Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/11/21

Area Forecast Discussion
National Weather Service Amarillo TX
617 PM CDT Sat Apr 10 2021 .AVIATION... For the 00z TAFs: VFR conditions will prevail throughout the valid TAF period. Main story here will be the potential for low level wind shear at KAMA tonight, and the cold front coming in tomorrow late afternoon/early evening. The front has slowed down somewhat from previous runs, but it still looks to pass through KGUY late tomorrow afternoon, and maybe edging its way towards KDHT as well. However, it doesn`t look like it will pass through KAMA until after sunset Sunday evening (beyond this TAF period). Guerrero && .PREV DISCUSSION... /Issued 153 PM CDT Sat Apr 10 2021/ SHORT TERM...Today through Tomorrow Night... An upper level low across Missouri will continue to swing northeast into the Ohio Valley by Monday morning. Meanwhile, RAP 500mb analysis shows the next system in western Canada as it is expected to dig into the northern Plains tomorrow with the Southern Plains under weak west northwest flow aloft. By Monday morning, this upper level low will have caught up with the original system in the Ohio Valley and merge as one. This puts much of the southwest and south central CONUS under zonal flow aloft. Light winds and pleasant conditions area expected today with temperatures warming nicely into the upper 60s to lower 70s. By Sunday, temperatures will rise even higher with over half the forecast area reaching the 80 degree mark. Winds will turn quickly to the north northwest by the morning hours tomorrow due to a weak surface trough swinging across the Panhandles. A cold front is then expected to enter the Oklahoma Panhandle by the evening hours tomorrow and be through the area just after midnight. Surface winds will turn to the northeast and become windy behind the front with some higher wind gusts possible through the evening and overnight hours. Soundings show a decent inversion around 700mb with only a potential for mixing of winds below that layer. A 35 to 45 knot jet is present at 850mb with a chance for these higher wind speeds to mix to the surface. No precipitation is expected through tomorrow night with mostly clear skies. A few mid-level clouds may fill into the northern Panhandles behind the front with a very shallow layer of moisture present at 700mb. Rutt FIRE WEATHER...Tomorrow... Elevated fire weather conditions are possible tomorrow with mostly relative humidity driven conditions. Minimum relative humidity values will be as low as 6 to 9 percent across the southeastern half of the combined Panhandles and below 15 percent minimum relative humidity for the entire Panhandles. Twenty foot winds will be around 5 to 15 knots with a few areas in the Oklahoma Panhandle getting closer to 15 to 20 knots during the early afternoon hours. Winds will be out of the west northwest through the afternoon hours before turning to the north northeast during the late afternoon and evening hours across the northern half of the Panhandles with an incoming cold front. Twenty foot winds will pick up to around 10 to 20 knots behind the front during the late evening and overnight hours. Fuels remain cured fine dead fuels on top of an underlying green base, therefore the chance for fire weather remains at elevated or below despite the relative humidity values. Rutt LONG TERM...Monday through Friday Surface ridge builds down into the Panhandles Monday allowing for much cooler and more moist upslope surface flow. Increasing cloudiness expected Monday as southwesterly flow aloft continues to bring in sub-tropical moisture across the forecast area. This pattern continues into Monday night and Tuesday with low level moisture advection and perturbations within the southwesterly flow aloft resulting in the development of convection by Tuesday. Closed upper low over the western states Tuesday will track east across the Intermountain West and Great Basin region Wednesday will move east across the central Plains states late next week. The upper low will draw abundant Gulf moisture northward into the Panhandles by the middle and end of next week. A more west southwest upper flow will continue to to bring perturbations from the western states across the Four Corners region and also from the southwestern states eastward into the Panhandles. Chances for convection, mainly showers with the possibility for some thunderstorms, the middle and end of next week. Upslope surface flow for most of next week as the surface ridge continue to build into the Panhandles will allow for much cooler and more moist conditions. A reinforcing surge of cooler air expected Friday night. Schneider && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$
Area Forecast Discussion
National Weather Service Columbia SC
