Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/14/19

National Weather Service Cleveland OH
1052 PM EDT Sat Apr 13 2019 .SYNOPSIS... Low pressure over the southern United States will move northeast overnight. This low will move over Ohio on Sunday and extend a warm front over the area by Sunday afternoon. The low will depart to the northeast on Sunday night and extend a cold front over the area by Monday morning. High pressure moving through the southeastern United States on Monday night will ridge into the eastern Great Lakes for Tuesday. Low pressure over the Central Plains on Tuesday night will extend a warm front over the area before moving east on Wednesday. && .NEAR TERM /THROUGH SUNDAY NIGHT/... Main update to the forecast this evening is to slow down the arrival of precip after midnight. Based the forecast update on the latest trends with radar and hi-res guidance, which holds off precip until generally after 06-07Z across the forecast area. Otherwise, just minor updates to temperature trends overnight. Looking at Sunday`s severe weather threat, the latest HRRR is trending stronger/westward with the surface low, bringing the warm front farther north through the area, and putting the area squarely in the warm sector. This trend would support an increased severe weather threat tomorrow afternoon for the central and eastern part of the forecast area. Will continue to monitor the latest trends in the guidance overnight and adjust the forecast accordingly. Original discussion... High pressure over the Upper Midwest extends east over the Great Lakes region this afternoon and is keeping the area dry. The only nuisance this evening will be some cirrus advecting in from the southwest. Low pressure over the southern CONUS will move northeast tonight and reach the lower Ohio Valley by daybreak on Sunday. This low will bring rain to the region on Sunday into Sunday night as the low moves northeast through the state of Ohio. With the low bisecting the state, this low will extend a warm front north into north central and northeast Ohio and temperatures will surge into the mid to upper 60s. The warm sector will be the focus for thunderstorms and perhaps some strong to severe thunderstorms as this is where the best instability will reside, along with the warm frontal boundary that may be a spot where thunderstorms may initiate and persist. With this, have thunder in the forecast limited to the warm sector or mostly counties along and east of I-71. On the back side of the low, temperatures will remain cold with temperatures in the 40s and 50s and rain will be much more stratiform in nature. As the low departs the region, rain chances decrease from west to east, but rain will linger from Sunday night into Monday. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... The surface low pressure system will be pulling away from the region on Monday. The upper level trough will be right over the area Monday and also moving eastward. We can expect mostly cloudy skies and breezy conditions with a few scattered showers on Monday. Weak high pressure will move over the area Monday night with lighter winds. Light southerly winds will return on Tuesday. A weak warm front lifting back northward may bring a few showers on Tuesday, especially closer to the lake. It will be milder on Tuesday and warmer on Wednesday. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... We will be watching for another strong storm system to develop in the central U.S. by the middle of the week. This weather system will be another dynamic system with a strong upper level through and a strong surface low developing. The system will have a good source of moisture and wind shear. Late Thursday afternoon into Thursday night will be the timeframe we will be watching for the possibility for strong to severe convection. The Storm Prediction Center already has a portion of the region in a day 6 outlook for this potential. Temperatures will be warm and Spring-like for the middle and end of the week. && .AVIATION /00Z Sunday THROUGH Thursday/... Low pressure will track northeast across Ohio on Sunday, with rain ahead of the system moving into the terminals during the first half of the period. VFR conditions will deteriorate to MVFR and potential IFR after 12Z as the low moves into southwest Ohio. As the low tracks northeast across the local area Sunday afternoon, a line of thunderstorms is expected to develop, possibly impacting KMFD to KCLE and terminals east, mainly from 21Z through the end of the period. Winds will becoming north to northeast ahead of the low overnight, with a shift to southerly winds along/south of the low track tomorrow afternoon with increasing gusts to 20-25 kts. Winds will become westerly behind the low towards the end of the period. OUTLOOK...Non-VFR likely into Monday and possible again Monday night into Wednesday. && .MARINE... A low pressure system will be approaching the region from the southwest tonight into Sunday morning. Light winds this evening will shift to northeasterly. Winds will increase 15 to 25 knots on Sunday. Waves on the lake will also build. The water level on the lake is already running high at about 20 inches above normal. Northeast flow on Sunday will likely cause water levels to rise on the western end of the lake. A coastal flood watch has been issued for western shoreline areas of the lake for Sunday. A small craft advisory has also been issued for increased winds and waves. An additional small craft advisory will likely be needed Sunday night into Monday for gusty west to northwest winds behind the passage of the cold front. There will northwest winds 15 to 25 knots on Monday as the surface low moves away from the area. Weak high pressure will move over the region Monday night with lighter winds. Winds will become southerly again for the middle and end of next week. Another strong area of low pressure will impact the region late next week with gusty winds. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...Lakeshore Flood Watch from 8 AM EDT Sunday through Sunday afternoon for OHZ003-007>009. PA...None. MARINE...Small Craft Advisory from 8 AM to 8 PM EDT Sunday for LEZ142>149. && $$ SYNOPSIS...Sefcovic NEAR TERM...Greenawalt/Sefcovic SHORT TERM...Griffin LONG TERM...Griffin AVIATION...Greenawalt MARINE...Griffin
Area Forecast Discussion
National Weather Service Grand Forks ND
