Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/30/20

National Weather Service Wakefield VA
951 PM EDT Wed Apr 29 2020 .SYNOPSIS... A cold front will slowly move across the area Thursday, pushing off the coast Thursday night. An upper trough settles across the Middle Atlantic Friday. High pressure returns for the weekend. && .NEAR TERM /THROUGH THURSDAY/... As of 950 PM EDT Wednesday... Latest analysis reveals deepening low pressure over lower MI/IN this evening. ~1000mb sfc low was analyzed over S MI at 00z, with the associated sfc front extending S-SW, bisecting the Ohio Valley and extending into middle TN and the west-central Gulf coast. Remaining breezy through the overnight, as pressure gradient tightens between high pressure offshore of the east coast, and previously referenced low pressure over the Great Lakes, with resultant SSE low-level flow ushering in more mild, moist air across the region. Remaining mild and breezy overnight with lows in the upper 50s across the west to mid 60s in the southeast. Overall, have made some minor timing changes per past few runs of the HRRR and the 18z CAMs. Pre-frontal showers increase from the west to the I-95 corridor late tonight after 09z/5 am EDT. Heavier rain holds off until just after sunrise Thursday morning. Midwest upper low progresses toward the region Thursday, with the strong differential PVA allowing the system to take on a slight negative tilt through midday. This will serve to slow the frontal passage slightly and keeps the cold front west of the area thru 12Z, with the front then marching east across the area Thu aftn before pushing offshore tomorrow evening. The heaviest rain will be along and just ahead of the front. The entire area will see a period of heavy rain and overall QPF will be between 1 to 2 inches. While timing is a bit more progressive with the CAMs and incoming 00z NAM, there remains some concern that a slow-moving front combined with the a deep Gulf of Mexico moisture feed could support a prolonged period of moderate to heavy rainfall producing flooding. In particular, concern is greatest that precip field will expand in areal coverage late in the day/Thu evening along the coast (E VA/eastern shore) as the mid- level trough axis takes on a stronger negative tilt. Latest ERO from WPC keeps much of the area in a Marginal Risk, with a Slight Risk from the eastern shore up into the northeast, with better dynamics and forcing farther north into the northern Mid- Atlantic. Still, localized flooding and heavy rain threat is a concern, and will maintain Flood Watch at this time. Regarding strong to severe storm potential...SPC has pushed the MRGL svr risk farther north for Thursday, which is supported some by a little higher SHERB. While minimal CAPE is anticipated, owing to the timing and expansive cloud cover, effective shear and SRH will be an issue...and appears to portend to a conditional high shear/low CAPE (HSLC) event with unidirectional winds and potential damaging winds being the main threat, especially in light of the strong 65-75 kt LLJ nosing in by morning. Will need to keep an eye to radar trends by late morning into the aftn with the well-forced line of showers pushing through the area. Outside of any low-topped convection, synoptic winds will also be a factor, with breezy to downright windy conditions to persist through the day. 25-35 mph gusts inland, with gusts to 45 mph at the coast. Will be sure to note this in the evening update to the HWO. Highs upr 60s- lwr 70s. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... As of 345 PM EDT Wednesday... The front pushes off the coast Thu evening and as of now it appears some short-lived clearing is possible Thu night, before clouds push back in late into Friday morning as the upper low pushes across. The trailing deep upper level low crosses the area through Friday, keeping skies mostly cloudy Friday with chc PoPs. Giving the lapse rates and moisture might expect some graupel (along with potentially some cool air funnels along the coast) in convective showers Friday as core of cooler air pushes across the region. Highs Friday in the low to mid 60s. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 305 PM EDT Wednesday... Forecast period begins with the warmest day of the next week on Sunday. Compressional heating/WAA ahead of next front will bring a warm, breezy day on Sunday with highs well into the 70s to low 80s, with some middle 80s possible over inland sections. Rain chances ramp up late Sunday night out ahead of the next system, as it moves out of the Great Lakes states into Monday morning. Despite typical temporal discontinuities at this time range, the 12z/29 GFS and ECMWF remain in decent agreement with generally digging the northern stream upper trough down from the Great Lakes/interior northeast across the northeast coast/northern Mid- Atlantic Monday through Monday evening. Though should also note that, once again, the overall timing has slowed slightly, owing to the more amplified model consensus. The associated cold front crosses the region Monday morning, with gradual drying behind the system from west to east Monday aftn/night. GFS still shows a weak warm front causing light precip across the forecast area, but the deterministic non-NCEP models (UKMet, CMC, ECMWF) as well as latest EC ensembles are dry due to high pressure across the area and subsidence behind the departing system. Will therefore keep Tuesday dry, but bring PoPs back on Wednesday, as another spoke of shortwave energy looks to push across and continue the unsettled pattern. For temps, expect generally seasonable values for this time of year. After the warmer temperatures on Sunday, look to have temps drop back to the low-mid 70s Mon-Wed behind the front. