Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/24/17

Area Forecast Discussion
National Weather Service Columbia SC
1027 PM EDT Wed Aug 23 2017 .SYNOPSIS... An approaching cold front will cross the area tonight into Thursday. High pressure will build into the region for the end of the week...bringing a cooler and drier airmass. Tropical activity could affect the region next week. && .NEAR TERM /TONIGHT/... Surface front slowly pushing southward and into the southern Midlands, with isolated to scattered showers and storms still north of the boundary. The hrrr continues to indicate scattered showers and storms north of the front the next several hours before all activity shifts east of the cwa. Brief heavy rainfall will remain possible in areas that experience the heavier storms or training of storms. Overnight low temperatures in the lower to middle 70s. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... Thursday morning, the cold front will be over the eastern Midlands with dry air pushing from the west. Recent model runs have pushed the dry air in more quickly, therefore lowered PoPs in the western Forecast Area (FA). There is some uncertainty in the location of the front for the rest of the day. Most models push the front, and develop afternoon convection, east of the FA. The GFS develops a weak low on the boundary which brings moisture back into the Pee Dee. The amount of moisture advection seems overdone, therefore favored a drier forecast. The best chance for thunderstorms will be in the eastern FA in the early afternoon as a shortwave moves over. Dry mid-level air would indicate a downburst wind threat if convection develops. Expect near normal temperatures in the mid 80s to lower 90s for Thursday with lows in the upper 60s and lower 70s Thursday night. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Dry high pressure ridging into the mid-Atlantic will dominate Friday and Saturday. NE flow will bring near normal temperatures to the FA. A low pressure system may develop along the old frontal boundary off the coast. Moisture advection over the surface ridge and a broad upper level trough will bring back chances for showers and thunderstorms Sunday into early next week. Moisture advection out of the Gulf of Mexico associated with tropical depression Harvey will bring increasing rain chances near the end of the extended period. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... A cold front is slowly moving eastward through the Midlands late this evening, with a few showers/isolated thunderstorms ahead of the front. Given the latest radar trends, will use VCSH at CAE/CUB until around 02Z. Some of the latest hi-res guidance is indicating potential for fog/stratus developing during the early morning hours on Thursday, especially at OGB and AGS. Elsewhere, a 15-20 knot low level jet and drier air filtering into the area in the wake of the front may help reduce fog potential. The front will be in the eastern Midlands Thursday morning promoting a low chance of showers and thunderstorms mainly east toward the end of the TAF period. EXTENDED AVIATION OUTLOOK...No significant restrictions to aviation expected through Sunday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service State College PA
1144 PM EDT Wed Aug 23 2017 .SYNOPSIS... A large area of high pressure will build southeast across the region. An upper level disturbance will move across the central and northwest mountains Thursday afternoon. Sprawling high pressure will then dominate the weather into the weekend. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Cyclonic flow aloft and a weak secondary cold front are responsible for some light rain showers currently along and just north of the NY border. The HRRR suggests one or two of these showers could survive the trek into the Northern Mountains, but the better bet is for them to continue to weaken. Cold air in the form of 850mb temps as low as 6C (1-2sigma below normal) will slide across the Great Lakes and settle in for the next several days. Boundary layer decoupling will lead to calm air tonight which will help to maximize radiational cooling and help fog to form in the valleys, but some cloud cover over the west may keep the fog in check. Mins will range from the chilly mid 40s over the north to around 60 across the south. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... A potent albeit moisture starved shortwave trough will approach the the area Thursday and Thursday evening. Some erosion in stability is made to occur as the cold pocket aloft moves our way during the afternoon. SPC does not have us outlooked for thunder, but with such cold air aloft and the time of year, some low topped storms would not surprise me. The chances are too low to include at this time. The best chance of showers look to be over the higher elevations of the west and north. High temps Thursday will be about 5-6 deg lower than this afternoon`s (Wed) values, or in the m60s NW-m70s SE PA. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... An extended period of refreshingly cool, pleasant and dry weather will continue through the upcoming weekend as high pressure remains in control of the weather pattern over the northeast quarter of the CONUS. It will feel more like early fall than late summer. A few spots in north-central PA could see morning lows dip into the upper 30s over the weekend. Global models suggest isolated, terrain-induced convection may be possible within return flow along the spine of the central Appalachians later in the period. However, ensemble means favor a continuation of the mainly dry and seasonable pattern through the end of August, as upper level ridging building into the Western U.S. supports troughing downstream over the central and eastern states. Interesting to note that the both the 12Z GFS/00Z ECMWF bring the remnants of Harvey toward the area by early September. After what appears to be a mainly dry end to the month of August in central PA, this could be something to monitor down the road. && .AVIATION /04Z THURSDAY THROUGH MONDAY/... A ridge of high pressure over the region will ensure VFR conditions and light wind late this evening. Some patchy dense valley fog is likely late tonight, mainly in the valleys of northwest Pa. Based on latest SREF, downscaled NAM and LAMP guidance, believe a period of IFR/LIFR conditions is likely late tonight into early Thursday morning at KBFD, with a brief period of fog also possible at KUNV/KAOO/KIPT around dawn. Elsewhere, believe MOS guidance is overly pessimistic at KJST, where radiation fog is rare due to its ridgetop location. Based on climatology and latest model guidance, believe most of the fog across northwest Pa will burn off by around 14Z. There is high confidence in widespread VFR conditions the rest of Thursday. However, can`t rule out a brief MVFR reduction from a passing shower in the afternoon. .OUTLOOK... Fri-Mon...Patchy AM fog possible, mainly northern Pa. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte/Lambert LONG TERM...Steinbugl AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Quad Cities IA IL
1036 PM CDT Wed Aug 23 2017 .UPDATE... Issued at 1033 PM CDT Wed Aug 23 2017 I`ve updated to add slight pops to the west after midnight through Thursday morning, as the short term guidance solutions supporting elevated showers are verifying. Bands of light to moderate showers are expected to move towards the area overnight, and could result in some spotty measurable rain. In the worst case for a few isolated areas, a tenth of an inch could occur if the moderate intensity would hold together. The clouds arriving later will help keep temperatures a bit warmer than earlier thought over Iowa, and have bumped up temperatures to the mid to upper 50s for lows there, but remained cool farther east under the prolonged clear conditions. ERVIN && .SYNOPSIS... Issued at 330 PM CDT Wed Aug 23 2017 High pressure was centered over the central part of Iowa this afternoon leading to early fall like weather. Afternoon fair weather cumulus clouds have formed across the area. Otherwise temperatures in to 70s with low RH were reported across the area. && .SHORT TERM...(This Evening through Thursday) ISSUED AT 330 PM CDT Wed Aug 23 2017 Two main forecast concerns in the short term forecast. The first is the slight chance for rain across the area tonight into tomorrow morning as a wave advects south into the Great Lakes and the other are the temperatures tonight. Guidance is suggesting clouds but with the clear skies and low Td and at sunset, could see temps plummet. All guidance suggests low end QPF across the far northern CWA as a wave advects in from the NW flow. The HRRR has been consistent with a band of light to moderate showers across northeast and east central Iowa towards daybreak. Main concern is that the best H5 forcing is to the north and east of the area and with dry air any rain that forms will have a hard time making it to the ground. With low confidence in this occurring, decided to keep schc pops across the far NE and the rest of the area dry. This will need to be watched by later shifts to determine if there is a greater chance for rain later. As far as temps tonight go, its going to be a race between temperatures dropping fast and clouds moving in. With temps this morning in the upper 40s, decided to keep them in the low 50s across the area. Once the clouds move in think that the temps at that time will be close to the actual lows. As far as lows went, went with MOSguide and tweaked a few degrees here or there for consistency. .LONG TERM...(Thursday Night through next Wednesday) ISSUED AT 330 PM CDT Wed Aug 23 2017 Thursday night and Friday...LLVL ridge will look to maintain acrs the western GRT LKS, while upper ridge undercutting upper wave/trof shifts slowly eats acrs the central plains. The jury is still out on how much low to mid level moisture lee side elevated warm air advection wing will have to utilize to try and produce some showers acrs the MO RVR Valley and IA, and suspect that the western CWA will just have some AC, virga, or few sprinkles trying to spill in from the west at times later Thu night into Fri morning. Still some chance of at least patchy fog in the eastern fcst area late Thu night/early Fri morning closer to lingering ridge axis and least/ last in line for some cloud cover. Will play Thu night lows at the coolest of guidance, or even undercut them in the east, again closer to the ridge axis and light convergent easterly sfc wind regime. with ongoing dry low to mid level east-southeast fetch, like the drier 12z run NAM for Fri...again probably just mid level clouds and mainly virga trying to make it into the western and northwestern CWA. Below normal temps continue to end out the week. ELevated wing of WAA showers to the lee of increasingly blocked northeastern plains upper low, will then look to gather more organization Fri night, but mainly along and north of the CWA acrs MN into WI. Saturday and Sunday...The latest run medium range models continue to suggest a general blocked pattern to maintain over the weekend acrs the GRT LKS, with increasing influence from the southwestern Gulf tropical system, as well as other waves off the Atlantic coast. If a cut-off upper low forms acrs MN By Sat night west of upper ridge lobe over the eastern GRT LKS and James Bay, a regional Rex Block may keep this feature almost in place or just allow it to slowly gyrate southward acrs or near the local area Sunday and into early next week. Thus while Sat may largely be dry, sctrd shower chances will then look to increase acrs the local area later Sat night into Sunday. with early indications of limited moisture feed into this system, just see light showers and sprinkles by Sunday, but associated cloud cover and evapo-cooling may make the fcst highs in the upper 70s to around 80 hard to attain. Monday through next Wednesday...If the latest trends on the medium range guidance and ensembles area correct, the blocked upper low will look to rotate almost overhead Mon into Tue, for continued cloud cover and sctrd shower chances. Would think and thunder threat embedded in the showers will be limited to only the afternoon, if any happens at all. Temperatures will continue to be tied to cloud cover and precip trends and fcst highs possibly optimistic this period. Will have to watch trends of the western Gulf to lower MS RVR Valley tropical system, as well as possible waves along the Atlantic as they will be big players in the synoptic scale pattern evolution how long the upper system lingers locally early to mid next week. ..12.. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) ISSUED AT 612 PM CDT Wed Aug 23 2017 Light north to northwest winds under 10 kts will become light and variable overnight, and turn east to southeast Thursday morning, while remaining under 10 kts. Some increase in mid level clouds above 10kft is expected, and a few very light sprinkles/virga may also occur, but no visibility restrictions are expected at any airport in eastern Iowa and northwest Illinois through Thursday evening. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...Ervin SYNOPSIS...Gibbs SHORT TERM...Gibbs LONG TERM...12 AVIATION...Ervin
Area Forecast Discussion
National Weather Service Green Bay WI
1057 PM CDT Wed Aug 23 2017 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Thursday Issued at 209 PM CDT Wed Aug 23 2017 The latest RAP analysis and satellite/radar imagery show northwest flow continues off Lake Superior early this afternoon, with moisture fluxes leading to a broken cu field over the northern part of the state. Still seeing sporadic obs of light drizzle being reported over Vilas County. The next shortwave is moving southeast over southern Manitoba where scattered light rain showers are occurring. The mid-level cloud deck associated with this system is already approaching northeast Minnesota. Precip chances with this system, and impact on temps are the main forecast concerns. Tonight...Shortwave trough over southern Manitoba will swing across the region late tonight. Mid and high clouds will be on the increase during the evening hours. But low levels will struggle to saturate due to the very dry airmass as evident by the 12z GRB sounding. As a result, precip chances look to be confined to mainly central Wisconsin between 08-12z approximately, and will increase precip chances some there. The influx of clouds will likely hold up temps for a period over north-central WI before they fall again late as skies begin to clear. Though patchy frost remains possible in the cold spots, concerns about cloud cover are high enough not to issue a frost advisory. Will instead issue an SPS in case the clouds diminish before reaching northern WI. Lows ranging from the mid 30s in the cold spots to near 50 degrees over the southern Fox Valley. Thursday...As the shortwave departs, clouds will be exiting central and northeast Wisconsin during the morning hours. High pressure will then reassert itself for the rest of the day, with a drier airmass than the one currently present over the area. As a result, should see less cloud cover during the afternoon hours. Highs ranging from the mid 60s to near 70. .LONG TERM...Thursday Night Through Wednesday Issued at 209 PM CDT Wed Aug 23 2017 Cool high pressure will continue to dominate the region Thursday night into Friday. Clear skies and light winds provide the potential of patchy fog Thursday night. Thursday night overnight lows across northern Wisconsin may also support pockets of frost over the climatological cool spots. Progs are trending for a wetter weekend for part of the area. While a surface high pressure system remains anchored over the Great Lakes region, return flow over the Northern Plains will spread over parts of the western Great Lakes region. Progs then drift an 850 mb low with surface low across the state Saturday night into Sunday. The more aggressive GFS model run provides up to a quarter inch of rain over much of the area Saturday night and Sunday while the ECMWF is a bit slower with the arrival Saturday night. The low pressure region then gradually shifts south Sunday into Monday but still near the area for continued rain chances. High pressure then attempts to build back into the area as upper heights increase. Precipitation chances then become more isolated or end and temperatures return to more normal levels. && .AVIATION...for 06Z TAF Issuance Issued at 1046 PM CDT Wed Aug 23 2017 An upper level disturbance will bring a chance of light showers to mainly central WI late tonight, along with BKN to OVC mid-level clouds to the rest of the region. However, conditions should remain VFR with this system. Skies will clear early Thursday morning across most of the area and remain mostly sunny and VFR through the afternoon with light winds. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Grand Rapids MI
1005 PM EDT Wed Aug 23 2017 LATEST UPDATE... Update/Marine .SYNOPSIS... Issued at 324 PM EDT Wed Aug 23 2017 A more early fall like weather pattern into the weekend as Canadian Polar Air remains over the area through Sunday. The coolest temperatures will be tomorrow and Friday then there will be a slow warm up. It would not be out of the question to have a little patchy frost near Route 10, east of Reed City tomorrow morning and Friday morning. && .UPDATE... Issued at 1005 PM EDT Wed Aug 23 2017 Have added low chc pops for lgt rain showers to the lakeshore counties toward daybreak as the shortwave now over nrn MN approaches. Upstream radar and latest HRRR runs support sliding these showers into our area after 10Z. Continued the lakeshore pops through early afternoon Thursday until the shortwave passes through, and also added a mention of sprinkles inland from the lakeshore through midday as that thick deck of mid clouds upstream associated with the shortwave drifts through. && .SHORT TERM...