Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/27/16

Area Forecast Discussion
National Weather Service State College PA
1009 PM EST Mon Dec 26 2016 .SYNOPSIS... A frontal system will move through the forecast area overnight and early Tuesday. High pressure will follow with cooler weather through midweek before a new cold front moves our way for Thursday. && .NEAR TERM /UNTIL 9 AM TUESDAY MORNING/... 10 PM Update... Temps rising in the higher elevations of the W and also at KTHV and KLNS. Valley locations still holding onto the colder (30s) air. Rain continues to advance slowly, but newest NAM not backing off on quick passage and fizzle of the precip as it moves thru the local area. Have bumped up winds/gusts in the second half of the overnight and much of the daylight hours tomorrow. We may not tap the fastest possible gusts, but have mentioned G >30kts in the higher elevations. 700 PM Update... A batch of showers has just slid to the east of the area. Recent radar trends show a little less showers/returns over the NW Co.s than the HRRR would indicate in the next 2-3 hrs (which might occur in advnace of the longer line). But the thin line of showers is now into KCLE and moving steadily into NW PA. Have timed the line (which is followed by a second line along what is likely the real cold front) into KBFD around 03z. This is a bit slower on the whole. Also, the chance for thunder is pretty low with dewpoints progressively lower as one looks farther to the east of KCLE where currently no thunder is occurring. Will therefore continue to not mention T in the grids. Good srly flow and gusts regularly into the 20s are seen as the line of showers nears. Many of models have the showers breaking up as they reach the IPT-UNV-AOO line as llvl convergence wanes/disappears. Prev... Scattered showers are breaking out over WRN PA, not quite as widespread as the HRRR would have them, but still supporting the idea that my northern zones will stands the best chance of getting wet into the evening hours. Surface based LI progs show the tenacity of the cold air damming, so while SW PA is enjoying a balmy afternoon in the 60s, we remain locked into the chilly 30s and 40s, though still mild for the time of year. Temps will likely continue to slowly rise throughout the remainder of the day into the overnight, and will probably even spike up several degrees as the cold front brings a wind shift and briefly scours out the cold air that is locked in the valleys. So the highs for the day will likely be near midnight in many locations. Current timing shows the front bisecting the CWA from NE to SW by 09Z/4AM accompanied by a decreasing area of rain showers. The front will continue off to the SE with showers drying up in the increasing NW flow behind it. && .SHORT TERM /9 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... A mild Tuesday morning will yield to a cooler and breezy afternoon as a gusty NW wind ushers in a new airmass, though nothing extremely cold for late December. Most of the shower activity will exit the SE by mid morning, with light scattered lake enhanced snow showers developing in breezy W/NW flow late in the day in the NW. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Made some minor adjustments to the package. Still not looking at much off the lakes for snow showers later Tue. Flow is westerly and the airmass is not real cold. Still looking at some snow showers with the cold front on later Wed night into early Thu. Sfc temperatures may be just warm enough for some rain mixing in across the south. Later Thursday into Friday will be windy and turning colder. The cold tapers off for the weekend. A clipper type system is fcst for the later part of the weekend. Have some snow showers in, but did not go real hard on this, as it is not real clear over the next week or so, if the large scale flow will phase. The models the last few days are not showing as much cold air lasting as long now, even with rather large highs fcst to drop southeast into the plains. For now, did have some lower pops in, some hints on the EC and GFS of perhaps another system late Monday into Tue. Could get rather mild again, but some spread. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Widespread IFR ceilings continuing into the overnight. Areas of IFR fog over the Lower Susquehanna Valley. Scattered showers will to move from west to east across Central PA starting after 03z. Showers may briefly cause ceilings to improve or become variable and winds gusty. Real improvement will not come until the cold front moves through later tonight. Winds are strong just up off the surface and hence LLWS is a possibility with the relatively light SE flow near the surface becoming SWLY 30-40kt a couple of thousand feet off the deck. LLWS will end with the frontal passage. The cold front will push southeast moving through BFD about 06z and UNV-JST about 09z and LNS about 12z. Scattered Showers are expected with the front. Ceilings are expected to improve most locations behind the front as drier air begins to move in. WNW downslope winds will help improve ceilings to VFR by midday. The northern mountains and Laurel Highlands will see lake enhanced clouds and showers develop with upslope flow later in the day Tuesday. By Tuesday evening, it will be cold enough to change back to snow showers in the northwest. Outlook... Wed...No sig wx early, chance of light snow and rain late. Thu...Restrictions possible in light snow and rain. Fri...Windy with snow showers possible N/W. Sat...Restrictions possible in light snow showers. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...Dangelo/La Corte SHORT TERM...La Corte/RXR LONG TERM...Martin AVIATION...Watson