1105 PM EDT Sat Apr 10 2021 .SYNOPSIS... Showers will move out of the area during the early morning hours with a front moving through the area Sunday afternoon with better precipitation chances to our east and south. Dry conditions expected Sunday night through Tuesday with high temperatures in the low to mid 80s. A front will slowly move through Wednesday providing a chance of mainly light rain. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Showers have mainly moved out of the forecast area with a few remaining across Chesterfield County. Over the next hour these showers will exit the forecast area with partly to mostly clear skies into the early morning hours. Toward daybreak another push of moisture will move northward from the eastern Gulf Coast with a slight chance of showers mainly in the CSRA. Overnight lows will be limited by cloud cover and elevated dewpoints with lows ranging from the upper 50s western Midlands to lower 60s eastern Midlands. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... A cold front moves through The Midlands and CSRA on Sunday. Precipitable water levels decrease to below one inch during the day which limits convective activity to isolated showers. A flat ridge of high pressure sets up over the Lower Mississippi River Valley early next week with the Southeast U.S. in the a west northwest flow aloft. Temperatures will remain above normal for mid April. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Model ensembles depict a wide spread of solutions with regards to the development of a closed or cut off upper level low pressure system over New England or just off the coast. This feature could drop a back door front into The Midlands and CSRA later next week for a cooling trend. The ensembles also forecast a slow increase of low level moisture from the Gulf of Mexico. This could bring a chance of showers to the region the second half of next week. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... VFR expected to be dominate for the next couple hours before some possible cig restrictions develop later tonight. Showers and isolated thunderstorms have been progressing through the region this evening as a cold front pushes through. These have generally been pretty weak, and haven`t resulted in wind gusts above what we`re seeing outside of showers. What is out there now should push mostly to the north of OGB and should clear the terminals between 01z and 02z this evening. Any shower should have with it briefly gusty winds upwards of 20-25 knots and some heavy rain. As these pass, winds should generally shift from the south and southeast to the southwest, and drier air above the surface will filter in. This will set up for what will be our primary aviation question tonight. To our west, there is currently just fair weather cumulus and mid-high level clouds. The cumulus should begin to die off after sunset. As this area of lesser cloud cover moves into the area, guidance really isn`t sure what to make of how our conditions evolve overnight. There is a wide range of possibilities - from the HRRR which shows nothing until tomorrow morning to the HREF which gives high probabilities of IFR cigs developing. Low level winds are forecast to remain elevated tonight across the CWA, so I don`t really expect fog or very low stratus. However, there seems to be enough guidance to suggest that at least MVFR cigs develop everywhere overnight underneath a weak subsidence inversion. Given this, I have backed off from previous forecasts and gone MVFR or MVFR with a TEMPO group down to BKN007. I am hesitant to even go that low at the Midlands sites, but will leave it up to the next forecasters to decide what to do with that. Either way, it looks like a deck of stratus/stratocu will develop overnight and cause at least MVFR cigs at all terminals. As I mentioned previously, winds should remain elevated, in the 4-8 knot range out of the southwest tonight. By tomorrow, much drier air is forecast to filter in. Any cig restrictions present will begin to lift around 15z, and most clouds should be gone by the afternoon. There is a chance for an isolated shower during the afternoon hours, but certainly not high enough to include in the TAFs. Winds should generally be out of the west- southwest in the 8-12 knot range. EXTENDED AVIATION OUTLOOK...CIG and VIS restrictions aren`t expected to remain an issue as we head into early next week. Much drier air will filter into the region behind a cold front on Sunday, limiting overall moisture for low clouds or fog. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...99
