Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/05/19


AREA FORECAST DISCUSSION
National Weather Service Albany NY
1003 PM EDT Sat May 4 2019 .SYNOPSIS... Rain will develop tonight and continue through the morning for areas from around the Capital District southward, as low pressure develops and moves along a stalled front over the Mid Atlantic States. Widespread rainfall will occur mainly south of Interstate 90, with areas to the north of Albany expected to be dry much of the time. Weak high pressure will build in Sunday night into Monday, providing a brief period of dry and seasonable conditions. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... As of 1000 PM EDT...The clouds continue to thicken and lower south of the Capital Region quickly as the next wave approaches moving along the stalled frontal boundary over the Mid Atlantic States. CLoud tops are cooling based on the IR imagery over portions on PA into NY with some moderate to heavy rain noted in northeast PA. The latest 3-km HRRR and NAMnest shows the rain moving in fairly quickly between 04Z-06Z especially south of the Capital Region, then quickly expanding northeast into the Capital Region and Berkshires. We retooled the POPs slightly for this trend in the CAMs and the latest radar imagery. Temp trends were also retooled based on observations. Likely/categorical pops for areas south of the Albany/Schoharie counties, such as the eastern Catskills, mid Hudson Valley, southern Berkshires and Litchfield Hills were continued in these areas especially between 08Z-12Z. Will keep chance pops in the Capital District, norther Berkshires and southern VT, with dry conditions farther north. With the increasing clouds and rain arriving, temperatures will be mild with mainly upper 40s to lower 50s except for cooler lower 40s in the Adirondacks where some partial clearing is expected. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... Rain will continue across the southern third of our area Sunday morning as the wave of low pressure tracks east to the Delmarva vicinity. The strongest 850-700mb F-Gen forecast from the NAM/GFS/ECMWF sets up just to the south of our region, closer to NYC/NJ and the southern New England coast. So while parts of southern Ulster, Dutchess and Litchfield Counties should see moderate rainfall amounts of around 0.50 to 0.75 inches, the heaviest rain of 1-2 inches is expected to remain south across NYC/NJ and SE PA. The NAM/GFS/ECMWF and even HREF mean are in fairly good agreement regarding the max QPF area. The Capital District will be right on the edge between dry conditions and spotty light rain, so will continue to mention chance pops although it does not look like a wash out locally. Dry conditions are expected across the Adirondacks and Glens Falls/Lake George area. Temperatures will be warmest across the northern half of the area where it is not raining and some breaks of sunshine will likely occur. It will cooler to the south of Albany where the steady rain will be falling. The rain should taper off to scattered showers during the early/mid afternoon as the main surface wave moves off the coast and the mid/upper level through axis passes through. It will remain cloudy except across northern areas. Showers should also end during the early evening as the upper trough shifts eastward into New England. Weak high pressure will build in Sunday night. Without a significant push of dry air, there still could be areas of low level clouds remaining. Monday looks to be the best day of the short term, as the weak surface high remains in place and boundary layer winds become southwesterly. This should allow for a mix of sun and clouds, with temperatures in the 60s to lower 70s with light winds. Dry conditions will prevail through at least the first half of Monday night. However, a cold front approaching from Canada will bring a chance of showers to the Adirondacks before sunrise. Elsewhere it will remain dry with temperatures slightly above normal. && .LONG TERM /TUESDAY THROUGH SATURDAY/... The extended forecast continues to feature an unsettled pattern especially for the latter portion of the work week and below normal temperatures persisting throughout. Tuesday...A cold front will be moving across the region based on the latest 12Z GFS/CMC/ECMWF/NAM and Ensemble trends. The best moisture and low-level convergence will be right along the cold front. The mid and upper level trough amplifies more over southeast Canada this model cycle for the front to move through quickly by the late afternoon into the early evening. The 12Z GFS did indicate some instability with SBCAPEs around 1000 J/kg and sfc dewpts in the lower to mid 50s south of the Capital District during the afternoon, as some sfc heating could occur. We did add a slight chance of thunderstorms for locations in the eastern Catskills, mid Hudson Valley, southern Berkshires and NW CT in the mid to late pm. Chance or low likely PoPs were used with the frontal passage. High will be in the mid 50s to mid 60s north and west of the Capital District, and mainly mid/upper 60s to lower 70s from the Tri Cities south and east. Tue night...The showers should be pretty much over in the early evening with the sfc cold front south of the region, and low and mid level cold advection occurring. Sfc high pressure will be building in from south-central Ontario and the northern Great Lakes Region. Lows will be chilly with some patchy or scattered frost possible in the Upper Hudson Valley. Lows will range from the mid and upper 30s north and west of the Capital District/eastern Mohawk Valley, and 40s to around 50s south and east. Wed-Wed night...A tranquil stretch of weather with a Canadian anticyclone building in over NY and New England during the day from southeastern Canada. Partly to mostly sunny skies are expected with temps still running a shade below normal, as H850 temps will be in the +1 to +5C range based on the 12Z GFS, as highs will be in the upper 50s to lower/mid 60s in the valleys, and upper 40s to mid 50s over the mtns. Mid and upper level heights increase over the region, as the next system moves out of the central Plains into the Upper MS River Valley and Midwest Wed night. The low and mid level warm advection increases toward daybreak, and mid and high clouds will be increasing quickly, and we placed a slight chance of showers reaching locations west of the Hudson River Valley. Lows are expected to be in the mid 30s to mid 40s across the region. Thu-Fri night...The weather becomes unsettled on THU with clouds thickening and lowering during the day with increasing isentropic lift ahead of a warm front to the low pressure system moving into the Upper Midwest and Great Lakes Region. The deterministic guidance trended a little slower this cycle with the ridge axis holding until the mid to late afternoon over eastern NY and New England. We increased the PoPs quickly in the afternoon to high chance and likely values, and continued likely PoPs Thu night when the best lift and moisture convergence occurs over the forecast area. A widespread soaking rainfall is likely into Friday morning. The primary low lifts northeast of Lake Ontario on Friday, as a secondary wave may form near NJ keeping a chance of showers going through the day. The system looks like it will lift northeast Friday night with an occluded front moving through with scattered showers ending. Total QPF is variable on the guidance but the latest WPC QPF is in the half inch to inch and a half range or so over the forecast area. Temps both Thu and Fri are expected to be below normal for maxes in the cool and damp air mass with upper 40s to lower 60s with lows in the upper 30s to upper Saturday...In the increasing cyclonic flow aloft over the Northeast and southeast Canada, a few showers may linger over the higher terrain to open the weekend early on, but high pressure will be attempting to build in from the Great Lakes Region for a mainly tranquil weekend. Temps will still be running 5 to 10 degrees below normal. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Low pressure will move along a frontal boundary along the Mid Atlantic states tonight bringing rain back into the region from the Capital Region and Berkshires southward. The low pressure system will pass south of southern New Jersey and Long Island during the morning into Sunday afternoon. The TAF sites will begin VFR with mid level clouds in the 6-9 kft AGL range over eastern NY and New England. A few showers ahead of frontal boundary near the NY-Canadian border may get close to KGFL between 02Z-05Z which will lower the bases to high MVFR, and we placed a VCSH group there. The bigger issue will be clouds thickening and lowering ahead of the sfc wave to the south with a low-level north to northeast maritime flow. Expect bases to quickly lower into the MVFR range 1.5-3 kft AGL at KPSF/KALB/KPOU between 02Z-06Z/SUN. Rain overspreads the area from south to north to about KALB/KPSF between 08Z-12Z/SUN. We went with IFR cigs/vsbys at KPOU/KPSF during this time frame with MVFR conditions at KALB in the rain. Further north, we kept MVFR conditons in terms of the clouds bases in the 1.5-3 kft AGL range but with no rain. The IFR conditions in the rain shield will continue the longest at KPOU until about 21Z/SUN. We expect an improvement sooner to MVFR conditions with the wave pulling away at KALB/KPSF at around 18Z/SUN. KGFL has the best chance of VFR conditions by the mid to late pm. The winds will be vary from the north to northeast at less than 5 kts tonight, and will be east to northeast at less than 10 kts during the late morning into the afternoon. Outlook... Sunday Night: No Operational Impact. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: High Operational Impact. Likely SHRA. Tuesday Night: Low Operational Impact. Slight Chance of SHRA. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Chance of SHRA...RA. && .FIRE WEATHER... Rain will develop tonight and last into Sunday for areas from around Albany southward, as low pressure develops and moves along a stalled front positioned over the mid Atlantic region. Widespread rainfall will occur mainly south of Interstate 90, with areas to the north of Albany expected to be dry much of the time. Rainfall amounts will range from around a tenth of an inch just south of Albany to over a half inch across southern Ulster, Dutchess and Litchfield Counties. Dry conditions will return for Monday with warmer temperatures. && .HYDROLOGY... A low pressure system will pass by just south of the area tonight into Sunday. Although areas north of Albany may see little if any rainfall from this system, southern areas are expected to receive around a quarter to three quarters of inch of rainfall. While some minor rises are possible on area rivers and streams, this rainfall won`t be enough to cause any flooding and rainfall rates will be low enough to prevent any problems in urban and low lying areas. Dry weather is expected Sunday night into Monday, but some more rain showers are anticipated for Tuesday, as a cold front moves southward through the area. A stronger and larger storm system may affect the region with widespread rainfall late next week. Please visit our Advanced Hydrologic Prediction Service /AHPS/ web page for specific area rivers and lakes observations and forecasts. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...JPV/Wasula NEAR TERM...JPV/Wasula SHORT TERM...JPV LONG TERM...Wasula AVIATION...Wasula FIRE WEATHER...JPV HYDROLOGY...Frugis/JPV