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
707 PM CST Mon Dec 26 2016 .UPDATE... The frontal boundary has slowed down across the northern Hill Country and expected to move over the I-35 corridor later tonight. Current radar observations are showing few spots with light rain along the boundary and ahead of it over the warm sector. Latest LAMP guidance and HRRR and RAP13 solutions do not show a lot of activity at least through midnight tonight. That said, adjusted the first 6 hours for the tonight period and brought down the chances for rain (10-20%). && .PREV DISCUSSION... /ISSUED 533 PM CST Mon Dec 26 2016/ AVIATION... VFR conditions are prevailing with all of the shower activity east of the terminals at this time. Think most of the forecast period for the TAFs will remain rain free and will not mention precip at this time. Will amend if necessary through the night. MVFR conditions should occur once again tonight with possible IFR for the San Antonio sites. VFR conditions will return again tomorrow afternoon. PREV DISCUSSION... /ISSUED 217 PM CST Mon Dec 26 2016/ SHORT TERM (Tonight through Tuesday Night)... A weak cold front was located just northwest of a Lampasas to Llano to Fredericksburg line, and has now sagged into the northwest and west CWA, having cleared Rocksprings, and Eagle Pass. Most of the CWA remains in the warm sector mid afternoon, with very warm temperatures prevailing. A record high temperature for this date has already been set in Austin and tied at San Antonio as of this writing. Widely scattered showers continue east of I-35 and isolated thunderstorms can not be ruled out through the remainder of the afternoon over this area, where MLCAPE values of around 2000 J/KG are currently observed. The front will continue slowly southeast tonight into early Tuesday morning, with scattered showers and an isolated storm or two possible along it through the southern Hill Country and I-35 corridor. The cold front should move south of the CWA during the morning on Tuesday. Weak isentropic upglide does develop behind the front Tuesday and Tuesday night across the southwest CWA, over the Winter Garden and Rio Grande areas. Cooler Tuesday with highs in the upper 60s to low 70s. LONG TERM (Wednesday through Monday)... A weak southerly flow resumes Wednesday as the front washes out. Patchy drizzle and isolated showers possible in the morning, then warmer with highs in the mid and upper 70s. Models still in agreement with a stronger cold front moving through the area on Thursday. Little precipitation is expected along it, and primarily over southern zones if it occurs. Cooler and breezy Thursday, with highs in the upper 50s to mid 60s and wind gusts around 25-35 mph possible. The GFS and ECMWF are still indicating a more active southern stream Friday through Monday. The first impulse may skirt across northern zones on Friday bringing a slight chance of showers. Eventually the upper level low that is currently cutting off southwest of California is forecast to open and shear east into the southern stream across the southern Plains Saturday. This may bring another chance of showers to the area during this time. A third impulse rounding out of the base of a digging western CONUS trough is shown by both the GFS and ECMWF to come out sometime Sunday or Monday, bringing a Pacific cold front into the region and possible chance for showers. Confidence in timing and placement of all these features is currently low this far out and could possibly change. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 58 68 59 76 54 / 50 20 10 10 - Austin Bergstrom Intl Airport 59 69 59 75 55 / 50 20 10 10 - New Braunfels Muni Airport 60 71 60 77 56 / 50 30 10 20 - Burnet Muni Airport 54 65 56 75 49 / 30 10 10 10 - Del Rio Intl Airport 59 69 60 75 55 / 30 30 10 10 0 Georgetown Muni Airport 55 65 57 75 51 / 50 20 10 10 - Hondo Muni Airport 61 72 61 75 57 / 50 30 30 20 - San Marcos Muni Airport 60 70 59 76 56 / 50 30 10 20 - La Grange - Fayette Regional 63 72 62 76 58 / 50 30 10 20 10 San Antonio Intl Airport 61 71 61 76 57 / 50 30 20 20 - Stinson Muni Airport 62 72 62 77 58 / 50 30 20 20 - && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...Hampshire Synoptic/Grids...17
