but as previously stated, forecast details including snowfall amounts remain uncertain at this time. The surface low departs east late Wednesday to early Thursday and ridging moves in. Conditions gradually dry out Thursday with temperatures on the upswing into the end of the week. Wednesday should be the coldest day of the week with highs near 40 and by Saturday we should be back into the mid 50s. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 737 PM EDT Sat Mar 30 2024 Large area of MVFR to IFR ceilings and visibility remains in place this evening, as moist air below 3,000 feet is cooling while air above 3,000 feet is drying. Guidance suggests some improvement in conditions around Muskegon (MKG) to Mount Pleasant (MOP) late tonight. However, expecting most TAF locations (particularly AZO- BTL-JXN) to be predominantly IFR through late Sunday morning. After 15 Z, better mixing of the lower atmosphere via daytime heating may result in MVFR stratocumulus hanging on until later in the afternoon. && .MARINE... Issued at 330 PM EDT Sat Mar 30 2024 North to northeast winds 10 to 20 knots might make for some chappy waves around Big and Little Sable points, otherwise fairly calm conditions through the weekend. Northeast winds will pick up on Tuesday and Wednesday and waves will build greater than 4 feet late Tuesday with gales possible by Wednesday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ UPDATE...MJS DISCUSSION...Ostuno/Thielke AVIATION...CAS MARINE...Ostuno
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
946 PM EDT Sat Mar 30 2024 .SYNOPSIS... High pressure remains over the area with warming temperatures this weekend. The work week starts dry with a cold front crossing the region by mid week, increasing shower and storm chances. Much cooler and drier air returns for the latter half of next week. && .NEAR TERM /THROUGH SUNDAY/... As of 930 PM: Tonight, a surface low tracks into the northern Mid-Atlantic with a trailing cold front pushing into the Central Appalachians. A little moisture south of the front within westerly flow may produce a stratocu deck along the northern NC/TN border late tonight thanks to upslope forcing. A few sprinkles or drizzle could result there, but a look at HRRR profiles near the mtn spine reveals so little moisture that PoPs were reduced well below 10 percent. Temps have been running above the forecast so far this evening at the sites where winds persist, but seeing how a few sites have managed to go calm already and temps slipped there, still feel good with min temps slightly on the lower side of guidance. That still however suggests values on the order of 5 to 10 degrees above normal. The front moves back northward Sunday as a weaker low pressure center moves east along it. There will be another weak lee trough over the area, but the overall pressure gradient will be less than the previous few days. There my be some low end gusts by afternoon, but overall winds will be lower than the previous few days as well. There will be cirrus and possibly some stratocu developing with warming, but there will still be quite a bit of sunshine. We already were carrying PoPs below slight-chance, but with this update lowered values even further, seeing continued lack of moisture and weak subsidence inversion on prog soundings. Southwesterly winds and rising heights/thicknesses will keep the warming trend going. Highs will be around 15 degrees above normal, which may threaten records (see Climate section below). && .SHORT TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... As of 205 PM Saturday: Quiet conditions start off the short term period, with a change coming by mid-week. The region remains under a steady quasi-zonal flow aloft as a deepening low off the west coast strengthens. To the south, an amplifying area of high pressure slowly slides eastward as the trough out west deepens and moves toward the central CONUS. Ahead of the system, guidance shows a broad warm sector setting up across the southeast as PWATs steadily increase due to the SW flow from the surface high off to the south. Monday remains dry and quiet, but the weather starts to change come Tuesday and Tuesday night. Over the central CONUS, guidance from both the GFS and EURO indicate the upper low strengthens and lifts toward the Midwest and Ohio Valley, leaving behind a very positively tilted trough elongating toward the east. The low gets caught in a semi blocking pattern up north and a strong FROPA aims to sweep across the CWA Tuesday night into Wednesday. As for any severe potential, guidance from the GFS and EURO develops a modest amount of sbCAPE and muCAPE across the CWA Tuesday afternoon through the evening. Modeled soundings show a mid-level inversion, keeping a cap in place for any muCAPE to be taped into until later in the evening. Another questionable and less favorable factor is the lack of forcing from the upper jet, which continues to remain north of the CWA. Current guidance keeps the sfc-3km shear around 40 to 45kts, but parallel shear vectors. The misalignment of the forcing and instability could keep storms strong, with a few severe, especially over the mountains on Tuesday night. By Wednesday morning, FROPA should continue to march across the CWA, wiping out moisture and lowering temperatures to near climo. Additionally, with the tight pressure gradient, expect winds to be gusty across the entire area Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... As of 215 PM Saturday: By the start of the extended forecast, an omega blocking pattern starts to form across the CONUS. As the strong low churns over the Ohio Valley, it reinforces NW flow aloft Wednesday night through the remainder of the period. Colder and drier air is expected to spill across the mountains, with a brief stint of NW snow possible