705 PM CDT Sat Apr 13 2019 .UPDATE... Issued at 702 PM CDT Sat Apr 13 2019 Fcst in good shape. Surface high pressure ridge axis roughly Roseau to Fargo and slowly moving east. HRRR model indicates best fog chances near or just east of this ridge axis later tonight which will be Bemidji-Fergus Falls region into eastern SD and farther south into SW MN. I will leave fog mention other areas per current fcst but chances appear more spotty for areas west of the sfc ridge over the central and northern RRV and far NW MN and NE ND. && .SHORT TERM...(This afternoon through Monday) Issued at 336 PM CDT Sat Apr 13 2019 Ridge aloft and surface high pressure keeping quiet conditions in place with moderating temps aloft and sunny skies supporting some locations as warm as 50 in our northwest this afternoon. All locations at or above freezing, though deeper snow pack in our south has limited warm up. Generally clear skies, calm winds, and lingering low level moisture (from daytime melting) will support fog development, though RAP/HRRR are not widespread in fog signal. NAM/ARW/NMM showing much stronger signal for dense fog. I kept patchy fog across our CWA with "areas" coverage where strongest overlap/consensus with shorter range guidance shows it. This will be the main concern for overnight/morning period. Sunday-Monday: After any fog lifts Sunday morning, dry/quiet expected through Sunday afternoon, with temps in line with today (40s maybe an isolated 50). Negatively tilted shortwave trough tracks along International Border Sunday night and east of our area by Monday morning. Strong forcing (WAA ahead of this system followed by strong 850-700MB frontogenesis) is shown to track across our CWA. Duration of forcing/moisture advection is quick, but this should support increasing precip chances (especially north). Lapse rates are favorable for possible more intense showers to develop, but due to duration, even convective allowing guidance is only showing high end QPF generally around 0.25". Current potential is there for a wintry mix of rain/snow (some sleet) and light snow accumulations before precip ends Monday monitoring. Westerly flow and drier air/clearing skies follows this system, so milder highs should arrive Monday for most of our area (50s for more locations). .LONG TERM...(Tuesday through Saturday) Issued at 336 PM CDT Sat Apr 13 2019 Model consensus favors near normal to slightly above normal temps, but there is more uncertainty in the middle of the week for temps and precipitation chances. Another strong system may develop into the Central US. Main track/forcing/QPF axis from latest ECMWF/GFS is further south. Late runs do show a possible 700MB deformation axis extending northward from this system into our CWA which could bring a period of higher precipitation into our area. Right now rain is favored based on current timing, but soundings at least support potential for more in the way of snow than rain. Evolution of this system, track, and timing of CAA all will play a role in impacts over our area, and confidence is low as models have varied on these details. This will need to be monitored. Another quick moving (weaker) system may bring precip chances by next weekend, but impacts would be lower and at this range it isn`t as much of a focus for concern. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 702 PM CDT Sat Apr 13 2019 Radiational ground fog is the issue later tonight/Sun AM. These are always tough to forecast ahead of time in terms of exact location and impacts at airports. It appears best chances would be Bemidji to Fargo and south/east of this area. Kept some light fog BJI, FAR, TVF overnight kept vsbys in the TAF in MVFR range. && .HYDROLOGY... Issued at 336 PM CDT Sat Apr 13 2019 Regionally, recent snowfall across is expected to begin melting in the coming days as temperatures climb and remain above freezing. This will drive either an increase in water levels or will slow down water level decline at most points along the mainstem Red River. The Red River at Fargo will see a secondary rise around mid-week as snowmelt works it`s way into the channel. Other notable rises could occur along the South Buffalo and Buffalo at Sabin, Hawley, and Dilworth. Water levels on the Snake River upstream of Warren have continued falling over the past 24 hours and have fallen below action stage. Slight increases in the coming days are possible as snow melt runs off into the river, but no rise to Minor flood stage is expected at this time. At Hallock, we will see the decrease in water level begin to level off as increased melting and runoff are expected to cause a secondary rise in river levels. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. Areal and river point flood warnings continue across portions of the region. Refer to the latest flood warnings and statements for detailed information on specific locations. && $$ UPDATE...Riddle SHORT TERM...DJR LONG TERM...DJR AVIATION...Riddle HYDROLOGY...TML
Area Forecast Discussion
National Weather Service Huntsville AL
925 PM CDT Sat Apr 13 2019 .NEAR TERM...(Rest of tonight) Issued at 925 PM CDT Sat Apr 13 2019 After coordination with SPC, have added a few more counties up to the TN border in the Tornado Watch until 08Z. The warm front continues to make progress northward with temperatures warming into the upper 60s to around 70, with dew points in the lower to middle 60s. Further south, southeast inflow continues with temps in the m70s and dew points in the m60s nosing into west central AL. This air will feed the incoming QLCS(s) in MS. The HRRR suggests that these QLCS will maintain a threat of damaging winds and tornadoes feeding off very high 1km SRH values of 400+ and MLCAPEs of ~500+ just south of the warm front. The threat may go beyond 08Z in our northeast AL counties. .SHORT TERM...(Sunday through Sunday night) Issued at 407 PM CDT Sat Apr 13 2019 As previously mentioned, the threat for severe weather will persist into Sunday morning. The main line is expected to exit the forecast area around 15Z and some drier air will filter in. There will be a break in activity before another round of storms is expected with the arrival of the cold front and the passage of the upper-level system. Instability will be lower but lapse rates will improve and 0-6km shear will be approaching 90kts. With winds more unidirectional than the overnight hours, the main threat will be damaging winds and hail for the afternoon hours. Locations east of I-65 will have the higher chances to see severe weather during this time. Precip will come to an end Sunday night as the system lifts NE. Daytime highs could reach the lower 70s and fall into the upper 30s/lower 40s behind the cold front. .LONG TERM...