(This evening through Friday night) Issued at 324 PM EDT Wed Aug 23 2017 The cold air has arrived in Southwest Michigan and will remain over this area through most of the weekend. There is an issue with lake effect rain showers and it is not out of the question that we could see patchy frost in the normally colder locations near Route 10, east of Reed City. We have a few cold air instability rain showers over our eastern and central CWA this afternoon but those should be gone with sunset. The coldest air we will see from this event is behind the next shortwave, which can be seen on the latest water vapor image loops north of International Falls MN. This shortwave dives southeast enough so that the polar jet axis will actually be south of the State of Michigan during the day time hours of Thursday. This brings 850 temperatures down to 4c as far south as Big Sable Point tomorrow morning. This is cold enough of lake enhanced rain showers but due to the north wind, this will not really impact much of our CWA as it turns out. Thanks to the shortwave there will be a fair amount of clouds around Thursday so I do not think highs will get out of the 60s in most areas. Thanks to surface high pressure over the area I expect winds to be light tonight and that will allow temperatures to fall below mos forecast values. It just may get cold enough in isolated locations to get some patchy frost but since current dew points are well above freezing, it would seem unlikely this would be widespread issue so I did not put that in our grids. The polar jet goes back north and east of this area by Friday morning. More often than not that morning turns out to be the coldest in this sort of weather pattern. Once again frost is not out of the question and I would not be surprised to see locations like Leota to get near freezing. Bottom line is early fall like weather through Friday night. .LONG TERM...(Saturday through Wednesday) Issued at 324 PM EDT Wed Aug 23 2017 This forecast is slightly wetter than the previous one and features at least some chances for rain showers Monday through Wednesday. The greatest chances for rain in the general area look to be Monday with thunderstorms also possible in the afternoon. Overall, forecast certainty is very low due to poor predictability with placing the key ingredient involved with producing rain. This key ingredient is an upper trough originating from southwestern Canada that digs and then cuts off over the vicinity of Illinois by late Monday. Medium range deterministic models like the GFS/ECMWF/CMC are in fairly good agreement with this evolution but afterwards start to diverge. This is not surprising for a cutoff low in general - and this one is extra tricky in terms of placement due to very split flow aloft associated with upper ridging over Ontario to the northeast. A large number of ECE and GEFS member solutions remain dry during this time and the overall wide range of solutions emphasizes the poor predictability. As such, this forecast is highly subject to change. But for now seasonably cool and unsettled seems like the best bet for the first part of the coming work week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 758 PM EDT Wed Aug 23 2017 Went with VFR conditions in the TAFs tonight and Thursday, but there are a couple concerns. First, there could be some patchy fog developing tonight into early Thursday morning which could lead to some vsbys restrictions. Second, a brief period of MVFR cigs (and even a few light showers) could occur on Thursday with the passage of the shortwave and next sfc trough/cold front. However was not confident enough in either of these two issues occurring to have lower conditions mentioned in the TAFs at this time. && .MARINE... Issued at 1005 PM EDT Wed Aug 23 2017 Winds and waves have subsided enough to cancel the Small Craft Advisory and Beach Hazard Statement. && .HYDROLOGY... Issued at 1213 PM EDT Wed Aug 23 2017 Area rivers are around normal levels for the time of the year and well below bankfull. The rivers have already recovered from the recent rainfall. No significant precipitation is expected through the weekend, so no river issues are expected. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...Meade SYNOPSIS...WDM SHORT TERM...WDM LONG TERM...TJT AVIATION...Meade HYDROLOGY...63 MARINE...Meade
Area Forecast Discussion
National Weather Service Wilmington NC
912 PM EDT Wed Aug 23 2017 .SYNOPSIS... An approaching cold front will bring thunderstorms tonight through Thursday, some of which may be strong. Canadian high pressure will bring an early fall feel Friday and through the weekend. We will be watching the tropics for possible development of low pressure off the Southeast coast early next week. && .NEAR TERM /THROUGH THURSDAY/... As of 915 PM Wednesday...The big convective line is weakening slightly as it approaches the coast of SE North Carolina. Ingesting the very humid but slightly cooler (and therefore initially capped) boundary layer is likely responsible for the storms` recent behavior. Although weaker, they should continue to sag southeastward and to the beaches in the next hour. Heavy rainfall, gusty winds, and frequent lightning are all expected. Redevelopment of storms off to the west from Marion and Johnsonville, SC all the way back through Timmonsville and Camden is a bit healthier than I would have thought two hours ago. Surface parcels are heavily capped back in this region, but recent SPC mesoanalysis graphics indicate central and eastern South Carolina is coming under the influence of a 250 mb jet streak located over the Mid-Atlantic region. Upper level divergence located within the right-entrance region of this jet is probably helping lift elevated parcels starting in the 5000-1000 foot AGL range. There`s no reason to expect this activity to dissipate given its disconnect from the boundary layer and the likely persistence of the upper level pattern. Likely (60-70 percent) PoPs have been expanded across a good portion of eastern South Carolina through early Thursday morning. Discussion from 730 PM follows... A synoptic cold front across central North Carolina extends from Greenville, NC to Fayetteville to near Charlotte and is dropping southward. A large cluster of thunderstorms has developed just ahead of the boundary, taking advantage of uncapped surface-based CAPE of 2500 J/kg. Precipitable water values near 2.0 inches normally doesn`t coexist with large DCAPE values, but in this case just large enough temp-dewpoint spreads exist