Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/12/18

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
717 PM CDT Tue Sep 11 2018 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...Satellite and radar images as well as surface observations indicate scattered convection continues across central portions of the CWA early this evening. A mix of low/mid/high clouds were across the Rio Grande valley. Ceilings were near 2100ft at KEBG to near 7500ft at KBRO. VISIBILITIES were near 3SM with heavy rain at KEBG. Expect VFR to MVFR conditions across the Rio Grande valley through the rest of the evening into early Wednesday morning as the 500mb trough across southwest Texas brings some drier air aloft across the western portions of the CWA tonight but low to mid mid level moisture will remain high across the eastern portions. Brief MVFR to IFR conditions can be expected with showers and thunderstorms in the vicinity of local aerodromes the rest of this evening into early Wed morning. && .PREV DISCUSSION... /issued 353 PM CDT Tue Sep 11 2018/ SHORT TERM (Tonight through Wednesday Night): Some signs showing now that the current heavy rain event is beginning to wind down. Current water-vapor satellite imagery showing that much drier mid- level air has overspread roughly the NW 2/3rds of the CWA, flowing in from the WSW around the mid-level low centered in the vicinity of SJT. Latest HRRR run also suggesting that any heavier bands of showers/thunderstorms along the coast tonight may stay just offshore. That being said, have opted to retain the Flash Flood watch for Hidalgo/Brooks counties eastward through 12Z tomorrow. Flash Flood Guidance for central/western Hidalgo and southwestern Brooks counties remains quite low due to nearly saturated soils, so it won`t take much additional rain to produce problematic runoff. WPC continues to highlight a Slight Risk of excessive rainfall in a narrow coastal strip as well. Recent trends in visible imagery show that a compact surface low near the Starr/Hidalgo county border has begun to open up and/or lift NE a bit, along the old frontal boundary. This could still help trigger some "wrap-around" showers and thunderstorms over the Ranchlands and coastal counties from this evening into the overnight period. Have begun walking PoP`s back a bit over the next 24 hours, especially out west, per latest MOS/blend numbers. GFS is really wanting to dry out the mid-levels tonight, but not completely . buying into this solution. Will focus best coverage and amounts in the coastal counties, toward midnight and later, as has been the case the past several nights. Models show better consensus in some fairly sharp drying aloft for Wednesday, again especially to the west. H25 trough axis passes tonight, with mid-level low mentioned above finally progged to fill over south-central TX. PW`s come down to 1.6-1.7" west to ~2.0" along the coast, vs. 2.2" observed in BRO 18Z sounding today. Hence, will hold PoP`s in scattered category and remove mention of heavy rain for daytime Wednesday and beyond. Temps should recover to the low 90`s (except at the immediate coast), perhaps back to the mid- 90s in the Zapata-Falcon dam area where there should be much more sun. A little uncertainty in the forecast for later Wednesday night. Models trying to regenerate some more "wrap-around" precip over the N. Ranchlands/coastal counties. NAM sags the old H5 vort max into the western CWA, pulling some richer PW back inland. MOS guidance rather unimpressed, though, so have kept rain chances generally 30% or lower for land areas. LONG TERM (Thursday through Tuesday): All eyes on the potential development of the disturbance centered just north of the Yucatan peninsula Tuesday afternoon for what it may (or may not) do for Deep S. Texas and the Rio Grande Valley during the first few days of the long term (Thursday through Saturday). Concentrated the focus on this period with few changes made beyond Saturday night and Sunday. At this point, uncertainty reigns for most parameters and potential impacts, and confidence for all but direct coastal impacts from waves/swell/tides is low (medium for these). There are some subtle signs that do offer some possibilities for what may actually occur and the sensible weather that comes with it. First...and for what it`s deterministic models (GFS,ECWMF, UKMET, Canadian GEM) all carry a circulation, with relatively modest pressure falls, to the coast somewhere along the Coastal Bend. The elongated look of the disturbance as well as a jump to the north-northwest to just north of the Yucatan peninsula rather than along the Peninsula may have helped to guidance to "lean" toward the mid Texas coast vs. the Lower Texas coast. Second, there remains notable wind shear in the western Gulf, courtesy of the overnight convection and an eastward nudge of the `atmospheric river` that brought the flooding rains to parts of the region and the end of the drought/dryness to others. That wind shear, should it be present even if weakened, would argue for the model consensus slow development of the system. A quick look at intensity forecasts suggest the potential for a depression or tropical storm at this point. That said, if the shear does relax over the next 36 to 48 hours, the system has a better shot to intensify, with plenty of deep layer moisture in the envelope as well as peak warm temperatures in the 