(Monday through Friday) Issued at 407 PM CDT Sat Apr 13 2019 The extended period will begin with dry northwest flow aloft in the wake of a trough lifting northeastward off the mid-Atlantic coast. Although any lingering postfrontal cloud cover should dissipate rather quickly in the morning, modest low-level CAA in the wake of a frontal passage Sunday afternoon will provide cooler max temps in the mid 60s on Monday and min temps in the mid 40s Monday night, as conditions will be favorable for radiational cooling. A warming trend is expected to begin on Tuesday, as a low-amplitude mid-level ridge translating across the region will provide mostly sunny skies concurrent with the return of southerly flow in the boundary layer. We expect highs to reach the m-u 70s both Tuesday/Wednesday, with lows Wednesday morning only falling into the l-m 50s in a regime of increasing low-level moisture. By the middle of next week, our attention will focus on an amplifying 500-mb longwave trough, which extended range models suggest will be migrating slowly eastward across the central Plains on Wednesday. At least a couple of weak disturbances ejecting northeastward in strengthening southwest flow aloft will cross the TN Valley from Wednesday-Wednesday night, perhaps bringing a few showers and thunderstorms to the northwestern half of the area. However, coverage of showers and thunderstorms is expected to increase across the same area early Thursday morning, as deeper moisture begins to return northward in advance of the approaching trough. Global models indicate that further deepening/amplification of the broad longwave trough can be expected on Thursday and Thursday night, as the system translates slowly eastward across the central Plains and into the MS Valley, with the intensification process expected to peak sometime early Friday morning. At the surface, a low initially across IA will lift east-northeastward into the Great Lakes, with a Pacific cold front extending southward from the low expected to push eastward across the local area Thursday afternoon/evening. Latest guidance suggests that strong forcing for ascent attendant to the longwave trough will result in upscale growth of a QLCS along the Pacific cold front, and based on a favorable combination of atmoshperic lift, instability and deep-layer shear we strongly suspect that this will produce another severe thunderstorm event for the TN Valley. Low-level flow will veer to southwest by early Friday morning, but should result in limited advection of dry air, and with the axis of the longwave trough remaining to the west of the region, we anticipate a continuation of clouds and perhaps some showers on Friday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 549 PM CDT Sat Apr 13 2019 VFR flight weather conditions will continue through around 06Z at KMSL and 08Z at KHSV. However, southeast surface winds will abruptly increase to 15-18kt with gusts around 28kt, with LLWS developing. Gusts should reach 30kt by 06-08Z with lower ceilings of 015-025agl expected (MVFR). A few showers or thunderstorms cannot be ruled out this evening, but the main line of thunderstorms arrives between 06-08Z at KMSL and 08-10Z at KHSV. Strong wind gusts will be possible with the line of thunderstorms. After the thunderstorms and showers end by 11-12Z, expect a wind shift to the southwest with continued gustiness up to 30-32kt. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...17 SHORT TERM...JMS LONG TERM...70/DD AVIATION...17 For more information please visit our website at
National Weather Service Jackson KY
1055 PM EDT Sat Apr 13 2019 .UPDATE... Issued at 1055 PM EDT SAT APR 13 2019 The latest model runs show the progression of the morning line of showers through eastern Kentucky to be slightly slower than was originally forecast. Looking downstream at current radar, these trends would agree. Also, there has been a downward trend in the strength of these showers. This is particularly true in the latest HRRR run, where an organized line of showers that was present is now more of a broken line. Therefore, have adjusted PoPs into the early morning hours to account for these trends. Also, with increasing cloud cover from the southwest late this evening, expecting the minimum temperature to occur before midnight tonight. Thus, have also adjusted minimum temperatures and the diurnal curve for the overnight. A new ZFP was sent to capture these changes. Updates have also been sent to the web and to NDFD. UPDATE Issued at 905 PM EDT SAT APR 13 2019 Monitoring as precipitation has overspread into much of western and central Kentucky this evening. Some light, isolated showers continue over the Cumberland Basin region as well according to current radar. Hi-Res models show that a line of heavier showers will advance towards eastern Kentucky after dawn tomorrow morning. PoPs during this time are consistent with the Hi-Res models, so only needed to make minor adjustments to late evening PoPs based on current trends. Also ingested current observations for temperature and winds and blended them into the forecast. Temperatures are generally in the lower 60s at present across the area. An updated ZFP was not needed at this time. Updates have been sent to NDFD and to the web. UPDATE Issued at 550 PM EDT SAT APR 13 2019 Adjusted PoPs into the evening based on the latest radar trends that show some light precipitation moving into the Cumberland Basin. No other significant changes were needed beyond this, other than to ingest and blend the latest observations for temperatures, wind, and sky cover. Current temperatures are in the upper 60s to low 70s late this afternoon. Sent a new ZFP to include PoP updates for the evening. Updates have been sent to NDFD and to the web. && .SHORT TERM...