Area Forecast Discussion
National Weather Service Huntsville AL
932 PM CST Mon Dec 26 2016 .NEAR TERM...(Rest of tonight) Issued at 930 PM CST Mon Dec 26 2016 A slow moving cdfnt is now pushing into wrn TN with a narrow line of shra and a few tsra along the cdfnt. New NAM and HRRR models were showing that this line of shra/tsra will start to effect the TN valley after 06z and then continue to move across the cwa during the overnight hours. Scattered shra and a few tsra will be possible Tuesday mrng before tapering off by Tuesday aftn. Most of the pcpn should be shra activity but can`t rule out a few tsra overnight/Tuesday mrng, but no svr wx is expected. With south winds arnd 10 mph and cloud cover, raised temps a few degrees to the lower 60s for mrng lows. Also pushed back the timing of pcpn to after midnight and adjusted pops. The cdfnt should be out of the TN valley by Tuesday aftn. .SHORT TERM...(Tuesday through Wednesday) Issued at 312 PM CST Mon Dec 26 2016 The cold front should be across or just east of the I-65 corridor at daybreak, and be east of the area before noon. Shower activity should taper off from NW to SE during the course of the day - but kept minimal PoPs in for our eastern areas Monday night. With the frontal passage and cooler air behind the front, no more record warmth. Highs on Monday should be close to 60 around midnight a cross far NW Alabama, but should hold steady or fall somewhat during the course of the day - mostly in the 50s. The front will become stationary south of us Monday night, then return northward as a warm front on Tuesday. Lows Monday night should cool into the mid 30s north to lower 40s south. The return of the front will bring back rain chances for the mid week. Again, mainly showers with lesser chances of thunder. Storms again should only produce locally heavy rains and wind gusts into the 40 mph range. .LONG TERM...(Wednesday night through Sunday) Issued at 312 PM CST Mon Dec 26 2016 High amplitude upper trough will swing across the Ohio Valley/Tennessee Valley and eventually to the Mid Atlantic Region on Thursday. This will bring a northwesterly flow and cooler weather to the region. With the center of the vorticity maxima and cold pool aloft remaining to our north, expect generally clear skies behind the trough passage for Thursday into Friday. However, the upper flow will remain quite progressive across the lower 48. Thus the next weather maker will already be taking shape to our west across the southern plains by late Friday. This system, aided by southerly flow off the Gulf of Mexico, will bring in an abundant surge of moisture beginning late Saturday and continuing into Sunday. Current timing would indicate a potentially wet period for New Year`s Eve festivities across our area as widespread precipitation develops along the advancing warm front. The medium range guidance does vary a bit for Sunday with the GFS showing the precipitation focused to our south where mid level diffluent flow will be maximized atop low level instability and convergence. Meanwhile, the ECMWF has the convergence axis associated with the warm front focused across the Tennessee Valley. Will continue with fairly high pops given the abnormally high PWAT values and strong forcing associated with the system. All the guidance is fairly consistent in lifting a final swath of heavy precipitation over the area on Monday as the surface low deepens rapidly and the upper trough takes on somewhat of a negative tilt. Instability looks somewhat marginal Sunday night into Monday currently in the guidance. Would not be shocked if we don`t end up adding thunder to the forecast in the coming days however given this particular pattern, but will keep out for now given some continued uncertainty with the timing and overall trends. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 528 PM CST Mon Dec 26 2016 A slow moving cdfnt is now extending from the ern Great Lakes thru extreme sern MO and into sern TX. There is a narrow line of shra/tsra along the cdfnt, mainly from srn LA to KY. Only some isolated shra were trying to form over Cullman county attm. Still looks like the best chc of pcpn will begin arnd 06 tonight and continue thru the overnight hours. The pcpn will begin to taper off across the taf sites by 21z. For now thinking that the main pcpn type will be shra, although cant rule out a few tsra overnight. Otherwise expect mainly mvfr, with occasional ifr conditions, thru the fcst period. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...007 SHORT TERM...RSB LONG TERM...15 AVIATION...007 For more information please visit our website at
Area Forecast Discussion
National Weather Service Wilmington NC