across the higher elevations of the NC mountains on Wednesday night. By Thursday, guidance from the GFS shows the drier air dominating and wiping out any remnant surface moisture, cutting off the remaining few snowflakes fluttering around the higher elevations. Little to no accumulations are expected at this time. Aloft, as the ridge amplifies over the central CONUS, NW flow persists through the end of the forecast period, with lee troughing across the mountains decreasing. This should help bring those gusty winds down, but the area should remain breezy. High temperatures will start to feel rather cool compared to the start of the week, with the drier and cooler Canadian air filtering in and persisting through the period. Expect temps to dip down below climo with much of the area east of the mountains to remain in the 60s. Overnight temps will also dip into the 30s and low 40s, but outside the mountains, guidance at this time keeps temps above freezing. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: VFR under only FEW-SCT cirrus tonight at the TAF terminals. Gusts still being reported at many obs sites at issuance time, but think these are likely to cease within the first couple hours of the TAF. Not expecting there will be enough cloud cover to inhibit radiation tonight, but gradient looks enough to keep winds from going calm, but mostly will fall below 6 kt after midnight. They should remain from the SW except at KAVL, which will stay NW into morning. LLWS criteria could be met just downwind of mtn ridges but not likely enough at KAVL to mention. Some low VFR cloud cover may develop near the TN border tonight but not likely seen at any of the sites. On Sunday, winds will pick up by late morning but are not expected to be as strong, with gusts infrequent and likely remaining less than 20 kt. Cirrus may increase during the afternoon. Outlook: VFR thru Monday as dry high pressure lingers over the region. Rain chances increase along with their associated restrictions on Tuesday and Wednesday as a cold front moves in from the west. Low clouds and scattered showers may linger over the mountains Thursday with gusty NW wind most locations. && .FIRE WEATHER... Overall wind speeds and gusts will be lower on Sunday than we have seen the past 2-3 days. Despite the continued warming trend, increases in low level moisture on the southwesterly flow will keep RH values above 25 percent. However, they will drop into the upper 20s to around 30 percent range. All this should be enough to preclude the need for a Fire Danger Statement. However, if temps are warmer or dew points lower, then one may still be needed. && .CLIMATE... RECORDS FOR 03-31 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 81 1963 39 1906 62 1938 20 1964 KCLT 86 1986 36 1887 63 2022 21 1964 1998 1938 KGSP 86 1986 44 1915 62 1998 24 1964 RECORDS FOR 04-01 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 83 1974 40 1919 60 1927 20 1923 KCLT 86 1986 40 1887 64 1998 24 1923 KGSP 85 2010 45 1965 62 2016 24 1900 1986 1896 1910 && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...CP NEAR TERM...RWH/Wimberley SHORT TERM...CP LONG TERM...CP AVIATION...Wimberley FIRE WEATHER...RWH/Wimberley CLIMATE...GSP
Area Forecast Discussion
National Weather Service Louisville KY
933 PM EDT Sat Mar 30 2024 ...Forecast Update... .KEY MESSAGES... * Breezy today with chances for showers and thunderstorms late this afternoon and evening. A strong storm or two cannot be ruled out, but severe weather is not expected in general. * Easter Sunday morning showers and some storms will move through the region. Small hail and gusty winds are possible in stronger storms. * Stormy pattern early next week, especially Monday night and Tuesday. Most likely timing for strong/severe storms would be after midnight Monday night through the daytime hours Tuesday. Confidence in the occurrence of storms is high, but confidence in exact storm evolution and timing remains low at this time. * Cold blustery weather arrives by Wednesday with the potential for snow across portions of the area by late Wednesday night into early Thursday morning. Little or no accumulation is expected. && .UPDATE... Issued at 933 PM EDT Sat Mar 30 2024 Storms have fired along the W-E oriented frontal boundary over the past couple hours, and have mostly produced pea to half inch hail. Earlier this evening, storms seemed to struggle around and above 20 K feet and AMDAR/RAP soundings showed a subtle inversion around that height. However, data also showed that mid level inversion eroding with time through the evening. More recently, we`ve seen a stronger supercell develop over the IND/PAH border and is now moving into Dubois county. This storm is marginally severe and in a favorable environment for maintenance. So, will continue to track it as it moves along and north of I-64. Mainly a hail threat, although can`t rule out an isolated damaging wind gust given the dry low levels and inverted V type of sounding near the surface. Should be a bit of a stable layer setting up near the surface with sunset, but overall think any stronger downburst winds might be able to punch through with a good enough core drop. Overall, expect convective activity to continue along the nearly stationary boundary through the night. Most activity should be sub- severe however can`t rule out a few stronger storms, especially if that eroding mid level inversion yields some better elevated instability values. Previous Update... Things are quiet across the CWA at the moment, although a couple of key features to watch over the next 1 to 2 hours for possible convective initiation. First off, visible satellite imagery shows some notably more agitated/congested cumulus over far SW Illinois in the vicinity of KMVN/KMDH/KSAR. This has been an area of focus