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1149 PM EDT Sat Apr 10 2021 .AVIATION... Showers will hold into the first few hours of the forecast, especially KPTK north before mid level dry slot works north into the region. MVFR cigs can be expected at times with this activity with lower clouds then clearing late tonight into Sunday morning. More scattered showers will develop on Sunday afternoon, mainly KPTK south as secondary low pressure pivots into far southern lower Michigan. MVFR to lower VFR cigs will return in this activity as times with lower cigs/vsbys possible into Sunday night as low level moisture remains trapped over the area and winds become light/variable. For DTW...Showers will end by 08z or before with MVFR cigs at times. Another round of scattered showers will evolve Sunday afternoon as a secondary low pivots into the vicinity. .DTW THRESHOLD PROBABILITIES... * High for ceiling 5000 ft or less overnight, medium again by Sunday afternoon, high by Sunday evening/night. && .PREV DISCUSSION... Issued at 406 PM EDT Sat Apr 10 2021 DISCUSSION... A line of showers and thunderstorms have developed this afternoon across far western Lenawee County. TDTW Z imagery shows fineline delineating the southern edge of a lake shadow off of Lake Erie. Air mass to the west of this lake shadow is considerably more humid/moist with dewpoints in the lower to middle 50s. Model soundings show this near surface moisture coupled with the lapse rates in the 800-650mb layer is good enough for MUCAPES of 300 J/kg. Given scaling of convective updrafts the potential does exist for storm gusts approaching 40-50 mph. The potential for strong thunderstorm activity should decrease moving forward this afternoon for Southeast Michigan cwa as deep moisture arrives and lapse rates become moist adiabatic. Easterly flow in place within the lake shadow will provide a degree of stability which should try to prevent surface based instability for Metro Detroit northward. Latest Swody1 has reintroduced and expanded Marginal Risk northward in Lower Michigan. Main moisture transport axis will lift south to north throughout the cwa beginning after 20Z this afternoon. Precipitation will be slower for the Thumb where onset time may wait until as late as 01Z. Deep moisture axis with system relative isentropic ascent along the 314- 320 Ke surfaces. Good setup for a period of moderate to intermittently higher rainfall rates this evening with environmental profile supportive of elevated convective instability between 4.0- 9.0 kft agl. Latest trends suggest 0.25 to 0.75 inch QPF being possible by 12Z Sunday. HRRR and RAP solutions have been checking in with less QPF tonight while other model consensus remains consistent. Latest in-house probabilistic guidance shows higher end QPF potential is lessening but again that appears to be due to HRRR/RAP. Plan view perspective of moisture shows very progressive dry slot lifting south to north into Southeast Michigan between 03- 09Z which causes rain to abruptly end. Models show heart of expansive mid to upper level dry slot over all of Southeast Michigan to begin the day Sunday. The dry air is expected to limit overall coverage of precipitation initially before daytime heating occurs. Wrap around moisture within the vertically stacked upper level low will then advect into Lower Michigan for 15- 00Z. Model soundings show favorable lapse rate structures in the lowest 6.0 kft agl indicative of good potential for low topped convective showers. Given the occlusion there is lack of cold upper level air which limits convective vigor and potential for any small hail. Upper level low is then forecasted to stall out over the central Great Lakes on Monday. A very interesting upper level pattern then emerges with signs pointing to very strong blocking flanking much of North America. What develops is a far ranging large scale shearing deformation axis from the Atlantic Ocean clear back to the Pacific Northwest. It is always difficult pinpointing coverage and duration of rain activity within upper level low pressure systems particularly within days old occlusions. Internal wave interactions and corresponding subtle moisture advections are normally difficult to time out. A separate wave packet and dynamic low shortwave is expected to dive southeastward driving a geopotential height fall region locally on Monday. Combination of daytime heating with deeper moisture through 15.0kft should drive robust afternoon shower development. Went against automated guidance and introduced PoPs at likely Monday afternoon. Latest indications are that stretching deformation may exist in a very weakened form through early Thursday. Low confidence exists in the temperature forecast during the early to middle of the week that will depend on opacity/coverage of clouds. MARINE... Low pressure will continue tracking northeast towards lower Michigan the remainder of today and into tonight bringing a period of unsettled weather that will last through at least Monday. Rounds of showers with embedded thunderstorms will accompany the low pressure system, with the best chance for thunderstorms confined to the southern Lake Huron basin, Lake St. Clair, and western Lake Erie. Moderate easterly winds will veer more southeasterly into tonight, with gusts generally holding below 25 knots. Wave runup along the tip of the Thumb between Port