Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/24/18

Area Forecast Discussion
National Weather Service Columbia SC
1042 PM EST Fri Feb 23 2018 .SYNOPSIS... Near record temperatures will continue into this weekend. High pressure centered off the coast will bring warm and moist air into region through Saturday. A cold front will cross the area Sunday into Monday bringing a high chance of showers. Temperatures will remain above normal next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Clouds diminish early tonight with the loss of heating. However with the abundant low-level moisture still across the area, expect that portions of the cwa will see the redevelopment of low stratus and some patchy fog late. A 20 knot low-level jet is being shown by Bufkit to develop by Midnight across the area, and this suggests that widespread low stratus should be more likely than widespread fog. Overnight lows remaining quite mild for this time of the year, with readings down around 60 expected by morning. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Saturday...An upper ridge off the Southeast Coast will weaken on Saturday. Surface high pressure will remain centered offshore. Low pressure over the Southern Plains will move into the Middle Mississippi Valley region. The associated cold front will move into the Tennessee Valley region late Saturday night. Moisture will deepen from the west on Saturday bringing just a slight chance of showers to the western portion of the forecast area. The HRRR and RAP do not show much activity in the area Saturday afternoon which appears reasonable given little forcing and a cap. Trimmed back pops a bit. Temperatures on Saturday will be above normal once again. Highs in the lower 80s and lows in the lower 60s. Sunday...Low pressure will move from the Northern Great Lakes region into Quebec on Sunday which will allow the cold front to cross the Appalachians and move into the western portion of the forecast area. Moisture will continue to deepen on Sunday with the chance of rain increasing. The NAM is still slower with the system than the GFS so there remains some uncertainty with the timing of the rainfall. Continued with likely pops west on Sunday closer to the frontal boundary and deeper moisture and chance pops further east. Instability appears quite limited with LI values near 0, but cannot rule out thunder. Believe the better chance of rain will occur Saturday night so have continued with likely pops across the area. The pressure gradient will tighten on Sunday ahead of the front with breezy conditions expected. Southwesterly winds around 10 to 15 mph with gusts up to 25 mph are expected. A lake wind advisory may need to be considered. Temperatures on Sunday will be above normal with highs in the upper 70s to lower 80s and lows in the upper 50s to lower 60s. && .LONG TERM /MONDAY THROUGH FRIDAY/... The cold front will continue to gradually progress through the area on Monday supporting likely pops. The GFS continues to push the moisture off the coast a bit more quickly than the NAM and GFS, but expect most of the rainfall to be out of the area by late Monday afternoon and evening. Surface high pressure will move northeastward into the Mid-Atlantic states on Tuesday with dry weather and mostly sunny skies expected across the forecast area. High pressure will shift off the coast Tuesday night with moisture and the chance of rain returning to the area for Wednesday. Low pressure over the Great Lakes region on Thursday will bring the next cold front into the area for the end of the work week with unsettled weather continuing. Temperatures through the period will continue to be above normal. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... Relative high confidence that cig/vsby restrictions developing during the pre-dawn hours Saturday morning. Stratus and fog will develop during the early morning and sunrise hours Saturday. A 20 kt low level jet suggests widespread low clouds will be more likely than widespread dense fog. Dense fog may be possible at AGS and OGB, but confidence is low at this time. Saturday morning, low clouds will begin to lift and break up around 15Z with VFR returning to all sites by late morning. Winds will be out of the SW as the high off the coast shifts further south. EXTENDED AVIATION OUTLOOK...Restrictions possible in late night and early morning fog and stratus Sunday morning. Chance of showers and associated restrictions Sunday afternoon through Monday. && .CLIMATE... CAE has tied the record of 82 set in 1962. AGS only reached 81 degrees today, thus not reaching its record of 82 set in 2012. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
908 PM CST Fri Feb 23 2018 .DISCUSSION...As of writing, a quasistationary boundary was draped from north to south from near KCOT to just east of KLRD. Areas of fog and drizzle were persisting to the west of the front (with dense fog impacting Laredo) while improved visibilities existed east of the front. Farther east along the Middle Texas Coast, stratus was lowering and thickening with sea fog developing along and just offshore. Due to the fluctuation of the aforementioned boundary, several changes have been made to the inherited forecast. Bumped min temps down a few degrees across the W Brush Country due to the boundary having shifted back east. Still think the boundary will shift farther west again late in the night which should result in an increase in temps at that time. Also added mention of fog for this evening (and continuing overnight) for the Brush Country. With a weak mid level vort max prog to shift NE overnight out of MX (partially evident on GOES 16 WV analysis and latest RAP output), chances of convection may increase overnight for the Brush Country. Convection is already ongoing across Nuevo Leon with some guidance (NAM/GFS/HRRR) hinting at some potential for convection to develop across the Brush Country after midnight. I have chosen to expand the chance POPs a little farther south with this update given that the current position of the vort max. No other changes made to the land forecast at this time. A southerly LLJ of 40 to 45 kts is prog to develop across much of the CWA overnight, which should allow for breezy conditions to continue and stratus to thicken. Temps should fall very little from current values (for those areas east of the surface front). && .MARINE...Have issued a Marine Dense Fog Advisory for area bays and the adjacent nearshore waters. Fog should continue to expand in coverage overnight as moisture values increase. However, by late in the night the wind direction from Port Aransas southward may become more southerly, which may allow for visibilities to improve some (at least for a couple of miles). Farther north, fog is likely to persist through mid morning. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 69 81 60 68 56 / 10 10 60 60 10 Victoria 68 80 57 65 52 / 10 20 60 70 10 Laredo 61 81 57 71 53 / 30 10 30 20 0 Alice 68 84 59 68 54 / 10 10 50 60 10 Rockport 68 78 60 66 57 / 10 10 70 60 20 Cotulla 60 81 53 71 48 / 30 20 10 20 0 Kingsville 69 84 63 69 56 / 10 10 50 60 10 Navy Corpus 69 78 63 67 59 / 10 10 60 60 20 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...Dense Fog Advisory until 10 AM CST Saturday For the following zones: Bays and Waterways from Port Aransas to Port O`Connor...Coastal waters from Port Aransas to Matagorda Ship Channel out 20 NM. Dense Fog Advisory until 5 AM CST Saturday For the following zones: Bays and Waterways from Baffin Bay to Port Aransas... Coastal waters from Baffin Bay to Port Aransas out 20 NM. && $$ RH/79...SHORT TERM
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