Area Forecast Discussion
National Weather Service Bismarck ND
953 PM CDT Sat May 4 2019 .UPDATE... Issued at 953 PM CDT Sat May 4 2019 We decreased the chance of precipitation in far south central ND and the southern James River valley trough the night with this update, leaving only a low-grade 15 percent PoP in place across parts of LaMoure and Dickey Counties through about 06 UTC. Most CAMs, including the 00 UTC WRF-ARW/NMM cores, continue simulating shower formation between Jamestown and Aberdeen the next few hours, but to this point observational trends offer little support for this in a post-frontal environment characterized by cold air advection and implied subsidence in the low/mid levels. Slope of the frontal zone into the cool air has been supporting some frontogenesis in the 850 and 700 mb layers per most models, but even that weakens by 06 UTC. Otherwise, only minor changes were made to the rest of the overnight forecast, with regional radar showing light precipitation encroaching on eastern MT as of 0245 UTC, which is a reflection of the next impulse that may bring light rain and snow to southwest ND late tonight and Sunday. UPDATE Issued at 709 PM CDT Sat May 4 2019 Only minor changes were made with this update to reflect recent observational trends. This included refining PoPs roughly along the Highway 200 corridor, but radar imagery shows precipitation along an east-west-oriented, southward-sinking axis is quickly diminishing as the forcing for ascent attendant to the right- entrance region of an ~100 kt 300 mb jet streak situated along the international border shifts eastward toward the Great Lakes concurrent with the upper-level speed maxima. We did maintain an area of shower chances in far south central ND into the southern James River valley this evening, where recent HRRR and ESRL-HRRR cycles have simulated development. However, GOES-16 visible satellite imagery provides little evidence of that development in an environment marked by steep midlevel lapse rates, but meager boundary layer moisture and a lack of forcing in a post-frontal environment with ongoing low- and midlevel cold air advection. Thus, confidence in shower development in the Linton to Ellendale corridor is low. Finally, evening wind speeds were increased in areas with less cloud cover where boundary layer mixing has been supporting modest momentum transfer, but those should diminish with the approach of sunset. && .SHORT TERM...(This evening through Sunday) Issued at 245 PM CDT Sat May 4 2019 The main forecast issue in the short term period will be rain and snow chances. Currently, a cold front has pushed through all of North Dakota with high pressure pushing into the northwest. In spite of the surface high pressure, an upper level Jet situated over the far northern counties, into southern Manitoba and southeast Saskatchewan has been responsible for a rather damp and cool day across the northwest portion of the state with temperatures generally in the 30s and scattered to numerous snow showers. Elsewhere, although it hasn`t been great, there has been enough sun to push temperatures into the 40s and even the upper 50s over the southern James River Valley. Tonight, expect the showers across the north to slowly dissipate and sink southward as the upper jet drops into the northern Great Lakes region. Some elevated lapse rates over the far southern James River Valley this evening may keep the shower activity lingering over this area into the early overnight hours. Another wave currently over southern British Columbia will drop through the broad upper trough over southern Canada and northern U.S. and bring another chance of rain and snow to the area late tonight and Sunday. This time the focus will be farther south, mainly the southwest and far south central portion of the state. Model differences do still remain in the timing and placement with the NAM displaced farthest to the south, and a general consensus with the GFS/EC/GEM in clipping the west central through far south central with some light snow accumulations, beginning in the far southwest late tonight, and continuing across the southwest and far south central Sunday into Sunday evening. Any accumulations at this time are expected to be light, and over mainly grassy and elevated surfaces as surface temperatures will remain relatively warm. After lows in the 20s north to 30s south tonight, highs on Sunday are expected to be cool once again with mid 40s southwest to mid 50s over the James River Valley. .LONG TERM...(Sunday night through Saturday) Issued at 245 PM CDT Sat May 4 2019 A persistent upper level ridge over the eastern Pacific will keep a (mainly cyclonic) northwest upper flow, over the Northern Plains through the extended period. Thus we are expecting temperatures mainly below normal through the period. Although given our time of year and the cyclonic flow, a stray shower can not be ruled out throughout the extended period. However, it looks like mainly isolated to scattered shower chances. The exceptions being Wednesday when a southern stream system tries to bring a little more moisture into the far southern tier counties, and Saturday when the GFS/GEM bring a northern stream upper level system into the Northern Plains, although much more uncertainty remains with the late week system. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 953 PM CDT Sat May 4 2019 VFR conditions will generally prevail over western and central ND through the 00 UTC TAF cycle. However, a weak disturbance could produce light rain and snow in far southwest ND along with MVFR ceilings and visibilities late tonight and Sunday. Recent trends in model guidance suggested the probability of sub-VFR conditions at KDIK are too low for inclusion in their TAF, but later cycles will continue to re-evaluate that possibility. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CJS SHORT TERM...TWH LONG TERM...TWH AVIATION...CJS
Area Forecast Discussion
National Weather Service Boston/Norton MA
1047 PM EDT Sat May 4 2019 .SYNOPSIS... Expect rain late tonight and continuing Sunday before tapering off late. Monday will be mild and dry. Sweeping cold front Tuesday with scattered shower, possible thunderstorm activity. Cold and dry Wednesday, while Thursday into Friday widespread rain is forecast. The weekend could end up being dry while early the following week we`ll see another shot of rain. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Main changes this evening were to rainfall chances, particularly the timing. The last few runs of the time-lagged ensemble HRRR looked to have the best handle on timing and location for the rest of tonight based on observed regional radar data. As such, it was used heavily to make adjustments this evening. Also tweaked temperatures to bring them back in line with observed conditions and expected trends. Previous Discussion... Clouds and scattered showers hanging around. A lot of moisture within the column beneath stretched mid-level energy within the zonal flow pattern (yet some measure of confluence) beneath the RRQ of a H3 jet streak. Not much of an ascending environment, but wherever low-level confluence and lift can manifest can the environment undergo some upward squeeze in where collision and coalescence can yield some shower activity. Keep it chance PoPs. Obviously any breaks of sunshine in the waning hours of the day will certainly aid in easily destabilizing the boundary layer beneath a conditionally unstable, moist adiabatic profile aloft. The greater concern has to do with the uncertainty of low clouds and fog. Dewpoints are impressively high with near 60 in the lower CT River Valley. But more than likely clouds hold in thick. Temperatures remaining stable, lows dropping down into the low to mid 50s ... its interesting to see that SREF / HREF guidance has confidence pinged at E/SE coastal MA for areas of dense fog, otherwise broken to overcast low ceilings around 500 to 1500 feet with the lowest over SE New England and the high terrain. Follow probabilistic trends. Would think more widespread fog and visibility impacts with high dewpoint air. Will simply have to closely monitor it tonight. Going into Sunday morning, subtle height falls in advance of upstream mid-level energy, cyclonic turning of the wind fields, with a continued moist environment. Subsequent flow E beneath the RRQ of a H3 jet streak, broad moist ascent subsequent which should yield a shield of over-running rain to encroach into S New England during the morning hours. Low conditions in terms of cloud decks and visibility persisting. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... 2 PM update ... Global and mesoscale guidance converging on a farther north storm track Sunday with surface low passing near or just south of 40N/70W benchmark. This also results in mid level wave traversing farther north and with wave transitioning from an open wave to a closed circulation at 700 mb over the area tomorrow. This yields increasing mid level Fgen along with some enhancement from RRQ of upper level jet streak and PWATs up to 1.7 inches off the south coast to come together and produce some bands of heavier rainfall. Definitely more like a cool season system, luckily it`s not cold enough for snow as the banded nature of the precip would make for a very challenging snow forecast. Obviously the atmosphere has no regard what the calendar says. Mesoscale guidance suggest these heavier rain bands are most likely across CT/RI into southeast MA including the south coast. 925 mb temps cool to about +5C as the day progresses indicating temps only 45-50 tomorrow along with a chilly/raw ENE wind off the ocean for southeast MA. Yeah, an ugly day by May standards. Up to an inch of rainfall possible especially vicinity of the heavier rain bands. ARW and NSSL suggest these heavier bands could be as far north as northern CT-RI into interior southeast MA. However diagnostic fields suggest Fgen/deformation could be as far north as BDL-ORH-BOS. Not typical to be examining winter type forecast procedures in early May. Sunday night ... A drying trend as system exits east into Georges Bank. However for southeast MA especially Cape Cod and the Islands it will be a much slower process with moist NE flow and slow departure of comma-head resulting in rain/drizzle taking much of the night to depart the area. Elsewhere cool maritime northeast flow with 925 mb temps on the NAM lowering to +3C suggest a cool night with lows mainly 40-45. && .LONG TERM /MONDAY THROUGH SATURDAY/... 