Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/26/18

Area Forecast Discussion
National Weather Service Columbia SC
1039 PM EDT Thu Oct 25 2018 .SYNOPSIS... High pressure centered over the mid-Atlantic region will extend into the forecast area through Friday. Low pressure developing along the Gulf coast will lift northeast tonight and spread rain across the forecast area through Friday. Cold air damming will result in temperatures well below normal over much of the area Friday. The low pressure system will move northeast of the area Friday night but a deep trough over the region will result in below normal temperatures through Saturday with some patchy showers. && .NEAR TERM /UNTIL 7 AM FRIDAY MORNING/... Moisture will continue to increase tonight ahead of a low pressure system currently centered over southern Mississippi. High pressure over the mid-Atlantic region is resulting in the development of a cold air damming wedge across the local area. A strong mid-level shortwave trough in the central Plains will cause the low pressure system to strengthen and track towards the Southeastern States tonight. Moisture flux and isentropic lift appears strong late tonight through Friday morning with strong low-level east flow 35 to 40 knots in the boundary layer above a strong surface based inversion with strong southwest flow in the mid levels. Deep layer shear is also strong. Rain is starting to move into the CSRA and is expect to overspread the area by morning. As far as temperatures are concerned, there is potential for evaporational cooling late tonight given initially dry low levels, but dewpoints have come up since this afternoon. Given current trends and wet bulb values, expect lows in the mid to upper 40s to low 50s south. && .SHORT TERM /7 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/... There could possibly be some heavier rain around daybreak as well as some elevated convection, especially across the southeast Midlands/CSRA. Models suggest wedge will be relatively strong across the Midlands. The surface low should stay just east of the area tracking across the coastal plain or the coastal waters Friday afternoon. With the warm front near the southeast Midlands there is potential for some convection, and given strong deep layer shear a little concern for severe thunderstorms. Hodographs suggest rotating updrafts with a marginal damaging wind/isolated tornado threat but mainly in the coastal plain as low-level stable air is more likely. Will keep isolated thunderstorms in the forecast southeast of CAE. Rain may diminish in the afternoon especially to the southwest as isentropic downglide develops as the surface low moves rapidly to the northeast along the coast. The temperature forecast is tricky of course. Think MOS is too high given wedge pattern, especially north of CAE. Prefer cooler local wedge guidance although southeast Midlands near warm front temperatures more uncertain. Little change in temperatures was made from earlier forecast. Mid and upper 40s north of CAE to lower to mid 50s central Midlands and upper 50s to low 60s southeast Midlands and along CSRA. Categorical pops with qpf 0.5 to 0.75 inches with heavier precip in the Piedmont where upslope stronger. Models are in good agreement with evolution of wedge and track of low pressure along/near the Carolina coast Friday afternoon/evening. Any threat of severe should have ended by Friday night as surface winds shift NW/W behind the departing area of low pressure. Southeast will remain under the mean trough through the period. A series of shortwaves will move through the trough Saturday through Sunday. Main trough axis will cross the area Saturday night but a stronger reinforcing shortwave trough will arrive Sunday night into Monday. Model time sections show low- level moisture lingering across the area Friday night through at least Saturday. Will keep a chance for light rain/drizzle Friday night then more showery type precipitation with each passing shortwave. As systems pass to our north, greatest chances for showers Saturday through Sunday night will be across the northern/central Midlands. Expect plenty of low clouds through Saturday with mostly cloudy skies for the most part through Sunday night. With cold air aloft, any heating will produce clouds during the day. Overnight lows will mainly range from the middle 40s to lower 50s. Afternoon highs will be in the middle 60s Saturday to upper 60s/lower 70s Sunday. Some slight warming ahead of s/w approaching Sunday night. && .LONG TERM /MONDAY THROUGH THURSDAY/... Trough will move off the coast Monday as surface high pressure builds into the region from the central Plains. This will provide pleasant fall weather through Wednesday. Both ECMWF/GFS show another strong shortwave trough digging south/southeast into the central Plains by Wednesday night into Thursday. The mid/upper flow across the Southeast will become more SW from the Gulf and rain chances will increase by late in the week. Went with chance pops for now Thursday, but timing and pops could change by that late in the period. Temperatures will moderate through the period. Expect below normal temperatures Monday and Tuesday with more seasonable/slightly above normal temperatures for Wednesday and Thursday. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... Widespread IFR conditions will develop. There will be low- level wind shear. Moisture and isentropic lift will be on the increase tonight ahead of low pressure approaching from the southwest. Ceilings will lower into the MVFR and IFR categories. We followed the HRRR for the timing. Visibilities will be reduced in heavier rain and fog. A wedge pattern and strong low-level jet suggests wind shear will be an issue. Followed the NAM and included LLWS in the terminal forecasts. There may be elevated thunderstorms. The models indicate cross totals in the lower and middle 20s during the day Friday. Expect these will remain scattered with the chance too low to include in the terminal forecasts at this time. EXTENDED AVIATION OUTLOOK...Widespread ceiling and visibility restrictions are expected through the rest of Friday night because of considerable low-level wrap-around moisture associated with low pressure tracking northward along the coast. Improvement is expected over the weekend with the system moving farther away and westerly flow in its wake. Breezy conditions may occur Saturday. && .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 Green Bay WI
956 PM CDT Thu Oct 25 2018 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Friday Issued at 201 PM CDT Thu Oct 25 2018 The latest RAP analysis and satellite/radar imagery show surface high pressure centered over the eastern Great Lakes and a trough of low pressure over the Dakotas. Mid and high clouds continue to stream north into the region ahead of this trough and various pieces of shortwave energy over the Plains. Although weak moisture advection contributed to showers over the Upper Peninsula that grazed the border area earlier today, most of the precip activity remains over Minnesota and Iowa so far. As this system slowly moves east, precip chances is the main forecast concern. Tonight...The trough of low pressure will move into Minnesota. Lingering dry air below 700mb will likely keep most of the area dry during the evening hours, but progged soundings indicate that this dry wedge will get partially eroded overnight. Light shower chances will be highest where the dry air gets eroded the most, mostly near the U.P. border and also from central WI into the southern Fox Valley. Due to ample cloud cover, temps will mainly fall into the middle and upper 30s. Friday...The shortwave energy will outrun the trough at the surface and proceed to move across Wisconsin. Forcing will remain very weak in the form of mid-level convergence, but any lingering mid-level dry air will continue to erode, which will give all locations a chance of light showers. Saturation depth continues to argue for the highest chance near the U.P. border and also from central WI to the southern Fox Valley. Under cloudy skies, temps will fall back a few degrees into the middle 40s to near 50. .LONG TERM...Friday Night Through Thursday Issued at 201 PM CDT Thu Oct 25 2018 Large-scale pattern evolution over the extended suggests low predictability overall as weakly split flow over the northern Great Lakes early in the period, gradually transitions to a trough over the northeast CONUS and intermountain west, with shortwave ridge in between by late Monday. Forecast area, at least through Saturday, situated in no man`s land with no clear-cut forcing to organize precipitation. On Friday night, primary southern stream shortwave forecast to continue to pass southeast of the forecast area. Meanwhile another weak disturbance quickly dives southeast toward Wisconsin by 12 UTC Saturday, however, the majority of the model guidance tend to weaken this impulse during the day on Saturday with only some light shower activity mainly west of the forecast area as column saturation still questionable further east. Also a bit deeper saturation near the Upper Michigan border will support a few more showers there. This seems to be supported by latest model blended QPF with only slight chance POPs over most of the forecast area during the day on Saturday so will not deviate from that. Any shower activity on Saturday will likely be light and widely scattered especially the far northeast with minimal rainfall amounts. Should remain mainly dry into Saturday evening with very weak surface ridge suggested by the model guidance. Still expect lots of clouds Saturday night as another more potent shortwave quickly approaches Wisconsin initiating more focused WAA. No definitive consensus from the various model guidance with respect to location of best concentrated forcing with this system. GFS ensemble mean and ECMWF suggest heaviest QPF will generally track across the southwest half of Wisconsin, while the Canadian and NAM are further north overall. Will therefore just continue with likely POPS across the entire forecast area starting late Saturday evening over central Wisconsin, then expand east overnight into the first half of Sunday. Rainfall amounts associated with this system will generally range from the around a tenth of an inch northeast, to perhaps a quarter of an inch over the southwest portion of the forecast area where deeper moisture will reside. At this time it appears boundary layer temperatures across