943 PM CST Fri Feb 23 2018 .UPDATE... This is a short update discussion to convey that the weather set- up for tomorrow still looks the same as it did earlier today. Around or slightly before daybreak, we expect an increase in storm coverage with numerous to scattered storms spreading northeast across the region. Eventually, some of these storms will form into a line that moves east, but storms will continue ahead of the line through the afternoon hours. The initial storms will be elevated with a threat for large hail and heavy rain. By the afternoon hours, any storms east of Interstate 35/35E will have the potential to become surface based as the warm front will have lifted north into that area. A threat for severe storms will continue with the line of storms, but storms ahead of the line will likely also have a tornadic potential owing to the nicely curved low level hodographs with near 30 kts of 0-1 km shear. Most of the area within the Dense Fog Advisory is no longer reporting dense fog, but visibilities in many places are still below 1 mile. The potential for dense fog to redevelop exists after midnight, especially if this round of light rain lifts north as suggested by hi-res models. Therefore, will leave the Dense Fog Advisory in effect as is for now. It currently expires at 4 am. JLDunn && .UPDATE... /Issued 746 PM CST Fri Feb 23 2018/ This update focuses on the near-term hours, and we will continue to assess the weather set-up for the late night and early morning Saturday hours. However, at this time, changes to the overall storm trends and severe weather threat do not appear different than what is represented in the ongoing forecast. For the most part, expect showers across part of the region through at least midnight, and then an increase in showers and storms closer to daybreak. Some of the storms may become severe producing mainly hail, but gusty winds may also be a threat. Foggy conditions continue to expand across the region and have recently expanded the Dense Fog Advisory to cover almost all of the region. Variances in the dense fog will likely occur, especially where light rain occurs, but a return to dense fog is likely after the rain passes. The warm front is not expected to make much progress north, at least through midnight, and we will reassess the dense fog potential throughout the night. Otherwise, just updated hourly trends and added the dense fog wording to the zones. Temperatures across most of the region will rise through the night, even with the warm front still to the south. JLDunn && .AVIATION... /Issued 619 PM CST Fri Feb 23 2018/ /00Z TAFs/ Metroplex Airports: LIFR conditions are expected to persist across the Metroplex for most, if not all, of the night due to a combination of low clouds and fog, and the fog will be dense at times. We are monitoring the northward advancement of a warm front to the southeast. The latest thinking is the warm front will remain south of the Metroplex keeping LIFR prevailing all night; however, if the northward movement is faster, conditions may improve at some time overnight. Light and variable winds for much of the night will become easterly and then southerly Saturday morning. However, a strong southerly low level jet of 35-45 kts will prevail just above the surface. Some showers will move across the Metroplex this evening, and then a lull in activity is expected before showers and storms ramp up again close to daybreak. Some of the storms in the morning may be severe with a threat for large hail and strong winds. A line of thunderstorms will move east across the region, affecting the DFW Metroplex between 14-17Z. After the storms clear, the ceilings will clear and west winds will prevail through the end of the TAF period. Waco Airport: Conditions around Waco are currently better than locations to the north, but a return to LIFR conditions due to low cigs and fog is expected tonight. There is a chance KACT may improve to VFR conditions this evening as the skies are nearly clear not too far east of the airport, and will amend the TAF if needed for these trends. Light south winds are expected to prevail through the night. Showers and thunderstorms will increase early Saturday morning and may affect the airport through 19Z. Some of the storms in the morning may be severe with a threat for large hail and strong winds. A line of thunderstorms is expected to move through between 17-19Z, and then dry conditions will prevail through the end of the valid TAF period. Westerly winds will occur behind the line of storms and conditions will improve to VFR. JLDunn && .SHORT TERM... /Issued 334 PM CST Fri Feb 23 2018/ /Tonight and Saturday/ The primary weather highlights in the short term forecast period will be the continued rain chances and consequent severe weather and flood risks. A this time, it appears that there could be two rounds of severe weather across North and Central TX. One in the morning and another in the afternoon. With these rounds of storms, the risk for flooding will continue and we`ve kept the Flood Watch running through 18 UTC Saturday. While activity will move swiftly from west to east, antecedent conditions mean that it won`t take too much to result in additional flood problems. Rain chances should rapidly diminish late tomorrow afternoon as a Pacific front/dryline sweeps through the area. For tonight---Showers and thunderstorms should persist across the Big Country and along our western most Red River counties as a conveyor of strong isentropic ascent along the 310K theta surface continues. Severe weather isn`t anticipated with this wave of activity this evening, but heavy rain could result in some minor flood problems. The moist regime and generally light winds at the surface should facilitate some fog development. Given the areal extent of low dewpoint depressions, I`ve included fog/drizzle across all of North and Central TX with some slight improvements across southeastern zones as the warm front lift northward. Low level flow will continue to ramp up across the area with a nice theta-e plume setting up across the Big Country. Convective allowing models do differ a bit on the exact placement of the most widespread activity. For now, I`ll side with the CAMs that have the highest convective coverage (70 to 80 percent) conceptually where it should be---along the tip of the theta-e plume. I can`t completely discount the HRRR solution, which advertises widespread convection down across the east and southeast, so I`ll carry a 50 PoP here. The first round of severe storms could take place during the pre- dawn hours on Saturday between 0800-1200 UTC. Deep layer shear will be around 60-70 knots with MUCAPE values approaching 1100 J/kg. With steep mid-level lapse rates (almost 8 C/km in some spots) and the elevated nature of storms---there should be an appreciable hail threat (perhaps up to the size of golfball). The most likely area for severe storms during the pre-dawn hours will be near and northwest of a Comanche to D/FW to Gainesville line. Simultaneously, a surface warm front will be lifting northward out of the Brazos River Valley as low level winds continue to increase. Winds across East and Central TX may increase through the morning hours such that any fog or drizzle dissipates. Where this boundary stalls will be paramount to the areal extent of the warm sector and thus the severe weather potential later in the day. While winds may shift to the south even north of this boundary, it appears probable that the true warm front will stall near and just south of the I-20 corridor and be oriented such that area near just west of I-35 remain on the cool side of this boundary. If GFS and ECMWF solutions are to be believed, however, it`s possible that this boundary could lift as far north as the Red River. For now, I`m a little hesitant to go with the coarser guidance and I`ll keep the boundary a bit farther to the south per the NAM and some of the other higher resolution data sets. The second round of severe storms will likely be somewhat of a continuation of remnant morning convection. What appears quite plausible is that as early morning convection marches eastward, it`ll become surface based, allowing it to realize an environment characterized by 1000-1500 J/kg of CAPE, deep layer shear values on the order of 40-50 knots and low level SRH in the 200-400 m2/s2 range. Should storms realize this type of environment, all facets of severe weather will be at play. Initially, a mixed mode of supercellular structures and line segments are expected with the dominant convective morphology becoming linear in nature through the afternoon. If the mode remains more supercellular OR convection develops ahead of the line---the risk for large hail and tornadoes may persist well into the afternoon. The most likely area for severe weather will be near and east of I-35 and south of I-30. If the warm front lifts farther to the north, a greater portion of East TX could be under the risk for severe weather. In addition to a severe weather risk, extraordinary moisture, per forecast 1.25`-1.50" precipitable water values will support a continued threat for heavy rain. While storms motions will likely be quite fast, the antecedent conditions suggest that any bout of heavy rain will only aggravate saturated soils and swollen creeks, small streams and rivers. With that in mind, we`ve elected to continue to Flood Watch through midday Saturday. It`s possible that parts of the Flood Watch may need to be extended a little later, but we will defer to later shifts to handle those details. Convection should gradually come to an end as a Pacific front/dryline sweeps eastward through the region. 