Austin and Port Sanilac will allow for choppy conditions that will lead to hazardous conditions for small craft tonight, as waves occasionally reach 5 feet at times. The low pressure system will begin to slowly weaken Sunday and especially into Monday as it stalls over the central Great Lakes, with continued light to moderate southeasterly flow in place over the local waters. Drier weather and lighter winds veering to the southwest will then prevail late Monday and into Tuesday as weak surface high pressure attempts to nudge in from the northern Ohio Valley. HYDROLOGY... Daily chances for showers and thunderstorms continue through early next week. The potential exists for rainfall amounts to conditionally exceed a quarter of an inch at times, especially this evening. Cumulative rainfall on the order of 0.25-0.75 inch is expected regionally by Sunday morning. Minor rises on area rivers and streams are possible with nuisance flooding in poor drainage areas during the heaviest bursts of rain. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Small Craft Advisory until 4 AM EDT Sunday for LHZ441-442. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....DG DISCUSSION...CB MARINE.......IRL HYDROLOGY....CB You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service New Orleans LA
328 PM CDT Sat Apr 10 2021 .SYNOPSIS... The MCS from this morning has moved well out into the Gulf of Mexico. A trailing shortwave moving across the northern Gulf, and the cold front pushing southward has produced isolated convection to the south of Lake Pontchartrain this afternoon, which is rapidly moving eastward offshore as well. Looks like the effective boundary, based on wind fields and dew points, is somewhere around Interstate 12 at 2 PM CDT. Where we`ve lost cloud cover sufficiently, temperatures have or will rebound to near 80 degrees, with dew points in the lower and middle 60s, compared to the lower 70s that were widespread ahead of the front. && .SHORT TERM (through Monday night)... Based on mid-level westerly flow, actual cold front may not make much more southward progress. Latest HRRR solution does indicate some threat of isolated showers overnight, so there will be a mention in a few zones. The 00z upper air soundings will be instructive as to whether an evening forecast update will be needed. Beyond tonight, high pressure will shift eastward over the next couple of days. Low level flow will eventually turn onshore late Monday or Monday night. Moisture increase will eventually be sufficient for at least isolated to scattered convection by late Monday night or Tuesday morning. Temperature guidance is pretty well clustered through Monday, and don`t see much of a reason to mess with it. 35 && .LONG TERM (Tuesday and beyond)... Main upper air pattern gets pretty blocky north of 35N at mid- week, with a surface boundary getting hung up somewhere close to the Gulf Coast. Weak shortwaves moving through the zonal flow to the south of the block across our area will present the threat of a few rounds of convection during the midweek period. The ECMWF solution is a little more vigorous with one on Tuesday, the GFS with one on Wednesday. At this point, severe weather doesn`t appear to be as much of a concern as the potential for at least some heavy rain at midweek. Considering that we`ve had a couple of batches of heavy rain in the last few days, we`ll need to monitor for any focus of heavy rain. We`ll keep to the blended PoPs and temperatures for now. 35 && .AVIATION (valid through 00z Monday)... Currently VFR at all terminals. Threat of TSRA at any terminal currently too low to carry in the forecast. There are currently BKN-OVC clouds between FL030-050 to the south of the frontal boundary, that are likely to lower into the MVFR range overnight. At this time will keep the ceilings out of the KMCB and KBTR forecasts. Don`t expect prime radiating conditions overnight, so, while we can`t eliminate the possibility of fog, threat is fairly low. Any flight restrictions that occur overnight should improve to VFR by 15z Sunday. 35 && .MARINE... Wind and pressure fields (especially direction) have been rather chaotic today due to the morning convection. Winds have dropped below Small Craft Advisory criteria, and with the pressure field weakening somewhat, will cancel the Small Craft Advisory, which was due to expire shortly, anyway. Outside of thunderstorms toward midweek, don`t see any major marine issues for the majority of this forecast package. 35 && .PRELIMINARY POINT TEMPS/POPS... MCB 52 77 52 82 / 0 0 0 10 BTR 54 79 54 84 / 0 0 0 10 ASD 57 80 54 82 / 20 0 0 10 MSY 63 79 61 82 / 10 0 0 10 GPT 59 79 57 79 / 10 0 0 10 PQL 60 79 54 79 / 10 0 0 10 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$
Area Forecast Discussion
National Weather Service Miami FL