2 PM update ... */ Highlights ... - Mild, dry Monday ... the pick of the week - Scattered showers, possible thunderstorms for Tuesday - Wednesday looking chilly and dry - Widespread on/off rains for Thursday into Friday - Weekend could end being pleasant and dry */ Overview ... Wave train of wet-weather disturbances continues. So long as the NE Pacific H5 ridge dominates, downsheared Pacific energy bowls through central N America, tapping into a sub-tropical S stream, associated moisture strewn clockwise round a Bermuda high, both stretching E through the maritime flow beneath some weak mid-upper level ridging, looking at the persistence of flat wet-weather disturbances across our region, holding more times than not N of attendant boundaries. Averaging out just slightly below-seasonable for early May (highs in the upper-60s, mid-40 lows), will break down the details below. */ Details ... Monday ... Pick of the week. Mild, seasonable, likely onshore sea-breezes as highs warm into the low 70s. However persistent cyclonic flow aloft. Consensus forecast guidance signaling instability showers W perhaps with a combination of high-terrain anabatic flow and/or pre-frontal surface trof preceding Tuesday`s cold front. Better chances where a H8-7 dry-inversion cap is weak to which there`s indications further N/W. May trickle into the Berkshires. Overnight... increasing S flow and surface dewpoints as the boundary layer cools. Perhaps some fog issues. Winds and clouds in mind, better chance likely S-coastal. Tuesday ... Scattered showers, possible thunderstorms late. Sweeping cold front associated with a S Hudson Bay low. Attendant continental-moist air- mass with precipitable waters to 1.25". Destabilizing prior beneath a conditionally-unstable, moist adiabatic airmass. However parallel W/SW winds along the front, also noted within forecast model hodo- graphs. Can`t rule out dry intrusions limiting activity. Forecast consensus of MUcape around 500 J/kg, indications of heavier rainfall included. Chance to likely PoPs. In the end it may be a band of rain with embedded heavier showers, maybe rumbles of thunder if dry air becomes an issue. Overnight... clearing quickly behind the front as cool Canadian air pours S with building high. Closer to 1030, the more likely the H85 0C isotherm digs S. N winds prevail, if waning then there`s the potential for radiational cooling along with frost- freeze concerns. Wednesday ... Dry, chilly. With the H85 0C isotherm likely aloft, the early May sunshine, expect deep-mixing to H8. Mix down drier air and breezy N winds. Expect 2m temperatures to over-achieve into the 60s as dew- points drop down around the upper 20s, possibly as low as the mid- 20s. Overnight... another opportunity for light winds, radiational cooling, frost / freeze concerns. Thursday and Friday ... Over-running rains. Leaning towards the EC suggesting a kinking warm- front setup parent with confluence across the northeast which keeps boundaries S. Canadian high exiting, undercutting cool, dry NE flow, heavier rains focused S and offshore of S New England. Expecting a repeat of dreary conditions with on and off rains under a low deck of clouds, E winds extending all the way S towards the lower Hudson River Valley of NY. Weekend ... Perhaps clearing out, cool and dry conditions. In continuance with the EC, weak mid-upper level ridging affords the opportunity for weak surface high pressure to provide a return of dry, seasonable conditions before the next potential shot of wet weather associated with a system bowling across the Great Lakes, outcomes across the northeast set for early the following week. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/...Moderate confidence. Tonight...Higher confidence IFR conditions across SE New England terminals and along the high terrain, with a mix of VFR and MVFR elsewhere. SCT SHRA becoming widespread RA towards morning, and with RA a greater likelihood of more widespread VSBY impacts. NE winds 5 to 10 kts, gusts to 15 kts. Sunday...Widespread RA along with MVFR-IFR CIGs and VSBYs. Higher confidence of lower conditions along the high terrain and along and S of the MA-pike, especially along the S-coast. E winds 10 to 15 kts, gusts to 25 kts, strongest along the S/SE- coast. Improving late in the day NW-SE towards VFR. Sunday night...CIGs and VSBYs continuing to improve NW-SE as RA concludes, some DZ and FG lingering over SE New England particularly the Cape and Islands. Winds turning N, becoming light, around 10 kts. Stronger winds along the E/SE coast. KBOS Terminal... RA moving in closer to 09z-12z. CIGs however lowering overnight through MVFR becoming IFR around early morning Sunday. KBDL Terminal... SCT SHRA near the terminal becoming more of a widespread RA by 06z-09z. CIGs lowering throughout towards IFR around the same time- frame. With RA, possible +RA, expect 2-5SM VSBY impacts. Outlook /Monday through Thursday/... Monday: VFR. Breezy. Monday Night: VFR. Tuesday through Tuesday Night: VFR. Chance SHRA. Wednesday: VFR. Wednesday Night: VFR. Slight chance RA. Thursday: VFR. Chance RA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/...High confidence. Tonight...Light NNE wind much of the night but then increasing to 15-20 kt toward daybreak, strongest wind in the RI waters. Areas of fog and showers limiting visibility 2-4 miles at times especially S/SE waters. Seas remaining below 5 feet. Sunday...Small Craft Advisories for southern waters of MA/RI with NE winds 15-20G25 kt as low pressure tracks near or just south of 40N/70W benchmark. Less wind over N MA waters toward NH/ME. Visibility 1-3 miles in rain. Seas 4-6 feet over S/SE waters. Sunday night...NE winds becoming NNE 15-20 kt with gusts up to 25 kt possible as benchmark low exits into Georges Bank. Light rain/drizzle limiting visibility 1-3 miles especially over the SE waters. Waves around 4-6 feet S/SE waters. Outlook /Monday through Thursday/... Monday through Monday Night: Winds less than 25 kt. Seas up to 5 ft. Tuesday through Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Wednesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain. Thursday: Winds less than 25 kt. Chance of rain. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 4 PM Sunday to 6 AM EDT Monday for ANZ254. Small Craft Advisory from 8 AM Sunday to 6 AM EDT Monday for ANZ255-256. && $$ SYNOPSIS...Nocera/Sipprell NEAR TERM...Belk/Nocera/Sipprell SHORT TERM...Nocera LONG TERM...Sipprell AVIATION...Nocera/Sipprell MARINE...Nocera/Sipprell
Area Forecast Discussion
National Weather Service Hastings NE
935 PM CDT Sat May 4 2019 .UPDATE... Issued at 934 PM CDT Sat May 4 2019 Some comments regarding weather earlier this evening and also through the next 24 hours: 1) Earlier weather: Late afternoon-evening storms played out fairly close to expectations of the past 24 hours. We came close to issuing a few Warnings (SVR), but instead issued several Special Weather Statements (SPS) to cover at-times near-severe signatures for wind and/or hail. The overall-strongest activity affected Furnas/Harlan/Franklin/Phillips counties. Ground-truth wise, assuming no more delayed reports roll in, thus far we only received reports of small hail and a few unofficial mesonet stations gusted into the 40-50 MPH range. Storm intensity was held in check by a combo of only modest instability (mixed- layer CAPE mainly 500-1000 J/kg) and deep-layer shear only 20-30KT. 2) Rest of tonight: Barring some surprises, the strong/severe storm threat appears to be done for the night, and have updated the Hazardous Weather Outlook (HWO) to reflect this. That being said, with some modest elevated instability sticking around, and in the presence of a relatively weak low level jet, there is a non-zero risk for at least very isolated/"random" storm development through the night. Post-midnight, our official forecast only mentions a storm possibility within our KS zones, but there is at least a 10 percent chance that a storm or two could flare up within our Nebraska zones as well (chances need to be 15+ percent to be formally mentioned in worded forecast products). 3) Sunday`s severe storm threat: Will defer to incoming night shift to better address our next chance of strong-severe storms Sunday afternoon-evening, but agree with preceding day-shifter that Sunday`s setup looks a bit more potent than today`s ever was, with mixed-layer CAPE likely closer to 2000 J/kg, and a low-level forcing/focus provided by a cold front moving in from the north. HOWEVER, mid-upper level forcing is fairly weak, so even though the overall probability of a few severe storms looks better, the overall-coverage of this activity is somewhat questionable. No matter, the 3-10 PM time frame looks to be our main concern. && .SHORT TERM...(This evening through Sunday) Issued at 317 PM CDT Sat May 4 2019 Aloft: Dominant teleconnections indicate a -EPO/-NAO. RAP dynamic tropopause analyses showed confluent low-amplitude flow was over the CONUS with a broad trof over the Cntrl/Nrn Plns. That will remain the case thru tomorrow. A weak shrtwv trof was currently over the Nrn Rckys. This trof will diminish further as it mvs SE and crosses the Cntrl Plns around midday tomorrow. Surface: MSAS data showed wk high pres extended from TX-GtLks- Hudson Bay with a fairly potent low along the MB-ON border. A cold front stretched from this low acrs the Nrn Plns back into the Canadian Rckys. This front will cont sagging S tonight as the low heads into ON. It will arrive into Nrn CWA tomorrow AM and sag to near I-80 in the aftn. Now thru 8 PM: Temps hv risen into the 70s with dwpts mixing down into the mid-upr 40s most locations...except E of Hwy 281. This has resulted in MLCAPE near 500 J/kg. With little CIN...shwrs began forming from AUH-JYR-OLU around 18Z. The main area of concern is from IML-LBF-TIF-ONL where sct tstms hv begun forming. CAMs suggest these tstms will cont to incrs in coverage and sweep thru most of S-ctrl NEB late this aftn and dissipate early this evng. Given that these storms will be high-based...outflow/downburst winds of 50-60 mph will be the primary svr threat. However...frzg lvls are around 8K ft...just abv cld base. That means these tstms will produce lots of small hail (peas/dimes/pennies)...but can`t rule out a a few quarters/nickels. Tonight: Sct tstms will rapidly diminish with sunset gvn the lack of QG forcing. Some mdls suggest a few shwrs and psbly a tstm could linger over N-cntrl KS...but I doubt it. Lows a little warmer than normal. Sun: The cold front eases in from the N. Sct tstms could fire along and S of the front after 20Z. Temps well into the 70s with dwpts in the low-mid 50s with steep mid-lvl LR`s of 8 C/km will result in better instability than today with MLCAPE 1200-2000 J/kg per 15Z/SREF. 0-6 km shear will be around 35 kt. This environment support svr tstms...probably general and multicell tstms. Can`t rule out a supercell...but low-lvl winds will be very wk. .LONG TERM...(Sunday night through Saturday) Issued at 317 PM CDT Sat May 4 2019 Aloft: The longwaves will become increasingly amplified over the CONUS thru Sat. The low currently W of CA will move onshore and into the Desert SW Sun-Tue. The E Pac ridge will then build forcing additional height falls over the Wrn USA. Here in the Cntrl Plns... zonal flow Mon will become SW Tue-Wed. The Desert SW low is fcst to wkn and lift NE acrs NEB/KS Wed. SW flow will cont in its wake Thu-Fri as trofs extend from Cntrl Canada thru the Nrn Plns into the Desert SW. The global mdls are indicating the flow over the Cntrl Plns will become NW by Sat as the Nrn stream asserts its influence. There are some modest diff`s among the last 2 runs of the GFS/GFS-FV3/EC/CMC/UKMET...but overall agreement is there suggesting abv normal confidence in the flow. Surface: The cold front bisecting NEB Sun night will cont inching S and should be S of the CWA by 00Z/Tue. Large/chilly high pres will slide E along the US-Can border Mon-Tue. Lee cyclogenesis should occur Tue. As this low ejects out of CO Wed...the front will rotate cyclonically...with the warm front psbly lifting back into the SE 1/3 of the CWA. Strong CAA will occur as this low moves into IA. Another chilly high will then drop out of Canada into the Plns Thu-Sat. Temps: We`ll be going backwards in time. While temps should be going up the deeper we get into spring...temps will be going down next wk. Expect svrl days of cldy/cool wx with low clds/stratus locked-in N of the front. As cool as our fcst temps are (lots of 50s)...believe they still are not cool enough. Would not be surprised to see temps jammed in the 40s N and W of the Tri-Cities Tue. Precip: There are low chances for spotty shwrs and psbly a couple sub-svr tstms Mon-Tue. The wettest and highest confidence period for beneficial/drenching rain will be Tue night into Wed....first by a strong pulse of WAA Tue night...then as the wrap-around/ deformation zone stratiform precip shield moves in Wed. Some parts of the CWA will probably measure 1-2". The 00Z EC ensemble QPF probs has a 100% chance of 0.50". 