24-Bain && .LONG TERM... /Issued 334 PM CST Fri Feb 23 2018/ /Saturday Night through Thursday/ We`ll see mild temperatures and a chance to dry out (at least for a few days) the remainder of the weekend and Monday, as the shortwave energy and final round of convection and locally heavy rainfall moves east away from the area and toward the Ohio/Tennessee Valleys. A weak cold front will nudge into the area late Sunday and Sunday night, but be devoid of any substantial cooler air. Highs both Sunday and Monday will be mostly in the 60s, though a few areas west of U.S. 281 where stronger insolation will be present may see highs nudge just above 70 degrees. As the surface high pressure ridge centered northeast of our area shifts east Monday night into Tuesday, south winds will transport Gulf moisture back northward. Southwest flow aloft will intensify in advance of yet another upper level low organizing over Arizona and California. Low level warm advection increases in advance of a lead shortwave ejecting northeastward from northern Mexico later Tuesday and Tuesday night for scattered showers and a few thunderstorms, especially east of I-35. A prominent elevated mixed layer (capping inversion) should keep activity below severe limits and possibly even elevated, though any stronger activity Tuesday night could put out small hail and localized heavier downpours. That said, amounts across eastern North and Central Texas should remain generally under an inch, so any flooding threat appears minimal at this time. As upstream upper level energy across the Eastern Pacific plunges southeast toward the Pacific Northwest, the California and Arizona closed low will open up and progressively move east over the Southern Rockies and possibly over the Southern High Plains by late Wednesday. This is where things get a little murky, however, as the GFS is much more progressive with this southern stream energy than the slower Canadian and European models and their deeper solution. Either way, a surface trough or dryline looks to move east either into, or just to the western edge of our CWA by early Wednesday evening. The associated forcing from both the surface and upper level features, along with increasing warm advection should at least promote higher end convective chances by Wednesday afternoon and night. However, with track and timing uncertainties, I felt it best to keep rain probabilities in the mid-high chance category across the eastern two-thirds of the CWA until timing and environmental uncertainties can be ironed out by future upper-air sampling and model output. Either way, it does appear some severe weather and/or localized flooding is possible during the mid-week period. This mid-week system will lift away from the area on Thursday, allowing a cold front to move through and dry the entire area out once again. As with the previous cold front late this weekend, the bulk of the colder air remains well northeast of the area with just a slight cool down into the 60s. 05/ && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 48 63 38 69 41 / 70 80 5 0 0 Waco 55 69 39 67 37 / 70 80 5 5 0 Paris 54 66 38 64 40 / 60 80 10 5 5 Denton 43 64 34 68 36 / 70 80 0 0 0 McKinney 50 61 36 66 37 / 60 80 10 0 0 Dallas 48 63 39 68 41 / 70 80 5 0 0 Terrell 55 67 38 67 40 / 50 80 10 5 5 Corsicana 54 69 40 68 41 / 50 80 20 10 5 Temple 55 72 40 67 40 / 60 80 5 20 5 Mineral Wells 39 66 31 69 33 / 70 80 0 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until 4 AM CST Saturday for TXZ092>095- 102>107-117>123-130>135-141>147-156>161. Flood Watch through Saturday morning for TXZ091>095-101>107- 116>123-130>134. && $$ 82/30
Area Forecast Discussion
National Weather Service Wilmington NC
1015 PM EST Fri Feb 23 2018 .SYNOPSIS... High pressure off the coast will bring unseasonable warmth through the weekend. A cold front is expected on Monday tempering the warmth some. Seasonable temperatures are expected Tuesday and Wednesday before another warmup Thursday. A stronger cold front will arrive Friday. && .NEAR TERM /THROUGH SATURDAY/... As of 1000 PM Friday...The pattern remains mostly unchanged from the past few days, with the primary exception tonight being the presence of a warm front just north of the area. This front got very close to our area today, but was driven back to the north by the strong ridge which has dominated the Southeast all week. Southerly flow is slowly veering to become more SW than the past few nights, but otherwise the forecast challenge tonight again involves fog and stratus potential. Winds tonight are a bit stronger than last night as noted by surface winds still around 5mph and LTX VWP showing 25-30 kts at 1 kft. However, latest RAP soundings suggest better near-surface moisture and several runs of the HRRR show fog developing across most of the area. Have maintained inherited areas of fog across the entire area, mostly after midnight, and some of this may again become dense. Sea fog has eroded for now, but may also re-develop according to SREF probs and may advect onshore especially across the Grand Strand overnight. Relevant portion of previous discussion below: As of 330 PM Friday...Very low-end shower chances off the water tonight, and again inland with heating Saturday afternoon, but moisture terribly lacking above 6000 feet will result mostly in moderate diurnal cumulus, and near record warmth. Record maximum temperatures for tomorrow include, ILM 81 in 1982, CRE 78 in 1996, and FLO 82 in 1962. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 3 PM Friday...Surface and mid-level ridge will continue to sink south and east in the face of approaching 5h trough Sat night. Region remains under the influence of ridging Sat night and Sun with temperatures well above climo. Increasing low level jet Sat night helps keep boundary layer well mixed. Mixing coupled with low level moisture and cloud cover will keep lows in low to mid 60s. Strong warm advection continues on Sun but weakening subsidence and increasing cloud cover may work to limit temps a bit. Despite some limiting factors highs will still end up more than 20 degrees above climo for most areas with low to mid 80s likely. GFS is faster than the ECMWF to bring in showers and the front, something which seems less likely to happen given the presence of such strong ridging, even if it is weakening and retreating. Plan to favor the drier solution offered by the ECMWF and only carry chance pop Sun with an increase to high chance or likely Sun night. As mentioned, best pop chances will be Sun night as the cold front moves into the area. Influence of ridging aloft will be weakening and forecast soundings suggest precipitable water may exceed 1.6 inches late Sun into Sun night. Although the flow aloft is divergent there is an overall lack of shortwave activity and it may end up low level convergence is the main driver of activity Sun night. This is not to say there won`t be some shortwave/PVA enhancement overnight, but the waves that are present are on the weak side. Result will be decent coverage of showers but total rainfall will be limited. Most areas are likely to end up with a quarter inch or less while a few spots may approach half an inch. Temperatures will continue above climo despite the location of the front. Cold advection is well displaced from the boundary and the front will be losing its push as it moves into the area. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 300 PM Friday...A slow moving cold front is forecast to come through on Monday. The surface boundary will be accompanied by a dry WNW mid level flow. Normally this is not conducive for significant rainfall and Monday appears to be no different. Tuesday will be the one day that high pressure wedges in from the north behind the front. By Wednesday the high moves offshore and return flow gets underway. Models are not in agreement regarding the pace at which this leads to cloudiness and rain chance. Will show a gradual trend through Wednesday into Wednesday night as usually with moisture advection slower solutions tend to be better ones. A more substantial cold front arrives late Thursday or Friday. Guidance varies considerably with the pattern aloft casting uncertainty regarding rain prospects with this stronger boundary. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... As of 00Z...Moderate confidence in IFR overnight as fog and stratus likely redevelop as it has the past few nights. Large Bermuda ridge remains in place across the Atlantic with a weakening front lifting north into VA. This leaves the terminals in a warm and moist advection regime on return flow, nearly identical to the past few nights. High res guidance and soundings suggest fog and stratus again affecting all terminals, and although nocturnal PBL winds are slightly stronger than last night, moisture content is a bit higher as well. Have used a combination of persistence and the HRRR to try to time IFR development, and expect all terminals will drop to IFR, with LIFR/VLIFR possible, especially at FLO/LBT. Confidence is not high enough attm to indicate any landing mins being exceeded, but that is possible, and will need to be addressed with the next TAF issuance. Fog and stratus will erode slowly after daybreak, with IFR lifting to MVFR, and eventually VFR by late morning. Once again, sea fog and stratus may slow improvement at the coastal terminals, especially the Myrtles on Saturday where SREF probs suggest a better chance for sea fog, but this is typically a very near term and low confidence forecast parameter until it develops. Winds will slowly veer from the south tonight, to S/SW on Saturday, with speeds climbing to 10 kts or more during Saturday aftn. Extended Outlook...Approaching cold front will bring increasing chances for showers and MVFR Sunday and Monday. VFR Tuesday. Showers possible Wednesday. && .MARINE... NEAR TERM /THROUGH SATURDAY/... As of 1000 PM Friday...Bermuda high pressure remains the dominant feature producing southerly winds of 10 kts or less across the waters. Earlier sea fog has eroded, but is likely to redevelop overnight into Saturday and have carried areas of fog once again in the wx grids. A marine dense fog advisory may be needed again, but confidence is low. Otherwise, seas will remain around 3 ft, up to 4 ft near the 20nm boundary as a 3-4 ft/9sec SE swell dominates the spectrum. Relevant portion of previous discussion below: As of 330 PM Friday...Aside from the hazard of reduced vision in sea fog, wind and waves will be welcoming. SE waves 3 feet every 9 seconds will be co-joined with a light chop. Seas possibly up to 4 ft outer waters, but this wave energy is not steep. No TSTMS this period, but isolated showers and bouts of sea fog should be expected tonight and Saturday. SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 3 PM Friday...High pressure will remain off the coast through the period. Southwest flow will gradually increase Sat night and Sun with speeds peaking in the 15 to 20 kt range Sun afternoon. Gradient will start to weaken later Sun or Sun night as slow moving cold front reaches the area. Flow remains out of the southwest but speeds will drop to 10 to 15 kt. Seas will run 3 to 4 ft through the period. LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 300 PM Friday...Frontal passage on Monday will lead to a shift from W to NW winds. This front will be weak and so not expecting any surge of high pressure, cold air, or gusty winds. High pressure behind the front does not drive very far south as it progresses off the coast to our north heading into Tuesday. This turns winds to NE and then E with no significant change in wind speeds. The onshore flow direction however will allow for slightly larger seas. No headlines are planned at this time. Wind and waves may build at the end of the period or just beyond with the approach of the next front, which will be much stronger. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...JDW/MJC SHORT TERM...III LONG TERM...MBB AVIATION...JDW MARINE...
National Weather Service Jackson KY
833 PM EST Fri Feb 23 2018 .UPDATE... Issued at 833 PM EST FRI FEB 23 2018 Short wave disturbance will push across the area late tonight into early Saturday morning. Nose of an H850 LLJ, between 40 and 55 kts depending on what model you look at, will provide some convergence in the lower levels across a good part of our area towards sunrise. Area will also be near the right rear quadrant of a relatively weak but definite upper level jet streak. It appears that these two features may go through a short period of coupling, perhaps providing a bit more enhancement to our initial QPF forecasts across the south. At present there is some disagreement between the higher resolution convective allowing and synoptic models in the details of exactly where the core of more intense precipitation will occur. The 12Z ECMWF and 18Z GFS both show a relative max across our southwest of between three quarters and an inch of rainfall. The 18Z NAM is lighter, a bit slower, and further northwest with the heaviest rainfall. The HRRR has been waffling with the track of more intense rainfall. Will be watching trends in the HRRR/RAP and compare to the initial few hours of the 0Z run as they become available before deciding whether to increase QPF across our south with the late evening update. && .SHORT TERM...(This evening through Saturday night) Issued at 450 PM EST FRI FEB 23 2018 Record warmth occurred again today as a warm front lifted northward and sunshine broke through the clouds. It created enough instability for scattered showers to percolate this afternoon, along with a few isolated, sporadic lightning strikes. A few showers were ongoing at forecast issuance, but have been on the decline. Models depict the frontal boundary slowly sinking back south into our area this evening, with more showers developing. However, there is disagreement on the rainfall amounts and the axis of the precip. That being the case, confidence in forecast specifics is low for this evening, and nothing more than broadbrushed chance POPs were used. Both models show deep layer RH increasing overnight, and a greater potential for showers. MOS POPS are quite high for tonight as well. Taking this into account, have hit the POPs hardest toward dawn. Showers should last into the day on Saturday. The frontal boundary is expected to lift northward again on Saturday, and forecast soundings also show weak instability developing during the day. A slight chance of thunder is included in the forecast for Saturday. Barring training, rainfall amounts do not look overly impressive tonight and Saturday. If training occurs and localized amounts are heavier than forecast, some water problems can`t be ruled out. With a flood watch already in place, will leave run. However, the heaviest rain will probably occur on Saturday night. On Saturday night, a strong low pressure system tracking through the Midwest will bring a definitive cold frontal passage and a band of showers, and possibly thunderstorms. Brisk low level flow from the southwest will develop ahead of the front. If enough instability can develop to mix down environmental winds, severe weather can`t be ruled out. However the better chance is further west. The front and its showers will be progressive, so that once it passes overnight and early Sunday morning, our hydro concerns will end for a while. .LONG TERM...(Sunday through Friday) Issued at 323 PM EST FRI FEB 23 2018 A cold front will exit southeast Kentucky on Sunday, and rain chances will decrease as the day continues. While the 12Z GFS pushes the front far enough southeast Sunday night that rain chances would come to an end, the 12Z ECMWF shows another wave moving northeast along the front and thus keeping at least a slight chance of showers in the far southeast into Monday. Our standard blended model approach actually takes this into account and our forecast will push rain chances back north Sunday night, with slight rain chances lingering into Monday afternoon in the far southeast. Forecast rain amounts Sunday morning will mostly be less than 0.25 inch. Any rain from Sunday afternoon into Monday will be on the light side with amounts of 0.10 or less. Weak upper level ridging then builds into the area and a surface high slides across the OH valley, before moving to the east coast Tuesday night. This results in dry weather for Tuesday. Rain chances return by Wednesday as short wave energy moves northeast from a western U.S. trough. Rain chances then continue until another cold front moves through the area on Thursday. Dry weather will then return Friday, though a few showers may linger in the east to start the day. Temperatures will remain above normal with only a very slight cool down with the frontal passage on Sunday. Temperatures return to close to normal values with the passage of the late week cold front. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 833 PM EST FRI FEB 23 2018 Disturbance will move in from the southwest overnight. This feature is currently kicking off showers and a few thunderstorms across the Mid-South and stretching northeast into central portions of the Commonwealth. CIGS and VSBYS will drop as this activity lifts into our area during the predawn hours, or sometime after about 8-10Z. Until then can not rule out some isold to widely scattered activity just about anywhere across eastern Kentucky, though have seen a definitely downward trend in activity with sunset. Model guidance has not been real helpful but has trended more optimistic with MVFR CIGS versus previous IFR territory. Winds will be generally light and variable overnight around 4 kts on average but will increase from the southwest at about 10 kts through the day Saturday. && .JKL WATCHES/WARNINGS/ADVISORIES... Flood Watch from midnight EST tonight through Sunday morning for KYZ044-050>052. && $$ UPDATE...RAY SHORT TERM...HAL LONG TERM...SBH AVIATION...RAY
Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
928 PM EST Fri Feb 23 2018 .SYNOPSIS... A warm front will gradually push north across the region tonight through Sunday morning. A cold front will then cross the region Sunday night. High pressure will return early next week. && .NEAR TERM /THROUGH SATURDAY/... Main changes for the overnight were to issue a dense fog advisory across the northern half of the fcst area were obs and live traffic cameras are showing fog developing and where models unanimously all agree in dense fog developing. It is possible the dense fog advisory may need to be extended to include the entire I-95 corridor down to Fredericksburg where RAP model shows fog developing and nighttime microphysics RGB product show more gray (fog) than bright aqua (stratus) colors. For Saturday, lowered MaxT as guidance typically have a warm bias in cold air damming situations. Used the MaxT from today and applied the 24-hr MaxT trend from the latest 24/00Z NAM12, so only a 5-7 deg rise across the north and up to 15F degs warmer in the south. Highs generally in the upper 40s along the Mason Dixon line to the mid 60s across the south. Previous afd... Tonight through Saturday, the low pressure will head eastward to our north. Southerly flow will encourage the warm front to push northward as well, but the odds it reaches very far into our CWA are not high. The more pessimistic but often more realistic (in these situations, at least) NAM shows the warm front reaching portions of the West Virginia eastern Panhandle and the Shenandoah Valley, but struggling to reach any portion of the CWA east of the Blue Ridge. There may be an attempt at a little clearing this evening as this all tries to occur, but otherwise, clouds and drizzle with patchy mist/fog will likely continue. With the main forcing staying to our north, significant rainfall is not expected across our region, but a few showers could skim the region, particularly western Maryland. Temperatures will be fairly steady, perhaps even rising a bit, but large changes are not expected in most of the region. On Saturday, the front may actually sink back south a bit as the passage of the low to our north causes the flow to shift a bit more northerly. Thus, the morning should be more of the same...damp and dreary, but not a washout. Later in the morning and in the afternoon, low pressure developing to the west over the Plains will bring increased warm advection aloft and FGEN across western zones, spreading eastward late in the day. This will increase the risk of steadier rain. Given ample moisture available, some locally heavy rain could occur in the western portions of the forecast area, but confidence is low regarding any flooding risk, so have not issued any flood watches yet. Highs on Saturday will be a bit warmer than today as the warm front once again attempts to lift north, with 50s and 60s becoming more common. However, if the front ends up further south than currently expected, it could stay cooler. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... Warm front makes more progress northward on Saturday night and Sunday as low pressure wave pushes northeastward to our northwest. This should allow temperatures to warm more significantly after the rain Saturday night, with 70s looking more likely on Sunday. An interval of relatively pleasant weather may occur late morning into early afternoon, with more sunshine, but then the cold front will approach from the northwest. Still some uncertainty on any severe threat, but certainly with the available moisture and warmth, some instability will be present, so allowed slight chance of thunder into the forecast Sunday afternoon. The front will slide southeast across the region Sunday night, so a drying, cooling trend will develop. However, the front will slow down overnight as yet another wave of low pressure develops to our southwest, so rain chances will not completely end in southern parts of the region. && .LONG TERM /MONDAY THROUGH FRIDAY/... With exception to a couple of lingering rain showers near Southern Maryland and parts of the central Chesapeake Bay Monday morning, conditions will dry out as a ridge of high pressure builds in from the west. The high will persist through Tuesday night before moving offshore early Wednesday. Interaction between the high pressure and a developing low pressure system over the central Great Plains will provide a southerly return flow into our region. Expect milder and more moist air to return Wednesday and Wednesday night. There could be a couple of rain showers develop over the Appalachians and in parts of the Central Shenandoah Valley later in the day Wednesday. A developing warm front over southwest Virginia and western North Carolina will work its way north across our region Wednesday night. Ahead of and along this warm front, additional rain showers will develop and spread northeastward across our region Wednesday night. Even more warmer and moist air is expected to follow the warm front northward Wednesday night into Thursday. Showers, some moderate at times, should persist into Thursday morning as the warm front moves to the Mason-Dixon region just ahead of an approaching cold front that should pass through our area Thursday night. Some drier and cooler air will work in behind the passing cold front; however, models are trying to push a cut-off low pressure system over the Great Lakes region eastward. This cut-off low, it`s upper level energy support, and a little daytime heating could spawn additional rain showers later Thursday night and during the day Friday. Northwesterly winds could become quite gusty as well in the wake of the passing surface cold front and ahead of the cut- off low pressure system. Overall, temperatures throughout next week will be mild with highs approaching 60 degrees or higher in any warm sector. Friday may be the exception and could be cooler, but for now we will keep temperatures near normal. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Expect fog and low clouds to drop overnight with VLIFR conditions expected except at KCHO. The warm front will probably stay south of all the terminals, save perhaps CHO, during the day Saturday, resulting in more of the same. Steadier rain may overspread the region, especially the northern terminals, by Saturday night. Conditions look more likely to improve from DC on south and west on Sunday as a warm front lifts northward, but BWI/MTN may have trouble breaking out of the low clouds and fog as the front may struggle to pass that area. Cold front then finally drops southeast across the region, bringing showers and perhaps a thunderstorm Sunday afternoon, but likely resulting conditions finally going back to VFR with drier air filtering south Sunday night. VFR conditions expected Monday through Tuesday night. Winds northwest 5 knots or less Monday and Monday night. Winds becoming southwest around 5 knots Tuesday and Tuesday night. && .MARINE... With weak gradient and a front to the south, expect winds to stay below Small Craft Advisory strength through Saturday evening across all waters. Late Saturday night, warm front approaching from the south may finally lift north of the middle Bay, allowing the strong southerly flow to reach the surface and bring gusts up to SCA levels, but for now am waiting to issue a headline. SCA looks likely across at least the southern waters we cover, perhaps reaching up to the northern bay as well, as the warm front lifts north and gusty south winds develop in the warm sector. As with the recent round on Tuesday and Wednesday, this will be primarily near-shore gusts, with weaker winds over the open waters due to the chilly water temperatures limiting mixing. Cold front will push southeast across the waters Sunday night, but at this time SCA does not appear likely with this frontal passage. No marine hazards expected Monday through Tuesday night. Winds northwest 5 to 10 knots Monday and Monday night. Winds becoming southwest 5 to 10 knots Tuesday and Tuesday night. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...Dense Fog Advisory until 8 AM EST Saturday for DCZ001. MD...Dense Fog Advisory until 8 AM EST Saturday for MDZ003>006-011- 013-014-503>508. VA...Dense Fog Advisory until 8 AM EST Saturday for VAZ053-054-505- 506. WV...Dense Fog Advisory until 8 AM EST Saturday for WVZ052-053. MARINE...None. && $$ SYNOPSIS...RCM NEAR TERM...LFR SHORT TERM...RCM LONG TERM...KLW AVIATION...RCM/KLW MARINE...RCM/KLW
Area Forecast Discussion
National Weather Service Miami FL
642 PM EST Fri Feb 23 2018 .AVIATION... Atlantic convection pushing towards the east coast terminals along the gusty, persistent easterly flow may produce brief bouts of MVFR this evening and tonight. Convection could linger through the morning hours as well. Short-fused amendments to introduce sub-VFR conditions are possible. APF could see a Gulf sea breeze develop again on Saturday afternoon. && .PREV DISCUSSION... /issued 321 PM EST Fri Feb 23 2018/ DISCUSSION... Broad high pressure continues to dominate the weather pattern across South Florida rest of today into Saturday. The breezy easterly flow experienced over the last couple of days will remain in place through Saturday before ridge begins to weaken veering winds to the southeast. Low level moisture caught up in the flow continues to push onshore from over Atlantic ocean. NWS radar and short term models, including the HRRR and WRF prog activity over the Atlantic waters moving east tonight enhancing showers along the eastern counties. Upper level high pressure will produce subsidence today, boosting high temps a couple degrees above seasonal norms through the weekend and early next week. This is especially true for the Gulf coast, as air tends to dry and warm while crossing the peninsula in a prevailing easterly flow. With forecast maximum temperatures in the mid 80s, Naples may only come a few degrees shy of reaching its daily maximum temperature record. As night approaches, winds will decrease in intensity, with only light breezes remaining along the immediate east coast. Medium to long term (Sunday to Friday)...Model guidance shows fair agreement in migrating the upper level ridge over the FL peninsula. This will bring more warm weather for the region, with subsidence aloft remaining strong. Look for high temperatures ranging from the low to mid 80s areawide. Long range models prog a cold front to approach the southeast CONUS. This should drive the aforementioned surface high eastward, leaving South Florida in weak flow, and allow for diurnally driven sea breezes to develop. Enough low level moisture and weak instability will exist to generate a few light showers, but not expecting any significant rainfall events. MARINE... High pressure will continue to dominate the weather pattern across South Florida waters. East to southeast winds will continue with wind speeds of 10 to 15 knots for the Gulf and 15 to 20 knots for the Atlantic. Small craft should exercise caution. A few showers are possible, mainly over the Atlantic waters, through the period. BEACH FORECAST... Breezy east surface winds will keep a high risk of rip currents along Atlantic beaches through Saturday evening. && .PRELIMINARY POINT TEMPS/POPS... West Palm Beach 71 80 70 82 / 40 30 30 10 Fort Lauderdale 73 80 72 81 / 50 30 30 10 Miami 72 81 72 82 / 40 30 30 10 Naples 67 84 67 84 / 10 10 10 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through Saturday evening for FLZ168-172- 173. AM...None. GM...None. && AVIATION...02/RAG
Area Forecast Discussion
National Weather Service Omaha/Valley NE
940 PM CST Fri Feb 23 2018 .UPDATE... Issued at 940 PM CST Fri Feb 23 2018 Strengthening lower to mid-tropospheric warm advection is fostering the development and northward spread of light precipitation south of I-70 in KS as of 03z. As the associated mid-level trough translates through the Four Corners toward the High Plains overnight, expect the warm-advection regime and attendant precipitation shield to progressively overspread our forecast area. Latest model guidance continues to indicate a high probability for freezing drizzle or light freezing rain south of a line from Lincoln and Omaha to Harlan, IA through mid morning with mainly snow over northeast Nebraska. By around midday, these data suggest the "all snow" line collapsing southeast toward Omaha and Lincoln with a continued southeastward shift of this transition zone through the remainder of the afternoon. While forecast soundings indicate thermal profiles supportive of that scenario, saturation may not extend upward into the dendritic-growth zone. As such, the freezing rain could linger a bit longer than the model guidance would otherwise suggest. In general, the current precipitation-type forecast is in reasonably good shape and we are not inclined to make any substantive changes. It appears that the primary deformation-zone-related snow band will remain to the west of our forecast area and as such, we may be a bit high on snowfall amounts over northeast NE. As mentioned above, we will leave the forecast "as is" and re-evaluate overnight. && .SHORT TERM...(Tonight through Monday) Issued at 310 PM CST Fri Feb 23 2018 The main forecast concerns are in regards to snow and ice amounts, with the winter weather system that will affect the area starting late tonight and continuing through the day on Saturday. Fairly complex/messy forecast with mixed precipitation across the forecast area starting late tonight. The zero degree isotherm at 850 mb this morning stretched from western KS into southeast NE then extended from southwest to northeast across IA. There was a fairly tight baroclinic zone in the lower and mid troposphere across the central part of the Plains. At 500 mb, a trough was to the west over the Rockies, with an area of height falls strongest over southern NV this morning. Two main areas of strong winds were noted at 300 mb, one digging southeast from the CA coast and another that extended from the Four Corners region to northeast of the Great Lakes region. Water vapor satellite imagery early this afternoon showed an elongated disturbance from southwest WY into UT and northern AZ. Surface analysis at 21z showed high pressure across much of the northern and central parts of the Plains, with low pressure organizing over northeast NM and southeast CO. Precipitation should develop over the area later tonight as moisture profile increases due to development of a weak low level jet, mid level isentropic upglide and diffluent upper level flow. Moisture depth initially in the southern parts of the area may not be deep enough to produce more than freezing drizzle, but lapse rates aloft will be increasing. Thus some showery type precipitation may develop as well. The 19Z RAP layer composite reflectivity forecasts suggest precipitation increasing after 08z in our western and northern counties. All of eastern NE and southwest IA counties served by the Omaha office are in a Winter Weather Advisory from 3 am to 6 pm Saturday. Models have decreased their QPF amounts a little, and thus we have lowered expected snow amounts a bit. Northeast NE should see mainly snow, mainly 3 to 5 inches, but possibly approaching 6 inches. 