on latest runs of the HRRR as a convective initiation point generally between the 22 and 00z time frame. We are seeing a slight uptick in surface moisture convergence to around 5 g/kg on the latest SPC mesoanalysis, so do think if we are going to see something soon, it will be in this area. From there, convection would likely head eastward as it moves down and roughly along the I-64 corridor into the evening hours. If convection is able to fire, the environment does appear to support some sustained updrafts as modest instability combines with more than enough deep layer shear. We should become more stable near the surface the deeper into the evening we get, so the main threat would be small hail, and perhaps some gusty winds. Stable layer should mitigate most of that, however the dry low levels and a bit of an inverted V sounding in the low levels does cause some concern for gustiness if you get a strong enough storm. Overall, don`t expect anything severe and still not 100% sure we are going to be able fire anything off for a while given a bit of an H7 inversion. Forecast is on track, just highlighting some areas to watch over the next couple of hours. && .SHORT TERM /THROUGH SUNDAY/... Issued at 258 PM EDT Sat Mar 30 2024 This afternoon and evening... The low pressure system and associated fronts currently located over southern Lake Michigan will continue to propagate southeast. As the cold front approaches the region, it will slow and eventually stall into a stationary front over the Ohio River. This front, coupled with increased moisture into the region should lead to enough instability to initiate convection around 22- 23Z. With steep lapse rates, could see some gusty winds and small hail with convection. With sunset, instability will rapidly diminish and showers and storms will dissipate. Tonight and Sunday... The quasi-stationary front will meander near the Ohio River in the overnight and morning hours. Another wave of showers and some embedded storms are possible as a 35-40kt LLJ moves through the region and continuous moisture is pumped into the low levels. Showers and storms are most likely along the frontal boundary in the I-64 corridor beginning at about 8Z and lasting until mid-morning. Weak, but sufficient instability, 35-45kts of effective bulk shear, and steep mid-level lapse rates could lead to a hail threat. Low temperatures will be in the 50s, with a gradient of low 50s in the north and warmer to the south. In the afternoon, the stationary front will begin to lift north and the region will be deeper within the warm sector. This will allow a stronger lid to develop and diminish chances for convection. Could see some showers and isolated storms over southern Indiana closer to the boundary. Continued southwesterly flow and warm air advection will bring high temperatures into the mid-upper 70s and even touching 80 in some areas. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Issued at 258 PM EDT Sat Mar 30 2024 Warm front will keep most of Sunday night`s convection focused north of our area, more toward the I-74 corridor. Can`t rule out a few showers or storms across some of our southern Indiana or northern Bluegrass counties, so we`ll keep a 20-30 POP there during the early evening. Frontal position a bit uncertain as it could wave north and south a couple times as sfc lows ride east along the front. Monday the warm front stays just north of southern Indiana/central Kentucky. However, as the day progresses the column will moisten and the cap will weaken as low pressure crossing Kansas and a Bermuda high pump Gulf moisture northward. H5 speed max will also be approaching from the west by late afternoon, and its interaction with the front will spark convection mainly across eastern MO/central IL/west-central IN. AS a result POPs really ramp up over our southern Indiana counties late in the day as storms approach. The strongest sfc waves eject out of SE Kansas/NE Oklahoma Monday night, with the first crossing southern Indiana just before daybreak Tuesday and the other during the afternoon. Convection will fire near or just NW of the Ozarks late Monday, and approach southern Indiana and central Kentucky in the pre-dawn hours of Tuesday as an increasingly messy squall line. Even with weakening convection, all severe modes are still on the table with strong winds just off the surface, strong shear, and moderate instability. Proximity to the warm front and backing of winds with sfc waves could enhance helicity enough to support spin-up tornadoes, and that threat lines up well with SPC`s Day 2 Slight over southern Indiana. Severre wx chances on Tuesday are dependent on the timing of cold fropa, which could shunt the better chances more into eastern Kentucky if the front crosses our area during the diurnal instability minimum. Flood potential will be limited by fairly quick storm motion, but there`s the chance for enough repeated convective rainfall to support a Marginal flash flood risk over southern Indiana and north of I-64 in Kentucky. At this time that looks like a short-fuse, flashy threat rather than any mainstem river flooding. Winds outside of thunderstorms will increase considerably as well, with 30-40 mph gusts likely late Monday night and most of Tuesday. Strong cold advection sets up behind the front Tuesday evening, and a deep closed upper low drops through the Great Lakes. Wednesday looks showery and unseasonably cool under a strong cold pool. Max temps will struggle to get out of the 40s, and as we cool well into the 30s Wed night, any lingering precip could change over to snow with fairly steep low-level lapse rates. At this point it doesn`t look like anything more impactful than a dusting of accumulation on grassy or elevated surfaces. Upper trof finally lifts out Thursday to begin a moderating