1049 PM EST Mon Dec 26 2016 .SYNOPSIS... A coastal trough will move inland tonight. A cold front will move across the area late Tuesday night. A stronger cold front will follow Thursday night. Chilly high pressure will build in on Friday through early Saturday before moving off the coast. Another cold front may reach down into the area on Sunday with unsettled weather possible for the start of next week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... As of 1030 PM Monday...Some re-alignment of QPF amounts, with an overall edge upwards. This based on the latest KLTX 88D trends of higher reflectivity. Otherwise, no changes needed from the prior update. Previous.................................................... As of 745 PM Monday...This update concerned with extending the pcpn occurrence thruout the night into Tue daytime mid-morning. Have followed the blend of latest HiResW and HRRR models with with respect to pcpn this evening...and closer to the HRRR for the overnight period with accumulation becoming more concentrated closer to the coast overnight into Tue. Basically, the best QPF, up to 0.10 inches, to occur east of a line extending from Myrtle Beach across Marion to White Lake, with again the hier pcpn amounts closer to the coast. Looking at stratiform light drizzle or rain as the common pcpn type. Patchy to areas of fog will encompass the ILM CWA, the threat for dense fog will become possible toward sunrise Tue, and there- after along the immediate coast from possible sea fog. Temperatures overnight will likely hold steady this evening thru the overnight, with some 1 to 2 degree notable increases toward daybreak Tues. The eventual milder SW flow may take until after daybreak Tue to mix down to the sfc thru a shallow sfc based cool layer. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... As of 300 PM Monday...Flow aloft will remain flat through the period, keeping surface features on the weak side with temps above climo. High pressure off the east coast at the start of the period will maintain southwest flow on Tue, ahead of advancing cold front. Although low level moisture increases significantly ahead of the front, westerly flow aloft limits the amount of deep moisture return. Cannot rule out sea fog ahead of the front given the elevated dewpoints, but winds will be out of the southwest which may limit sea fog to Brunswick and New Hanover counties and possibly northern Horry. Guidance has been trending toward a drier fropa late Tue or Tue night with each successive run. 12Z is no different with the latest GFS only managing to squeeze out a few hundredths across coastal NC with the frontal passage. Inherited widespread chc pop may end up being on the high side and plan to trend inland pop down to slight chc realm for much of the area. Cold front moves across the region Tue night then stalls south of the area Wed as high pressure to the north weakly builds in. Zonal flow aloft quickly moves the high to the north off the coast Wed afternoon and Wed night. This allows the front south of us to return north as warm front Wed night, accompanied by increasing precip chances. Forecast soundings indicate an abundance of deep moisture during the second half of Wed night along with some elevated instability and a 30 kt low level jet. Low level stable layer should prevent winds from being an issue but scattered showers within the elevated unstable layer will be capable of dropping moderate rainfall in some locations, hence chc pop late Wed night. Temperatures will remain above climo through the period with highs well above climo Tue dropping close to 10 degrees Wed. Despite the large drop highs Wed will still be 3 to 5 degrees above climo. Lows will remain well above climo with temps in the mid 50s Tue night and mid 40s to around 50 Wed night. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 300 PM Monday...Mid to upper trough extending down from the Great Lakes will push a cold front through on Thursday. Increasing S-SW flow ahead of the front will produce the warmest temps of the week with highs expected near 70 most places. With the warming will also come an increase in clouds and chc of showers through early afternoon. Looks like pcp chances and clouds will diminish late afternoon through early evening as front moves off shore. As front moves through temps will begin to drop. Therefore may see temps max out earlier in the day in waa ahead of front. Will not see too much in the way of moisture return as pcp water values reach up near 1.35 in SC by Thurs morning and about an inch in NC. Drier air begins to move in as winds veer to the SW-W by early aftn pushing best moisture near or off the coast. The moisture return also does not align well with best dynamics which remain well to the NW. Therefore expect only isolated higher QPF amounts. Pcp water values drop to less than a quarter of an inch in cold and dry advection through Thurs evening. Cold and dry air will advect in with gusty NW winds Thurs night into Fri. Temps will drop just below 40 most spots inland overnight Thurs and will not make it to 50 on Fri. The gusty winds will subside late Fri as high pressure shifts closer overhead. The clear and calm conditions Fri night will make for a chilly low down within a few degrees of freezing. By Sat aftn the center of high pressure will shift off shore allowing for a milder return flow but after a very cool start to the day, max temps will only reach in the mid 50s most places. Area will remain pcp free from Thurs night through Saturday. Flow remains fairly progressive with high pressure well off shore by Sat night and a deeper SW return flow bringing an increase in moisture through Sunday. May see tail end of cold front drop into the Carolinas and stall or return north as warm front on Monday leaving unsettled weather to start off next week. Temps will depend on how far south the cooler air will penetrate before waa begins Sun night into Mon. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... As of 23Z...Ample low-level moisture is in place along with a weak coastal trough early this evening. Weak isentropic lift has resulted in some areas of -RA/-DZ with most areal coverage just offshore. High confidence in IFR conditions developing this evening and impacting all of the terminals through the early morning hours. VSBYs and CIGs expected to slightly improve generally after 15Z as southwesterly flow increases ahead of the next cold front. Extended Outlook...Low confidence TEMPO MVFR/IFR ceilings with showers late Tuesday. VFR Wednesday into early Thursday with possible TEMPO MVFR ceilings and showers late Thursday into early Friday morning. VFR conditions Friday afternoon through Saturday. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 1030 PM MOnday...No changes applied from the recent update. Still need to watch significant seas, will not take much from wind driven waves added to the SE ground swell to result in 3 to 5 ft seas and close to SCEC conditions minus the winds. Previous.................................................... As of 800 PM Monday...The weak inverted sfc trof in the vicinity of where the coastal and offshore waters meet, is progged to slowly drift westward as it lifts northward overnight into daytime Tue. Windspeeds will remain around 10 kt or less due to a weak sfc pg. However, the wind directions may become variable at times due to the trof making some headway into the coastal waters before finally lifting north of the area altogether by or just after daybreak Tue. With SSTS in the 50s, will hold off from pushing this coastal trof completely westward and onshore overnight due to the cool maine sfc based layer in place. Thus, will hold onto a eNE-E-ESE direction for as long as possible. Significant seas will run 2 to 4 ft with much of it coming from a healthy 1 to 3 foot ESE to SE ground swell at 9 to 10 second periods. The coastal waters will see reduced vsby from light rain and drizzle with the threat for sea fog likely holding off until daytime Tue. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 300 PM Monday...Surface high off the east coast and cold front approaching from the west will result in southwest flow across the waters Tue into Tue night. Winds will gradually increase Tue as the gradient tightens ahead of the advancing front. Southwest flow peaks around 15 kt Tue afternoon/evening before front passes and offshore flow develops. Sea fog could be a concern Tue given the strength of the cold advection. Surface high builds in following the front but lacks significant cold advection and is quick to move east. Center of the high shifts off the coast late Wed afternoon or Wed evening. Northerly winds veer to east Wed night and by the end of the period will be out of the south-southwest. Gradient remains weak Wed and Wed night and speeds are likely to be 10 kt or less. Seas 3 to 4 ft for much of the period will increase slightly Tue afternoon/evening on the back of increased south to southwest flow. May see a few isolated 5 ft near 20 nm during the time but widespread 4 seems more likely. LONG TERM /THURSDAY THROUGH SATURDAY/... As OF 300 PM Monday...Southwesterly return flow will increase and veer to the west ahead of a cold front on Thurs. The front will move through the waters Thurs evening followed by strong off shore flow behind it. The southerly push should produce a rise in seas from less than 3 ft early Thurs up possibly into small craft thresholds by Thurs night. WNA model shows a brief window of SCA but with the strong off shore flow, the highest seas will remain well off shore and most of the waters within 20 nm may remain in precautionary headlines from Thurs eve through Fri aftn in gusty winds preceding, and especially in off shore surge following fropa. Winds and seas will diminish late Fri into Saturday as high pressure shifts closer overhead. Seas will be down less than 3 ft by Fri night with The center of the high will lighter more variable winds. A return flow will set up once again on Saturday aftn as the center of the high shifts farther off shore. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...RGZ NEAR TERM...DCH SHORT TERM...III LONG TERM...RGZ AVIATION...SRP MARINE...