90% chance of 1" and a 50% chance of 2" N of a line from ODX-GRI-JYR. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday) Issued at 736 PM CDT Sat May 4 2019 General overview: Confidence is high that the majority of the period will feature VFR ceiling/visibility, although there are some question marks especially ceiling-wise during the final 9-10 hours Sunday daytime (see below for more details). Precipitation-wise, while there is a non-zero chance of a passing shower/thunderstorm this evening, and perhaps again late Sunday afternoon (mainly after 21Z), neither chance warrants more than a generic "vicinity" (VCTS) mention at this point. Wind-wise, surface winds will remain somewhat breezy from the south through the night (gusts 20-25KT at times), before easing up late in the night. While confidence in exact timing is a bit shaky, a noticeable directional shift to northerly winds is anticipated sometime Sunday afternoon. Currently have this depicted at 21Z, but this could easily be off a few hours either way. As for low level wind shear (LLWS) concerns, despite what should be fairly breezy surface winds overnight, have opted to maintain a marginal LLWS mention from previous TAF cycle (03-10Z). This is due to south winds increasing to generally 40-45KT within roughly the lowest 1,200 ft. AGL, resulting in roughly 30KT of shear magnitude between the surface and this level. Read on for more on ceiling uncertainty... Ceiling: High confidence in VFR through at least the first 12-14 hours, but there are suggestions in some model data that at least a brief MVFR ceiling could materialize during the day Sunday, perhaps initially in the morning, and maybe again later in the afternoon behind the northerly wind shift. Did not yet have the confidence to introduce/maintain a formal MVFR ceiling for either time frame, but am at least hinting at the potential with "SCT020". && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ UPDATE...Pfannkuch SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Pfannkuch]
Area Forecast Discussion
National Weather Service Grand Junction CO
909 PM MDT Sat May 4 2019 .SHORT TERM...(Tonight through Sunday night) Issued at 223 PM MDT Sat May 4 2019 Mostly dry westerly flow brought mostly sunny skies this afternoon resulting in daytime highs about 5 to 10 degrees higher than yesterday. The higher temperatures may induce isolated showers or thunderstorms this afternoon over the Grand Mesa through the central Colorado Mountains around sunset this evening as per the HRRR and NAM Nest. Skies remain mostly clear tonight with overnight lows remaining near seasonal. Sunday is going to be very similar to today, but with more coverage in the isolated to scattered afternoon showers. Models are showing these showers to be affecting mainly the northern and central Colorado mountains, and they will last through the evening. Daytime highs tomorrow will climb another 5 to 10 degrees compared to today. .LONG TERM...(Monday through Saturday) Issued at 223 PM MDT Sat May 4 2019 A closed low off of the Southern California Coast makes its way towards the desert southwest on Monday turning the zonal flow over our region more southwesterly. Moisture embedded in this flow will bring another round of afternoon/evening showers and thunderstorms over the high terrain Monday into Tuesday. The main surge of moisture associated with the aformentioned disturbance does not arrive until around 6z Wednesday, which is a bit slower than previous model runs. The closed low gets absorbed into a larger trough passing over the Rockies on Wednesday bringing more widespread precipitation through the day. This trough really slows down and continues to bring precipitation through Friday. 700 mb temperatures look warm enough keep snow levels above 10-11,000 feet. Then things get a little more complicated as the base of the trough closes off and retrogrades west back towards the coast of California over the weekend. This new closed low meanders there through the start of the new week. The brings the possibility of afternoon showers through that entire period. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 906 PM MDT Sat May 4 2019 VFR weather pattern remains in place through Sunday evening. Isolated showers and thunderstorms, mainly during the afternoon and evening hours, will bring gusty outflow winds to 40kts and BKN CIGS between 7 and 10k. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...JPF LONG TERM...JPF AVIATION...JDC
Area Forecast Discussion
National Weather Service Indianapolis IN
1156 PM EDT Sat May 4 2019 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 425 PM EDT Sat May 4 2019 Rain will move out of the area late this afternoon as a narrow axis of high pressure builds into the area. Some fog may result late tonight as skies clear over the wet ground. Sunday and Monday will be mostly pleasant days with warmer temperatures, although there will be a small chance for thunderstorms northwest Monday afternoon. Another frontal system will begin to impact the area and bring near constant chances for showers and occasional storm chances much of the coming work week again. && .NEAR TERM /Tonight/... Issued at 903 PM EDT Sat May 4 2019 Current forecast in good shape. No updates planned at this time. Previous discussion follows. Expect that rain will be clear of the area by 00Z and will carry no pops tonight. Skies will clear steadily overnight, and with wet ground, concerned about fog potential, perhaps even dense fog. Conflicting advice from some of the guidance. NAM soundings look very good for dense fog, but the NAM is often overly aggressive on fog. GFS looks ok but shows surface temp/dewpoint spreads that would likely be a bit too high. HRRR soundings are somewhat supportive of the more aggressive NAM, and current obs show dewpoints in the mid to upper 40s in spots a decent way upstream. Thus, will go with the slight preponderance of the evidence and mention patchy fog after 06Z and patchy dense fog after 09Z, particularly with the ground so wet. There is a small but non-zero chance that widespread dense fog could develop, but will have to simply monitor trends overnight to see. Consensus temperatures appeared reasonable and result in temp/dewpoint spreads of around 1 by morning, further supporting potential for fog. && .SHORT TERM /Sunday through Tuesday/... Issued at 425 PM EDT Sat May 4 2019 Dry forecast will suffice through Monday most areas, although will need a low chance for thunderstorms northwest Monday afternoon. Otherwise, pleasant weather is expected with temperatures warming back into the 70s. Another frontal zone drops into the region late Monday into Tuesday and this will require chances for showers and storms. Generally accepted builder pops which were maximized reasonably around frontal position, but this may need refining as we get closer to Monday night into Tuesday, as given the relative lack of midlevel impulses, there will be the potential for convection to be primarily diurnal in nature. However, developing upper level jet streak may provide enough large scale ascent to support the chances at non diurnally preferred times as well. Consensus temperatures were reasonable and required only minor tweaks. && .LONG TERM /Tuesday Night through Saturday/... Issued at 310 PM EDT Fri May 3 2019 Models in good agreement a wave of low pressure will ride up along a nearby front late next week. Southerly flow ahead of the front will supply moisture, and the result will be the threat of unsettled weather Tuesday night through late next week. Eventually, an associated cold front will move through late in the week which is expected to result in a cooler but dry Saturday. Confidence is not great on timing of highest PoPs, so will leave the blend alone which suggests the most widespread shower activity will be Wednesday night and Thursday. && .AVIATION /Discussion for the 050600Z TAFS/... Issued at 1153 PM EDT Sat May 4 2019 Crossover temperatures would suggest good potential for fog development overnight, although confidence in this is not particularly high at this time, as it appears lower dewpoints will be advecting into the area. Some diurnal cloud development based 025-030 expected towards the midday hours of Sunday. Generally light surface winds overnight will become 020-040 degrees at 5-8 kts by midday Sunday. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Nield NEAR TERM...Nield/JAS SHORT TERM...Nield LONG TERM...MK AVIATION...JAS
Area Forecast Discussion
National Weather Service Northern Indiana
739 PM EDT Sat May 4 2019 .SYNOPSIS... Issued at 728 PM EDT Sat May 4 2019 It will be a dry and pleasant evening with partly to mostly cloudy skies and light winds. Some fog may also form overnight, especially over north central and east central Indiana and northwest Ohio. The fog will be short lived with mostly clear skies and warmer weather on Sunday into Monday morning. High temperatures will reach into the upper 60s to middle 70s Sunday and Monday. Clouds increase Monday afternoon along with chances of showers and thunderstorms which will continue at times through Thursday night. && .SHORT TERM...(This Evening through Sunday) Issued at 355 PM EDT Sat May 4 2019 Light rain showers will persist over the next few hours across far southeast locations as low level trough axis associated with passing upper trough interacts with low level baroclinic zone. Diminishing cloud trend in the form of transition from low clouds to high clouds to mainly clear skies will spread eastward through remainder of the afternoon into early evening. The main item of uncertainty for tonight deals with cloud cover across far northeast Indiana/northwest Ohio. Departing sfc reflection with this afternoon`s short wave and elongated ridge axis building southeast from the Great Lakes will keep low level northeast low level flow in place. These trajectories will allow for best residual near sfc moisture to linger across extreme northeast Indiana and northwest Ohio tonight, where some stratus may linger or redevelop. Some patchy fog also possible across portions of north central Indiana south of Route 24 where light rain was more prevalent this afternoon. Clearing skies and light winds tonight should allow for decent radiational cooling and lows in the 40s, although moist soils will provide some limitations to how low temperatures drop. The remainder of the short term period will be pleasant with mid level trough axis building into the region tonight and Sunday with transition to synoptic scale subsidence. Gradual modification of airmass, slow eastward departure of low level thermal trough, and good insolation for Sunday should allow high temperatures to rise into the upper 60s/lower 70s Sunday afternoon. && .LONG TERM...