trend, which could initially be slow as just enough cyclonic curvature remains that clouds could be stubborn. Better chance for clearing will be Friday as heights rise and the sfc high drifts into the Mississippi Valley. && .AVIATION /00Z TAFS THROUGH 06Z TUESDAY/... Issued at 736 PM EDT Sat Mar 30 2024 Showers and a few storms have developed along a W to E oriented frontal boundary across the area. Given the nearly stationary aspect of this front, it could bring a prolonged threat of a few showers and storms to all of the TAF sites along and near the I-64 corridor through mid to late morning on Sunday. After that, it is expected to lift north as a warm front, temporarily taking the threat of showers and storms away. In addition to the shower and storm threat, also expect some lowering ceilings after Midnight at all four I-64 TAF sites (HNB/SDF/LEX/ RGA). The ceilings could settle on either side of the 2K foot mark, but fully expect some MVFR either way. Some minor vis restrictions could also occur in this corridor, although lesser confidence in that scenario. Surface winds will be light and variable while the front hangs over the area, and then take on a SSW component through the afternoon on Sunday as the warm front lifts north. BWG will stay south of all of this activity, and only expect some mid level clouds, but continued VFR through this forecast cycle. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE...BJS SHORT TERM...SRM LONG TERM...RAS AVIATION...BJS
Area Forecast Discussion
National Weather Service Marquette MI
1055 PM EDT Sat Mar 30 2024 .KEY MESSAGES... - Quiet weather through tonight. - Snow from developing system in the Great Lakes late Monday to Wednesday appears like it will stay mostly south and east of the forecast area. - Temperatures will trend to above normal by next weekend. && .SHORT TERM /THROUGH TONIGHT/... Issued at 223 PM EDT Sat Mar 30 2024 Upper air pattern consists of a 500 mb closed low off the CA coast, a shortwave in Saskatchewan, and a shortwave in the upper Great Lakes. The shortwave will be moving out of the upper Great Lakes while the next shortwave moves towards Lake Winnipeg by this evening. This next shortwave moves into western Ontario by 12z Sun. Snow continues to wind down across the area as the narrow band of snow, heavy at times moved through. The snow has been moving out quicker than what models are depicting, so have been playing catch up with this all day. A quick 1-3 inches of snow fell with that band in about an hour or two. This will have moved out late this afternoon and dry, but mostly cloudy weather will set in. Overall, did not make too many changes to the going forecast. && .LONG TERM /SUNDAY THROUGH SATURDAY/... Issued at 304 PM EDT Sat Mar 30 2024 There`s remarkable agreement in the overall structure of the forthcoming pattern across North America when considering the 0z and 12z deterministic guidance packages. The Canadian, GFS, and Euro all highlight the near zonal flow across the Northern Plains and deep troughing moving into the West Coast becoming split flow between a broad trough over Hudson Bay, a series of shortwaves moving through Manitoba/Ontario, and the deep trough ejecting out of the Southern Plains early next week. From there, each also narrows in on the pattern amplifying in response to the phasing process beginning between a shortwave moving into the Northern Plains and a southern stream shortwave lifting through the middle Mississippi River Valley, resulting in cyclogensis over the Lower Great Lakes region. By Wednesday night, this transitions to an Omega pattern, with the resultant closed low making its way into New England, ridging moving out of the Rockies, and another trough moving into the West Coast. A look at their respective ensemble systems show the same agreement, but also include individual members varying in space, time, and magnitude of key features within this pattern. Narrowing in though, does support very good agreement and thus, high confidence in this forecast through at least Tuesday when the surface low begins deepening somewhere between the Ohio River Valley and Lake Huron. The forecast on Sunday will be marked by mostly dry conditions and highs in the 40s, except some 30s in the Keweenaw. A weak surface trough will drop southeast through Ontario, scraping the northern portions of Lake Superior through the day, which will keep skies cloudy. Most models maintain a dry layer between 4-8k feet through the day, but some like the HRRR and RAP resolve precip by afternoon across the east thanks to right entrance/left exit jet dynamics and seeder-feeder action. High pressure builds in behind this shortwave, moving through Ontario overnight and Monday. To the southwest, a robust shortwave will begin to lift out of the Southern Rockies, then gradually shift through the Central Plains by afternoon. Overrunning, isentropically forced precip will be possible across much of middle America Sunday night and Monday in response to this unfolding, but the high pressure shifting through Ontario will fight to keep our region dry, eliminating precip chances across the forecast area for all but the far south-central. Through Tuesday, the same will take place, but a shortwave dropping out of the Northern Plains in the afternoon will begin taking on a weakly negative tilt by evening, amplifying the surface low near the Ohio/Indiana stateline. Uncertainty in the forecast starts here, as the resultant deepening surface low and occlusion Tuesday night and Wednesday will occur somewhere between Lake Huron, Ohio, and Lake Erie. The more northern options could result in some cyclonic, upslope enhanced precip downwind of Lake Superior and/or synoptic precip near Lake Michigan and eastern Upper Michigan. Probability for this solution is currently low (25% or less), but can`t be ruled out at this point. Beyond this, high pressure and mid-upper level ridging stretch across central CONUS/North America Friday and into the Great Lakes this weekend, as the closed low shifts east into New England and a deep trough presses into the West Coast. This should support a dry and warming trend for us Friday and into the weekend. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 1055 PM EDT Sat Mar 30 2024 Amendment: KSAW and KCMX have actually been worse than expected for the past few hours. While they should see an overall improving trend throughout the next several hours, it may take longer for these terminals to improve than previously forecasted. Low-level cloud cover stays over the area tonight into Sunday as a weak low continues leaving to our east and a second shortwave low moves towards southern Lake Michigan. Ultimately, we should be seeing a very slow, but gradual, improvement across the TAF sites over the next 24 hours; we could see conditions improve to VFR late across the TAF sites, particularly at KIWD and KCMX. && .MARINE... Issued at 304 PM EDT Sat Mar 30 2024 A weak inverted trough and another surface trough will move through the Upper Great Lakes this afternoon and again Sunday, but these will result in only wind direction changes. Winds should be light and under 20kts through at least late Tuesday, when increasing pressure gradient results in increasing winds to near 30-35kts out of the northeast to north. The culprit behind this is a deepening surface low late Tuesday through Wednesday between the Thumb and Lake Erie. The EC ensemble system suggests 20% chance or less of gales in this period. If the system ends up tracking near the Thumb, these probabilities should increase. As the low weakens and moves east late week, northerly winds then fall back below 20 knots on Thursday, continuing through the rest of the work week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...07 LONG TERM...JTP AVIATION...TAP MARINE...JTP
Area Forecast Discussion
National Weather Service Reno NV
330 PM PDT Sat Mar 30 2024 .SYNOPSIS... The region continues to see bouts of mountain snow and a valley rain-snow mix going through the rest of the holiday weekend. Impacts to travel will persist especially over the Sierra Mountain Passes as a result. Drier and warmer conditions are expected to start the work week following this weekend`s precipitation. By the later half of next week, another active weather system looks to impact the region bringing increased precipitation chances and cooler temperatures. && .DISCUSSION... Rest of Today through Sunday: The latest RAP analysis shows an upper air low currently spinning about 150-200 miles west of central CA coast and causing a generally southerly flow over the CWA. The latest forecast model runs then project this low to moving south-southeast along the CA coast through the rest of the day and into the night. On Sunday, models forecast the low to open up more into a trough during the morning hours over southern CA and turn the CWA`s upper air flow more north- northeasterly through the rest of the day with trough continuing to progress eastward a bit. With this occurring above, periods of mountain snow and a valley rain/snow mix look to be on tap for the region through the rest of today and into tomorrow before tapering off to the southeast during Sunday evening. The latest additional forecast snowfall totals look to range about 5-15 inches in the Sierra Mountains with locally higher amounts possible while portions of the valleys may see up a trace up to around 4 inches possible. Models do not appear to be doing well reconciling snow levels which has been making the totals difficult to forecast. Currently, snow levels look to be down 4000-4500 ft during the night for the southern half of the region with portions of Mono County seeing levels almost down to 3500 ft. There is also the potential for some snowband development tonight which may allow for some greater snowfall totals in the valleys. The 12Z run of HREF probability tracker looks to target the areas around Lake Tahoe beginning this late afternoon and going until about midnight. Will continue to keep an eye on conditions should any additional products need to be issued or totals need to be updated. Forecast model soundings also show some convective potential, so there may be a rumble of thunder coming from a passing shower though severe thunderstorms are not anticipated at all. Hazardous traveling conditions continue to be expected going through the rest of today and into Sunday morning especially for the Sierra Mountain region with slick roads and lower visibilities due to the snowfall. If you must travel during the remainder of the holiday weekend, it is advised to take caution and prepare for these conditions. For the latest updates on the Winter Storm Warning and Winter Weather Advisory products as well as forecast additional snow totals, please check out www.weather.gov/rev/winter. Monday through Wednesday Morning: Forecast guidance shows a positively tilted Pacific upper air ridge moving over the west coast by Monday morning causing the CWA to take a northeasterly flow as the aforementioned trough departs to the east. This western ridge is expected to progress eastward through Monday as well as Tuesday with the axis of the ridge passing over the CWA by the late morning hours of Tuesday. By Wednesday morning, the CWA`s upper air flow starts to turn more west-southwesterly as an upper air trough moves in behind the ridge. This setup causes a surface high to move into the region on Monday that starts to move out late Wednesday morning. Mostly sunny skies, dry conditions, as well as warming trend are all in the forecast for the beginning of the week. Wednesday Afternoon into