Area Forecast Discussion
National Weather Service Paducah KY
308 PM CST Mon Dec 26 2016 .SHORT TERM...(Tonight through Wednesday night) Issued at 308 PM CST Mon Dec 26 2016 We continue to be on the look out for heavy rainfall from training echoes late this afternoon into the evening, and a brief damaging wind and tornado event, mainly over west Kentucky. The heavy rainfall threat appears to be increasing as overall areal coverage of heavier elements is expanding from the Boot Heel into southern Illinois and the Purchase area of Kentucky in the last hour. Have already had 1-2" of rain over much of this area, and the additional heavy rainfall could lead to more substantial flooding issues. At this time, the 50dBz echo coverage is quite limited, so will hold off on a Flash Flood Watch at this time. The latest HRRR data has this area shifting steadily eastward through the rest of the area mostly by 06Z. It may hang up into the overnight hours in the far southeast corner of the area. The northwest portion of the area is not likely to see any more rainfall. The 12Z models bring another storm system with a minor surface trough through the region Wednesday into Wednesday night. Most of the models generate some light QPF at least over the southern or southeast half of the area. They have limited the precipitation to the 18Z Wednesday to 06Z Thursday time-frame, so temperatures should be well above freezing. The NAM and GFS both have some very minor elevated instability, so could argue for a slight mention of thunder. However, will leave it out at this time, and wait for a stronger signal. As for temperatures, generally went close to the consensus of all available guidance through the period. The surface pattern is a bit convoluted this afternoon, with a dry line of sorts along our northwest periphery, and the cold front well to the west over central Missouri. This has led to a delay in the cool, dry advection tonight, and a slight uptick in low temperatures. .LONG TERM...(Thursday through Monday) Issued at 308 PM CST Mon Dec 26 2016 Increasing confidence in the extended. The latest model runs show much better continuity with the latest runs. There were some discrepancies with timing as the GFS was a little faster with this weekend start of precip than either the Canadian or the ECMWF. Plan on weighting toward the Canadian/ECMWF solution considering the ECMWF has been a little more steadfast with its solution. In addition it now enjoys the support of the Canadian. A low will track eastward out of the plains into the great lakes region. As it does we will have a warm front lift through overnight Friday lifting a warm front north of the area. Saturday we will be in the warm sector and we do expect at least some warm advection showers. A cold front will swing through Saturday night as a weak perturbation aloft pushes through. This may enhance the showers some. However not much in the way of instability at the surface with LI`s positive and with an inversion. After this weekend system depart Sunday a warming trend will develop. Another storm system is poised to move through on the heels of the Saturday system. A fast moving upper low is expected to lift out of the plains and move through the area Sunday night into Monday...Lower confidence with this last system but will monitor closely for any changes. Overall near normal temperatures with a considerable warm up starting late in the weekend. && .AVIATION... Issued at 1155 AM CST Mon Dec 26 2016 Guidance has a fairly wide range of timing for the best convection this afternoon into this evening. Most guidance is too pessimistic for ceilings and visibilities to begin with, with or without precipitation, so have gone a bit on the optimistic and quicker side with the convection. Brief periods of IFR or lower conditions are possible, but think ceilings will hold mostly in MVFR territory and improve to VFR rather quickly behind the precipitation. South to southwest winds will continue to gust 20-30kts this afternoon and into the early evening before veering to the northwest with the cold front late tonight. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ SHORT TERM...DRS LONG TERM...KH AVIATION...DRS
Area Forecast Discussion
National Weather Service Portland Oregon
242 PM PST Mon Dec 26 2016 .SYNOPSIS...A frontal system will come in off the Pacific this afternoon and tonight with precipitation spreading across the area through tonight. Onshore flow brings showery weather Tue behind the front. The showers will slowly taper off Tue night and Wed as a ridge of high pres builds in aloft. Another frontal system may brush the region late in the week. && .SHORT TERM...This afternoon through Thursday...Radar shows some scattered returns this afternoon with more moderate rain just arriving at the immediate coast. 1930Z ASCAT winds placed the approaching front about 250 miles offshore and 21Z HRRR shows an initial bout of moderate rain near the coast but most of it holding off until closer to 00Z, which makes sense based on the front location. Still expect precip everywhere with this system, so not many adjustments needed to the forecast through tonight. In the Cascades a fairly strong westerly 850 mb flow develops tonight, peaking at around 40 to 50 kt, which will provide favorable orographics for the terrain and likely shadow at least the western Willamette Valley. The flow continues into Tue before beginning to weaken late Tue and Tue night. Still expect to see quite a bit of snow in the Cascades as showers will stick around through Tuesday with that stout flow. However, Tuesday may turn out more dry than wet in the interior lowlands. Models agree on a weakening westerly flow Tue night and Wed as a modest ridge of high pres builds in, finally tapering off showers by Wednesday morning, even in the Cascades. With the upper ridge in place, most of the area will remain dry from Wednesday through at least Wednesday night with the exception of the S Washington and far N Oregon coasts, which look like they`ll