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... As of 840 PM EDT Wednesday... VFR conditions across area terminals expected through the overnight period, with rapid deteriorating flying conditions after 12z Thu. Winds remain gusty out of the S-SE through the night, before increasing after sunrise Thu morning. MVFR ceilings are expected from mid to late morning through Thu aftn, with moderate to briefly heavy showers reaching the terminals between 12-18z (RIC 13-14z...reaching coastal terminals between 15z to 17z). Expect IFR/LCL LIFR CIGs during periodic heavy rain between 14-17z at RIC, 16-20z at coastal terminals. Gradually improving conditions expected after 21z at RIC, and after 23z into the evening along the coast. Other concern will be with LLWS. Have mentioned low-level wind shear at all coastal terminals Thu/Thu aftn, as the low level jet nudges into the area after sunrise Thu morning. Outlook: Additional showers will be likely overnight Thu into Friday and into the day on Friday, as a reinforcing cool front and the parent upper low crosses the area. Drying out by Friday aftn all terminals. && .MARINE... As of 800 PM EDT Wednesday... SSE winds are mainly 15-25 kt with gusts up to 25-30 kt this evening and will steadily increase into Thursday morning, as a frontal boundary approaches from the west. Waves in the Bay will build to 3-4 ft and seas build to 5-8 ft. The SSE winds will be strongest during Thu right ahead of the frontal boundary. Winds will be 20-25 kt with gusts 30 to 40 kt Thu morning through Thu evening. Wind probs for Gale gusts have increased to 60-90 percent on the coast esply, so have a Gale Warning for the coastal waters and the mouth of the Ches Bay during Thu. Waves in the bay will build to 4-5 ft, with 6 ft at the mouth of the bay. Seas expected to build to 6-11 ft. Cold front crosses the area waters Thu night into Fri morning. Winds behind the front will become W/SW 5-15 kt. Gale warnings will become SCAs again for Thu night into Sat morning, as elevated seas will be slow to subside. && .HYDROLOGY... As of 800 PM EDT Wednesday... Expect significant rises along the James/Appomattox and Chowan river basins Thursday night into Sat due to the rainfall runoff. Current forecasts already reflect these trends. James River Westham gauge shows the potential of reaching minor flood level by Friday evening. && .TIDES/COASTAL FLOODING... As of 800 PM EDT Wednesday... Strong southerly flow ahead of an approaching cold front will result in rising tidal anomalies on Thursday. Minor coastal flooding will be possible during Thursday morning`s high tide along the Chesapeake Bay side of the lower MD Eastern Shore and also adjacent the Potomac River on the Northern Neck. Additional minor tidal flooding may be possible in these same locations with the Thursday evening high tide cycle. A Coastal Flood Advisory has been issued for these areas. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...Flood Watch from Thursday morning through Thursday evening for MDZ021>025. Coastal Flood Advisory from 5 AM to 10 AM EDT Thursday for MDZ021>023. NC...Flood Watch from Thursday morning through Thursday evening for NCZ012>017-030>032-102. VA...Flood Watch from 6 AM EDT Thursday through Thursday afternoon for VAZ048-060>062-064>069-079-080-087-509>511-513>515. Flood Watch from Thursday morning through Thursday evening for VAZ075>078-081>086-088>090-092-093-095>100-512-516>525. Coastal Flood Advisory from 5 AM to 10 AM EDT Thursday for VAZ075-077. MARINE...Small Craft Advisory until 7 AM EDT Thursday for ANZ634-650- 652-654-656-658. Gale Warning from 7 AM to 7 PM EDT Thursday for ANZ634-654-656- 658. Gale Warning from 7 AM to 10 PM EDT Thursday for ANZ650-652. Small Craft Advisory until 6 PM EDT Thursday for ANZ635>638. Small Craft Advisory until 7 PM EDT Thursday for ANZ630>633. && $$ SYNOPSIS...MAM NEAR TERM...MAM/JAO SHORT TERM...JAO LONG TERM...MAM AVIATION...JAO MARINE...CMF/JDM/TMG HYDROLOGY... TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service State College PA
1131 PM EDT Wed Apr 29 2020 .SYNOPSIS... Mainly dry and pleasant weather will continue for the rest of today with a mix of mid level clouds and sunshine. A moderate to heavy rainfall will begin late tonight and last through much of Thursday. The heavy rain may result in urban/poor drainage, small stream and river flooding. Showers will linger through Friday before conditions dry out on Saturday. Expect near seasonal temperatures for the first weekend of May before the cooler temperature trend resumes next week. && .NEAR TERM /THROUGH THURSDAY/... 