the Weekend: By late Wednesday afternoon, models have the CWA turning southwesterly with the forward portion of the trough making its way over the CWA as the trough digs down across the Pacific coast through the rest of the day. On Thursday, models appear to agree with having an upper air low developing within the base of the trough though the GFS places it off the coast of northern CA while the ECMWF has it more to the north off the coast of OR/WA. The uncertainty between models just grows going forward because of this displacement discrepancy as the GFS tracks the low moving east- southeastward across the southern portion of the CWA on Friday and then into the Rockies on Saturday. The ECMWF on the other hand has a somewhat slower progression with the low making its way over the CWA on Friday night and out east into ID/UT/WY on Saturday. Details still are pretty fuzzy on this upcoming system as a result, but there does look to be the return of precipitation chances to the region late Wednesday through Friday with conditions drying out again on Saturday at this time. Also, there are signals for breezy to gusty winds to return on late Wednesday and Thursday following a cold front passage. Will continue to monitor this late week system for better model agreement going forward. -078 && .AVIATION... Periods of mountain snow and valley rain/snow mix expect to continue throughout the region care of the low pressure off the coast of CA going through the rest of today and into tomorrow. With this precipitation in the area, MVFR ceilings are in the forecast for the Sierra terminals while models show the lower elevation terminals look to see IFR-MVFR ceilings with lower ceilings mostly occurring this evening and going into the morning. There is concern that visibilities will drop IFR to LIFR at times this evening too as there is the potential for some convectively driven showers passing most of the terminals (the exception being KMMH) that will increase increase precipitation intensity. This looks to be a little harder to pinpoint exact timing, but the HREF signals band potential increasing after 22-23Z until around 06-07Z. Will continue to monitor conditions and amend TAFs as needed, but there is pretty good confidence for at least sub-VFR conditions for today going into tomorrow. -078 && .AVALANCHE... An impactful weather system continues to affect the region through Sunday, with heaviest snowfall expected tonight/Sunday morning. * Additional liquid totals (SWE) through Sunday: For Mono county above 7000 feet, 0.30-0.75 inches. For the Tahoe Basin, generally 0.50-1.25 inches with heaviest amounts along the crest. * Additional snowfall: around 4-10 inches south of Sonora Pass and around 8-16 inches north of Sonora Pass through Sunday. * Peak Snowfall Rates: The latest run of the HREF shows snowfall rates still generally between 1-1.5 inches per hour, but there is potential for up to around 2 inches per hour particularly in the Tahoe Basin during this evening and overnight. * Snow-Liquid Ratios: Continues to be generally around 10-14:1 for the rest of the system. * Winds: winds look to pick up over the night a little bit out of the west-southwest around 30-40 mph in the higher locations. -078 && .REV Watches/Warnings/Advisories... NV...Winter Weather Advisory until 11 AM PDT Sunday NVZ001-003. Winter Storm Warning until 11 AM PDT Sunday NVZ002. CA...Winter Weather Advisory until 11 AM PDT Sunday CAZ071. Winter Storm Warning until 11 AM PDT Sunday CAZ072-073. && $$
Area Forecast Discussion
National Weather Service Springfield MO
617 PM CDT Sat Mar 30 2024 .KEY MESSAGES... - Temperatures 10-15 degrees above normal through Monday. - Low chances (20-40%) for showers/thunderstorms toward central Missouri tonight and Sunday night. - Increasing potential for severe thunderstorms Monday. The Storm Prediction Center has issued a Slight (2/5) to Enhanced (3/5) risk for our area. - Conditional flooding threat Monday. The Weather Prediction Center has issued a Slight (2/4) risk for portions of the area. - Brief cooldown for the middle of next week. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 135 PM CDT Sat Mar 30 2024 Synoptic Pattern and Current Conditions: Water vapor imagery and upper air analysis showed the next storm system spinning off the California coast. Zonal flow aloft with weak mid level ridging extended east through the central US. A surface front was located from northern Oklahoma, through areas just north of Joplin, to Lake of the Ozarks and then northeast into Illinois. An area of clouds was located near this front and latest visible imagery suggests that the front is in the process of stalling as surface winds remain southwest to westerly. Low level moisture continues to get drawn up from the south with low to mid 50 dews across the area. Temps varied from the low 60s north of the front to the low 70s across south central Missouri. Tonight: Surface low pressure will begin to deepen across the lee of the Rockies. A 40kt low level jet looks to become established across Texas, western Oklahoma and into central Kansas overnight with some veering into southwest Missouri. The stationary front across the area will begin lifting north. Latest HREF mean MU CAPE along with the RAP MU CAPE/CIN plots shows an area of 500-1000j/kg of MU CAPE with an eroding cap after 9pm for areas north of I-44. This is mainly lifting parcels freely from 800-850mb. Large scale lift looks weak given the mid level height rises therefore coverage looks low as shown in high res paint ball plots. A consensus of short term models and the NBM shows a 20-40% chance of showers and storms north of I-44 tonight. Surface winds will begin to increase out of the south and combined with clouds will keep temps mild again with lows in the upper 50s to lower 