the north on Saturday night will be too warm to support a rain/snow mix with readings generally hovering in the middle to upper 30s. Later Sunday afternoon, any lingering light rain or drizzle should come to an end with CAA and mid-level drying quickly following in the wake of this disturbance. To start the work week, Monday still looks to be a pretty decent day as shortwave ridge builds in. Under partly sunny skies, highs will generally range from 45 to 50 degrees with light northwest winds. As surface ridge passes to the east on Monday night, WAA will be on the increase especially after midnight as LLJ kicks in ahead of progressive shortwave trough pushing across the central Plains. Associated surface low will likely pass well north of Wisconsin with trailing cold pushing across the area late Tuesday and Tuesday night. ECMWF and GFS are in the ballpark on the timing of the fropa across the forecast area with majority of the shower activity falling between about 00Z and 12Z Wednesday. Given progressive nature of this system and that gulf moisture will be somewhat limited, expect only modest rainfall amounts. Through the extended period, temperatures will be at or perhaps slightly below late October normals and stayed close to the blended model guidance. && .AVIATION...for 06Z TAF Issuance Issued at 955 PM CDT Thu Oct 25 2018 VFR conditions expected through much of this TAF issuance. An upper - level trough will slid into the area this afternoon/evening, leading to increasing chances of light rain showers and potentially some MVFR to IFR ceilings. Winds are expected to remain light through this TAF issuance. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......ESB AVIATION.......Cooley
Area Forecast Discussion
National Weather Service Miami FL
739 PM EDT Thu Oct 25 2018 .UPDATE... Aside from a stray shower here and there throughout the day today, not much happened weather wise. Overall, another quiet night is forecast with a slight chance for rain showers across the east coast and over both Atlantic and Gulf waters. HRRR and Hi-Res WRF models are bringing swift moving rain showers from the Gulf over inland Glades/Collier Counties around 09-12Z tonight. There is also a slight chance for thunderstorms in the Atlantic, but overall, convection associated with an approaching warm front and deepening longwave trough is not forecast to spark until the mid- morning hours. Essentially, the higher chance for convective activity remains over the Gulf and Atlantic waters. Otherwise, the remainder of the forecast looks to be on track with no further updates are anticipated through midday. && .PREV DISCUSSION... /issued 736 PM EDT Thu Oct 25 2018/ AVIATION...Both Gulf/Atlantic seabreezes should diminish 02Z-04Z, becoming light/vrb. Pre-frontal trough approaches late, with winds becoming SSW towards daybreak. Speeds increase to 8-10kts after 13Z, and 12-15kts after 16Z ahead of main front that arrives after current TAF cycle. Initial trough may bring SHRA or TSRA vcnty KAPF late tonight, but chances too low to mention currently. Isold SHRA and TSRA threat for all sites tomorrow afternoon, may need to be added in later TAFs. PREV DISCUSSION... /issued 425 PM EDT Thu Oct 25 2018/ DISCUSSION... Widespread showers pestering the East Coast throughout the day today are expected to dissipate throughout the overnight hours before ramping up again tomorrow morning ahead of an approaching frontal system; however, showers and potential thunderstorms over the Atlantic will continue to persist due to warmer temperatures over the water. Overnight temperatures will range from the low- mid 60s in the northern CWA and upper 60s to lower 70s elsewhere. 15Z WPC analysis depicted a surface low spinning over the Central Gulf states with a cold front extending from the south of the feature and a warm front extended out towards the east and across Central FL. This warm front will lift northwards overnight, allowing for a shift in wind direction from the southwest across South Florida. On Friday, the combination between the lifting warm front and a longwave trough deepening across the southeast CONUS will initiate a brief surge in low level moisture and greater instability across South Florida. Satellite derived PWAT values look to increase up to 2.00". Not only do POPs increase, but so will temperatures (compared to the past couple of days, anyways) as they climb into the upper 80s across the majority of the CWA. A chance of thunderstorms will persist across the region as well, and this will continue into Saturday evening (after FROPA). On Saturday, a cold front associated with the low pressure trough is forecast to sweep through South Florida, drastically dropping PWATs into the 0.50-0.75" range. Then Saturday night into Sunday, after FROPA, winds shift from the Northwest and eventually from the north. Dewpoints drop into the mid-upper 50s across most the CWA with the occasional low 60s for coastal sites. Drier and cooler weather conditions will continue into early next week as high pressure builds. MARINE...Relatively quiet southeasterly winds in the 5-10 kt range will persist into the overnight hours across the Atlantic. For Friday, moderate southwesterly flow is expected ahead of a cold front with winds