11 PM update: Main north-south rain band still inching eastward from a Pittsburgh to Clarksburg line. A few showers racing north ahead of this have moved through the area. Short term high res models move the main area of rain, with embedded lines of heavy rain, through mainly the western half of the forecast area through sunrise. Previous discussion: Descending, thermally indirect branch branch of a 115 kt upper jet encroaching on the region from the west will continue to shield most of the region from rainfall through dusk across the west, and midnight over the Susq Valley and points east. The rest of the day will feature a good amount of sunshine through mainly thin mid and high clouds with a gusty southeasterly breeze and temps ranging from 60-65F across the northern and western mountains, to between 65-70F throughout the Central and Southern Valleys. A brief, light shower is possible from the mainly mid cloud deck across the far east and far western portions of the CWA, but any rain that does fall through the rest of the daylight hours will barely wet the ground if that. Both HREF and latest RAP run indicate basically nothing in the rain dept through 23Z, though a band of showers forming over far eastern Ohio attm could edge into our Western Mtns toward dusk. Strong low pressure will track across southern MI tonight with trailing cold front reaching the Appalachians by the end of the period. Hires models show north-south oriented band of moderate to locally heavy rain along/ahead of aforementioned cold front moving into the western zones btwn 06-12Z Thu. Lows will be mainly in the 50s tonight, thanks to a blanket of thick stratus forming/advecting rapidly north into the region on the wings of a 55-65 kt LLJ (+4-6 sigma anomaly-wise with respect to its v-component). The lows will be 10 to 15 degrees above normal tonight. && .SHORT TERM /THURSDAY NIGHT/... Deep southerly flow/LLJ with PWs 1-1.5 inches should trigger locally heavy rains across the Laurel Highlands into the south- central PA early Thursday. Flood Watch is in effect for a stripe of counties along and just to the SE of the Allegheny Front very late tonight through early Thursday afternoon, and across the Susq Valley and points east from 18Z Thur through 18Z Friday where 1.5 to localized 3.0 inch rainfall amounts are forecast. Terrain enhancement shows up well in the hires model data given strong southeast low level flow. Flooding risk comes in multiple varieties from shorter- term urban/poor drainage areas and smaller streams to longer duration mainstem rivers which would likely not crest until later Friday.. The other twist to this event is that this deep moisture and anticipated thick, multi-layer cloud cover within the PWAT and LLJ axis will yield high 0-1 km and 0-3km shear/helicity but relatively low cape across the Susq Valley and surrounding areas Thu afternoon. Any embedded low-topped TSRA that form Thursday could tap this high shear and show some compact/elevated moderately strong rotation. A north/south ribbon of sfc based cape on the order of several hundred J/kg could be just enough for a few cells to become rooted in the near sfc layer and allow some of the stronger winds within 2 kft of the sfc to be mixed down to the sfc in warm/moist downdrafts. The cold front will slow down as it moves across central into eastern PA on Thursday. This is in response to deep mid level trough digging southeast into the southern Mid-Atlantic states with secondary low developing near the Delmarva. Confidence remains high for heavy rain with relatively wet antecedent conditions and modestly elevated streamflows both contributing to overall elevated flood risk. Heavy rain axis shifts eastward late Thursday night with rain intensity trending lower. Showers now linger through Friday as upper level trough/closed low rotates across PA. Will have to wait until Saturday morning before drying things out. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Minor changes made as of mid evening. Earlier discussion below. Showers linger through Friday as upper level trough/closed low rotates across PA. After a decrease in the showers Fri morning, higher lapse rates develop in the unstable air from midday onward as showers again become numerous across the region, and a rumble of thunder not out of the question. The showers retreat to mainly the NE portion of the CWA Fri night and lighter scattered showers may persist there into Sat. Exiting upper trough and weak ridge sliding through should result in a lower chance of showers Saturday into midday Sunday with gradually moderating temperatures. Sunday looks like the warmest day we`ve had around here in a few weeks, as high temps creep just above seasonal normals, reaching the mid 60s to lower 70s. But clouds thicken for the afternoon with showers moving in late as weak trough slides through. Mon/Tue look generally dry and breezy with below normal temperatures. The endless parade of shortwave troughs bring shower chances through the 2nd half of next week while keeping temperatures below normal. && .AVIATION /04Z THURSDAY THROUGH MONDAY/... As expected, CIGS starting to come down. Made some minor changes to the TAFS as of 1130 PM. Some rain across south central PA as of 1130 PM, but the heavier rain across far western PA at the current time. Early evening discussion below. For the 00Z TAF package, I did slow down the rain and lower CIGS some. While there is a few showers into the south central areas now, CIGS quite high, will take a few hours to see more in the way of widespread rainfall and lower conditions. Gusty winds and heavy rain taper off from west to east later on Thursday. Earlier discussion below. Dry conditions and VFR expected through the rest of the daylight hours with a mainly bkn, mid-level cloud deck. Steadier rain and deteriorating cigs and vsbys arrive tonight and will continue through much of Thursday ahead of a slow moving cold front with abundant, deep- layer moisture streaming north into the state along and ahead of it. Outlook... Fri...Scattered showers/tempo vis reductions, esp NW Mtns. Sat...No sig wx expected. Sun...Scattered showers possible, especially later in the day. Mon...Still a chance of showers. && .HYDROLOGY... 