be on the southern edge of a system passing to the north. During the day Thursday, a piece of energy from that system will sink southward and bring PoPs back up across the local area, but precipitation amounts look unimpressive. Snow levels Thursday generally look fairly high, above about 4000 ft, but will have to keep an eye on the cold air through the Columbia River Gorge with developing offshore flow. Bowen .LONG TERM...Thursday night through Sunday...The upper level trough finally passes through the area Friday and models agree with the general theory that it will strengthen as it moves south, pulling the local area into a cool north to northeast upper flow. With surface high pressure briefly building over Oregon behind it on Saturday, should see a break in the precip that day. The next system Saturday night and Sunday may begin to usher in some changes. Although models don`t agree on the details, they show a similar pattern with low pressure moving south along the North American west coast, into Oregon during the day Sunday. At this point, it looks like snow levels would remain above about 1,000 ft during the wettest portion of the system. However, 850 mb temperatures are looking potentially downright frigid just beyond the end of the current 7-day forecast as models bring Arctic high pressure east of the Cascades, spilling its cold air into the local area. If the cold air arrives before showers completely dissipate behind Sunday`s system, could see some wintry precip near the valley floor, but it`s far too early to have any confidence in that happening. The other concern will be on the back end of the cold air sometime next week whenever the next precipitation arrives. Bowen && .AVIATION...Generally VFR early this afternoon, except for isolated pockets of IFR in the north and central Willamette Valley. Precipitation arrived on the S Washington and far N Oregon coast around 19Z and will spread SE over the next several hours. Expect coastal sites to lower into MVFR by 00Z Tue. Heavier precipitation occurs along the coast between 03Z and 09Z Tue, likely resulting in areas of IFR. Inland areas remain VFR through early evening then lower into MVFR, with local IFR possible after 05Z Tue. Frontal passage at the coast around 06Z Tue, then reaching the Cascades between 09Z and 12Z. Improvement to VFR shortly after frontal passage. Higher terrain, including the Oregon Coast Range and Willapa Hills of SW Washington, become obscured this evening through Tue morning. KPDX AND APPROACHES...VFR at the terminal as of early afternoon. Rain expected to begin around 00Z Tue, with conditions lowering to MVFR between 04Z and 06Z Tue. Frontal passage around 09Z Tue, but improvement to VFR shortly after 12Z. Weishaar && .MARINE...Wind speeds early this afternoon near the cusp of gale force over the north waters. Buoy 029 had a peak gust of 35 kt at 21Z. No changes to the current Gale warnings. Southerly gale force wind gusts of 35 to 40 kt to spread from north to south across the waters through the evening. Gusty west to northwest wind of 25 to 30 kt will occur after frontal passage, which will be around 03Z Tue for the outer waters and closer to 06Z along the coastline. The 25 to 30 kt W-NW wind continues for much of Tuesday. High pressure returns to the waters Tue night and holds through at least Wed night. Longer range models have come into better agreement regarding the weekend. Looks like fairly strong North flow develops over the waters late Sat and continues into early next week, likely resulting in small craft advisory wind speeds for at least the outer waters. Seas running around 5 ft early this afternoon, but will ramp up to above 10 ft by late afternoon or early evening due to a large wind-wave component. Seas build to around 15 ft late tonight and Tue morning. A long 20-30 kt W-NW wind fetch will boost seas to the upper teens Tue afternoon. Seas ease to the lower teens late Wed or Wed night. ENP and spectral guidance continue to show a core of very large seas, 35-ft on the ENP, near buoy 005 12Z Sun. Trended a little higher for this forecast, to the upper teens, but it appears the highest waves remain over the outer waters and beyond 60 nm. These forecast wave heights likely to increase a little more if future model runs continue in good agreement. Weishaar && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Winter Weather Advisory from 6 PM this evening to 6 AM PST Tuesday for Upper Hood River Valley. Winter Weather Advisory from 6 PM this evening to 2 AM PST Tuesday for Western Columbia River Gorge. Winter Weather Advisory from 6 PM this evening to 4 AM PST Tuesday for Central Columbia River Gorge-Northern Oregon Cascade Foothills. Winter Storm Warning from 6 PM this evening to midnight PST Tuesday night for Northern Oregon Cascades. Winter Weather Advisory from 8 PM this evening to midnight PST Tuesday night for Cascades in Lane County. Winter Weather Advisory until 8 PM PST this evening for Coast Range of Northwest Oregon. WA...Winter Weather Advisory from 6 PM this evening to 2 AM PST Tuesday for Western Columbia River Gorge. Winter Weather Advisory from 6 PM this evening to 4 AM PST Tuesday for Central Columbia River Gorge. Winter Storm Warning from 6 PM this evening to midnight PST Tuesday night for South Washington Cascades. Winter Storm Warning from 6 PM this evening to noon PST Tuesday for South Washington Cascade Foothills. PZ...Gale Warning until 1 AM PST Tuesday for Coastal Waters from Cape Shoalwater WA to Cascade Head OR out 60 nm. Small Craft Advisory for winds until 6 PM PST this evening for Coastal Waters from Cascade Head OR to Florence OR out 60 nm. Gale Warning from 6 PM this evening to 3 AM PST Tuesday for Coastal Waters from Cascade Head OR to Florence OR out 60 nm. Small Craft Advisory for Rough Columbia River Bar from 10 PM this evening to 4 PM PST Tuesday. && $$ Interact with us via social media: This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. The area is commonly referred to as the forecast area.