60s. Sunday through Sunday night: The area looks to be well into the warm sector with the warm front located along or just north of I-70. The latest HREF does indicate a substantial amount of mid to high clouds during the day as the flow becomes more southwesterly. Current NBM temperature forecasts suggest widespread high temps in the upper 70s to near 80. However 850mb temps look to reach the 15-18C range therefore if any clearing occurs then temps could soar several degrees higher. Southerly winds will be gusty with 25-30mph gusts likely during the afternoon, especially west of Springfield. No precip is expected during the day. By Sunday night, a 40kt low level jet will overspread the area and impinge upon the front north of the area. Showers and thunderstorms look more likely north of the area however a few storms could creep into areas of Benton and Morgan counties. Low temperatures look to remain even warmer than the previous night with many areas only dropping into the lower to middle 60s. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 135 PM CDT Sat Mar 30 2024 Monday through Tuesday System: A deep upper level trough will move into the plains with southwest flow aloft continuing to pump moisture into the area on Monday. Surface low pressure looks to develop across northern Oklahoma with the front stretching northeast into central Missouri. Large scale lift will spread into the area through the day with a 140kt upper level jet nosing into the area. Ensembles continue to suggest the potential for substantial clouds and precip during the day ahead of the front. Temperatures will be tricky for Monday as clouds/precip could keep temps in the lower 70s however breaks in the clouds could push temps higher. Clouds/precip will have an impact on the amount of instability available for when the front pushes into the area Monday evening. Wind shear looks to be more than favorable for organized/severe storms (50-60kts 0-6km bulk wind differences) however the amount of instability is in question. Mid level lapse rates continue to look poor (5-6C/KM) given the amount of clouds and ongoing precip. Latest NBM data suggests 80-90% chances for >500j/kg of surface based CAPE across the area however chances for >1000j/kg drop off substantially therefore this could be a high shear/low CAPE event which often times still produces severe events across the area. These types of events typically have a "messier" component to them given the potential for mixed modes and the formation of storm clusters. We should begin to get a better handle on the instability as we get closer and into the high res model range. Given the amount of wind shear available, large hail, damaging winds and tornadoes will all be of concern with this system and the SPC outlook for Monday covers these threats in even more detail. Continue to monitor updates as we get closer to Monday. The other concern with this system will be flooding. The WPC excessive rainfall outlook still shows a slight risk for flooding, especially along the frontal boundary. Forecast PW values look to be in the 1-1.5in range and given the orientation of the system and front would support training of showers and storms. Latest NBM probs of 1 inch of rain or greater are currently in the 40-60% range across the area. Tuesday through Friday: Lingering clouds and light precip look to linger on Tuesday which will keep high temps in the 50s. The upper level low will slowly shift into the Ohio River Valley Wednesday with continued cool and dry northerly winds. High pressure builds on Thursday morning which could bring low temps down into the lower 30s. This could produce frost and will need to monitor temperature trends. Ensembles then suggest mid level ridging building into the central US late in the week which will likely lead to a sizable warmup by Friday. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 617 PM CDT Sat Mar 30 2024 Surface low pressure will build across the plains tonight and Sunday. Winds will be light early this evening and will become more southerly tonight with gusty southerly winds expected on Sunday. Isolated showers and storms will be possible late this evening into tonight, but the better chances will be just north of the TAF sites across central Missouri. && .CLIMATE... Issued at 135 PM CDT Sat Mar 30 2024 Record High Minimum Temperatures: March 31: KSGF: 62/1967 April 1: KSGF: 62/1946 Record Precipitation: April 1: KVIH: 0.88/1945 && .SGF WATCHES/WARNINGS/ADVISORIES... KS...None. MO...None. && $$ SHORT TERM...Burchfield LONG TERM...Burchfield AVIATION...Wise CLIMATE...Burchfield
Area Forecast Discussion
National Weather Service Topeka KS
650 PM CDT Sat Mar 30 2024 .KEY MESSAGES... - There is a 20 to 30 percent chance of thunderstorms Sunday morning across northeast Kansas. If storms develop, there may be some large hail. - A few severe storms may be possible across east central KS Saturday evening with 60 MPH wind gusts and large hail possible if storms develop. - Thunderstorms will redevelop early Monday morning and continue into the afternoon hours, ( A 30 to 50 percent chance). Severe thunderstorms will be possible across east central KS, with large hail as the primary hazard. && .DISCUSSION... Issued at 233 PM CDT Sat Mar 30 2024 Early this afternoon, an amplified upper trough was moving southeast onto the central CA coastline. A broad upper level southern stream jet has shifted northeast across Plains. An upper level trough was existing off the New England coast line. At the surface, a cold front was pushing southeast across OK and the TX PNHDL. Weak low-level CAA was causing Temperatures to be a bit cooler early this afternoon, with lower 60s across the southeast counties to lower 50s along the NE border. Tonight through Sunday night: The upper level trough centered