(This evening through Sunday night) Issued at 354 PM EDT SAT APR 13 2019 We are continuing to monitor the potential for strong winds and severe storm potential on Sunday. Still a bit of uncertainty on the extend of severe weather on Sunday as there are lots of concerns and potential limitations which will be discussed below. The confidence is a bit higher on the potential for large scale wind gusts reaching or exceeding 40 mph. Presently, s potent vort max is ejecting out of a base of a mid level trough in the southern plains leading to a developing low pressure system and a threat of severe storms over the lower Mississippi river valley. This will be the system we will be watching for tomorrow. To the northeast of this developing system, a baroclinic zone is oriented northeast to southwest across eastern Kentucky, providing a nice spread in dewpoints across the area. Presently dewpoints range from the mid 30s in the north to the mid 50s in the south. Cloud cover has limited the temperature spread from north to south. This boundary will jump to the north tonight as the low level jet strengthens as the deepening area of low pressure tracks into far western Kentucky. With the jet strengthening overnight, winds above 3000 feet in southeast Kentucky may start to get a bit gusty. With some uncertainty with how low the inversion will be tonight, opted to not go with a wind advisory for these areas through tonight, but evening and overnight shifts may need to start the advisory earlier if the inversion ends up below the ridgetops. Moisture transport and jet dynamics will lead to increasing rain chances for our western areas by dawn. This activity will be fighting the downsloping flow, but should be enough to overcome this across our western zones, so have gone with categorical pops in the west by dawn. Tomorrow, showers and embedded thunderstorms will continue to spread east during the morning hours but gradually weaken as they run ahead of the weakening jet and lack of better upper level support. Thus, pops will have a diminishing trend during the morning hours with a a period of lower pops for the middle of the day. South wind will continue to ramp up tomorrow with the BUFKIT momentum transfer showing wind gusts potential in the 40 to 45 mph range areawide. MAV/MET numbers are also some of the highest we have seen with the MAV at LOZ showing 25 knots. Given the high wind potential for tomorrow, have opted for a wind advisory for the entire forecast area. Now addressing the severe threat. Winds will likely stay almost due south through the day and never really switch to a southwest direction. Thus, current thinking is that dewpoints could be overdone on the models and readings near 60 may not be reachable. Given instability was already a question mark, put lower dewpoints on the table, and you will get even less instability. Thus, will there be enough surface moisture advection to overcome the downslope potential, especially with the strong flow expected off the terrain? Certainly going to go lower with the dewpoints than the model blends would entertain. The better chance for higher dewpoints could be across our Bluegrass region where they may be less impacted from the downsloping flow. The other aspect to deal with tomorrow is cloud cover and potential lack of clearing/warming. If we cannot clear, it may be hard for us to overcome the expected lower dewpoints and generate much instability at all. Finally, the other aspect is that the shear is so impressive with 0-6km shear values in the 80-90 knot range. Thus, updraft potential may be limited as they get toppled with the strong shear. However, if any storm organization can take place, it won`t take much to generate widespread damaging winds. Thus, this is a precarious situation as we will be walking a fine line. The 12z HREF does show some weak probabilities for some updraft helicity over eastern Kentucky, and does support the better threat across the Bluegrass region. The area remains in an enhanced risk for severe storms, and at this point cannot completely argue against it, but as mentioned above, there are many aspects to this event that could yield fewer severe storms. At this point, damaging winds will be the primary hazard given the tremendous unidirectional shear in place with any convection likely developing into linear bow segments. By Sunday night, cold advection will kick into full gear with some wrap around moisture spreading into the coal fields. This will yield scattered rain showers or drizzle through much of the night. A few snowflakes cannot be completely ruled out by dawn Monday on some of the highest ridgetops along the Virginia border. Lows will fall back into the 30s for most locations. .LONG TERM...(Monday through Saturday) Issued at 354 PM EDT SAT APR 13 2019 The 500 mb trough axis will have moved east of the area at the start of the period with rising heights expected from the Southeast into the Lower OH Valley region. Further height rises are anticipated into Tue night. Meanwhile at the sfc, the area of low pressure and cold front that will bring convection in the near will move further to the north and east with sfc high pressure building into the Commonwealth from the Gulf States. By Tuesday the sfc high is expected to be centered along the coast of the Carolinas before shifting into the Atlantic by Tuesday night. Further west, meanwhile, a mid and upper level trough should move onshore of the west coast of the Conus from late Monday into Monday night and then progress east across the Rockies through Tuesday night and then emerging into the Plains at midweek, when a sfc low will develop/deepen in the Central Plains. This pattern will bring drier, but initially colder weather to East KY. Temperatures should not climb out of the mid 50s across much of the area on Monday. Clearing skies under the influence of ridging on Monday night and dewpoints in the low to mid 30s support some mid and upper 30s for sheltered southeastern valleys, when patchy frost will be a possibility. Tuesday and Wednesday should be considerably milder as the sfc high moves further east and the region gets into a return flow of initially warmer and eventually more moist air. Temperatures should climb well into the 70s on Tuesday and at least the upper 70s on Wednesday. From late Wed into Wed night, the shortwave trough is expected to close off to an upper low over the NE/KS vicinity and meander toward the MS Valley by Thu night and Fri. Uncertainty remains in the timing and track of this upper low with quite a bit of variability from run to run and model to model. The model consensus is for the upper low/trough to move east of the MS River by the end of the period. The sfc low should track into the mid MS Valley by early on Thu and into the Great Lakes Thu night and Friday and Ontario and Quebec late in the period. The trailing cold front should cross the Commonwealth by late Thu night to early on Friday. Under the increasing influence of the trough/upper low, unsettled weather will return with the best chances for showers and some thunderstorms nearer to the cold front itself which at this point appears to cross the region Thu night to early on Friday. Wind fields may be sufficiently strong and potentially some limited instability to coincide such that storms along or near that front could produce gusty winds. However, the timing generally expected to be at night or possibly early on Friday morning should be a limiting factor. The evolution of this system will continue to be monitored in the coming days. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 805 PM EDT SAT APR 13 2019 A low pressure system will approach eastern Kentucky later tonight. This will bring rain showers and the potential for some thunderstorms overnight tonight and into tomorrow morning. Confidence is low if any early morning storms would affect the TAF sites, so did not include thunder for the morning at this time. A second wave of showers and thunderstorms will then affect the region in the afternoon. This will be the period with the greatest potential for strong to severe thunderstorms and thus, have included the mention of thunder for all TAF sites. Accompanying the heavier showers and storms will be reduced visibilities. Lower ceilings to MVFR are also expected tomorrow afternoon as the second wave of showers and storms moves through. The other concern for the period will be LLWS overnight tonight and then strong winds through the afternoon tomorrow. Easterly winds will shift to be southwesterly and increase to be between 15 and 20 knots tomorrow afternoon. Wind gusts between 30 and 40 knots are also likely during this time, with locally higher gusts possible in the higher terrain of southeastern Kentucky. && .JKL WATCHES/WARNINGS/ADVISORIES... Wind Advisory from noon to 8 PM EDT Sunday for KYZ044-050>052- 058>060-068-069-079-080-083>086-104-106>117-119-120. Wind Advisory from 8 AM to 8 PM EDT Sunday for KYZ087-088-118. && $$ UPDATE...CGAL SHORT TERM...KAS LONG TERM...JP AVIATION...CGAL
Area Forecast Discussion
National Weather Service Key West FL
1042 PM EDT Sat Apr 13 2019 .SHORT TERM... There are a lot of similarities between this evening and the previous 2 evenings. Have been watching clouds above 5,000 feet move north from Cuba, the leftovers of afternoon convection there. Now that it is late evening, a few small showers are starting to reach north to near Key West. The 01z HRRR shows a few additional showers developing south of the Middle and Lower Keys overnight and moving north toward the island chain, especially between about Sugarloaf and Vaca Keys. Indeed, the 00z KEY sounding showed a PW value of 1.41" and a capping inversion just below 10,000 feet, which is also similar. With so many similarities to the last 2 nights which have seen no thunder, have removed thunder from the forecast for the rest of tonight. Any showers will lift north of and away from the Keys around or very soon after sunrise on Sunday. This will leave a mostly dry and sunny day behind. The deep low center that is moving across the Tennessee Valley late tonight will exit up the Ohio Valley on Sunday. A trailing cold front will weaken significantly as it approaches the Keys on Sunday night and passes the Keys on Monday. Some low-level convergence along and in advance of the front could squeeze out a few showers on Sunday night and Monday as surface winds veer around out of the southwest then northwest. Am growing more skeptical on thunder chances. Upper level high pressure will grow strong over the Keys on Tuesday, with the 500 mb forecast map showing a 591 decameter high centered directly over the Keys. This will keep surface-based moisture too shallow from Monday night through Tuesday for any noteworthy shower activity, even as surface winds turn from north to east. && .LONG TERM...(Tuesday night thru Saturday) From Previous Discussion: Surface ridging will slowly move east driving a similar moderate gradient across the Keys thru the week. Chance for showers will still be slight thru Wednesday Night, but temperature highs and lows will return above normal Tuesday thru Wednesday night. For Thursday through Saturday, ample moisture will be in place and given convergence, have maintained a low chance for showers, 30%. This will be out ahead of another approaching trough which will transport abundant moisture out of the Caribbean Sea allowing for elevated chances for rainfall. Above normal for mid to late April. && .MARINE...Winds have been rising this evening at ob sites from the Middle Keys to Pulaski Shoals, with both Smith Shoal and the NAS on Boca Chica Key recently gusting to 24 knots. This made for an easy decision to expand the SCA to include all marine zones except Florida Bay. Looks like winds will be peaking over the Lower Keys around midnight, then late tonight over the Upper Keys. Winds will ease during the day on Sunday in advance of a weakening cold front that will pass the waters on Monday morning. High pressure will then move across the Southeast on Monday, at first bringing northerly winds to the Keys. As high pressure move off the Carolina coast on Tuesday and out to Bermuda on Thursday, winds will turn out of the east, then southeast by mid-week. Moderate to fresh southeast breezes on Wednesday and Thursday. && .AVIATION... Mostly VFR conditions expected for the next 24 hours at the island terminals. The only exception could be during the upcoming overnight period, when a few showers moving north across the Lower and Middle Keys could bring temporary BKN cigs in the 018-025 range. Otherwise, looking at the usual FEW-SCT coverage of fair weather cumulus clouds during the day on Sunday, with bases in the 020-025 range. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...Small Craft Advisory for GMZ032>035-042>044-052>055-072>075. && $$ Public/Marine/Fire...Haner Aviation/Nowcasts....Haner Data Collection......DR Visit us on the web at Follow us on Facebook and Twitter at:
Area Forecast Discussion
National Weather Service New Orleans LA