above the boundary layer to support DCAPE as large as 1300 J/kg -- leading to the gusty winds we have seen in today`s storms. A gust to 55 mph was measured at the ASOS in Lumberton, NC, and trees were blown down in Dillon, SC. Evolution of this event through the evening is shown very well on the last few HRRR runs as well as the 18Z NAM. A massed-line of storms should work down into Wilmington and the Cape Fear region by late evening, joined by scattered showers and storms across the Myrtle Beach area. One weak upper level vort max is supporting our current storms, but a second vort digging across eastern Tennessee and western North Carolina later tonight may begin to back the mean flow just enough late tonight to cause activity to cease its eastward progress and hang up across the coastal waters and perhaps the coastal counties as well. On this latest update PoPs were increased to 70-100 percent for SE North Carolina, with QPF raised to 1+ inches in spots. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...Some cooler and drier air will be filtering in Thursday night from the northwest behind slow moving cold frontal boundary. A little rain may linger along the coast due to the later arrival of the drying. By Friday the front will stall just far enough south for a rain-free day as a sprawling, cool season-like 1025mb high is centered over the Great Lakes. This high will show little to no movement Friday night. The movement of the front, if any will thus be determined by any potential low pressure development off of JAX. This could also lead to a coastal increase in moisture. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 300 PM Wednesday...A stationary front will be located well offshore and S of the area Sat with an area of low pressure positioned on the front, but well offshore. High pressure will be ridging across the Carolinas from New England. The pressure gradient between these two features will keep a fairly brisk NE wind in place across the Forecast Area through the weekend. This will ensure the cool air is continually reinforced and highs during the weekend should only be in the lower to mid 80s and this will be coupled with comfortable humidity levels. Model profiles continue to be quite dry with precipitable water values below climatological normals and thus will not include any mention of a shower or thunderstorm during the weekend. This pattern looks to hold through Sun. The flow becomes more onshore and the column begins to moisten Mon and Tue. There may also be some mid- level shortwave energy impinging on the area from the SW. Will paint more in the way of cloudiness as a wedge likely sets up and introduce the potential for some showers and perhaps a thunderstorm. The probabilities for precipitation will be highest at the coast. The heat is not to be found, even early to the middle of next week with highs only in the lower to mid 80s. Lows will be in the mid 60s to near 70 through the period. As a caveat, we will be watching the tropics early next week to see if a weak disturbance is able to develop somewhere off the SE coast. Confidence in any development is very low as is its eventual track. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 00Z...A large cluster of thunderstorms across the Coastal Plain will move east-southeast toward the coast this evening. Storms should reach the ILM and CRE airports between 02-03Z, and perhaps MYR around 04Z. Gusty winds and visibility falling to MVFR (or even briefly IFR) in heavy rainfall are expected. Current thunderstorms should move away from the FLO and LBT airports, but we are watching for showers and weaker embedded thunderstorms to redevelop and affect the interior Coastal Plain through 04Z. All this convection is the result of a cold front plowing southeastward into a hot and unstable airmass across the eastern Carolinas. The front should reach the South Carolina border early Thursday morning between 09-13Z, with winds shifting more northwesterly at the LBT, ILM, and possibly FLO airports. This could also allow IFR stratus to develop just before daybreak. Thursday afternoon`s seabreeze should turn winds back onshore, with converging low- level winds leading to another round of showers and t-storms Thursday afternoon, particularly near the coast. Extended Outlook...Showers and t-storms Thursday associated with a cold front could produce localized IFR conditions. Most showers and storms will push offshore Thursday night into Friday. MVFR ceilings could linger, especially near the coast Friday. && .MARINE... NEAR TERM /THROUGH THURSDAY/... As of 915 PM Wednesday...Storms are moving rapidly toward the beaches of SE North Carolina. They are weakening but are still capable of producing some hefty wind gusts as they move offshore. Please reference the latest Marine Weather Statement for details. Additional storms are developing across central and eastern South Carolina and will likely affect the areas south of Cape Fear closer to midnight and into the early hours of Thursday morning. No changes have been made to synoptic forecast reasoning through the night. Discussion from 730 PM follows... A cold front currently across central North Carolina is moving southeastward and should reach Cape Fear by daybreak Thursday. Steady southwesterly winds around 15 knots ahead of the front should become disturbed by late evening as a large line of thunderstorms across the interior Coastal Plain moves out across the waters. Variable wind gusts in and near these storms should settle down to a weaker, more westerly average wind after midnight. Mariners planning to be out on the waters, especially north of Myrtle Beach, should closely watch these storms now through midnight. SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...Cold front comes through early Thursday night turning winds to the NE by midnight. The NE to E winds will last for the remainder of the period as a large area of high pressure sits centered over the Great Lakes and the front remains stalled to our south. Low pressure developing on the boundary off NE FL coast gradually should pinch the gradient and allow for a slow building of wind and seas. LONG TERM /SATURDAY THROUGH MONDAY/... As of 300 PM Wednesday...Persistent and brisk NE winds will likely require a Small Craft Advisory for much of the period. The tightening pressure gradient will be the result of high pressure ridging down into the Carolinas from the N and an offshore front and area of low pressure. NE winds will be around 25 kt for much of the period. Seas will be 5 to 7 ft and perhaps up to 8 ft by Mon. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...RJD NEAR TERM...TRA SHORT TERM...MBB LONG TERM...RJD AVIATION...TRA