(Sunday Night through Saturday) Issued at 355 PM EDT Sat May 4 2019 Not a great deal of change with respect to long term forecast for this forecast cycle. Sunday night will feature a stronger upper level short wave tracking across south central Canada taking low level front southward across the Great Lakes region. Better precip chances with this front for local area not likely to arrive until later Monday afternoon into Monday evening. This front still appears to become somewhat divorced from better mid/upper level forcing by the time it reaches the local area however. With decent accompanying low level convergence with the boundary and somewhat favorable diurnal timing, will maintain low to mid chance PoPs Monday afternoon/Monday night. Potential for stronger storms should be limited for this period as southeast CONUS anticyclone does not provide a real opportunity for good moisture return. Sfc boundary will settle south of the area Tuesday, but northward retreat of elevated warm front later Tuesday into Tuesday night argues for maintaining at least low chance PoPs this period. The period of potential greater impact for local area still appears to be the Wednesday night/Thursday timeframe with continued indications in medium range models of stronger upper PV max lifting northeast from southwest CONUS. Preceding advective/LLJ forcing Wed night followed by stronger mid/upper level forcing on Thursday suggests maintaining highest PoPs for this period. Potential of some stronger storms does exist this period but ultimately will depend on track/strength of this feature, and complicating effects from potential widespread rain overnight Wed/Thu that could limit northward extent of better instability. With continued high water levels on area rivers, will need to continue to watch this period for some potential renewed river flooding also. Long range signals point toward return to below normal temps once again under cyclonic flow behind this system for next weekend, with mainly moisture-starved additional short waves progressing across the Great Lakes region. && .AVIATION...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 727 PM EDT Sat May 4 2019 VFR to start this period but concern lies with potential MVFR and IFR conditions developing overnight, primarily around KFWA. Weak winds and residual moisture from rainfall along with drier air aloft will set the stage for potential fog and/or stratus development. HRRR and consensus blends in agreement with development over eastern Indiana and northwest Ohio. Have introduced these conditions with a tempo group for now at KFWA. It appears enough dry air advection to keep KSBN VFR overnight but will have to monitor with recent rainfall, light winds and clear skies there as well. VFR after sunrise Sunday with light northeast wind 5 knots or less becoming northwest to west in afternoon in the 4 to 7kt range. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...Lashley SHORT TERM...Marsili LONG TERM...Marsili AVIATION...Lashley Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1109 PM EDT Sat May 4 2019 .UPDATE... Issued at 1109 PM EDT SAT MAY 4 2019 Given no nearby lightning sources and MUCAPE of 500 J/kg or less, have pulled thunder from the forecast. Localized high water or flooding issues will remain possible as the main slug of moisture moves through eastern Kentucky tonight. UPDATE Issued at 824 PM EDT SAT MAY 4 2019 Showers continue to fill back in across eastern Kentucky along/downstream of several surface waves and an upper impulse migrating from Dixie Alley into the southeastern Tennessee Valley. Have kept thunder chances in the forecast for now due to this abundant lift and vicinity of a stalled out frontal boundary, but instability is certainly meager given overcast skies and earlier rainfall. May be able to decrease or drop thunder chances in subsequent updates depending on cloud top cooling/glaciation upstream nearer the approaching lobe of energy. && .SHORT TERM...(This evening through Sunday night) Issued at 244 PM EDT SAT MAY 4 2019 At 18Z a wavy front extended from central PA to southern WV, then across northeast KY, to southwest KY, and then southwest to LA. A surface low was along the front over western KY. Radar shows a first wave of showers and thunderstorms impacting the southwest part of the forecast area at 18Z. This first wave of showers and storms should move northeast of the area by 22Z. However the HRRR has been consistent in showing another round or two of showers and storms from 23Z this evening through about 08Z or 09Z Sunday. The 09Z SREF supported the idea of a heavy rain threat a little further south and west than the original flash flood watch from early this morning, and that was one reason the flash flood watch was expanded earlier today. The 12Z HREF does show a few low probability 1 hour QPF values greater than 1" in a few spots over far southeast KY from 22Z to 02Z. This is all within the current flash flood watch area. Precipitable water from the 12z soundings was 1.1 inches at ILN and 1.4 at OHX. Earlier today we were able to get some GOES satellite measured total precipitable water in southeast KY, with 1.2 to 1.3 inches noted, which was in line with the soundings. The precipitable water would be around the 75th percentile, so heavy rain is definitely possible. The first round of showers and storms currently moving across the area will help promote better run off with any additional showers and storms this evening. There is some question with exactly how intense any additional showers and storms will be tonight, with the 12Z NAM seeming to be on the extreme side of QPF. The heavier rain with the NAM seems to associated with an additional area of low pressure it moves along the front overnight. It should be noted that the CAMs are not particularly intense with any additional convection tonight. With all that being said will continue with the flash flood watch in the updated configuration issued just before noon EDT. The watch is in good agreement with the WPC day 1 excessive rainfall slight risk area. Thanks for earlier coordination with WPC, RLX and MRX concerning the heavy rain threat. The front currently across KY will shift south of our area overnight, and it will be noticeably cooler on Sunday and Sunday night. With damp ground and clearing skies Sunday night some dense fog is possible Sunday night. .LONG TERM...(Monday through Saturday) Issued at 403 PM EDT SAT MAY 4 2019 The long term portion of the forecast begins with fairly zonal flow across the U.S. and surface high pressure in the Ohio Valley. This will result in fair mild weather to start the new work week. However, the fair weather will be short lived, and a wet pattern will set up for the coming week. Mid/upper level troughing will be taking shape in the western U.S. at the start of the week, with ridging in the east. At the surface a front will gradually push south on Tuesday, extending from New England back to the central plains. With the mean ridging in the southeast U.S. the front will have a hard time pushing south, and should stall somewhere in the OH valley by mid week. As a significant short wave ejects from the mean western trough midweek, a surface low will develop and track northeast towards the Great Lakes. There are considerable model differences on the timing, track and strength of the surface low. However it does appear the already mentioned stalled front will move back north as a warm front with surface low pressure moving from the plains towards the Great Lakes. With the surface low passing to our north, a cold front will push across eastern KY Thursday night or Friday morning. Exactly how far south of the area the front pushes is in question and it may stall just to our south for next weekend. With all this being said we are in for a wet week. Depending on the track and timing of the system on Thursday, some strong storms will also be possible on this day. At this time the severe threat looks to be just to our west on Thursday per the latest SPC Day 6 Thunderstorm Outlook. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 824 PM EDT SAT MAY 4 2019 Conditions continue to be determined by shower activity filling in and progressing eastward across the eastern Kentucky airspace. SYM/SJS currently reporting LIFR ceilings while many other sites sit in the VFR realm. Will see ceilings across all of eastern Kentucky down to at least IFR levels tonight as additional rainfall moves through and low stratus lingers behind a departing frontal boundary. Visibilities will periodically drop to IFR/MVFR criteria underneath moderate/heavy rainfall through the night. Although rain will come to an end Sunday morning, low clouds will be slow to lift and exit Sunday with MVFR ceilings likely hanging strong through much of the day. && .JKL WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch until 4 AM EDT Sunday for KYZ085>088-104- 106>120. && $$ UPDATE...GUSEMAN SHORT TERM...SBH LONG TERM...SBH AVIATION...GUSEMAN
Area Forecast Discussion
National Weather Service North Platte NE
739 PM CDT Sat May 4 2019 .SHORT TERM...(This evening through Sunday night) Issued at 307 PM CDT Sat May 4 2019 Lapse rates are fairly steep this afternoon given the fact that showers and thunderstorms developed by mid morning. The models continue to advertise modest shear and CAPE with 500mb winds around 30-35kts and MLCAPE values between 1500 and 2000 J/KG. The HRRR suggests hail as the primary threat late this afternoon and this evening as strong wind gusts are absent in the model until the storm activity moves east into central Nebraska. The next rain chance develops Sunday evening. By this time, wrn and ncntl Nebraska are in a post-frontal environment and northwest flow aloft is underway. Still, the NAM indicates elevated CAPE, steep lapse rates and some level of potential for large hail. SPC suggests a marginal severe weather threat but the NAM model-derived radar product does not indicate strong convection. For this forecast, the threat of strong or severe storms would appear to be today and tonight only. Highest POPs for the Sunday night rain event are centered across northern Nebraska and in the likely category. .LONG TERM...(Monday through Saturday) Issued at 307 PM CDT Sat May 4 2019 A cool wet weather pattern sets up Monday through Saturday. The main feature is the upper level low off the West coast which will move east through the Central Plains and produce substantial rainfall across wrn and ncntl Nebraska Tuesday and Wednesday. Precipitable water approaches 1.0 inches which is about 200 percent of normal. Once this upper level low moves east late Wednesday, a batch of cold air from northern Canada drop south. Rain chances end, but unseasonably cool air remains across wrn and ncntl Nebraska the rest of the week. The ECM which was the coolest model has warmed slightly and this morning`s run has backed off on accumulating snow across wrn Nebraska Wednesday night. The forecast continues a chance of snow in that area as temperatures aloft will support the changeover. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 735 PM CDT Sat May 4 2019 Skies should be mainly clear for most of the night across western and north central Nebraska. A cold front will move south across the area very late tonight. A low stratus cloud deck is expected to move south into northern Nebraska behind the front. Appears that MVFR and local IFR ceilings will occur. The stratus is not expected to make it as far south as I-80 and the North Platte TAF site. MVFR ceilings may linger much of the day Sunday across northern portions of the state. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Taylor