411 PM CDT Sat Apr 13 2019 .DISCUSSION... Basically two systems to deal with in this forecast package. First is responsible for the severe weather threat late this afternoon through tonight. Second will bring another chance of severe weather midweek. Starting with today... Storms have been a little slower to move east than originally thought. While there have been some scattered showers across the northern zones today, there has been very little lightning at all in our entire forecast area thus far. Main action is still off to the west and north of the local area. That won`t be the case forever though. The surface low should start moving more quickly toward the northeast in the next few hours. In turn, this will force the convective focus farther east as well. Still looking like a significant threat of severe weather, with impressive shear and instability values as the main focus moves eastward through tonight. Original thinking was that a squall line would solidify and progress through the area, but all day the CAM runs have struggled to solidify a QLCS. This could be both good and bad. The good news is that broken lines tend not to produce as widespread damage as solid lines with bows. The bad news is that individual cells are more conducive for tornadic development. And in fact, the HRRR has been hinting at a broken line of cyclic rotating storms as the system moves across the area, with the more impressive storms being across the northern half of the area. This lines up well with the SPC outlook for potentially significant tornadoes which runs along/north of a line from Lafayette to Hammond to Hattiesburg. Timing is tough to nail down, but expect the main threat timing to begin around 6pm or 7pm for our far west/northwest zones. It will progress eastward through the evening and overnight, and the threat should be over before daybreak across our far eastern zones on the MS Coast. Also of note is the strong winds that we have been experiencing well ahead of these storms. A tight pressure gradient has led to widespread sustained winds of 20 to 25 mph with frequent gusts in the 30 to 35 mph range. Several sites have also been reporting occasional gusts near or just over 40 mph. Wind will continue howling until the cold front gets closer and the pressure gradient relaxes a bit, likely around midnight. The trailing cold front will usher in much cooler weather for tomorrow with highs generally only reaching the upper 60s to lower 70s most places. Strong cold air advection will also lead to a second round of strong winds, and another wind advisory may be needed mainly on the south shore of Lake Pontchartrain. Winds will begin to drop off tomorrow night as the high becomes centered closer to the area. Lows should drop into the mid to upper 40s north and in the lower 50s south, which is around 10 degrees lower than normal for this time of year. The high shifts eastward by Monday night, with winds turning onshore again and beginning the return flow process as another low pressure system takes shape over the plains states. This system looks to bring another threat of severe weather to the area sometime from late Wednesday through Thursday. SPC has currently outlooked the area for Thursday, which is unusual given the 6 day lead time. CIPS analogs also continue to hint at potential for severe weather during this time frame. Given the lead time, there`s not a lot of detail to be gleaned at this time, but it`s certainly something to monitor as we move into next week. && .AVIATION... Main concern is severe weather impacting terminals through the evening and overnight hours. Broken line of storms should begin to approach BTR and MCB between 01-03z and then work east approaching ASd and MSY/NEW around 03-06z and then coastal MS GPT/PQL around 05-10z. These storms could be severe with damaging winds and even tornadoes possible. Have indicated winds of 30-35kts with gusts of 45-50kts. LLWS may become an issue this evening as the wind right at the sfc begin to back off a tad but just off the deck remain around 40-50kts. && .MARINE... Strong onshore flow will continue to ramp up throughout the afternoon and evening with small craft advisories in affect for all marine zones from Saturday morning through 12Z Sunday. A front will pass through the waters toward daybreak, and in the wake of the front, expect strong cold air advection to strengthen the winds even further. Have issued a Gale Watch for all of the open waters in effect from 12z Sunday through 00z Monday, and have extended the small craft advisory for the lakes and sounds for the same time frame. Winds will begin to relax late Sunday night as surface high builds in overhead. A light return flow will take hold by Tuesday and continue through Thursday. Another strong system expected Thursday evening with northwest winds expected Friday and into the weekend behind the system. && .DECISION SUPPORT... DSS code: Orange. Deployed: None. Activation: None. Activities: Moderate risk of severe weather through tonight Wind Advisory through midnight River flood warnings Decision Support Services (DSS) Code Legend Green = No weather impacts that require action. Blue = Long-fused watch, warning, or advisory in effect or high visibility event; Marginal risk severe or excessive rain. Yellow = Heightened impacts with short-fused watch, warning or advisory issuances; radar support for slight risk severe or excessive rain. Orange = High Impacts; Enhanced risk severe; nearby tropical events; HazMat or other large episodes. Red = Full engagement for Moderate to high risk of severe and/or excessive rainfall, or direct tropical threats; Events of National Significance. && .PRELIMINARY POINT TEMPS/POPS... MCB 55 63 43 75 / 80 10 0 0 BTR 55 65 45 75 / 60 10 0 0 ASD 60 69 45 74 / 80 10 0 0 MSY 60 69 52 74 / 80 10 0 0 GPT 63 70 48 72 / 70 10 0 0 PQL 65 74 45 75 / 70 10 0 0 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...Wind Advisory until midnight CDT tonight for LAZ034>037-039-040- 046>050-056>072. GM...Small Craft Advisory until 7 AM CDT Sunday for GMZ530-532-534- 536-538-550-552-555-557-570-572-575-577. MS...Wind Advisory until midnight CDT tonight for MSZ068>071-077- 080>082. Coastal Flood Advisory until 1 AM CDT Sunday for MSZ080. GM...Small Craft Advisory until 7 AM CDT Sunday for GMZ532-534-536- 538-550-552-555-557-570-572-575-577. && $$ Aviation...CAB Rest of Discussion...95/DM
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
630 PM CDT Sat Apr 13 2019 .SHORT TERM... (Through Late Sunday Night) Issued at 431 PM CDT Sat Apr 13 2019 A strong Spring storm system is moving through the central portion of the U.S. This system will bring a variety of weather to the forecast area over the next 24-30 hours including rain, a chance of a few thunderstorms, and likely some snow to portions of northeast Missouri and west central Illinois. Current radar is showing a rain shield moving up from Arkansas in to southern Missouri. Short range models show strong moisture convergence along and south of the 850mb front tonight as the central of the storm system moves up from the lower Mississippi Valley into the Tennessee Valley. Most models are showing elevated instability across southern Missouri and southern Illinois tonight...and the latest runs of the RAP show 300+ J/Kg MUCAPE as afar north as east central Missouri into south central Illinois. This may be a bit much especially given the much more conservative values that the NAM and GFS are showing. None-the- less, I