29-30C range (September in the Gulf). If that were to happen, the ability of the cyclone to track a bit farther south might improve as the 500 mb ridge between Florence and the southern Plains could become just dominant enough to bring more of a westward, than northwestward, movement. Because of the uncertainty, it`s just a bit too soon to bite off on any one solution, and better just to lean in a little bit toward the pragmatic answer which does favor a more northwest movement and slower intensification at this point. With this in mind, have followed the WPC/NHC idea for moderate rain chances and more modest QPF for the region, with slightly higher amounts on a southeast to northwest line along the coast (South Padre to Falfurrias) and lesser values in the populated mid Valley, which could use a break after the big rains since last Saturday night. Beyond Saturday night/Sunday the 500 mb ridge returns, and should bring more sunshine and temperatures a few degrees above average with modest east to southeast flow. One situation that bears watching is how rainfall potential develops across the Rio Grande Plains by Saturday afternoon and night. Models favor the area along/west of the Rio Grande between Laredo and Del Rio to get bigger rainfall, and WPC`s forecast does the same. Such a situation could create additional flood waves down the Rio Grande, which might affect areas north of Falcon in Zapata but more importantly push additional water into Falcon Reservoir, such that percentage of capacity, Texas share, could head toward 50% or higher as was the case in late September 2017. That`s always great news for irrigation come late winter and spring. Potential Impact Confidence: Elevated rip current and some tidal run up...medium. Forecast tides are at astronomical higher levels, and an additional foot or foot+ of increase could produce 1 to 1.5 feet of water at the typical shoreline interface, which would push water up to the dune line at high tide. Rainfall flooding...low. Strong winds...low. MARINE: (Now through Wednesday Night): A weak pressure gradient will continue through Wednesday, with a stalled frontal boundary in the area, which will maintain light to occasionally moderate winds and seas generally 3 feet or less. Deep tropical moisture will continue to support scattered to numerous showers and scattered thunderstorms, with possible brief heavy downpours, locally gusty winds, and isolated to occasional cloud-to-water lightning. Winds may back to a more NE direction Wednesday night as a tropical wave moves into the western Gulf of Mexico. At this time, speeds don`t appear to reach SCEC level in the short-term, but will have to monitor in case the tropical system develops more organization and tightens the gradient offshore. Could see some 4-ft. waves offshore by that time as well. Thursday through Sunday Night...much will depend on the evolution of the disturbance, both for intensity and track. A straight ECMWF/Canadian solution would bring northeast, then north, then northwest winds with the passage of the system followed by south to southeast winds Saturday and Sunday which could be the highest of all periods. A modest system - for example, a tightly wrapped tropical storm that makes landfall north of Corpus - would keep wind speeds 10 knots or less until the back side when south/southeast winds could kick up to 15-20 knots. Waves/seas are highly dependent on where and how quickly the system develops, and theoretically could range from 2 to 4 feet ahead of the cyclone to 4 to 6 feet in the longer fetch southeast flow behind it. A stronger system, even if tight, would be able to kick out swells and higher waves propagating to the Lower Texas coast...but how high cannot be determined at this time. && .BRO WATCHES/WARNINGS/ADVISORIES... TX...Flash Flood Watch until 7 AM CDT Wednesday for TXZ250-251- 253>257-351-353. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV 61/59/56
Area Forecast Discussion
National Weather Service State College PA
1048 PM EDT Tue Sep 11 2018 .SYNOPSIS... A slow moving cold frontal boundary will stall just to the southeast of the state tonight. The region will remain in a moist easterly flow between a high to our north and the circulation associated with Hurricane Florence well off to our south. There is the potential for the region to be impacted by rain from (the future remnants of) Hurricane Florence by the weekend or more likely next week, though the eventual track and timing of the storm are still very uncertain. && .NEAR TERM /THROUGH WEDNESDAY/... Meso analysis indicates the occlusion associated with the long dissipated Gordon has all but dissipated. Looking at the 950mb dewpoints suggests the best support for a frontal boundary, the old warm front, extends from southern New England SW into NRN VA. I lowered POPs overnight looking at the HRRR taking the scattered showers over portions of the lower and mid Susq Valley moving out and not much new expected through early Wednesday morning. The airmass is still rather humid with dewpoints in the 60s, so prospects for significant drying are not promising. With plenty of cloudcover, overnight lows will remain on the mild side ranging from the mid 50s over the north to mid 60s over the south east. Clouds and scattered showers look to hang around Wednesday as a deep easterly flow develops south of the sprawling high off to our north. && .SHORT