749 PM EDT Sat Apr 10 2021 .AVIATION(00Z TAFS)... Scattered showers and thunderstorms will continue across Palm Beach and northern Broward counties this evening. Periods of MVFR or IFR conditions are possible in and around any shower or thunderstorm. A cold front will bring additional chances of showers and thunderstorms across the region on Sunday. Winds will remain gusty as well out of the south southwest on Sunday across all terminals. && .UPDATE... Updated the current forecast based on radar trends. Scattered showers and thunderstorms continue this evening across portions of Palm Beach and northern Broward counties. These storms could contain gusty winds, small hail, and heavy downpours. An additionalround of showers and thunderstorms associated with a decaying MCS will start to move into the northern and western areas this evening. These storms will continue to weaken as they push southeastward through the rest of the evening and into the overnight hours. A cold front will continue to push closer to the area on Sunday. This will trigger additional chances of showers and thunderstorms especially during the afternoon and evening hours. There will be enough instability in place to support some strong to possibly severe thunderstorms during this time frame. The strongest storms could contain gusty winds, heavy downpours, and hail. && .PREV DISCUSSION... (Issued 307 PM EDT Sat Apr 10 2021) ..A Few Severe Thunderstorms Possible Sunday... SHORT TERM (This Evening through Sunday)... The lengthy trial of quiet weather ends today. First, we are watching along the Atlantic sea breeze, specifically over Broward and Palm Beach Counties where CAMs indicate some convective development this afternoon and perhaps early evening. Mid-levels are cool so some small hail and perhaps with shear values increasing later a funnel cloud or two wouldn`t be impossible...along with a damaging wind gust or two. Secondary concerns would be localized ponding on roadways due to heavy rainfall, but this would be concentrated only within the more urbanized locations in the metro. Outside of the possible sea breeze generated convection, there is currently a MCS pushing through the central Gulf Coast and Panhandle region. Mesoscale models are in agreement that this feature will eventually dive southward. It should arrive within our Gulf waters sometime around 8-10pm tonight if current projections are correct. A nice upper level impulse along with some jet dynamics will help maintain the MCS through the day, however, as it begins to near our area the impacts of both will decrease. Still, can`t rule out a strong wind report or two over Collier County. Outside of a few isolated showers and maybe a rumple of thunder tonight, it should be mostly quiet after the MCS decays or moves just west of our CWFA. The next round of storms will begin to develop upstream early Sunday in closer proximity to the cold front and where the best jet dynamics resides. Just looking over a few parameters ahead of another possible MCS tomorrow, instability looks moderate (in some cases around 3,000 J/KG) and bulk shear values becoming sufficient (40-50kt), think that there will some strong to possibly severe storms within this feature. With the upper level heights falling/cold air advecting upstairs...hail will be possible along with strong gusty winds and as a secondary threat localized flooding within metro areas. There very well could be a second round of showers and storms with some prior model data (WRF3km) suggesting this. However, latest HRRR guidance suggests that scenario is becoming less likely. Timing appears to be early afternoon first impacting the Lake Okeechobee region before settling southward through Miami-Dade and Mainland Monroe through the end of the period. LONG TERM... Sunday Night and Monday... Showers and thunderstorms may be ongoing early Sunday evening as the first mesoscale convective system (MCS) or its remnants push south through southern portions our area and/or the Atlantic waters. Thereafter the weather picture becomes murkier for late Sunday night into Monday morning. The high resolution convection allowing models nominally suggest the development of a secondary thunderstorm cluster over the eastern Gulf waters around 00-03z before bringing it southeast into central/south Florida during the overnight (generally after 10 PM) hours. That said most (but not all) of the solutions show these storms weakening with time leading to uncertainty in QPF/impacts across our area. So while we can`t rule out the potential for strong thunderstorms overnight any severe risk is highly conditional and dependent upon how worked over the environment is from the previous convection. Keep up with forecast changes. Rain chances should decrease from north to south through midday on Monday as the cold front pushes towards the Florida Straits thus allowing drier air to filter into the area. Tuesday and Wednesday... Northwesterly flow should prevail aloft as surface high pressure centers in the Atlantic waters just north