increasing into the 10-15 kt range for both the Atlantic and Gulf waters. Winds are going to stay on the breezy side for the majority of the weekend while simultaneously shifting from the north as the aforementioned front approaches the region. Wave heights are not expected to exceed 4 ft. Similar to earlier today, rain chances will remain isolated to widely scattered this evening, with an additional spread of showers and thunderstorms with the front Friday into the early part of this weekend. BEACH FORECAST...Moderate Risk of Rip Currents remains in effect for Atlantic Beaches this evening throughout the day tomorrow. Like the past several days, lunar tides will continue for tomorrow. Tides of 1/2 to 1 foot above normal are possible for the Atlantic beaches during this period. This could result in localized minor flooding issues as a result. However, widespread issues are not anticipated at this time. && .PRELIMINARY POINT TEMPS/POPS... West Palm Beach 72 89 73 87 / 20 20 20 20 Fort Lauderdale 76 88 76 87 / 20 20 20 20 Miami 74 88 74 88 / 10 10 10 20 Naples 72 86 73 84 / 20 30 40 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. && UPDATE...03/Fell DISCUSSION...03/Fell MARINE...03/Fell AVIATION...88/ALM BEACH FORECAST...03/Fell
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday) Issued at 342 PM CDT Thu Oct 25 2018 Low clouds and widespread rain/drizzle soon come to an end, with clearing skies and warming temperatures for Friday. A complex upper tropospheric longwave trough with multiple embedded shortwaves is occluding over the central U.S. this afternoon, with the well-defined dry slot wrapping northeastward into eastern Kansas in water vapor imagery and a subsequent deformation zone arching from north-central Kansas into southern Minnesota. Widespread rain transitioned into more of a drizzle under the dry slot, with light to moderate rain noted in a wide swath from Minneapolis to Marysville. This deformation zone should continue to pivot and shift eastward over the next 3-6 hours, gradually weakening as the overall mesoscale forcing wanes. The question then turns to how quickly clouds clear out tonight. Most short-term guidance solutions keep the majority of the area under a broken to overcast cloud deck overnight, but there are some indications of this cloud shield breaking up to some degree after sunset. The RAP is the most bullish in this trend, and given the current clearing rates in southwest Nebraska, this solution has some merit. Such trends would clear out the stratus in north- central Kansas before 06Z and reach Topeka before sunrise. Any location in which the clouds clear would be susceptible to fog formation given the light winds and recent precipitation. Maintained mention of fog in the western CWA where the stratus has the best chance of clearing tonight, which is supported by recent RAP forecast soundings showing either a very low stratus deck (which would lead to reduced visibilities in any areas with terrain) or fog developing after 08Z. The last clouds associated with this system depart during the day on Friday with warming temperatures from west to east as a +8 to +10 C H850 downslope airmass begins infiltrating into the region. Highs should top out around 60 around the KS/MO border to near 70 in north-central Kansas. .LONG TERM...(Friday night through Thursday) Issued at 342 PM CDT Thu Oct 25 2018 The weekend looks to start warm, with a cold front moving through Sunday morning keeping temps near seasonal norms into next week. Continued advection of warm downslope air will push temperatures into the low to mid 70s for Saturday ahead of an fast-moving Alberta Clipper system that drops through the Dakotas Saturday night and reaches the Mid-Mississippi River Valley by sunrise on Sunday. The biggest impact this system would have on the local area will be a rapid increase in winds Sunday morning behind the barotropic cold front, with differential CAA at H850 steepening BL lapse rates and enabling a 40 to 50 kt jet to potentially mix to the surface. There is some disagreement amongst the medium range solutions as to the track of this clipper and the resultant pressure gradient over the Central Plains. The GFS/EC take the low on a southern course and bring stronger winds to NE Kansas, while the NAM/GEM take the low on a more northerly track that keeps the stronger winds in Iowa. For now, have stuck closer to the GFS/EC blend for forecast consistency. After the passage of this system, longwave ridging builds into the central CONUS, keeping quiet weather and seasonal temperatures in place to start the work week. The next chance of precipitation comes on Tuesday as this ridge shifts east and sharp H300 trough digs into the central U.S., with a cold front advancing eastward ahead of this trough. Surface ridging builds in for Halloween on Wednesday, bringing with it cool and quiet weather. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 543 PM CDT Thu Oct 25 2018 For the 00Z TAFs, low stratus continues to impact the terminals along with -SHRA becoming less common as -DZ becoming the more predominant precip type through about 02Z at KMHK and then precip ending later around 04Z at KTOP/KFOE. Do expect mostly MVFR CIGS and VIS to be persistent through much of the overnight hours. Therefore, have extended MVFR through 12Z time frame before working a more dry airmass fully into the area. Not completely out of the question that fog does form if clouds do actually clear earlier than expected. This may be what models are struggling with. However, satellite trends would indicate that clouds will be slow to clear. So, have not gone too aggressive with the idea of fog at this time. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Skow LONG TERM...Skow AVIATION...Drake