Area Forecast Discussion
National Weather Service Lincoln IL
904 PM CDT Wed Aug 23 2017 .UPDATE... Issued at 904 PM CDT Wed Aug 23 2017 High pressure ridge is sitting right over the CWA this evening and will slowly move east overnight. This has created clear skies and light winds, which will continue overnight. Current forecast has good handle on everything, including temps falling into the lower to middle 50s. So no update planned at this time. && .SHORT TERM...(This evening through Thursday) ISSUED AT 245 PM CDT Wed Aug 23 2017 High pressure at the surface will dominate the short term, despite a weak upper shortwave in southern Manitoba expected to progress into north-central Illinois late tonight and Thursday morning. The RAP and NAM-nest show some convective elements developing in NW Illinois after 10z, pushing the shortwave across Illinois during the morning. The NAM/GFS/GEM/EC all point toward the wave weakening and any radar returns that do develop will remain virga, due to dry overall airmass. Have kept the forecast dry through Thursday, with just an increase in cloud cover north of I-72 coincident with the passage of the wave. The mid-afternoon minimum dewpoints point toward the potential for some chilly low temps tonight. Lacon dewpoint of 48 and Peoria 49 give credence that a few northern locations could even dip into the upper 40s late tonight. Guidance numbers have not latched onto that trend just yet, but we trimmed the northern temps a couple degrees toward 50F. Highs on Thursday will be dependent on how long cloud cover lingers in the NE half of the area, but in general we expect highs to be a degree or two warmer than today, in the upper 70s to around 80. .LONG TERM...(Thursday night through Wednesday) ISSUED AT 245 PM CDT Wed Aug 23 2017 The extended will be dominated by an upper trough in eastern Canada/Great Lakes and an upper ridge in the Plains and Rockies, setting up a persistent northwest flow into Illinois through this weekend. The next weather disturbance of enough significance to cause rain/storms looks to be as early as Sunday afternoon and extend through as late as Tuesday afternoon due to a cut-off low type situation. The confidence in the extended forecast past Sunday is low, due to the unknown path of Tropical Depression Harvey, and how close it will come to Illinois when it ejects from Texas toward Tennessee/West Virginia. Harvey could linger for several days in eastern Texas and the nearby waters of the Gulf of Mexico from Friday through Tuesday, according to the ECMWF and GFS. The Canadian drifts Harvey west into N Mexico and dissipates it there, as the outlier solution. In any event, the central Illinois area looks to be in the path of a low pressure system arriving from the NW from Sunday afternoon into Monday at least. However, an approaching Canadian upper trough and the approach of Harvey could possibly cause that precip potential to extend into Tuesday night and Wednesday as the approaching systems work to amplify the eastern CONUS trough. For now, we have limited PoPs to low chance and slight chance in the Sunday through Wed time frame. The blended extended actually has areas of dry conditions in portions of our forecast area during that time, especially Monday night, due to forecast uncertainties in strength of the low that arrives from the NW, available moisture, and timing/path of Harvey. Moisture return into Illinois from the south may be limited by Harvey to some extent as low and mid level flows into IL remain relatively weak during that time. Temperatures look on track to remain below normal for late August, with highs in the 70s and lows in the 50s, as the heat remains bottled up in the western CONUS. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 615 PM CDT Wed Aug 23 2017 VFR conditions will prevail at all TAF sites this evening and into tomorrow. A few CU/SC out there now, but will dissipate byu 00z so all sites will be clear tonight. Center of high pressure just to the west of the area and this will move over the area by morning. Clouds should be east of the area/ridging but still some going with only few clouds tomorrow. Winds will be light northwest tonight ahead of the ridge and then become light northeast tomorrow. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Auten SHORT TERM...Shimon LONG TERM...Shimon AVIATION...Auten
Area Forecast Discussion...CORRECTED
National Weather Service North Platte NE
630 PM CDT Wed Aug 23 2017 .SYNOPSIS... Issued at 312 PM CDT Wed Aug 23 2017 H5 analysis this morning had closed low pressure over Quebec with a trough of low pressure extending south into the central Appalachian Mountains. High pressure was south of the trough over the western Atlantic, off the coast of northern Florida. High pressure extended west to northern Mexico, where a secondary high pressure was located south of Arizona. A ridge extended north of this feature into the northern Rockies and into northern Alberta. At the surface, high pressure was located over southeastern Nebraska near Falls City. A surface trough of low pressure was located across eastern Wyoming into eastern Colorado. Between these two features, a nice pressure gradient had developed this morning across the western sandhills and north central Nebraska. This has resulted in breezy southerly winds this afternoon. Under clear skies this afternoon, 2 PM CDT temperatures ranged from 80 at O`Neill, Broken Bow and North Platte to 87 at Valentine. && .SHORT TERM...