1 to locally 3 inches of rain is forecast across central and eastern PA Thursday-Thursday night. Significant rises are expected with minor to moderate small stream and river flooding is possible. Crest on larger mainstem rivers may not occur until later Friday or even early Saturday based on ensemble river forecasts. Antecedent conditions are relatively wet and streamflows are modestly elevated. A flood watch has been issued for much of the area. && .CTP WATCHES/WARNINGS/ADVISORIES... Flood Watch from Thursday afternoon through Friday afternoon for PAZ028-037-041-042-046-049>053-056>059-063>066. Flood Watch from 4 AM EDT Thursday through Thursday afternoon for PAZ012-018-019-025>027-034>036-045. && $$ SYNOPSIS...Lambert NEAR TERM...Lambert/Tyburski SHORT TERM...Lambert LONG TERM...DeVoir/RXR AVIATION...Lambert/Martin HYDROLOGY...Lambert/Steinbugl
Area Forecast Discussion
National Weather Service Glasgow MT
839 PM MDT Wed Apr 29 2020 .DISCUSSION... Evening update... Main change to the previous forecast was to introduce POPs in the morning in the western part of the CWA, with showers/storms tracking eastward through the day per CAM guidance. Models are hinting at a ridge-riding shortwave being the trigger tomorrow, which is currently producing storms in eastern Oregon. Of note in the RAP forecast soundings for tomorrow is the inverted-Vs generally east of the Phillips/Valley County line throughout the day into the early evening. Any convective showers that develop, thunder-producing or not, would have the potential to bring some gusty winds down to the surface. 850mb winds peak in the early evening at around 30 kts. or so. With low RHs expected, this should be watched for potential fire weather concerns. 97 Previous discussion... An upper level ridge covering the entire western United States is bringing plenty of sunny skies, dry weather, and temperatures in the upper 70s and to lower 80s today and tomorrow. A round of precipitation may arrive Thursday. Southwest flow along with a surface low dipping into Eastern Montana Thursday will set the region up for rain showers and possible isolated thunderstorms through Friday morning. QPF totals around a few hundred in the east to a third of an inch west. Any thunderstorm activity could bring totals higher in isolated locations. The ridge will attempt to build again at the end of the week, leaving the majority of Montana under zonal flow Friday and weak ridging on Saturday. Temperatures will be near 70. Midlevel winds, lapse rates, and temperature advection are conducive for breezy conditions Friday along with higher gusts. As new models arrive, will need to consider Lake Wind and Fire Weather hazard concerns. The next system to watch for is over the Eastern Pacific Ocean that will bring an elongated trough of moisture into the area beginning Sunday through Tuesday morning. There is some uncertainty on the development and location of this low and will need to be monitored. Storm total amounts range from a tenth to half inch. High pressure is expected to return over the western US by midweek next week. 86 && .AVIATION... FLIGHT CAT: VFR WINDS: light and variable tonight. Winds shift to the west and northwest Thursday morning and stay W-NW around 10 kts. during the day and into the evening DISCUSSION: Cloud cover will increase this evening, with mostly cloudy skies expected on Thursday. Ceilings are expected to remain well above VFR criteria. Convective showers, and associated CBs, are possible near TAF sites after 17z Thursday. 97 && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$
National Weather Service Hastings NE
700 PM CDT Wed Apr 29 2020 .SHORT TERM...(This evening through Thursday Night) Issued at 244 PM CDT Wed Apr 29 2020 Wind speeds have been on a slow decline through the afternoon, but will drop off pretty dramatically this evening with the loss of diurnal heating and mixing. Winds will become light and variable overnight as surface high pressure moves overhead. Any lingering cumulus will also dissipate this evening, leaving clear skies through the overnight hours. These clear skies along with the light winds will set us up for a relatively cool night. I nudged forecast low temperatures down a couple degrees to the mid to upper 30s. This is definitely on the low end of guidance, but recently we`ve "overachieved" on good radiational cooling nights. As such, some low-lying areas could end up with patchy frost, but we will hold off on issuing a Frost Advisory for now. High pressure exits the area on Thursday as upper level ridging amplifies over the western CONUS. This will bring a return of southerly winds and will push high temperatures back into the mid 70s to low 80s. For a discussion on the fire weather threat, see the fire weather section below. A weak perturbation will move through the area Thursday night into early Friday morning. This may lead to some light showers or sprinkles, but most of the area will remain dry. .LONG TERM...