700-750 mb specific humidity values are still expected to be around 3 g/kg from the GFS, with about a 9 to 12 hour period of moderate lift and some elevated frontogenesis. Will need to watch for potential banding of snow, which could enhance amounts in our area. Farther south, ice accumulations are the issue with around a tenth of an inch to near two tenths possible. These numbers are solidly in advisory levels. Ice aloft is generally lacking through the morning in southeast NE and southwest IA, so if that holds true snow amounts will be less than farther north, and that is how our current snow amounts are depicted. Areas near the KS and MO borders could reach above freezing during the day Saturday, then turn colder as winds shift to the northwest. Expect precipitation to be ending by around 6 pm, but there is a small chance that light freezing drizzle could linger a bit longer. The period from Sunday into Monday looks dry with a warming trend. Highs Monday should reach mainly into the 40s with some 50s near the KS border. .LONG TERM...(Monday night through Friday) Issued at 310 PM CST Fri Feb 23 2018 From Monday night through Tuesday evening, have kept the forecast dry. The 500 mb pattern still favors a trough from south central Canada back to toward southern CA. Our area should remain in southwest or westerly flow aloft, with a weak split flow pattern. Model spread starts to develop by mid week and then increases by late week, so confidence drops to below average by Friday. Still, the period from Wednesday into Thursday looks somewhat active based on a model blend. By Friday, is appears that a mid level ridge will build over the Plains, at least temporarily. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 518 PM CST Fri Feb 23 2018 Stratocumulus has temporarily scattered out this afternoon, a trend which will likely persist for a few more hours. Thereafter, strengthening low-level warm-air and moisture advections will foster MVFR to eventually IFR ceilings with light precipitation developing in the 10-12z timeframe. At KOFK, precipitation type will likely remain all snow --moderate to heavy at times-- which should begin to taper off toward the end of the forecast period. At KOMA and KLNK, precipitation type is more uncertain. A mixture of freezing drizzle and light snow will be possible initially before transitioning to freezing rain or a mix of freezing rain and snow through much of the day. Precipitation could trend toward snow toward the end of the forecast period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Winter Weather Advisory from 3 AM to 6 PM CST Saturday for NEZ011-012-015>018-030>034-042>045-050>053-065>068-078- 088>093. IA...Winter Weather Advisory from 3 AM to 6 PM CST Saturday for IAZ043-055-056-069-079-080-090-091. && $$ UPDATE...Mead SHORT TERM...Miller LONG TERM...Miller AVIATION...Mead
Area Forecast Discussion
National Weather Service Charleston WV
713 PM EST Fri Feb 23 2018 .SYNOPSIS... Nearly stationary front meanders about the area into Sunday, as surface waves pass. Areas of significant rainfall possible into the weekend. The front finally charges through on Sunday. && .NEAR TERM /THROUGH SATURDAY/... As of 700 PM Friday... Sent an update to lower PoPs to isolated for the most part tonight. Radar and satellite images show only very isolated rain showers moving northeast producing little rainfall accumulations. Removed thunder from forecast through the overnight hours. Synoptic models overdoing pcpn tonight. Went closer to the high resolution model HRRR for PoPs through tonight. Showers, Isolated in nature, increasing in coverage and intensity and spreading west to east around 09Z tonight. As of 250 PM Friday... The front that has been oscillating about the area the past few days, surged northward, as a warm front, today. In the warm unstable air, quick-standing convection has fired up, with brief heavy downpours and gusty winds, taking advantage of 45 kts deep layer bulk shear, and nearly a kj/kg CAPE. The convective nature of the precipitation should wane this evening. However, the front sags southward tonight, ahead of several waves that will moves northeastward across the area tonight through Saturday. These frontogenetic waves increase low level convergence along the front overnight tonight, the front and associated convergence then moving back north Saturday, This will bring increasing area coverage of rain, which could be heavy because of elevated convection in strong moisture transport that increases PW values toward 1.25 inches, near the climatological max. Convection may become closer to surface based Saturday, south of the front, with up to 60 kts deep layer bulk shear at times, so strong heavy thunderstorms are possible. Temperatures continue to reflect the baroclinic zone, with daytime insolation south of the front increasing the contrast during the peak heating hours. Guidance was having a somewhat difficult time with this. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 322 PM Friday... east-west oriented stationary front at the beginning of the period should push north of the area Saturday night with a cold front then expected to sweep east on Sunday. As the cold front pushes east, precipitation chances should end from the west. Until the front pushes east, models indicate precipitation chances will remain high with the highest QPF still expected across the southeast Ohio counties as well as the West Virginia counties adjacent to the Ohio River. Current thoughts are that QPF values between 0.75 to 1.25 inches along and northwest of the Ohio River with amounts near 0.50 inches elsewhere. This heavy rain, coupled with the precipitation expected on Saturday, should result in some main stem rivers experiencing flooding on Sunday night and Monday. This is especially true for the Ohio River, where major flooding is forecast along many of our official forecast points. The current forecast levels compare closely to Ivan in 2004, which produced significant flooding along the Mighty Ohio. An area of low pressure is then expected to move northeast along the front, which may be located just to our southeast. This will result in some scattered showers Sunday night into Monday. Temperatures will remain very warm on Sunday, with slightly cooler temperatures Monday. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 322 PM Friday... High pressure will then take control of the weather with dry weather anticipated Monday night into Tuesday night. A warm front will then approach the region on Wednesday resulting in increasing chances for showers. An associated area of low pressure will push east on Thursday dragging a cold front across the area. Most areas should see wet weather Wednesday night and Thursday with decreasing chance of showers by late Thursday. Airmass could become cold enough for some of the precipitation to change over to snow across the highest elevations Thursday night. Went with a model blend for temps. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... As of 700 PM Friday... Radar and satellite images show isolated rain showers over KY and some exiting northeast from WV. However, a large area of scattered to numerous showers along a cold front is evident across central OH. Models suggest this feature will move slowly east to affect portions of southeast OH and WV tonight into early Sunday. With near saturated soils from previous rain, and the slow motion of the cold front, expect this rainfall activity to move over our area to produce IFR/LIFR conditions along with the heavier showers overnight into Saturday. Low level stratus could continue into mid morning Saturday. Then, the cold front will push further south to bring the shower activity over our sites. It is uncertain about the timing of the associated IFR/LIFR conditions at this point. Will code MVFR conditions over the extended part of TAF, coding more details as possible during the first 6 hours of the period. Light and variable wind tonight, will remain light or calm for the most part on Saturday. Moderate to strong southwest flow is expected once again Saturday afternoon. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SUNDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing and degree of lower flight categories may vary with timing of rain, and with possible fog and stratus overnight tonight into Saturday. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SAT UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 CRW CONSISTENCY H H H H H H H H H H L L HTS CONSISTENCY H H H M H M M H H M L L BKW CONSISTENCY H H H H H H M M M M M L EKN CONSISTENCY H H H H H H H H H L L L PKB CONSISTENCY M H M M H H H H M M M L CKB CONSISTENCY H H M M M H M H H H M L AFTER 00Z SUNDAY... IFR possible at times in showers Saturday night into Sunday. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flood Watch through Sunday afternoon for WVZ005>011. OH...Flood Watch through Sunday afternoon for OHZ066-067-075-076- 083>087. KY...Flood Watch through Sunday afternoon for KYZ101>103-105. VA...None. && $$ SYNOPSIS...ARJ/TRM NEAR TERM...ARJ/TRM SHORT TERM...JSH LONG TERM...JSH AVIATION...ARJ