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
935 PM EDT Sat May 4 2019 .SYNOPSIS... A cold front will approach from the west Sunday then move offshore late Sunday night. High pressure will build over the region early next week, then slide offshore mid to late week. && .NEAR TERM /OVERNIGHT/... As of 935 PM Sat...Latest radar imagery shows earlier convection now morphing into an area of moderate stratiform rain just to the west of the forecast area. Will continue with higher pops across the far western portions for the next few hours, though expect bulk of precip to remain west of the forecast area. Isolated to widely scattered showers and storms expected late tonight into early Sun, with HRRR showing best chances towards sunrise. Widespread low clouds is likely to develop after midnight in the very moist low level airmass. Muggy overnight with lows in the upper 60s to around 70 deg. SW breeze should limit any fog threat. && .SHORT TERM /SUNDAY/... As of 345 PM Saturday...A cold front approach the area tomorrow and is expected to push through the area late Sunday night. Deep layer SW flow will bring a warm and humid airmass while a mid-level shortwave moves the area which can bring additional forcing for scattered to numerous showers and thunderstorms, especially during the afternoon and evening hours with added frontal forcing. A few stronger storms are possible as CAPE values are AOA 1500-2000 J/kg, LI around -5 and shear increasing to around 35 kt. SPC continues to indicate a marginal risk of severe storms. Temps continue to be several degrees above normal this period with highs Sun in the mid 80s inland to upper 70s along the coast. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... As of 310 PM Saturday...A cold front will push through the area late Sunday before high pressure builds into the area early next week ushering in dry and warm weather. An unsettled pattern may return mid to late week with high pressure moving offshore. Sunday night...Cold front will be pushing across our area at the start of the period and is forecast to be offshore overnight, taking showers and thunderstorms with it. Lows expected in the upper 50s to lower 60s with a slightly cooler airmass advecting in with northerly flow behind the front. Monday through Tuesday night...High pressure builds into the region early next week with ridging building aloft bringing dry weather and somewhat cooler temps and lower dewpoints. Highs Mon expected in the upper 70s to around 80 inland to around 70 to mid 70s NE and coastal sections; evening lows expected in the upper 50s inland to lower 60s coast. Increasing heights and plenty of sun Tuesday will aid in pushing highs into the mid 80s inland, upper 70s coast. Lows Tue night expected in the low to mid 60s with southerly return flow as the high slides offshore. Wednesday through Saturday...Uncertainly in the mid to late week forecast remains high with the latest 12Z model suite as their agreement and consistency remains poor across the Southeast regarding the strength and timing of an upper level ridge. The GFS remains flatter with the ridging and moves it offshore quicker Wed bringing near- zonal flow across the area with several weak impulses moving through the flow aloft bringing periods unsettled weather across the region. The ECMWF suggests stronger ridging will lift these impulses to the north with generally dry conditions across the area. With the surface high offshore bringing warm and humid conditions across the area and dewpoints well into the 60s, isolated to scattered showers and thunderstorms will be possible each day and made little change to precip chances - chance PoPs through peak heating in the afternoon and slight chance PoPs other times. Temps look to be several degrees above normal this period with highs in the mid to upper 80s inland and upper 70s/lower 80s coast; lows in the upper 60s to near 70. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... Short Term /through Sun/... As of 935 PM Sat...VFR conditions currently across the TAF sites early this evening, and should prevail through at least 06z. Area of light to moderate rain may impact the sites, mainly ISO and PGV through 04z. Increasing moisture overnight could support MVFR ceilings developing after 06z, though SW breeze should limit any fog threat. Any MVFR cigs could linger through mid morning before improving to VFR as stronger mixing develops. SW wind gusts 20-25 kt Sun afternoon ahead of the front. Scattered to numerous showers and storms expected Sun afternoon into early evening, with periods of sub-VFR possible. Long Term /Sunday night through Thursday/... As of 315 PM Saturday...Sub-VFR ceilings possible behind the front Sunday night into early Monday. High pressure builds into the region early next week with predominantly VFR conditions expected. Showers and tstms may return Wed afternoon but model consistency remains poor as we move into the middle of the week. && .MARINE... Short Term /through Sunday/... As of 935 PM Sat...Latest buoy obs show S/SW winds 10-20 kt, with seas 2-5 ft, highest across the outer central waters. SW winds 10 to 20 kt overnight, peaking at 15-25 kt with gusts up to 30 knots Sunday afternoon ahead of an approaching cold front. Seas building to 3-5 ft overnight. Seas will peak 4 to 7 ft Sunday afternoon south of Oregon Inlet. SCAs have been issued for coastal waters south of Oregon Inlet and the Pamlico Sound starting Sunday mid-morning. Could be close for the northern waters, but will next shift take a closer look. Long Term /Sunday night through Thursday/... As of 325 PM Friday...Cold front will be moving across the waters to start the period with SW winds initially 15-20 knots (20-25 knots possible outer cntrl waters) becoming N around 10-20 kt behind the front, then veering to NE Mon at 10-15 knots. Seas expected to be 4-6 feet at the start of the period subsiding to 3-4 feet by Monday morning - thus SCA conditions expected into the overnight hours. NE winds diminish to around 10 kt or less Mon night into early Tues and then continue to veer to E to SE through the day, becoming S to SW Tue night and Wed as high pressure slides offshore. Seas expected to mainly be around 2-4 ft but could see up to 5 ft at times, especially across the central waters. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...Small Craft Advisory from 11 AM Sunday to 2 AM EDT Monday for AMZ152-154. Small Craft Advisory from 11 AM to 11 PM EDT Sunday for AMZ156- 158. Small Craft Advisory from 2 PM to 8 PM EDT Sunday for AMZ135. && $$ SYNOPSIS...MHX NEAR TERM...CQD/BM SHORT TERM...JME LONG TERM...DAG/SK/MS AVIATION...CQD/BM/MS MARINE...CQD/BM/MS
Area Forecast Discussion
National Weather Service Mount Holly NJ
942 PM EDT Sat May 4 2019 .SYNOPSIS... Surface low pressure will track along a stationary front through the Mid-Atlantic region later tonight and Sunday. As the low passes east on Sunday, the front will push to the south. High pressure will arrive for Monday before the next front moves south toward the area late Tuesday into Wednesday. This front may then stall across or just south of the region for the middle to latter part of next week. && .NEAR TERM /THROUGH SUNDAY/... For the 930 PM update, showers on the increase from near the Poconos into portion of the Lehigh Valley near an incoming short wave and convergence zone. The HRRR has been keying in on this general area, therefore used its PoPs for the next few hours then blended that into continuity for the overnight. Instability is rather limited, however a few cloud to cloud lightning strikes were detected over the last half hour therefore included isolated thunder through about midnight. Made some tweaks to the hourly temperature, dew point and wind grids to keep them current. Temperatures are a little slower in dropping thus far than forecast especially farther inland. Otherwise, no major changes were needed at this time. Otherwise, main action occurs overnight and Sunday and the main concern looks to be hydro and potential for flooding as increasingly high PWATs are advected in from the south and west. For the overnight, expect a more organized area of low pressure to develop over Virginia as the main upper level wave approaches from the south and west. There will also be good right jet entrance dynamics setting up over the area along with PWATs reaching 1.5+ inches as there will be a deep saturated layer. The upshot of all this is that showers/storms will transition to a more widespread, synoptic type moderate to heavy rainfall event over the region. There will still be some instability to work with but this will become increasingly confined to the southern Delmarva...near and south of the system`s warm front. Flash Flood Watch in effect for a large swath of the CWA centered near the I-95 corridor as this looks to be where the heaviest rain will fall. While precipitation won`t really be as convective by later tonight, deep layer moisture and forcing will be strong enough for persistent moderate to heavy rainfall that if the heaviest persists over the same area this could result in Flash Flooding...especially urban areas. Small stream flooding looks to also be an issue within the Watch area. Sunday shaping up to be a very wet day. Expect widespread moderate to at times heavy rain to fall through the morning at least into the first part of the afternoon before precip starts to wind down late day. This will occur as the surface low tracks from Virginia east across the Delmarva then off the coast. Flooding concerns discussed above will persist in tandem with this heavy rainfall so Flash Flood Watch runs until 4 PM Sunday. There could still be some embedded thunderstorms with the rain over the southern Delmarva and far southern NJ but otherwise most of the instability will be south. However, moderate to heavy precip looks to be aided through early afternoon by good jet entrance dynamics in the upper levels, mid level F-gen forcing, and strong low level convergence along and north of the system`s warm front coupled with the high PWATs 1.5-1.7 inches. Temps will be cool...highs mainly in the upper 50s to low 60s due to raw NE winds. && .SHORT TERM /SUNDAY NIGHT/... Any lingering rain/showers quickly winds down through the evening as the low progresses off to the east and weak high pressure begins to nose in overnight. Expect lows by Monday morning mostly in the upper 40s to low 50s under variable cloud cover. && .LONG TERM /MONDAY THROUGH SATURDAY/... High pressure will be in place on Monday, before shifting offshore Monday night. High pressure typically features a dry forecast, however, we have a slight chance of showers for portions of the area during this period. There is some enhanced moisture that will remain in place across portions of northeast Pennsylvania and northern New Jersey. There will be a couple of weak short wave/vorticity impulses moving across the area during this time, coupled with enhanced low- mid level lapse rates, especially Monday afternoon, to help lead to a slight chance of showers. The shower activity will diminish by Monday night. On Tuesday, a cold front will be approaching the area from the northwest, crossing our area during the afternoon and into Tuesday night. This will lead to increasing rain chances across the area. What happens to this front is still uncertain. The GFS stalls the front just south of the area through the end of the week, with several waves moving along the boundary. The ECMWF shifts the front more to our south by Wednesday, before lifting it back northward, again with several waves moving along the boundary. So for the Monday through Wednesday period, it doesn`t appear there will be a prolonged, widespread rainfall, but there is still enough in the models to paint some slight chance/chance PoPs in the grids each day across portions of the CWA. Thursday into Friday looks to be a wetter period as both the warm front and cold front affects the region as deepening low pressure works across the Great Lakes. Like this past week, the coming week`s temperatures looks to be on the same roller coaster. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight and Sunday...VFR ceilings lowering to MVFR then IFR toward 06z. Some showers (perhaps an isolated thunderstorm near ABE and RDG) transitions into widespread rain during about the 04-08Z time frame. Rain continues through 18Z Sunday, then showers continue through much of the remainder of the afternoon. MVFR to at times IFR visibilities due to varying rainfall intensity. Easterly winds near 5 knots or light and variable tonight, then northeasterly around 10 knots on Sunday (some gusts to 20 knots mainly at ACY in the afternoon). Lowered confidence regarding the onset of the widespread IFR conditions (ceilings). OUTLOOK... Sunday night...MVFR ceilings overall. Monday...MVFR ceilings continue into the first half of the day, but likely begin to lift and return to VFR by the afternoon. Monday night...VFR conditions expected. Tuesday-Tuesday night...Generally VFR conditions expected. However, a cold front will cross the area later Tuesday into Tuesday night, bringing rainfall and MVFR conditions to the area. Southwest winds may gust 15-20 knots during the day Tuesday. Wednesday...A frontal boundary will likely stall to our south Wednesday. The question is how far south? Forecast confidence is lower for Wednesday at this time, but chances of MVFR ceilings and rain are higher across southeast Pennsylvania, southern New Jersey, Delaware, and eastern Maryland. Thursday...MVFR and possibly IFR conditions expected. && .MARINE... Sub SCA conditions for tonight but there could be some patchy fog along with showers and storms which will become more widespread rainfall overnight. Sunday...SCA conditions developing north to south through the day as low pressure organizes over Virginia then passes through the southern waters. Rain with embedded storms persisting. NE winds increasing with gusts up to 25 knots and seas 4-7 feet by late day. OUTLOOK... Sunday night...Small Craft Advisory Conditions possible early Sunday night, before diminishing overnight. Monday-Wednesday...Conditions are expected to remain below advisory levels, although seas will linger around 4 feet and winds could gust around 20 knots at times. Thursday...SCA conditions possible. && .TIDES/COASTAL FLOODING... A light onshore flow will redevelop along the coasts of New Jersey and Delaware for tonight. The onshore flow is expected to strengthen on Sunday as low pressure passes off the Delmarva coast. Positive tidal departures will be on the increase. We continue to keep an eye on Sunday evening`s high tide for the potential for some minor tidal flooding in coastal areas of New Jersey and Delaware and into Delaware Bay. Parts of the tidal Delaware River may also be affected during Sunday night`s high tide. Positive departures around 1 foot would cause spotty minor flooding. If departures increase closer to +1.5 feet, then the minor flooding would be a bit more widespread and an advisory may become necessary. No issues are anticipated for the upper eastern shore of Maryland. && .EQUIPMENT... The KDIX radar is out of service until further notice due to a hardware failure. Surrounding radars include KDOX, KOKX, KLWX, KCCX, KBGM and TPHL. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Flash Flood Watch through Sunday afternoon for PAZ060>062-070- 071-101>106. NJ...Flash Flood Watch through Sunday afternoon for NJZ007-009-010- 012-015>019. DE...Flash Flood Watch through Sunday afternoon for DEZ001. MD...Flash Flood Watch through Sunday afternoon for MDZ008-012. MARINE...Small Craft Advisory from 6 AM Sunday to 6 AM EDT Monday for ANZ450>452. Small Craft Advisory from 3 PM Sunday to 6 AM EDT Monday for ANZ453>455. Small Craft Advisory from 6 PM Sunday to 2 AM EDT Monday for ANZ431. && $$ Synopsis...Kruzdlo Near Term...Fitzsimmons/Gorse Short Term...Fitzsimmons Long Term...Kruzdlo Aviation...Davis/Gorse/Kruzdlo Marine...Fitzsimmons/Kruzdlo Tides/Coastal Flooding...Iovino Equipment...
Area Forecast Discussion
National Weather Service Pocatello ID
147 PM MDT Sat May 4 2019 .SHORT TERM...Tonight through Monday. Seeing some cumulus buildup this afternoon, could see an isolated shower develop across some of the eastern highlands this evening. A passing weak upper level trough may help to produce a better shot at isolated thunderstorms across the high country Sunday into Sunday night. On Monday, we see some moisture arrive from a low pressure system making landfall in central California. We could see a few more thunderstorms Monday afternoon, mainly across the southern and eastern highlands from this moisture. Valle .LONG TERM...Monday Night Through Next Saturday. The upcoming week is likely to start out quite showery as longwave troughing becomes established over the Rockies and a closed low heads inland/weakens across CA and AZ. In particular, late Tues AM through Wed afternoon features the best precip chances with an embedded shortwave diving in and some possible moisture contribution from that closed low to our SW, and we increased PoPs during this period over NBM guidance. One-tenth to one-quarter inch of QPF is possible, with higher amounts in the eastern Central Mntns. Overall, these values are a bit lower than what we would look for in terms of a significant hydrologic response, especially coupled with fairly cool/seasonable temps. Will continue to monitor. Enough instability is present Tues afternoon/eve to include thunder. While the GFS/EC/Canadian are in reasonable agreement with these features and scenario on their 12Z runs, run-to-run consistency has been low, and we would consider forecast confidence moderate at best through Wed night. A drying trend appears likely from Wed night onward as the longwave trough axis tends to shift E/SE of our forecast area, and we stuck close to NBM guidance. Our cool/comfortable spring will continue, with temps near or on the cool side of climatology. In fact, temps may allow some wet snow to mix in near and above pass level Tues AM and again Wed AM, with any accumulation confined to the peaks and ridgelines (no impacts for travel). && .AVIATION... Forecast confidence is high in VFR/unlimited cigs and vsbys at nearly all terminals this afternoon through early Sun afternoon. The one exception in our confidence levels will be KDIJ, as some of the high-res HREF members and HRRR still try to develop a few showers late this afternoon/this eve near and north of the airport as a weak shortwave disturbance moves across the region. Maintained VCSH 22Z to 03Z, and actually switched it over to VCTS given slightly negative LIs per RAP/NAM guidance suggesting some weak instability. Still, confidence in precip is very low (lift/moisture seem pretty marginal), and unless the "best cell of the day" moves directly over the terminal, VFR conditions are still likely as reflected in the TAF. Otherwise, diurnally-timed winds increase at all terminals to values that may be of interest to particularly GA aircraft, but trajectories (quite common for our area) should line up pretty well with runway configurations at KBYI/KPIH/KIDA and generally preclude crosswinds. Nearly all guidance including MOS/LAMP has trended more toward a usual diurnal shift into the SE at KSUN compared to earlier concerns for more of a westerly component, and surface wx stations are already showing this further up the Wood River Valley. Thus, light crosswind concern has lessened here, although maintained a trend toward SW winds after 22Z. Beautiful aviation wx expected overnight with lighter winds and no concerns. - KSmith/Valle && .HYDROLOGY...Most streams and rivers are within their banks across the region. We will see warming temperatures through the weekend and could start seeing bankful conditions once again on a few rivers towards early next week. Valle && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Blacksburg VA
934 PM EDT Sat May 4 2019 .SYNOPSIS... A cold front will approach the region overnight and cross the region early Sunday morning. High pressure will work its way into the area by late Sunday afternoon and remain parked over the region through early Tuesday. A series of frontal boundaries will bring precipitation back to our forecast late Tuesday through the start of the next weekend. && .NEAR TERM /THROUGH SUNDAY/... As of 925 PM EDT Thursday... A Flash Flood Watch remains in effect for southeast West Virginia into Tazewell and Smyth Counties through 5AM. The first band of showers and thunderstorms was moving through the Virginia and North Carolina piedmont as of 900PM and should be east of Charlotte and Buckingham Counties by midnight. The 500 mb short wave and associated surface low in central Kentucky will bring another batch of showers and thunderstorms through southwest Virginia, northwest North Carolina and southeast West Virginia overnight. Have a brief lull in the probability of precipitation between these two areas, then increases probability again from west to east based on the RAP and NAMnest guidance. Fog is expected to develop and be across much of the region overnight. Some locally dense fog is also possible. Low temperatures tonight will again be on the mild side for this time of year. Anticipate mid to upper 50s across the mountains and lower 60s across the Piedmont. For Sunday, the cold front is expected to be exiting the southeast part of the area shortly after sunrise. However, it will make limited additional progress eastward thanks to a shortwave trough heading along the front. This feature will have the influence of maintaining a broad area of rain showers across primarily eastern parts of the area through at least mid-day. It will be at this point that the axis of the shortwave trough shifts east, and thus allows the cold front to shift closer to the coast. Showers will still across the area by the late afternoon, but be more isolated to scattered in coverage. Peak heating of the day and the proximity of the cold front will help with the development of some isolated afternoon thunderstorms across the southeast portions of the region. With the passage of the cold front, plenty of clouds and precipitation around the area, look for high temperatures a little cooler than those of today. Across the mountains highs will range from the mid to upper 60s with low to mid 70s across the Piedmont. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 145 PM EDT Saturday... Sunday night through Tuesday night is expected to be rather uneventful as weak high pressure builds across the central Appalachians in the wake of the departing cold front. Will start Sunday evening with residual showers diminishing with the loss of daytime heating, and will then head into the overnight period on the dry side. Expect pockets of fog considering the wet soil conditions from rainfall on Sunday, however am not yet sure how dense the fog will become considering the light northerly/northeasterly winds may keep the dewpoints slightly separated from the air temperatures. For Monday, any shower and isolated thunderstorm activity will be driven almost exclusively by daytime heating and will be confined to the mid-afternoon through sunset timeframe. This activity will be disorganized in nature and should stick pretty close to the crest of the Blue Ridge. This will be followed with another night of localized fog and otherwise dry conditions. Tuesday will prove to be slightly more active as another cold front sinks southward from the Ohio River during the afternoon and evening. Given the stronger daytime heating, believe we will see somewhat greater coverage of showers and a few thunderstorms develop during early afternoon in the vicinity of the Blue Ridge, with some of this activity drifting east across the Piedmont during the evening. Can`t rule out one or two storms becoming severe but, given the lack of dynamics, do not anticipate organized severe activity. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 345 PM EDT Friday... Latest run of the longer range models indicates good agreement that the cold front will sink southward across the Piedmont early Wednesday to at least the VA/NC state line as a strong upper level disturbance approaches from the west. Believe the combination of cool east/northeasterly windflow behind the front and areas of rain will strictly limit heating for the day, and have lowered high temperatures 4-6 degrees from the previous forecast. A lot of uncertainty remains in how this pattern will play out, so went on the conservative as to how much temperatures were lowered. Should this wedging pattern come to fruition as the models suggest, the forecast for Wednesday afternoon could easily be several degrees too warm still. At any rate, a warm front will lift northward across the region Wednesday night into Thursday afternoon, introducing the potential for locally heavy rain as the supporting upper level disturbance passes overhead. Passage of the front will allow winds to shift southwesterly, as well as for any rainfall to become more spotty and showery in nature. Increased sunshine during the afternoon will allow for warmer afternoon temperatures over those of Wednesday. Thursday night and Friday will bring the passage of a cold front, resulting in another round of locally heavy showers and thunderstorms. Westerly windflow in the wake of the cold front will bring drying conditions to the region. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... As of 745 PM EST Saturday... Band of showers and thunderstorms from KHSP to KDAN will continue to move east this evening and will be eat of KLYH by midnight. Ceilings and visibility will be MVFR in the heavier storms. A second band of MVFR showers and thunderstorms will move into the mountains of southwest Virginia, northwest North Carolina and southeast West Virginia along in association with another short wave. Otherwise ceilings will lower to IFR overnight across the area with MVFR to IFR fog. Once a surface low crosses through North Carolina Sunday, wind become northwest to north and ceilings will lift back to MVFR or VFR. Confidence is below average for ceilings and average for wind and visibility. EXTENDED AVIATION DISCUSSION... Primarily VFR conditions will exist Sunday night through Wednesday as high pressure dominates our weather pattern. The exception will be the potential for some late night/early morning fog within the river and mountain valleys. The potential for sub-VFR conditions will increase Wednesday night and Thursday as first a warm front lifts north through the region, and then a cold front approaches from the west late in the day Thursday. Confidence in the extended portion of the aviation forecast is average. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Flash Flood Watch until 5 AM EDT Sunday for VAZ007-009. NC...None. WV...Flash Flood Watch until 5 AM EDT Sunday for WVZ042>044-507-508. && $$ SYNOPSIS...DS NEAR TERM...AMS/DS SHORT TERM...NF LONG TERM...NF AVIATION...AMS
Area Forecast Discussion
National Weather Service Tallahassee FL
923 PM EDT Sat May 4 2019 .UPDATE... Broken line of showers and thunderstorms is located from Albany to Tallahassee to Carrabelle and moving east around 40 MPH. So far most of the storms have stayed below severe limits with wind gusts to 50 MPH possible. Short term guidance shows a slow weakening trend to the line as it moves eastward over the next few hours. Overnight, a redevelopment of showers and storms across our western sections as the cold front approaches. Have used the HRRR and ECAM guidance for timing and rain chances for the rest of the night. Lows will dip into the mid to upper 60s overnight. && .PREV DISCUSSION [719 PM EDT]... .NEAR TERM [Through Tonight]... A deep upper trough is moving through LA this afternoon with deep layer southerly flow over the region. This is bringing in abundant moisture with dew points in the low 70s at the coast and in the mid to upper 60s inland. With the aid of weak lift, a widespread cu field has developed as well as scattered showers. Since 1230PM EDT, we are starting to see quite a few intra-cloud and cloud to ground lightning strikes. This scattered convection will continue through the afternoon. This is very pulse/summer like convection so with the mid level dry air and the high instability, downbursts with strong winds are possible, as well as some small hail. The line of stronger storms is moving along the S. MS coast and slightly inland at 2PM EDT. This will continue to move east through the evening. This line should get to our western border by 7-8 EDT/6- 7 CDT and will be moving into a favorable environment to sustain stronger updrafts and the potential for a few severe storms. Instability will be sufficient (almost 3000 J/KG of SBCAPE as of 2PM from the LAPS and should remain near 2000 J/KG per the RAP tonight) and shear/lift starts to increase actually after sunset. This is just enough to keep embedded severe storms and the line strong. Instability will be highest south of AL/GA border so the highest potential for stronger storms would be there. These should remain strong to severe through Tallahassee where guidance has them start to weaken and dissipate before the Big Bend. However, the mid level low is slow to move through and the actual cold front will move through and be near Tallahassee at 12z Sunday morning. The first line previously mentioned should stabilize us and remove most of the instability. The front will bring a slight uptick in convection in the areas east of Tallahassee where the early convection had dissipated. Wouldn`t think any additional severe storms would be expected overnight with this second batch. .SHORT TERM [Sunday Through Monday Night]... Sunday begins on an active note with a broken line of showers and thunderstorms continuing to progress eastward across the area. By 8 AM, areas generally west of the Flint and Apalachicola Rivers should be in the clear, with a marginal risk of severe thunderstorms continuing east of a line from roughly Apalachicola, Tallahassee, Moultrie, and Fitzgerald and points southeast. The primary hazards are damaging winds and marginally severe hail. The threat should decrease by early Sunday afternoon with the passage of the cold front. But scattered showers and a rumble of thunder are still possible, mainly east of the Flint and Apalachicola Rivers. Winds will become brisk out of the west behind the front, with gusts up to around 20 mph at times. Any remaining showers will diminish early Sunday night, with dry weather to follow through Monday night. In fact, it will be noticeably less humid by Monday. Some patchy fog and low clouds may develop late Monday night. Daily average temperatures will be a few degrees above normal through the period. .LONG TERM [Tuesday Through Saturday]... A slight chance of a thundershower returns Tuesday afternoon, but any activity would be limited in coverage. Greater coverage is possible with scattered thundershowers on Wednesday afternoon as a shortwave traverses the region. Thereafter, activity on Thursday through Saturday is more dependent on the sea-breeze circulation and a frontal boundary just north of the region. Overall, precip chances through the period are greater north of I-10, especially on Friday and Saturday. At this time, the severe weather threat is low. Daily average temperatures will remain above normal through the period. .AVIATION... [Through 00Z Monday] Line of strong to isolated severe thunderstorms roughly from DHN to ECP continues eastward around 35-40 knots. There are isolated to widely scattered showers and thunderstorms ahead of this line as well. As far as timing of thunderstorms in the local TAFs, used a blend of radar trends and HRRR. The HRRR also depicts a slow weakening trend to the line as it approaches the Apalachicola river after 00Z as well as the other coverage of convection as well. A redevelopment is expected in the overnight hours as the actual cold front moves closer and into the region. Therefore, there will be two rounds with a lull in between. Outside of convection, cigs will lower to MVFR or high IFR overnight through mid morning Sunday. .MARINE... Tranquil boating conditions are expected through the period with winds and seas below Small Craft Advisory criteria. Expect locally higher winds and waves in the vicinity of any thunderstorms, mainly tonight and Sunday. .FIRE WEATHER... Red flag conditions are not expected for the next several days with relative humidity remaining above critical levels. High dispersion indices over 75 are expected across the Florida Big Bend Sunday afternoon. .HYDROLOGY... Average precipitation amounts around one inch are possible across the region through Sunday, with additional amounts mainly below one inch thereafter into next Saturday. Expect localized higher amounts in thunderstorms. Aside from poor drainage flooding in low-lying areas, there are no flash flooding or river flooding concerns. .SPOTTER INFORMATION STATEMENT... Spotter activation is requested. Spotters should safely report significant weather conditions and/or damage by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 68 86 66 89 65 / 80 60 10 10 0 Panama City 69 79 68 83 68 / 90 40 10 0 0 Dothan 66 82 62 86 64 / 90 30 10 0 0 Albany 67 84 64 87 65 / 80 40 10 10 0 Valdosta 69 85 66 89 64 / 70 60 20 10 0 Cross City 70 83 69 89 66 / 70 70 20 20 0 Apalachicola 71 80 69 84 68 / 90 50 10 10 0 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ UPDATE...Scholl NEAR TERM...LN SHORT TERM...LF LONG TERM...LF AVIATION...Scholl MARINE...LF FIRE WEATHER...Wool HYDROLOGY...LF