(This evening through Thursday) Issued at 312 PM CDT Wed Aug 23 2017 In the near term, Thunderstorm chances tonight and Thursday is the main forecast concern. For tonight: Current surface obs from eastern Colorado, indicate a thin band of low level moisture surging north into far southwestern Nebraska and the southern panhandle this afternoon. The latest NAM12 soln does indicate an adequate amount of moisture and convective potential this afternoon to support storms in the sern panhandle and far swrn zones, however a glance at mid level lapse rates and fcst soundings, indicates a decent cap and plenty of cin in these areas at peak heating. Further west, a more favorable set up for convective development appears along the Cheyenne ridge of se Wyoming and am expecting convective development there. As this activity moves east it is expected to dissipate as the low level jet is anchored well east of the panhandle. Overnight lows will be in the mid to upper 50s. A more favorable set up for thunderstorms will push into the forecast area on Thursday. Thanks to a continuation in southerly winds late tonight into Thursday morning, increased low level moisture will overspread southwest and western Nebraska. With surface heating Thursday afternoon, SB capes will reach 2000 to 3000 J/KG with very limited CIN noted. At the same time, a mid level disturbance will enter the panhandle late morning Thursday with mid level warm air advection increasing from the western sandhills into southwestern Nebraska. Precipitation chances will increase from midday Thursday into Thursday evening. Deep layer shear is fairly weak mid day into the early afternoon hours, but increases to 25 to 30 KTS late afternoon. This will provide a limited severe weather threat from 21z to 03z Friday given the forecast CAPE of 2000 to 3000 J/KG and 25 to 30 KTS of deep layer shear. .LONG TERM...(Thursday night through Wednesday) Issued at 312 PM CDT Wed Aug 23 2017 Thursday night through Saturday night: There will be a continued threat for thunderstorms Friday night into Saturday night as persistent southerly winds allow moisture to remain anchored across the forecast area. Additionally, a surface trough will remain anchored across the panhandle and eastern Colorado, and weak disturbances will track east of the central Rockies with a continuation of zonal flow aloft. Timing will be tricky with respect to the disturbances, and have hedged the highest pops toward the late afternoon and early evening hours. Shear will weaken Friday into Saturday, so any severe threat should be minimal attm. Sunday through Wednesday: Like yesterday, the mid range model solutions trend toward the development of an upper level high across the intermountain west Sunday. This feature will remain anchored across the west through the remainder of the forecast period. this will lead to northerly flow aloft and a limited threat for precipitation after Sunday. Temperatures will be seasonal with highs in the 80s and lows in the 50s. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 629 PM CDT Wed Aug 23 2017 VFR is generally expected tonight and Thursday morning. Isolated thunderstorms are possible this evening across Wrn Neb, west of highway 83. Another area of concern could develop 06z-12z tonight across Ncntl Neb along and north of highway 20 east of Valentine where a small cluster of showers and thunderstorms may develop across to the RAP and HRRR models. Scattered to numerous thunderstorms are expected to develop 18z- 00z Thursday mainly affecting areas west of highway 83. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...CDC
Area Forecast Discussion
National Weather Service Pueblo CO
350 PM MDT Wed Aug 23 2017 .SHORT TERM...(This evening through Thursday) Issued at 350 PM MDT Wed Aug 23 2017 Isolated thunderstorms were developing over the mountains again this afternoon, with greatest coverage along and north of the Arkansas River. Expect storms to continue to develop and push eastward away from the higher terrain from late afternoon into the evening, though coverage will remain generally isolated as upper forcing remains weak. Enough instability (CAPE 1-2k J/KG) on the plains to keep a low threat of an isolated storm in place along and east of I-25, though latest HRRR and 18z NAM now show little in the way of convection through the evening. Storms fade fairly quickly in the evening, with persistent sly flow across the plains likely leading to some patchy fog along the KS border toward sunrise. On Thu, upper trough moves across the state while a weak cold front drops south through the plains. Moisture remains in place across the region, leading to some fairly healthy CAPE (2k J/KG) along and ahead of the boundary in the afternoon. Given the stronger forcing and instability, area should see more widespread and vigorous convection, with perhaps a severe storm or two over the plains where instability is greatest. Main argument against more widespread severe storms is weak 0-6km shear of only 20-30 kts, so SWODY2 of only marginal risk over the eastern plains looks reasonable at this point. Max temps look little changed, with near seasonal readings at many locations. .LONG TERM...(Thursday night through Wednesday) Issued at 350 PM MDT Wed Aug 23 2017 Outside of Thursday evening(which is expected to be active due to a healthy passing upper disturbance), a relatively tranquil meteorological pattern is anticipated during the balance of the longer term as varying degrees of upper ridging impacts the forecast district. At this time, main longer term meteorological concerns appear to be temperatures and pops for the forecast district. Recent longer term computer simulations, forecast model soundings and PV analysis indicate that upper ridging centered near EL Paso, Texas Thursday evening shifts into the 4-Corners region by Saturday before relocating over Nevada and Utah from later this weekend into next Wednesday. In addition, varying degrees of eastern Colorado lee-side troughing is anticipated from Friday into Saturday night and then again from later Monday into next Wednesday. In addition, at this time, it appears that the strongest