TERM /WEDNESDAY NIGHT/... High pressure trying to nose in from the NW looks like it will be thwarted by a stalled front just off to the SE, keeping low level moisture trapped in place which will keep clouds plentiful. Low level flow turning around to the S/SE won`t help the situation either, and will feed development of generally light showers, becoming a bit more numerous each day through Friday as flow gradually increases. Timing / placement of these banded showers a tough task when trying to indicate enhanced PoPs over next couple of days, but generally highest likelihood will be over the south and east. Mesoscale models will aid in focusing/enhancing PoPs further during a sliding 12-24hr window. The best chance of staying dry Wed will be NW of a line from Clearfield to Mansfield. Temps remain pretty constant for next several days, with highs pretty much in the 70s and lows pretty much in the 60s. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Frontal boundary that pushed slowly east across the region Monday (in the wake of the remnants of what was once Tropical Storm Gordon during the middle of last week), has stalled out across the Susq Valley and Scent PA, and will slowly weaken and retreat back to the northwest over the next few days as an inverted trough well in advance and to the NW of powerful hurricane Florence. All model and EFS guidance indicates scattered to numerous showers and perhaps a isolated/brief low-topped afternoon tsra Thursday and Friday, with high temps climbing back to near, or slightly above normal under a persistent, but mainly light east to southeast llvl flow. Still, slightly diverging medium range U.S. and EC guidance occurs with respect to the timing and ultimate track of powerful Hurricane Florence as she nears the NC coast later Thursday into Friday, then either stalls for 24 to 48 hours or drifts slowly west or SW. There will likely be some significant differences in sensible weather conditions from north to south acrs PA with the thickest layered clouds, best chance for drizzle or some periods of light rain, and a slightly gusty east to SE sfc wind limited to the southern tier or half of PA Sat and Sunday. A fair amount of sunshine, pleasant near-normal high temps, low humidity and light wind. Blended in about 50-70 percent weighting of the Operational EC and EC ensembles (which have shown the most consistency run to run over the past few days, along with its slightly more southern landfall and inland track compared to the GFS/GEFS and official TPC track). That being said, and integrated into the regional CWA forecast, will paint just a slight chc for some Fri night/Sat morning drizzle and low clouds across mainly the southern part of the PA and otherwise just isolated rain showers. As the greatly weakened remnants of Florence beings to drift north through a weakness across the Ohio River Valley, that exists between two large areas of upper level high pressure, it will bring an increasing chance for showers and TSRA with bands of locally heavy rain possible Monday through Tuesday night (especially across the western half of the state that experienced the heaviest rain from the recent passage of the remnants of TS Gordon). && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... The boundary remains stalled with showers through eastern PA as of 00Z Radar. MVFR cigs overall dominate the skies with only UNV and IPT IFR. While a brief period of VFR should continue, cigs and vsbys will drop tonight due to low level moisture trapped under the inversion. This will bring widespread IFR reductions overnight along with patchy fog. Expect conditions to drop between 05Z to 07Z. Light low level flow turning to the S/SE tomorrow will make it tough for conditions to improve much. Latest SREF and HREF models due show some improvement from IFR to MVFR by late morning. However MVFR should continue through tomorrow afternoon with scattered VFR possible again with scattered showers. We`ll repeat that MVFR during the day and IFR at night cycle through the end of the week as showers become more numerous each day. Hurricane Florence will impact the Carolinas/Mid Atlantic region late week and this weekend. A high pressure area building to our north looks to potentially advect some drier air in Sat/Sun with improving conditions at least for the central/northern sections. .Outlook... Wed...AM low cigs/fog possible. MVFR/VFR cigs with sct showers. Thu-Fri...Patchy AM fog possible. MVFR/VFR cigs. Scattered to numerous showers. Isold PM tsra impacts possible. Sat-Sun...Patchy AM fog possible. PM rain/low cigs possible southern Pa. && .HYDROLOGY... Spotty showers today should not allow for renewed rises on area streams/rivers. Smaller streams and creeks are retreating this afternoon, with rivers and some larger streams still experiencing at least minor flooding (we`ve got 15 river points still in flood at 18z). The West Branch Susq R is still going to be rising significantly into Wed. The Juniata basin, easily the hardest hit area, peaked with moderate to major flooding and is now generally falling. Beech Creek (West Branch basin) cresting in Major flood category. Much of that water did an end-around the Sayers Dam, falling in the Marsh Creek and Beech Creek basins. Those points are now falling. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...RXR LONG TERM...Lambert AVIATION...Ceru/RXR HYDROLOGY...