along the central CA coast will dig southeast across southern CA into northwest Mexico and southwest AZ by 12Z MON. A northern stream H5 trough will dig southeast across western Canada into south central Canada and the upper Midwest. Southwesterly H5 flow across the Plains will increase to near 50 KTS and a lee surface trough will deepen across the central and southern high Plains. The surface front across OK will stall out Tonight across south central OK while southerly 850mb winds transport richer moisture northward across the southern and central Plains. The front across OK will move back north as a warm front. Isentropic lift north of the front will cause showers and thunderstorms to develop late Tonight across east central and northeast KS. As the surface warm front shifts northward across the CWA during the mid morning and afternoon hours, the stronger isentropic lift will shift northeast of the CWA and there may be a break in the showers and thunderstorms during the mid and late afternoon hours. A few of the CAMs show the cap breaking along the warm front across west central MO. These surface based storms may be supercells with MLCAPES of 1200-2200J/KG and 50 to 60 KTS of effective shear. The forecast hodographs show low-level curvature, which would provide for stream- wise horizontal vorticity ingestion into any robust updraft. When the streamwise horizontal vorticity is tilted vertically by the updraft, stronger low-level mesocyclone may develop which could lead to tornadogenesis. The only question would be if the the strengthening EML may create a stronger CAP across west- central MO and east central/northeast KS along the surface warm front. The severe threat would be conditional but the 18Z HRRR did show surface based storms developing after 00Z MON, southeast of KC and back building west-southwest into southern Douglas and Franklin Counties. So, this possibility for severe thunderstorms will need to be watched across portions of east central KS Sunday evening. Sunday night, the transport of richer moisture northward along with embedded perturbations rounding the main upper trough across the southwestern US, and with a strengthening LLJ will provide a chance for mainly elevated thunderstorms. MUCAPEs will be in the 1000-1500 J/KG range and there will be 60 to 70 KTS of effective shear. Therefore, if elevated storms develop they could produce strong mid level mesocyclones which could produce large hail. The severe threat will last into Monday morning. Monday through Tuesday: A section of the southwestern H5 trough will lift northeast into the Plains Monday afternoon. Strong low-level CAA will push the stationary boundary southeast across the CWA during the late morning and early afternoon hours. 850mb winds begin to veer across the southern Plains ahead of the southeast moving cold front and dryline across OK. A line of severe storms will develop along the front across central MO, extending southwest across southeast KS and then south-southwestward across central OK. For a few hours these surface based storms may be scattered discrete supercells. A surface low will deepen across northeast OK and track northeast across south central MO. The best potential for tornadic supercells will be along the the warm front across south central MO into central IL where the low-level shear would be more favorable. Supercells that develop along the front across southeast KS into northeast and central OK may produce large hail and damaging wind gust. There may be a window of strong elevated thunderstorms behind the cold front across east central KS. These storms may develop intense mid level mesocyclones and may produce large hail southeast of the KS turnpike Sunday afternoon. The strong CAA behind the front may drop 850mb and surface temperature enough for some snow to mix in with the rain or turn briefly to a wet snow before the precipitation ends Tuesday morning across the western half of the CWA. Tuesday night through Wednesday night. The main H5 trough will phase with an amplified upper trough digging southeast out of central Canada into the upper Midwest. The resulting amplified closed upper low will shift slowly southeast across the southern Great Lakes. This will keep the Plains under northwesterly mid and upper level flow. The surface CAA will build a surface ridge of high pressure southward across the Plains. Expect cooler temperatures with highs in the mid to upper 50s. Most of the area will see a freeze early Thursday morning. The sheared southern stream section of the original H5 trough will retrograde southwest into northern Mexico and fill. Thursday through Saturday: Expect a warming trend as the surface ridge shifts east across the OH River Valley. A northern stream H5 ridge will move east across the Plains Thursday and Friday. An amplified upper trough will slowly shift east into the western US. The upper ridge axis will move east across the MS river Valley by Saturday. Highs will reach the 60s on Thursday. Expect lower to mid 70s on Friday afternoon and mid 70s to near 80 degrees by Saturday afternoon. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 626 PM CDT Sat Mar 30 2024 VFR conditions for the next several hours before low stratus returns in advance of a surface warm front that is progged to begin returning north. Should see mostly marginal VFR Cigs through the period, but there could be a few hour window for IFR conditions into the mid morning hours. Can`t rule out a shower in the morning as well especially around the KTOP/KFOE terminals but the chances remain too low to mention. Any Cigs should lift into the afternoon and perhaps clear. Storms could form once again Sunday evening but may hold until the after this period. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Gargan AVIATION...Drake