upper disturbances impacting the forecast district during the longer term will be noted into Thursday evening, from later Sunday into Sunday night and then again from later Monday into Tuesday night. The combination of these factors as well as adequate atmospheric moisture will allow basically daily rounds of isolated to scattered primarily afternoon and evening pops(generally favoring higher terrain locations) during the longer term. At this time, the highest potential for more widespread precipitation should be noted from Thursday evening into Thursday night, later Sunday into Sunday night and then again from later Monday into Tuesday evening. Also, as has been the case, minimal gradient wind and fire weather concerns are anticipated during the longer term. Finally, minimum and maximum temperatures should generally run above late August climatological averages over the majority of the forecast district during the longer term. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 350 PM MDT Wed Aug 23 2017 VFR conditions expected at all TAF sites the next 24 hours. Isolated tsra over the mountains will drift toward lower elevations late this afternoon and this evening, and will continue a VCTS mention at KALS and KCOS until 02-03z. Gusty erratic winds up to 40 kts and brief VFR cigs/vis will be possible with tsra through early evening. Storms fade away overnight, with some patchy fog developing on the eastern plains near the KS border toward sunrise. On Thu, tsra will be slightly more numerous as weak upper disturbance moves across CO and cold front drops south through the plains. Expect a chance of tsra at all terminals after about 20z, with a chance of a few stronger storms producing hail and brief MVFR conditions along and east of I-25. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$
Area Forecast Discussion
National Weather Service San Angelo TX
858 PM CDT Wed Aug 23 2017 .DISCUSSION... Scattered showers and thunderstorms are slowly decreasing across the area, with the loss of daytime heating. PoPs were adjusted slightly to account for current radar trends. The HRRR continues to show redevelopment of at least isolated to scattered showers and thunderstorms during the early morning hours, mainly across the southern and eastern portions of the forecast area. Given this possibility, chance PoPs were continued after midnight for these areas. No other changes are needed at this time. && .PREV DISCUSSION... /issued 632 PM CDT Wed Aug 23 2017/ AVIATION... /00Z TAFS/ Look for challenging flight weather to develop, during this forecast cycle. Thunderstorms will continue for a few more hours this evening, mainly south of our Interstate 20 corridor. Then, watch for MVFR ceilings to develop overnight, mainly for locations north of our Interstate 10 corridor. Expect VFR conditions to return by mid morning tomorrow. Tomorrow afternoon, thunderstorms are again possible, across all of West Central Texas. PREV DISCUSSION... /issued 314 PM CDT Wed Aug 23 2017/ SHORT TERM... (Tonight) Satellite imagery shows the cloud coverage has begun to diminish across the area. Temperatures have responded to the decrease in cloud coverage by climbing into the upper 80s in areas where the sun has broken out. A weak MCV south of the I-10 corridor has allowed for the development of showers and thunderstorms across Kimble and Mason county this afternoon. Across the rest of the area, a weakening ridge over far West Texas will continue to slowly slide west and continue to flatten out, allowing for northwest flow to persist across the region. With this northwest flow aloft and a weak cold front over the southern Big Country, numerous showers and thunderstorms will develop along that boundary this afternoon. Both the Texas Tech WRF and the HRRR show large clusters of thunderstorms across the area late this afternoon. Severe weather is not expected with these storms. Main hazards with the stronger storms will be brief heavy downpours leading to minor flash flooding and dangerous lightning. Overnight lows will be in the upper 60s to low 70s. (Thursday) Breaks in the clouds during the afternoon will allow for increasing instability across the area tomorrow. HI-RES models indicate CAPE values climbing above 1000 J/KG with little convective inhibition. This instability and lack of capping inversion will allow for scattered thunderstorms to develop along leftover outflow boundaries from previous convection and the weak surface front positioned over the Concho Valley. Strong thunderstorm winds and dangerous lightning will be the main hazards with the stronger storms. Highs will be in the mid to upper 80s. LONG TERM... (Thursday night through Wednesday) A weak upper level shortwave will approach the area from the west early Friday. Although this feature will pass north of the region, it will couple with abundant moisture and likely result in scattered showers and thunderstorms. By Friday night/Saturday, all eyes will turn to tropical cyclone Harvey. It is expected to remain east of the region, but the westward extent of its rain shield will likely impact the area, especially southeastern portions of the forecast area. Harvey is progged to slowly start moving back to the east by Sunday and into early next week, taking any rain with it. Overall, Harvey will not have too big of an impact on west central Texas, however, continue to pay close attention to the forecast over the next several days, as any shift in the track of Harvey will affect our forecast. Given the precip chances and increased cloud cover, temps will be held down across the area. Mostly mid 80s are expected through Sunday, with some warming early next week (upper 80s/lower 90s) as Harvey moves east, taking the clouds and rain with it. Overnight lows will generally be in the mid/upper 60s. && .PRELIMINARY POINT TEMPS/POPS... Abilene 70 84 69 86 / 30 40 30 40 San Angelo 70 85 70 87 / 30 30 30 40 Junction 71 86 71 88 / 40 40 30 40 Brownwood 71 85 70 85 / 50 40 30 40 Sweetwater 70 84 69 84 / 20 30 30 40 Ozona 71 85 70 86 / 40 30 30 40 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ Daniels