Area Forecast Discussion
National Weather Service Springfield MO
949 PM CST Fri Feb 23 2018 ...Update on Flooding Potential... .MESOSCALE DISCUSSION... Issued at 923 PM CST Fri Feb 23 2018 The setup will remain favorable overnight for flooding potential. We have expanded the Flood Watch a bit to the north with increasing confidence that those regions will also see heavy rainfall. The nose of a low level jet stream will shift northeast across southern Missouri overnight with an increasingly large area of isentropic upglide occurring over the top of a developing warm frontal structure. Meanwhile, a pseudo upper level jet coupling structure is in place across the region and aiding in deep tropospheric ascent. This has resulted in a large swath of light to moderate precipitation expanding across the Ozarks this evening. Anomalously high values of moisture also continue to advect into the region with precipitable water values pushing 1.25" expected to push into far southern Missouri late tonight. Short term guidance and analysis of upstream soundings also indicates weak upright instability now beginning to push into the region. Bursts of heavy rainfall with embedded convective elements will therefore become increasingly likely throughout the night. This is already occurring across eastern Oklahoma. At this time, inspection of RAP 850 mb moisture transport vectors and theta-e advection indicate that the heaviest rainfall overnight will fall in the general proximity of the I-44 corridor (roughly along and 30 miles north/south of the interstate). We therefore added to the northern edge of the previous Flood Watch. Overall, 1-3" amounts are expected overnight within the aforementioned swath. We will have to closely monitor the progress of convective elements for the potential of localized flash flooding overnight. && .SHORT TERM...(This evening through Saturday Night) Issued at 320 PM CST Fri Feb 23 2018 An upper level trough is currently located across the southwestern U.S. this afternoon. The Trough will track east towards and through the region this weekend with additional rounds for moderate rain expected across region. An upper level disturbance ahead of the main trough is currently tracking northeast across the region this afternoon. An area of rainfall has developed across Oklahoma and Arkansas and is begnning to spread north into southern Missouri and southeastern Kansas late this afternoon. The rain will continue to spread north into the area into the overnight hours. The heaviest rainfall will general occur along and south of I-44. A few storms will be possible tonight as instability starts to slightly increase across southern Missouri. No severe weather is expected through tonight. The bulk of the rainfall should spread east of the area by Saturday morning, though there could be some drizzle or a rouge shower around in the morning but all in all there should be a brief break in the rain. Lows tonight will not drop off much from what temperatures are currently across the area this afternoon. Temperatures may actually start to warm later tonight across southern Missouri as warmer air spreads north ahead of the approaching trough. As the upper level trough spreads across the Plains on Saturday a cold front will spread east into and through the area. Another round of moderate to heavy rain will develop and track across the area, again with the heaviest rains occurring across southern Missouri from late Saturday morning into the early evening hours. More instability will be in place ahead of the front, so will see more in the way of scattered storms along the front. The strongest instability will remain across south of the area, but around 500 J/kg of MLCAPE will likely be able to develop across far southern Missouri, generally east of Hwy 65 and south of I-44. As a result there will be a risk for some severe storms mainly across southern Missouri where the better instability will be in place. The storm mode will like be more of the way of line segments leading to the main risking being damaging winds. Low level shear will increase ahead of the system. Any line segments that can surge to the east of east northeast will have a meso vort potential across far southern Missouri Saturday afternoon/early evening. This system should be fairly progressive and the rain should move east of the area by the overnight hours Saturday. Total rainfall amounts from this afternoon through Saturday evening will range from 1 to 3" with locally heavier amounts. The heaviest rain will occur along and south of the I-44 corridor. A Flood Watch remains in effect through Saturday evening for southern Missouri. .LONG TERM...(Sunday through Friday) Issued at 320 PM CST Fri Feb 23 2018 A brief dry period is then expected Sunday into early next week as an upper level ridge builds towards the area. Highs early next week will warm into the 60s. Another system will then track across the region during the middle of next week bringing additional rain chances to the region. Behind that system an upper level ridge and dry weather is expected late next week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 511 PM CST Fri Feb 23 2018 A IFR night is in store with IFR ceilings and vis likely at the TAF sites as light to moderate rain moves through the area. Winds will primarily be light tonight and tomorrow. Patchy fog will be possible as well tonight given the build down of stratus. There will be some potential for low level wind shear at SGF and BBG. Rain will likely persist off and on during the day on Saturday with very low potential for rising into MVFR conditions. A few thunderstorms are possible Saturday, mainly at BBG and have VCTS currently for them. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...Flood Watch through Saturday evening for MOZ057-058-069>071- 079>083-088>098-101>106. KS...Flood Watch through Saturday evening for KSZ101. && $$ MESOSCALE...Schaumann SHORT TERM...Wise LONG TERM...Wise AVIATION...Burchfield
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
725 PM EST Fri Feb 23 2018 .UPDATE... 00Z water vapor and H4 RAP analysis show the Florida peninsula continues to reside under unseasonably strong mid/upper level ridging...resulting in day after day of near-record to record heat across the region. The forecast through the weekend does not change much as this ridge holds firm...and temperatures remain well above normal. Will see the development of a sea-breeze each afternoon that will make slow progress inland. A few isolated and brief showers are not impossible along this boundary by late afternoon/early evening...but with the degree of dry air aloft, any updrafts will be fighting a mostly loosing battle above 10KFT. When the synoptic pattern does not change, usually the forecast does not change a whole lot either, and this is the case for the next few days. More of the same, and likely more record highs. && .AVIATION (24/00Z through 25/00Z)... VFR conditions will prevail at west-central and SW Florida TAF sites through the evening and much of the overnight. Coastal TAF sites have flipped to onshore winds with the passage of the sea-breeze, but will see lighter winds come back around to the east by later this evening. Patchy and shallow fog may briefly drop visibility into MVFR categories around dawn for KLAL/KPGD/KRSW, but significant aviation restrictions are not anticipated, and any early morning fog will lift quickly. VFR conditions under a developing sct-bkn cumulus field will then prevail for the daylight hours Saturday. Just a slight chance of a late afternoon shower along yet another inland propagating sea-breeze. && .Preliminary Point Temps/PoPs... TPA 67 83 68 83 / 10 20 20 0 FMY 66 84 66 85 / 10 20 10 10 GIF 64 85 66 86 / 0 10 20 10 SRQ 67 81 67 80 / 10 10 20 0 BKV 63 85 64 85 / 10 20 20 0 SPG 68 83 68 83 / 10 10 20 0 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...None. Gulf waters...None. && $$ UPDATE/AVIATION...Mroczka