Area Forecast Discussion
National Weather Service Charleston WV
934 PM EST Mon Dec 26 2016 .SYNOPSIS... A cold front passes later tonight with a stronger cold front Wednesday Night into Thursday. A low pressure system arrives by && .NEAR TERM /THROUGH TUESDAY/... As of 900 PM Monday...Made several minor changes based on latest trends and hi res models. Increased temps early before rain begins, increased wind gusts overnight ahead of the front, especially across the northern mountains but no advisories, hastened the pops on leading edge of precip shield in the southwest along with slight chc thunder across the southwest until 07Z. As of 215 PM Monday... With the surface and upper level low making more of a northeastward track away from our CWA, the cold front may slow down its eastward progression through the area. At the moment, cold front is still well to the west, and have several observations of temperatures at or above the 70 degree mark. Have slowed down the forward progression of the front a touch given the aforementioned track of the system, with the concern that these scenarios often times lead to the formation of a surface wave along the front along the middle Ohio Valley. HRRR and RAP not showing this as of yet, but if it does, it may need to be slowed down even more. From a QPF standpoint, not looking at concerning amounts of rain, and should be under a half inch. High pressure returns Tuesday, with the center actively moving over the area in the short term, and have all precipitation exiting the CWA by 21Z Tuesday. No lingering upslope moisture expected, with the NAM fairly dry at 925/850mb. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 320 PM Monday... The main feature this period will be a cold front in a fast zonal flow aloft sweeping across the area Wednesday night and Thursday morning. Expect rain showers with the front, although QPF amounts will be on the light side. Cold advection behind the front on Thursday, will combine with developing northwest flow off the Great Lakes to keep scattered rain showers in the low lands, except rain showers will change to snow showers in the higher elevations of the northern mountains. Thursday night will see all precipitation becoming snow showers, especially on the western upslope areas of the mountains where some snow accumulations are likely. Temperatures will go from above normal on Wednesday under sunny high pressure with highs in the 40s, to below normal by Friday. However, no extreme temperatures are foreseen. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 330 PM Monday... In the fast flow aloft, the colder air will last for just a day, but then the pattern becomes more amplified with systems slowing down for the weekend into early next week. Look for high temperatures Friday in the 30s, but with snow showers ending from west to east as high pressure builds in. It will be dry and coldest Friday night under high pressure with temperatures well down in the 20s. High pressure will shift east by Saturday as low pressure approaches from the southwest. Increasing moist southerly flow ahead of the low will bring milder air and mainly rain showers over the area, especially Saturday night onward. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... 03Z Tuesday thru 00Z Wednesday... Thru 11Z...A cold front passes tonight and early Tuesday with a band of showers, affecting all terminals. Included isolated thunder in small southwest portion of area til 07Z, but not included in major TAFS. Restrictions will be limited primarily to MVFR in both ceilings and visibilities, with a couple exceptions to IFR, mostly in the mountains 09Z-14Z. Cold front will be a relatively quick mover, with south wind 10 to 20 KTS with some higher gusts ahead of the front, especially mountains. Visibilities will follow a similar suit, and should stay mostly MVFR, but will add this to the alternate scenarios below. After 11Z...Look for rapid improvement from west to east, with rain showers ending and becoming VFR by 11Z Ohio River, by 14Z CKB-CRW line, and by 20Z mountains. West winds behind front 5 to 10 KTS, but higher in mountains. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of the showers may vary slightly. May need brief IFR with the heaviest showers at any terminal. 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 TUE 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 L H H H M HTS CONSISTENCY H H H M M M H M H H M L BKW CONSISTENCY H H H H H L L H M H H M EKN CONSISTENCY H H H H H H L H M H L M PKB CONSISTENCY H H M M M L H H M M M M CKB CONSISTENCY H H H H H H M L H H H L AFTER 00Z WEDNESDAY... IFR possible in snow showers Thursday night into Friday. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...JMV/26 NEAR TERM...JMV/26 SHORT TERM...JMV LONG TERM...JMV AVIATION...JMV