Area Forecast Discussion
National Weather Service Tulsa OK
918 PM CDT Thu Oct 25 2018 .DISCUSSION... Moisture wrapping around the upper-low moving into Missouri has been resulting in patches of light rain across northeast Oklahoma and western Arkansas, along with patches of drizzle and fog. As the low continues east the precipitation and fog will diminish with time. Deep-layer drying has resulted in the clouds breaking a little this evening in Choctaw Co. Overall the clearing will be slow to expand as area stays beneath cyclonic flow aloft. We have been tweaking the forecast this evening, following the latest trends. Another forecast tweak will be released shortly. && .PREV DISCUSSION... /Issued 627 PM CDT Thu Oct 25 2018/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. Areas of drizzle will remain possible for the next few hours across NE OK/NW AR in association with upper vort max. Otherwise IFR/brief LIFR conditions will continue overnight into Friday morning. Ceiling heights will begin to slowly rise through the day with VFR conditions possible in most areas by mid/late afternoon, except far northwest Arkansas where lower clouds will likely persist. PREV DISCUSSION... /Issued 324 PM CDT Thu Oct 25 2018/ DISCUSSION... The main challenges in the short term will be drizzle chances this evening, low cloud coverage thru tomorrow and then fog potential tomorrow night. Rain/thunder chances with next week`s storm system are another item of mention. WV imagery and RAP analysis shows a PV max rotating around the basal portion of an eastward progressing shortwave trough across northern OK this afternoon. WV imagery also indicates that the air has dried out aloft from the initial wave, with only BL saturation lingering. Lift in advance of the northern OK PV max is bringing another round of drizzle to NE OK attm. This area of drizzle will slide east with time this evening into NW AR, where higher PoPs for low QPF will be maintained. As expected, low clouds have persisted over the region today and will continue over the region tonight. Guidance is clearing these low clouds fairly quickly tonight into Friday, but this is usually too fast. For the forecast, the back edge of the higher NAM BL moisture was used as an approximation of the low clouds. As such, the forecast will reflect a much slower west to east clearing on Friday. A more aggressive clearing will occur Friday night into Saturday as the BL flow gains more of a westerly downslope component in the wake of another subtle wave rotating down the back side of the departing central CONUS trough. Radiational cooling of a cool saturated airmass near the surface Friday night west of the clearing low cloud deck should lead to some fog development Friday night. Used a blend of raw model and short term guidance for lows tonight, which show temps holding in the mid to upper 40s under a blanket of low clouds. A slower clearing of the low clouds on Friday suggests that highs will not be as warm as previously thought. Saturday will be the warmest day of the forecast with downslope flow ahead of the front for Sunday. Cooling will not be significant behind this front. Yesterday it looked like winds would be strong and gusty on Sunday afternoon behind said front. Today`s data has backed off from this, mainly due to the fact that a strong shortwave trough in the developing NW flow over the Plains will be displaced farther to the northeast from our area compared to yesterday`s forecast. This places the gusty NW winds farther up into MO and have thus backed off on winds for our area. The GFS and ECMWF now show more run to run consistency in regards to next week`s storm system and front, showing a faster progression thru the region. As such, will reflect higher PoPs with the initial frontal push Tuesday and Tuesday night. What is less certain is the amount of energy holding back in the basal portion of the digging upper trough. The ECMWF maintains energy to our west and has more post-frontal precip into the day on Halloween, while the GFS dries things out. Will maintain some PoPs into Wednesday for this reason. Moisture return will be fairly meager with the initial frontal push, as it will be too fast to plow thru our area before some decent moisture can return north from the Gulf. Nevertheless, models do show some low end instability and have thus inserted isolated thunder mention. As for Halloween evening festivities, the potential remains for these to be wet, especially if the ECMWF verifies, though this potential appears to be greater across eastern and southern portions of the forecast area versus the northern and western areas attm. Stay tuned for updates. Lacy && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...08