of the Bahamas. This should result in generally quiet weather across the region. With no really notable cold air advection behind the front temperature readings will remain just a little above seasonal means with highs in the 80s to around 90 (warmest towards inland SW FL) and lows in the 60s and 70s. Thursday through Saturday... A progressive flow pattern evolves aloft as a series of southern stream perturbations cross the southern CONUS. There remains low predictability in timing when the best rain/storm chances are for our area but with warm temperatures and increasing moisture rain chances look to be in the cards at some point during this period. AVIATION(18Z TAFS)... Mainly VFR conditions expected. There could be convection develop along the Atlantic sea breeze for Palm beach and Broward terminals this afternoon. Additionally, APF may experience a shot at convection later this evening as well. Covered both opportunities with VCTS until more timing confidence is realized. Southerly winds has picked up today with some gusts up to around 20 knots at times, especially along the coasts. MARINE... Cautionary headlines for both the Atlantic and Gulf waters as surface winds increase out ahead of an approaching cold front. As the front nears and pushes through the region, scattered showers and thunderstorms will be possible over all south Florida waters. The strongest activity will produce frequent cloud-to-water lightning, heavy rainfall (limiting visibility) along with perhaps small hail and damaging wind gusts. Cautionary headlines may be needed behind the front as well, but due to a rather lackluster pressure gradient, SCA threshold likely will not be met. Favorable marine conditions expected early next week through the end of the period. BEACHES... There is a high risk of rip currents along the Atlantic Coast today. Additionally, with scattered showers and thunderstorms developing over the next day or two, lightning may become a hazard. && .PRELIMINARY POINT TEMPS/POPS... Miami 73 87 72 89 / 30 70 70 40 West Kendall 72 88 71 90 / 30 70 70 40 Opa-Locka 73 87 70 88 / 30 70 70 40 Homestead 72 86 70 88 / 30 70 70 40 Fort Lauderdale 74 86 71 88 / 20 70 70 40 N Ft Lauderdale 72 86 70 87 / 20 70 70 40 Pembroke Pines 73 87 70 89 / 30 70 70 40 West Palm Beach 71 87 69 86 / 30 70 60 30 Boca Raton 73 85 70 88 / 30 70 60 40 Naples 71 82 70 85 / 50 50 60 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through Sunday evening for FLZ168-172-173. AM...Small Craft Advisory until 8 AM EDT Sunday for AMZ650-670. GM...None. && $$ Update/Aviation...CWC Tonight/Sunday and Marine...Frye Sunday Night through Saturday...SPM Visit us at Follow us on Facebook and Twitter at:
Area Forecast Discussion
National Weather Service Paducah KY
542 PM CDT Sat Apr 10 2021 .SHORT TERM...(Tonight through Monday night) Issued at 318 PM CDT Sat Apr 10 2021 Strong gusty winds have developed under a dry slot associated with the low pressure system over the mid Mississippi Valley. Abundant sunshine has warmed temps enough to promote mixing to around 7000 feet, based on the rap model sounding for kpah. Gusts to around 30 kt will continue through sunset. These winds have been handled with a special weather statement. Winds will be slow to subside this evening, since the low pressure center is deepening and low level lapse rates are forecast to remain steep well into the night. The deepening surface low over northern Illinois tonight will wrap moisture east/southeast across parts of our region. Radar mosaics indicated the leading edge of light rain was near the I-44 corridor this afternoon. The consensus of short range guidance pops keeps most of the rain north of a kcgi to Madisonville line tonight. With increasing clouds and brisk winds, lows tonight will be around 50 despite cold advection aloft. Sunday may start out rather cloudy, with some light rain showers continuing in sw Indiana and the I-64 corridor of Illinois. The clouds and rain will pull away to the northeast as the storm system lifts northeast. Highs will range from the mid 60s in parts of sw Indiana to the lower 70s in southeast Missouri, where sun will be prevalent. Sunday night and Monday, a weak cold front will pass southeast across our region with very little moisture to work with. A period of cloudiness will accompany the front, along with a wind shift to northwest. Highs Monday will be in the 65 to 75 degree range from north to south. .LONG TERM...