(Friday through Wednesday) Issued at 244 PM CDT Wed Apr 29 2020 Friday will be the warmest day of the week, with highs still expected to be in the mid 80s to low 90s. Precipitation chances creep back into the forecast on Saturday as the first shortwave trough approaches the area. The best chances for rain and thunderstorms will be Saturday night, and at this time it doesn`t look a significant severe threat for most of the local area. Models generally keep the highest instability confined to portions of Kansas. It now appears that Sunday will remain mostly dry before the next system arrives Monday and Monday night. Despite these multiple rain chances through this period, model ensembles are generally only outputting 0.50-1.00 inch of QPF through the 7 days. This will be welcome given our relatively dry stretch we`ve been in, but it might not be enough for some locations. After this system moves through, overall drier and cooler weather is forecast to persist into the middle of next week. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday) Issued at 700 PM CDT Wed Apr 29 2020 VFR conditions forecast. Wind should continue to decrease this evening as the low-level lapse rate lessens with loss of daytime heating. && .FIRE WEATHER... Issued at 244 PM CDT Wed Apr 29 2020 Winds are trending down this afternoon, but will remain supportive of critical fire weather criteria through sundown. Relative humidities largely will remain in the 30 to 40 percent range, only dipping to around 20 percent in the western extents of the current RFW counties. Tomorrow`s fire weather potential is a little more uncertain. Most models have RH values lower than today, but winds will be more questionable. Southerly winds will pick up during the day, but there is some question to whether they actually get strong enough to support a Red Flag Warning. The 15Z RAP and 12Z NAMnest are both quite low with their gusts tomorrow afternoon, but the global models are a bit stronger. Therefore, we will hold off on any fire headlines for now. The midnight shift will be able to take another look at the near-term models before making a decision. Friday will be even warmer with lower RH values, but fortunately the winds are forecast to remain below critical thresholds. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...Mangels LONG TERM...Mangels AVIATION...Heinlein FIRE WEATHER...Mangels
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
632 PM CDT Wed Apr 29 2020 .SHORT TERM...(This evening through Thursday night) Issued at 300 PM CDT Wed Apr 29 2020 Warmed temperatures up for Thursday with 850 temps nearing 20 to 26 degrees celsius. There should be some good mixing by afternoon allowing surface temperatures to warm into the mid 70s and 80s. There may even be a possibility we could see some areas across western Nebraska hit 90 degrees. If any place sees 90 degrees this would be the first time since the end of September, regardless if temperatures reach 90 or not this will be one of the warmest days so far this year across western and southwest Nebraska. Winds were another concern in the short term. Forecast soundings do show winds aloft around 25 kts that would be able to mix down, however there is a little concern in how much mixing will happen. Confidence is low to medium with mixing potential across western Nebraska, this area might see WAA and unidirectional winds up to the mixing level which could hinder the potential mixing height, which would lead to lower wind gust. Confidence is a little higher in wind gust reaching close to 25 kts from near HWY 83 eastward, however min RH is slightly higher in this area. This creates marginally favorable conditions for critical fire weather concerns as RH values will generally 18 percent and lower across much of western and southwest Nebraska. Since there is still low confidence in the winds, after collaboration with surrounding offices, a Fire Weather Watch was issued and will continue to monitor conditions with next forecast whether or not this would need to be upgraded. .LONG TERM...(Friday through Wednesday) Issued at 300 PM CDT Wed Apr 29 2020 Temperatures remain warm through the forecast period. Friday will be another warm and dry day with only isolated precipitation chances on Thursday night, conditions will continue to remain favorable for fire weather concerns on Friday as well. Friday night there is a chance for showers and maybe even a few thunderstorms. The best chance looks to be across the northern Sandhills and north central Nebraska with a little bit more uncertainty across our southern CWA. Then going into the weekend there are a lot of uncertainties with precipitation chances this Saturday and Sunday. There are discrepancies in timing and location with the models on convection Saturday night, Sunday and Sunday night. Forecast confidence is medium in precipitation chances Saturday night but forecast confidence is low for precipitation chances on Sunday, one model brings in a disturbance through the forecast area which may aid in shower and thunderstorm development but at this time given the uncertainty PoPs remain low. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 615 PM CDT Wed Apr 29 2020 VFR is expected throughout western and north central Nebraska tonight through Thursday afternoon. An upper level ridge of high pressure will continue to present generally clear skies across the region. Some high clouds will drift through the area. These clouds are associated with a storm system affecting the West Coast. && .FIRE WEATHER... Issued at 630 PM CDT Wed Apr 29 2020 The late afternoon run of the HRRR and RAP models show a good size swath of 20 percent or less RH spreading into the Fire Weather Watch area Thursday afternoon and evening. The Watch has been been upgraded to a Red Flag Warning and extended until 9 pm CDT or 8 pm MDT Thursday. 500m AGL winds increase to near 20kt which supports sfc winds of 20 mph. && .LBF WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM CDT /8 PM MDT/ Thursday for NEZ204- 206-210-219. && $$ SHORT TERM...Gomez LONG TERM...Gomez AVIATION...CDC FIRE WEATHER...CDC
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1015 PM EDT Wed Apr 29 2020 .SYNOPSIS... A warm front will make its way northward through the area into this evening, as low pressure over the Great Lakes stretches a strong cold front into the Ohio Valley. This front will cross the area through Thursday evening. Weak high pressure will build to our south heading into the weekend, with another cold front approaching from the west Sunday night. && .NEAR TERM /THROUGH THURSDAY/... Very little of significance was changed headline wise for the evening package. Main adjustment was an attempt to refine the most likely time for heavier rain. Otherwise, a warm front bisects central Maryland this evening. The warm front will continue to lift to our north overnight. Low pressure situated on the east side of Lake Michigan will push a cold front into Ohio this evening, knocking on the western fringes of our CWA after midnight. Ahead of the front, we will see surging PWATs in the 1-1.5 inch range while dewpoints approach 60 degrees. The wind field at the surface and aloft will be increasing out of the south as the front nears and the upper low/trough digs southeastward. Rain will encroach on our far western zones around or shortly after midnight, with moderate to heavy rain expected as it slowly pushes eastward. A Flood Watch goes into effect for our Blue Ridge westward zones starting at 4am, as the heaviest axis of rain overnight will remain primarily over this area. While instability will be limited, an embedded thunderstorm will be possible given the digging trough and approaching upper jet. Winds will be gusty overnight as southerly flow gets cranking, with winds gusting 30 to 40 mph at times. Combined with saturated soils, could see some instances of downed trees with isolated power outages possible. The highest rainfall totals through daybreak will fall along the higher terrain of the Alleghenies and central VA Blue Ridge, with rainfall totals in the 1 to 2 inch range, with locally higher amounts possible. Flooding of low lying areas and small creeks/streams will be possible through the overnight hours. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... The heavy rain will shift slowly eastward during the day on Thursday, pushing east of the mountains during the morning hours, favoring the I-95 corridor and eastward during the midday and afternoon. A Flood Watch for our zones east of the Blue Ridge goes into effect at 10am Thursday, as the heavy rain marches eastward. Again, the potential for flooding will exist across any low lying areas and small streams/creeks. With instability still limited, the upper jet/low will be favorably positioned to allow for the added lift and an enhancement in rainfall rates, especially along and east of I-95. Rainfall totals will range generally between 1 to 2 inches, with locally higher amounts up to 3 inches possible. The highest totals are expected to reside higher terrain of the Blue Ridge Mountains and across northeast Maryland. Do think the axis of heaviest rain starts to push east of the Chesapeake Bay during the late afternoon and early evening hours, with the front tracking right along with it. Any flooding, particularly any river flooding, will persist Thursday night into Friday. The upper low will dive into West Virgina and western Virginia Thursday night, dropping down toward the VA/NC border on Friday. This will maintain cloudy conditions and continued shower chances, with cooler than normal temperatures persisting. The upper trough finally kicks east of the Delmarva Peninsula Friday night as drier conditions prevail. Temperatures Thursday through Friday will run below normal with the elevated rain chances and cloud cover, with highs in the 60s, while lows remain mild in the 50s. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Low pressure over the mid-Atlantic Coast will deepen slightly more Friday into Friday evening as reinforcing energy approaches from the west. The combination of wrap-around and residual moisture will feed this additional energy to spawn additional rain showers across much of our region midday Friday into Friday evening. Any additional warmth could aid in spawning a thunderstorm or two due to differential heating. Temperatures should be in the middle 60s for the most part. As the low slowly pulls away from the East Coast, the rain showers will lessen in coverage and intensity with high pressure building in from the west later Friday night and Saturday. A gusty northwest wind could also become a factor with the interaction between the low pressure and the building high pressure through midday Saturday. As clouds fade behind sunshine Saturday afternoon, temperatures will warm a couple of degrees compared to Friday. Skies will become partly cloudy Saturday night and continue into the day on Sunday. While temperatures should become 5 to 7 degrees warmer Sunday than Saturday due to increasing thicknesses, a light southwest flow, and some sunshine, a few pop-up showers can`t be ruled out midday Sunday and become more scattered Sunday afternoon into Sunday night. Temperatures should top out in the middle 70s. A cold front should slice through the region Sunday night that will bring this added threat for rain showers. A thunderstorm can`t be ruled out in the afternoon and early evening. High pressure will build in behind the front Monday and Monday night. A light and cool breeze could develop and bring our temperatures downward a couple of degrees to start next week. A low pressure system could impact the area Monday night and Tuesday. At this time, models have this low tracking to our south or at least across our southern areas. This would result in a stratiform rainfall versus showers and thunder. Temperatures perhaps topping out in the upper 50s to middle 60s. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... A warm front has been lifting northward through the terminals this evening as southeasterly winds gust up to 20 knots and VFR conditions prevail. Clouds will thicken and lower overnight, approaching MVFR status after midnight as a strong cold front approaches to the west. Winds will remain strong and gusty out of the south through the overnight period as rain begins to spread eastward through daybreak. Rain will be heavy at times tonight at MRB/CHO. Southerly winds will gust up to 30 knots at times tonight and into Thursday morning, with LLWS being a factor. Moderate to heavy rain will continue Thursday morning and afternoon with IFR conditions likely at all terminals. The front will finally push to our east Thursday evening, allowing for slowly improving conditions as we head into Friday, however MVFR CIGs may linger with passing showers possible. Upper level disturbance pushes to our east Friday night, resulting in a return to VFR conditions. MVFR conditions with rain showers Friday into Friday evening. The IAD, DCA, BWI, and MTN terminals seem more likely than MRB and CHO. Winds generally northwest around 10 knots, becoming gusty to around 20 knots by Friday night. VFR conditions overnight Friday through Saturday night. Winds diminishing northwest to southwest 5 to 10 knots. && .MARINE... A warm front has been lifting northward through the waters this evening, allowing southeasterly breezes to increase and become gusty. As such, SCA conditions have emerged and persist through Thursday evening as a strong cold front slowly crosses. Gusty southerly winds will near gale force on Thursday, but confidence in frequency and occurrence is low at this time. Moderate to heavy rain at times Thursday afternoon and Thursday night will result in reduced visibility over the waters as well. Winds look to slacken behind the front late overnight Thursday and into Friday, but as the low begins to rap up along the New England coast, SCA gusts could return to the waters late Friday and Friday night. No marine headlines anticipated Saturday and Saturday night. && .TIDES/COASTAL FLOODING... Water levels have settled down to around a foot above normal. Anomalies have not yet surged and at a glance it looks like the next cycle will fall short, but given southerly flow, am mainly maintaining course, keeping Advisories for Annapolis and Baltimore and adding an Advisory for SW DC. The big push comes Thursday and perhaps into Thursday night. The range of possibilities has diminished from yesterday, but there are still questions yet to answer. Forecast more closely reflects higher CBOFS, which performs better in these situations. Added a Coastal Flood Watch for DC. Again, the rest is the same. The next challenge will be how quickly the water recedes. Some Watches may be a little long based on 12Z guidance, but that is a detail that can settle out in the cycles ahead. There is also a hint that there may be a either freshwater contribution at Georgetown or the tide will be significant enough to bring minor inundation that far north. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...Flood Watch from Thursday morning through Thursday evening for DCZ001. Coastal Flood Watch from 8 AM EDT Thursday through Friday morning for DCZ001. Coastal Flood Advisory until 8 AM EDT Thursday for DCZ001. MD...Flood Watch from 4 AM EDT Thursday through Thursday afternoon for MDZ003-502. Flood Watch from Thursday morning through Thursday evening for MDZ004>006-011-013-014-016>018-503>508. Coastal Flood Watch from 4 AM EDT Thursday through Friday morning for MDZ017. Coastal Flood Watch from Thursday morning through Thursday evening for MDZ508. Coastal Flood Watch from 4 AM EDT Thursday through late Thursday night for MDZ014. Coastal Flood Advisory until 4 AM EDT Thursday for MDZ014. Coastal Flood Watch from 6 AM EDT Thursday through late Thursday night for MDZ011. Coastal Flood Advisory until 6 AM EDT Thursday for MDZ011. VA...Flood Watch from 4 AM EDT Thursday through Thursday afternoon for VAZ025>031-036>040-503-504-507-508. Flood Watch from Thursday morning through Thursday evening for VAZ050>057-501-502-505-506. WV...Flood Watch from 4 AM EDT Thursday through Thursday afternoon for WVZ050>053-055-502-504>506. MARINE...Small Craft Advisory until midnight EDT Thursday night for ANZ530>534-537>543. Small Craft Advisory until 6 PM EDT Thursday for ANZ535-536. && $$ SYNOPSIS...BKF/RCM NEAR TERM...BKF/RCM SHORT TERM...BKF LONG TERM...HTS AVIATION...BKF/HTS/RCM MARINE...BKF/HTS/RCM TIDES/COASTAL FLOODING...HTS/RCM
Area Forecast Discussion
National Weather Service Melbourne FL
920 PM EDT Wed Apr 29 2020 .DISCUSSION... Current-Overnight/Thursday...All eyes turning toward the approaching line of storms nearing the east central Gulf this evening. Latest HRRR model speeding up timing with initial round approaching Lake/Volusia counties near 2AM, then showing a weakening trend as this first wave moves across the I-4 corridor ahead of sunrise. There is some re-development past sunrise and into mid-morning as showers/storms approach the Space Coast and through Osceola County. Moving into late morning-early afternoon the Treasure Coast and Okeechobee County should get in on the action. Any duration of stronger storms for a particular area will last up to two hours. Storms will be moving toward the east-northeast at 40 to 50 mph. Storm impacts remain frequent lightning, strong to damaging winds of 40 to 60 mph, small to quarter-size hail, and torrential downpours averaging around one-half inch, but locally could approach 1 to 2 inches if multiple rounds of precip are received. Cannot rule out an isolated shower out ahead of the line. The Storms Prediction Center (SPC) will monitor for a Weather Watch later overnight. Otherwise, a mild night with lows well into the 60s to L70s. Mostly clear skies this evening will gradually thicken as moisture increases ahead of the approaching showers/storms. A cool front will follow the precip and move through during the day on Thu. Clouds will decrease later in the day into the evening behind the front. Highs Thu in the U70s to around 80F north of I-4 with L-M80s southward. SERLY winds this evening will veer to southerly overnight, then SW/W during the day on Thu. The wind will increase later in the morning and afternoon with breezy/gusty conditions expected. Speeds approaching 15-20 mph sustained with frequent higher gusts in the late morning/afternoon. A Lake Windy Advisory may be necessary, but a mix of clouds/precip could distort the wind field enough to keep the Advisory mention absent. && .AVIATION...Expect increasing cloudiness through late evening and overnight ahead of an approaching line of showers and storms. Latest HRRR model has sped up this activity with arrival into the I-4 corridor past 2AM and perhaps Orlando Metro by 4AM continuing to spread southeastward through the morning and early afternoon. SERLY winds will veer southerly overnight, then SW/W during the day on Thu. Wind speeds will increase during the late morning/afternoon approaching 15-20 kts with frequent higher gusts at many terminal sites. A cool front will move southward during the day behind the last band of precip. MVFR CIGs/VSBYs with precip and ISOLD IFR. Clouds will decrease from north to south by late day/early evening Thu. Storm threats include lightning, gusty winds in excess of 35-45 kts, small hail, and torrential downpours. && .MARINE...Overnight-Thu...Deteriorating marine conditions as the pressure gradient tightens in advance of an approaching line of fast- moving showers/storms (40-50kts) ahead of a cold front that will move across the waters late in the day on Thu. Expect offshore moving activity to push across the Volusia coast after 4AM and possibly at the Cape ahead of daybreak should activity hold together. Models suggest weakening of this first line with a secondary development pushing off the Space Coast thru mid-morning and points further south late morning-early afternoon. Storm threats include cloud to water lightning, wind gusts in excess of 35-45 kts, small hail, and torrential downpours. A Small Craft Advisory exists for offshore waters north of Sebastian Inlet (until 12Z/8AM Thu morning) and near shore Volusia waters until 08Z/4AM -- will extend by two hours with evening update. Some models are suggesting some stronger winds into Thu morning/early afternoon and will allow next shift to explore any extension from here. Seas will build to 5-7 ft over the Advisory area and will need Cautionary Statements most everywhere else. Both winds/seas will be on a slow decrease thru the day on Thu. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory from 4 PM this afternoon to 2 AM EDT Thursday for Flagler Beach to Volusia-Brevard County Line 0- 20 nm. Small Craft Advisory from 4 PM this afternoon to 8 AM EDT Thursday for Flagler Beach to Volusia-Brevard County Line 20-60 nm-Volusia-Brevard County Line to Sebastian Inlet 20- 60 nm. && $$ Sedlock/Volkmer/Watson