Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/18/18

Area Forecast Discussion
National Weather Service Charleston SC
947 PM EST Mon Dec 17 2018 .SYNOPSIS... Dry high pressure is expected through Wednesday. A storm system will impact the area Thursday and Thursday night, followed by cooler and drier high pressure through early next week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Late this evening: Still no changes needed to the forecast. Entertained the idea of adding in some patchy fog since a few inland southeast Georgia sites have periodically reported fog this evening but decided against it. Sounding show that any moisture is extremely shallow, so the expectation is that any fog that develops will also be very shallow. Updated hourly temperature trends to better align with recent observations and to feature a quicker cool down under good radiational cooling conditions. High pressure over the Northern Mississippi Valley will build into the Ohio Valley tonight while extending into the Southeast United States. Although not an ideal pressure pattern for complete decoupling due to some isobar kinking downwind of the Southern Appalachians, expect some degree of decoupling to occur away from the coast with winds going calm to light/variable by midnight under a strong noctural inversion. Clear skies and light winds will promote solid radiational conditions with lows ranging from the upper 30s inland to the upper 40s at the beaches. A light northwesterly flow across Lake Moultrie could keep some locations immediately downstream such as Moncks Corner a few degrees warmer than surrounding areas (lower 40s versus upper 30s). This signal shows up nicely in both the RAP and H3R surface temperature fields. Some of the normally colder, more sheltered areas such as the Francis Marion National Forest could dip into the mid 30s prior to daybreak. Could see some shallow ground fog form a few hours before sunrise, but should remain fairly insignificant. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... Tuesday will feature relatively warm temperatures in the low/mid 60s and sunny skies under deep layered high pressure. Wednesday should remain dry though mid and high level clouds will overspread the area as a result of shortwave energy approaching. A deepening upper trough over the central United States Wednesday night will close off by Thursday while slowly moving east. Meanwhile a surface low will take shape over MS/AL, ahead of which moisture will spread into the Southeast. Overrunning along and north of a warm front will result in increasing coverage of rain showers Wednesday night. A plethora of shortwaves will move through on Thursday while a surface low moves northeast through central SC/GA. Right-rear jet divergence is expected over the area, in addition to 1.5" Precipitable Water values. We are expecting widespread rain on Thursday with approximately one inch of QPF. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... The bulk of the rain should be gone by Friday although some showers could linger much of Friday given continued upper forcing. Cooler and drier conditions should then return Friday night and continue for the weekend, and possibly through Monday as well. Temperatures mainly look to stay above normal. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... VFR for both KCHS and KSAV through 00z Wednesday. Extended Aviation Outlook: MVFR ceilings possible Wednesday. Increasing chances for MVFR/IFR conditions Wednesday night through Friday night as a storm system moves through, accompanied by moderate rain showers and low clouds. Gusty winds also possible Friday. && .MARINE... Tonight: West winds will veer to the north overnight with winds generally 10-15 kt, slightly less across the far southern nearshore zones. Seas will average 1-2 ft nearshore and 2-3 ft offshore. Tuesday through Saturday: No marine concerns Tuesday through Thursday morning. Strengthening southerly flow late Thursday will bring potential 25 kt gusts and 6+ ft seas Thursday night through Saturday morning. Thus Small Craft Advisories are likely during this period. The tightest gradient and thus strongest winds are expected Friday afternoon and evening. We`re showing a short window of some 34 kt gusts over the outer portion of the Charleston nearshore as well as the GA offshore waters. Cannot completely rule out a Gale Watch or Warning at some point. High pressure will bring improving conditions over the weekend. && .EQUIPMENT... The KCLX radar will be down until further notice. A technician is scheduled to make repairs on Tuesday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...BSH/ST SHORT TERM...JRL LONG TERM...RJB AVIATION...BSH/JRL MARINE...ST/JRL EQUIPMENT...