Area Forecast Discussion
National Weather Service Wilmington NC
640 PM EDT Tue Sep 11 2018 .SYNOPSIS... Hurricane Florence, a powerful category four storm, will approach the Carolinas Thursday through Friday. Catastrophic impacts from wind, flooding rainfall, and storm surge flooding are expected to develop for portions of the eastern Carolinas. Florence may linger through the weekend with the potential for flooding rainfall continuing. && .NEAR TERM /THROUGH TONIGHT/... As of 500 PM Tuesday...Hurricane Watch and Storm Surge Watch have been upgraded to a Hurricane Warning and Storm Surge Warning for all coastal counties and a few inland counties, for Major Hurricane Florence forecast to impact the area Thursday through at least Friday. Current radar shows mainly inland scattered showers and thunderstorms along and south of the I-95 corridor. Convection is following an outflow boundary along the leading edge, heading towards the northwest. The HRRR has initialized quite well with ongoing convection and its solution depicting continued northwest movement with erosion on the southeastern edge. Most shower and thunderstorm activity should dissipate by 00Z or shortly thereafter. Overnight lows should be quite close to guidance, so didn`t stray too far. Only made slight changes to drop temps a degree or 2 in locations that touched 70 last night. Before the night is over, models show nocturnal convection moving inland. Thus, have maintained low end POPS from the previous forecast. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... As of 330 PM Tuesday...Wednesday will give us one final day to prepare for the arrival of category four Hurricane Florence. Partly cloudy skies, scattered showers, and continued warm/humid conditions are forecast. Adding 3-5 degrees to MOS high temperatures at inland sites has been a winning strategy over the past several weeks, and I`ll continue do this this Wednesday. The first outer bands of showers from Florence could push onshore before daybreak Thursday in the Cape Fear area. Thickening clouds and more rain bands will spread inland during the day, with winds anticipated to reach tropical storm force in the Cape Fear area during the afternoon. Conditions will go downhill in a hurry Thursday night as the center of Florence approaches the coast. I don`t have much to add beyond what the National Hurricane Center and Weather Prediction Center have forecast for the area. The very dry antecedent conditions we`ve had over the past six weeks won`t buy us much reprieve from flooding given the exceptional rainfall amounts expected along the coast north of Myrtle Beach. Just Thursday night alone 8-10 inches of rain will probably fall in the Cape Fear area, with additional heavy rain continuing into Friday. This will likely be the storm of a lifetime for portions of the Carolina coast, and that`s saying a lot given the impacts we`ve seen from Hurricanes Diana, Hugo, Fran, Bonnie, Floyd, and Matthew. I can`t emphasize enough the potential for unbelievable damage from wind, storm surge, and inland flooding with this storm. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 330 PM Monday...So much uncertainty with the extended especially early depending on the evolution of Hurricane Florence. I did increase pops, cloud cover, and QPF amounts at least for Friday. The weekend remains a toss up as well as guidance wants to linger the vortex inland. Here again I increased the relevant parameters albeit at a more muted clip. The next mid latitude trough and front to possibly impact the region may arrive next week although this far out in time confidence is low. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 00Z...Convection winding down and is mainly out of the CWA. Tonight, some convection could possibly drift onshore, best chance ILM. Mainly MVFR fog is expected. Wednesday, lots of subsidence ahead of Hurricane Florence, so expect only isolated convection along the resultant boundary. Extended Outlook...Mainly VFR through Wednesday outside of ISOLD showers and TSTMs. Patchy morning MVFR fog possible. Hurricane Florence will begin to affect the area Thursday with increasing wind and wind-shear, and deteriorating ceilings/visibilities, continuing into Friday. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 500 PM Tuesday...Hurricane Watch has been upgraded to Hurricane Warning for our local coastal waters, for Major Hurricane Florence forecast to impact the area Thursday through at least Friday. Light onshore winds are expected tonight along with a small but very long period swell from Hurricane Florence. Scattered showers will develop mainly after midnight. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 330 PM Tuesday...The approach of category four Hurricane Florence is the single concern in this period. Long-period swells ahead of the storm will increase in amplitude throughout the day Wednesday, creating extremely hazardous conditions in inlets during outgoing tides. Situations like this in the past have created large breaking waves 10-20 miles from shore along Frying Pan Shoals. Hurricane-force winds will overspread the area Thursday afternoon and evening. LONG TERM /FRIDAY THROUGH SUNDAY/... As of 330 PM Tuesday...Obviously the evolution of Hurricane Florence will be dictating conditions with rugged seas and either hurricane or tropical storm force winds basically through the entire period. && .CLIMATE... As of 330 PM Tuesday...Depending on the exact landfall position of Florence, there is some potential that a new all-time low barometric pressure reading for Wilmington could be established. Operational models are showing forecast pressures anywhere from 948 to 965 mb in the eye of the storm as it approaches the coast. Here are the current records for Wilmington. 1 Hurricane Floyd 9/16/1999 959.7 mb 28.34" 2 Hurricane Fran 9/5/1996 961.4 mb 28.39" 3 Hurricane Donna 9/11/1960 962.1 mb 28.41" 4 Hurricane Bonnie 9/26/1998 969.9 mb 28.64" 5 Nor`easter 3/6/1932 970.2 mb 28.65" More at https:/ && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Hurricane Warning for SCZ054>056-058-059. High Rip Current Risk until 8 PM EDT this evening for SCZ054- 056. High Rip Current Risk from Wednesday morning through Wednesday evening for SCZ054-056. NC...Hurricane Warning for NCZ105>110. High Rip Current Risk until 8 PM EDT this evening for NCZ106- 108-110. High Rip Current Risk from Wednesday morning through Wednesday evening for NCZ106-108-110. Hurricane Watch for NCZ087-096-099. MARINE...Hurricane Warning for AMZ250-252-254-256. && $$ NEAR TERM...ME/RGZ SHORT TERM...TRA LONG TERM...SHK AVIATION...43
Area Forecast Discussion
National Weather Service Wilmington OH
1021 PM EDT Tue Sep 11 2018 .SYNOPSIS... High pressure over New England and southeast Canada extending back into the Midwest will keep mostly dry conditions across the area through the week. Temperatures will be slowly moderating each day as warmer air returns with a light southerly flow, as well as increased humidity. A few showers may develop on Thursday and Friday with the increased moisture, primarily over central and eastern Ohio, but most locations will remain dry. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Clouds persist across all but the northwest corner of the forecast area. RAP continues to show this area clouding up as thermal trough slowly shifts northwest overnight. Forecast lows look on track. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Weak low level warm advection will continue on Wednesday which should erode the thermal trough to some degree -- and allow for low clouds to slowly break up. Unfortunately for sunshine lovers, thickening mid/high level clouds on southwesterly flow aloft and a near-continuous stream of sheared mid level vorticity from the Gulf Coast to the Ohio Valley will train through the area. Result will be still plenty of clouds, though there should be more sunshine than recent days. Could even see a sprinkle out of mid level echoes tied to the stronger vort maxes pushing through this weak southwesterly flow on Wednesday afternoon into Wednesday evening, but most areas will not see measurable rain. Temperatures were held a little cooler than statistical guidance given today`s poor MOS performance under thicker clouds. So have run on the cooler side for highs on Wednesday, and the warmer side on Wednesday night. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Expansive mid and upper level ridge will stretch from the southern Plains into New England late this week into the weekend. This will keep the Ohio Valley region mainly dry with a warming trend. Highs on Thursday to range from 80 to 85, with lower and middle 80s expected Friday through Sunday. Boundary layer CAPES of 1000-1500 j/kg develop Thursday thru Saturday. Forcing is weak but isolated showers or thunderstorms can not be ruled during the afternoons, with the best chance across our far eastern areas. Will limit pops to slight chance category during peak heating. Large spread in the model solutions and therefore a good deal of uncertainty exists in the forecast late this weekend into early next week. The portion of the ridge over the Ohio Valley gradually breaks down and weakens. This will be a big player in determining the track of the remnants of Florence. 12Z deterministic GFS solution has trended closer to the previous ECMWF deterministic and ensemble solutions, which takes the remnants further west into the Ohio Valley. Latest ECMWF is still south but slow with movement. Due to the weak steering flow and therefore the uncertainty will limit pops to chance category. Will allow these pops to develop into the southeast Sunday and across the entire region Sunday night into Monday and Tuesday. Due to lack of instability will not mention thunder at this time. Clouds and pcpn will affect temperatures with highs generally in the upper 70s. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... VFR ceilings at the start of the period will likely lower slightly overnight, just enough to reach MVFR at all sites except the Cincinnati area. Ceilings will gradually lift on Wednesday morning with this deck eventually becoming scattered later in the TAF period. OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Binau NEAR TERM... SHORT TERM...Binau LONG TERM...AR AVIATION...