(Tuesday through Saturday) Issued at 318 PM CDT Sat Apr 10 2021 During the midweek period, a merged low pressure system in the Great Lakes area is progged to eject eastward toward the Atlantic seaboard in response to ridging building over Manitoba/western Ontario. In addition, the medium range models suggested ridging aloft will increase across the central Plains through the daylight hours Wed in response to a large low pressure system moving eastward out of the Rockies. This will keep the PAH forecast area under fairly fast west- northwesterly flow aloft into late in the week, with high pressure maintained at the surface. By early Fri, measurable pcpn may flirt with westernmost parts of the region as northern stream mid level shortwave energy merges with part of the elongating trof out west, but measurable pcpn (mostly just showers) appears most probable in the extended period to be on Sat (Day 7) as deeper moist southerly flow would have increased across the MS River valley by then. Surface winds are forecast to have a solid northerly component through the extended forecast period. As a result, temps near seasonable levels, with no wild swings to above or below average, can be expected. && .AVIATION... Issued at 542 PM CDT Sat Apr 10 2021 For the WFO PAH 00z Sunday TAF issuance, focused on the mean VFR ceilings this evening, after the loss of diurnal heating around the closed surface low centered in northwest Illinois at 23z Saturday. As the surface low moves east, MVFR ceilings and vicinity showers can be expected at KMVN, KEVV, and KOWB between 03z and 21z Sunday. VFR conditions will continue to work back north toward the end of the forecast period as the low eventually lifts northeast away from the WFO PAH TAF sites. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ SHORT TERM...MY LONG TERM...DB AVIATION...Smith
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
822 PM MDT Sat Apr 10 2021 .UPDATE... Issued at 816 PM MDT Sat Apr 10 2021 02z surface analysis had cold front from KD50 to KBYG, moving southeast around 30kts. Pressure rises have increased to 4-6mb/3hr. HRRR has been persistent increasing the strength of the frontal passage/cold air advection with a rather well defined area of 45-55kt wind gusts for a couple of hours behind the front. This is starting to ring true looking at observations upstream, so have hoisted High Wind Warnings to account through the early morning hours. && .DISCUSSION...(This Evening Through Saturday) Issued at 222 PM MDT Sat Apr 10 2021 Mean upper level troughing will dominate in the period, supporting below normal temps with unsettled and breezy conds. This will all ensue via an advancing clipper like system, which will arrive tonight bringing strong winds and CAA. Clear skies and overall light winds ongoing across the FA today with many places seeing 60s for highs. Strong cold front will arrive late this evening into early Sunday morning with an initial round of strong gusty winds, strongest in the lee of the Black Hills where a period of warning level winds will materialize via acceleration around the hills. Gusts over 60 mph can be expected there and have opted to upgrade the high wind watch given CAA, pressure rise couplet, and expected flow acceleration around the hills. Also issued a wind adv for the rest of NW into central SD, running it through Sunday, catching the cold front and the next round of breezy winds Sunday late morning/afternoon. There will likely be a period of sub adv winds Sun morning, but decide to keep things simple and just run the adv through Sunday. The high wind warning area will need to be converted to a wind adv or extended if stronger flow is progged. Hence, to keep things simple will defer headline change to the mid shift. Not much moisture with this system, but still expect some post frontal snow showers over NE WY into NW SD, including the northern Black Hills where up to an inch is possible. Cold pool aloft will time with diurnal heating, Sunday, supporting convective showers Sunday afternoon, best chance over NW SD where a little better moisture will be found. Otherwise, cool, breezy, and increasingly unsettled weather can be expected next week, with increasing chances for a late week storm to affect all of a portion of the region as the western NOAM upper trough moves east. Too much uncertainty remains in track, timing, moisture transport, and best collocation of lift to predict any snow/rain amounts in the Thur-Fri period at this time. && .AVIATION...(For the 00Z TAFS Through 00Z Sunday Evening) Issued At 519 PM MDT Sat Apr 10 2021 A strong cold front will cross northeast WY 02z-06z and western SD 05z-11z. Gusty northwest winds are expected behind the front with gusts over 35kts common and gusts around 50kts just east of the Black Hills through early Sunday morning. A few shrasn expected behind the front with areas of MVFR conditions, mainly from northeast WY into far western SD. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Wind Advisory from 2 AM MDT /3 AM CDT/ to 6 PM MDT /7 PM CDT/ Sunday for SDZ014-032-043-046. High Wind Warning until 4 AM MDT Sunday for SDZ001-002-012-013- 025. Wind Advisory from 4 AM to 6 PM MDT Sunday for SDZ001-002-012- 013-025. High Wind Warning until 8 AM MDT Sunday for SDZ026-031-072-073. WY...High Wind Warning until 1 AM MDT Sunday for WYZ054>058-071. && $$ Update...Helgeson DISCUSSION...JC AVIATION...Helgeson