did bump thunderstorm chances slightly further north...especially after midnight tonight to account for the potential for a bit more instability. Regardless of how much thunder there is, all that moisture convergence should produce plenty of rain across the area tonight with as much as 1 to 1.5 inches across southeast Missouri and around an inch as far north as a line from Columbia MO to Pittsfield IL. The deformation zone precip will move across the area in the wake of the warm advection late tonight and early Sunday morning. Forecast soundings continue to look cold enough to support a change over from rain to snow as this occurs across parts of northeast Missouri and west central Illinois. Boundary layer conditions may be iffy, but it does look like there will be enough dry air being pulled in behind the storm in the low levels for temperatures to cool enough for the snow to get all the way to the ground. That being said...2 inch soil temperatures are pretty warm in the low 50s at this time. If snowfall rates are high enough though some accumulation is much is still uncertain given the antecedent warmth...but up to 1 inch on grassy and elevated surfaces still looks reasonable. Precipitation should end from southwest to northeast from mid- morning through mid afternoon. Temperatures are not expected to rise above the mid 40s in most locations on Sunday. A weak ridge is expected to build across the region Sunday night into early Monday morning. At this time, it looks like dew point temperatures will be in the low 30s with temperatures falling into the low to mid 30s as well. This would be an excellent set up for frost for the we`ll need to monitor this closely for a possible Frost Advisory Sunday night. Carney .LONG TERM... (Monday through Next Saturday) Issued at 431 PM CDT Sat Apr 13 2019 Spring returns on Monday after a cold start with southerly flow ahead of the next storm system spinning up over the Great Plains. Temperatures should rebound into the 60s and low 70s under strong mid-April sunshine. The warming trend will continue on Tuesday under the influence of south-southwest flow as the Plains storm continues to gain strength. Ridging aloft along with 850mb temperatures pushing 14-15C should be good for highs in the mid 70s to around 80. The next chance for rain begins developing late Tuesday night into Wednesday as the main upper level wave moves off the Rockies into the central Great Plains. The stacked system pushes into Kansas by 00Z Thursday and the GFS and ECMWF look to be in good agreement that there will be showers and thunderstorms developing ahead of the system in the mid Mississippi Valley Wednesday into Wednesday night. Showers and thunderstorms continue into Thursday with the potential for lingering light rain on the western side of the system as it pulls away from the Mississippi Valley Friday into Saturday. Carney && .AVIATION... (For the 00z TAFs through 00z Sunday Evening) Issued at 620 PM CDT Sat Apr 13 2019 Forecast remains on track with rain currently spreading north into the area. Current obs show visbys along the initial thrust of rain dropping to MVFR, so went ahead and dropped visbys to 4SM in the STL metro TAFs where rain is expected to be the heaviest. Cigs will drop to MVFR a few hours after the onset of rain and continue to drop through the night, reaching IFR in the early morning hours at the STL metro TAFs. A light rain/snow mix is expected for locations near UIN. Precipitation will clear out of the area tomorrow morning, though reduced flight categories will linger through much of the day thanks to ample lingering moisture. SPECIFICS FOR KSTL: The main difference at STL will be the intensity of the initial shot of rain and the cigs tomorrow morning. It appears as though the rain at STL will be strong enough to drop visbys to IFR before relenting somewhat around 06z. Cigs will then fall through MVFR into IFR by the early morning hours. The good news is that cigs should at least crawl into MVFR shortly after the precip clear out of the region. BSH && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Blacksburg VA
1115 PM EDT Sat Apr 13 2019 .SYNOPSIS... A strong cold front will bring rain and an enhanced risk for severe thunderstorms to the region Sunday and Sunday night. Following the front, high pressure will settle over the region for the first half of next week. && .NEAR TERM /THROUGH SUNDAY/... As of 1110 PM EDT Saturday... Enhanced Risk for Severe Weather and a Marginal Risk for Excessive Rainfall Sunday and Sunday Night... Low clouds had advanced north to a Bluefield to Lynchburg line and will continue to spread over the rest of southeast West Virginia and southwest Virginia overnight. Have slowed down the chance of rain along the southern Blue Ridge and foothills this evening in line with current radar trends and close to the timing of the HRRR and Hires guidance through 8AM/12Z. Have added some fog in the mountains where the ridges will be in the clouds and where the temperature/dew point spread was near zero. Muggy overnight lows expected with readings in the upper 50s to lower 60s. Active weather pattern with strong storm system to impact the region Sunday. A favorable set-up for severe weather Sunday per strong mid- upper level trough poised to advance across the Ohio Valley and into the Appalachians during peak heating Sunday. A deepening area of low pressure is forecast to move east- northeast across the Ohio Valley through the day Sunday, and then across the central-northern Appalachians Sunday evening. Showers and thunderstorms are forecast to be ongoing in a north- south pre-frontal band from Indiana to Alabama Sunday morning. As modest heating of a moistening pre-frontal warm sector commences, 500 to 1000 J/kg mixed-layer CAPE is expected to evolve ahead of the ongoing band of convection, from the Ohio Valley to the Gulf Coast. This should result in a gradual intensification of storms through the afternoon, aided by a very strong deep-layer wind field accompanying this storm system, including 60+ kt south-southwest flow at mid levels. A second round of storms will accompany the cold front Sunday evening and night. Primary storm mode Sunday afternoon is progged to begin cellular, then gelling into complex bows and rotating updrafts. Damaging winds will likely be the primary threat, though tornadoes also a possibility. Risk should diminish gradually through the evening, though gusty post frontal gradient winds will likely persist through Sunday night and into Monday. Heavy rain may become a concern pending persistence of the thunderstorm activity. However, confidence is low attm with respect to flooding as the storms are expected to be transient. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 130 PM EDT Saturday... Sunday evening, a surface cold front will head east of the area, and then be following shortly behind by the parent upper level trough axis by midnight. Indicators are still looking promising for robust shower and thunderstorm activity as the system passes through the region, along with the potential for locally heavy rains. Southside Virginia and neighboring portions of north central North Carolina have had multiple days now of brief heavy rains, so this region will be in particular need for monitoring. The Storm Prediction Center is still outlooking the region to be within Enhanced and Slight risk areas with the greatest threat being straight line winds and large hail with a lesser, but not zero, potential for an isolated tornado. Once we get past about midnight Sunday night, the area will be on the backside of the upper trough, and 850mb winds will increase significantly from the northwest. Guidance has been persistent, thus confidence is rising, that Wind Advisory level gusts may be obtained through a generous portion of the second half of Sunday night through the daytime and perhaps early evening hours of Monday. Likewise, also at this time, there has been persistence on the wind gusts not reaching High Wind Warning criteria. Therefore, we are a little too early in time for the hoisting of a Wind Advisory, and a High Wind Watch is not looking probable, so we will continue to reflect the appropriate wind speeds and gusts in the forecast grids, and continue to highlight the concern in the Hazardous Weather Outlook. These gusty northwest winds will help to maintain upslope cloud cover and isolated scattered precipitation across mainly the higher terrain of southeast West Virginia, south into the Northern Mountains of North Carolina Sunday night and early Monday morning. As notably colder air rushes into the region, a few of the highest peaks within this region may see rain showers change, or mix with, snow showers by daybreak Monday, and receive a light coating of snow on the ground, generally less than one-half inch. Coverage of the precipitation and cloud cover will decrease on Monday as drier air continues to progress rapidly into the area. The pressure gradient, and thus the wind speeds/gusts, will slacken as we progress through Monday night into Tuesday. High pressure will dominate our weather pattern with dry conditions and limited cloud cover Tuesday and Wednesday. Temperatures during this portion of the forecast will trend cooler, with readings averaging around normal for this time of year by Tuesday. Confidence in this portion of the forecast is moderate to high. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 230 PM EDT Saturday... During this portion of the forecast, we will encounter a weather pattern similar to what is playing out across the region today into tomorrow. An upper level trough is expected to deepen over the Rockies and head eastward into the Central Plains states where it develop into a strong upper level low during the Wednesday into Thursday time frame. A strong southerly fetch of moisture will race north from the Gulf of Mexico in advance of this system and progress into our region. The upper low`s associated cold front is expected to cross our area Thursday night into Friday. Model vary on the timing, but currently this is the general span of time offered for this occurrence. Some guidance track an additional shortwave trough northward along this front on Friday, slowing its departure, and thus keeping the potential for active weather into Friday night. The parent upper low and its associated trough axis is expected to cross the area Saturday or Saturday night. What the above scenario means for our region will be temperatures on the mild side in advance of this approaching upper low/trough. Plenty of moisture and lift to have showers probable Thursday through Friday, and perhaps even Friday night. Thunderstorms, some potentially on the strong side thanks to notable low level shear and marginal SBCAPE, will be possible Friday afternoon and evening. Cooler weather and gusty northwest winds are expected behind the system, but this detail currently will fall outside the extent of our seven-day forecast, more within the Saturday night into Sunday time frame. Temperatures during the Wednesday through Friday time frame are expected to average 10 to 15 degrees above normal. On Saturday, readings will be closer to 5 to 10 degrees above normal. Confidence in this portion of the forecast is moderate. The biggest question is how any change in timing of the upper low and its associated surface features will impact the sensible weather. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... As of 750 PM EDT Saturday... A cold front extended from eastern North Carolina to a low in northern Louisiana this evening. This front will move north as the low tracks into the Great Lakes. The cold front will this system will bring two bands of thunderstorms across the Mid Atlantic region on Sunday, mainly in the afternoon and evening, with MVFR ceilings and visibilities, very heavy rain and gusty wind. Some of these storms may be severe with damaging winds and hail. Tonight IFR to LIFR ceilings are expected to develop across much of southeast West Virginia, southwest Virginia and northwest North Carolina. Areas of MVFR fog are also likely, especially in locations that had rain Saturday morning, including KDAN and KBCB. If the stratus develops first, the areal extent of fog may be limited but ridges will be obscured. Winds will be light out of the southeast tonight but will become south ahead of the front Sunday morning with increasing wind speeds and gusts of 20 to 25 knots. Confidence is average for the ceilings and above average for the thunderstorms and wind. Confidence is below average for fog and visibilities. EXTENDED AVIATION DISCUSSION... A front shifts east to the mountains by late Sunday with showers/storms, some strong to severe, so expect poor flying conditions at times into late Sunday night. Monday should be returning to VFR as high pressure builds in, aside from lingering upslope MVFR in the mountains. Winds will be strong and gusty behind the front Monday. High pressure will keep Tuesday through Thursday VFR. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RCS NEAR TERM...AMS/RCS SHORT TERM...DS LONG TERM...DS AVIATION...AMS/RCS