Area Forecast Discussion...CORRECTED
National Weather Service Wichita KS
549 PM CST Mon Dec 17 2018 .SHORT TERM...(This evening through Thursday night) Issued at 153 PM CST Mon Dec 17 2018 Southerly winds have returned to much of central Kansas with breezy conditions further west across the high plains. Southerly flow will expand eastward tonight and Tue as low pressure deepens across the high plains of eastern Colorado. This southerly flow will eventually tap into some low level moisture and we could see a stratus deck impact portions of south central and southeast KS late tonight and into the day on Tue which may dampen the diurnal temperature rise for locations along and east of the Kansas Turnpike area. As a subtle shortwave trough approaches Tue night we could see a brief shower impact portions of southern KS but any precipitation is expected to remain light with minimal coverage anticipated. Wed-Thu...better chances for showers will arrive on Wed afternoon across mainly southeast KS as a mid/upper trough deepens as it moves out of the Southern Plains states and into the Lower Mississippi Valley area. An increasing pressure gradient force on Wed will result in increasing south to southwest winds while large-scale forcing for subsidence in the wake of the storm system on Thu will allow strong northwest winds to develop across the area. The MSLP anomalies of 1.5-2 standard deviations and H85 winds at or above 50 knots will likely drive speeds into the advisory level across much if not all of the forecast area on Thu. .LONG TERM...(Friday through Monday) Issued at 153 PM CST Mon Dec 17 2018 A mid/upper ridge is progged to overspread the region at the beginning of the period bringing above normal temperatures and dry weather conditions to the region. A shortwave trough moving across the Northern Plains states will drive a cold front south across the area over the weekend allowing temperatures to return to more seasonable values with highs in the 40s on Sunday. A progressive mid/upper flow regime will steer additional storm systems toward the area as we move through next week but confidence in timing remains fairly low at this time. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 544 PM CST Mon Dec 17 2018 VFR conditions are forecast at all sites throughout the period. Some influx of low level moisture from the south is anticipated around daybreak. NAM was discounted as being way too agressive with moisture, while GFS and RAP were similar but show varying locations for influx. Signals suggest any clouds would probably be VFR level and opted to go scattered for now. Will reassess for 0600 UTC issuance with 0000 UTC model data. -Howerton && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 34 55 38 55 / 0 0 10 20 Hutchinson 32 54 35 55 / 0 0 10 20 Newton 33 54 36 53 / 0 0 10 20 ElDorado 34 54 38 54 / 0 0 10 20 Winfield-KWLD 34 54 39 54 / 0 0 20 30 Russell 32 54 31 53 / 0 0 0 30 Great Bend 32 55 32 54 / 0 0 0 20 Salina 33 54 35 53 / 0 0 10 20 McPherson 32 53 35 53 / 0 0 10 20 Coffeyville 34 56 41 56 / 0 0 10 60 Chanute 33 54 40 54 / 0 0 10 40 Iola 33 54 40 54 / 0 0 10 40 Parsons-KPPF 34 55 41 55 / 0 0 10 50 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...MWM LONG TERM...MWM AVIATION...ADK
Area Forecast Discussion
National Weather Service Mobile AL
512 PM CST Mon Dec 17 2018 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION... 00Z issuance...VFR conditions prevail through the remainder of this evening. Patchy fog, possibly dense at times, develops late tonight into early Tuesday morning. Fog dissipates after sunrise, with VFR conditions and light winds prevailing during the day Tuesday. /49 && .PREV DISCUSSION... /issued 358 PM CST Mon Dec 17 2018/ NEAR TERM /Now Through Tuesday/...A short-wave upper level ridge moves east over the deep south and deamplifies as it tracks over the southeast US Tuesday. In its wake, a high level southwest flow becomes established as next southern stream storm system digs across west TX late in the day. At the surface, axis of high pressure becomes positioned over the Appalachians by daybreak Tuesday, then from the New England States to the southeast US by the close of the day. Although high based cirrus spreads west to east over the deep south and Gulf tonight, it appears to be thin enough as to allow for radiative type late night fog to reform. Latest short range ensembles indicate a 40% or higher probability of visibilities lowering to 3 miles or less mainly along and north of I-10 late in the night to daybreak Tuesday. High resolution guidance (NAM12, RAP and to a lesser degree the HRRR) supports some potential of fog becoming locally dense in some areas. Overnight lows cool. With surface high more to the east on Tuesday, A light return flow setting up off the Gulf supports highs mostly in the mid 60s which is a few degrees above climatology on average. No rain forecast in the near term. /10 SHORT TERM /Tuesday night Through Thursday night/...A large upper level trough extending from the central Great Plains to southern Mexico, with an embedded closed low over north Texas, will slowly move eastward through midweek. The northern portion of the trough will merge with a fast moving shortwave moving east across southern Canada on Wednesday. As a result, the trough will become highly amplified just west of the Mississippi River, and extend from south central Canada to the Bay of Campeche by late Wednesday night. A deep southwest wind flow will bring moisture and clouds back over the forecast area midweek as the large upper trough to our west approaches the region. The trough will shift east of the Mississippi on Thursday, with the upper low and associated cold core between -22 to -27C at 500mb expected over the forecast area by late Thursday night. Meanwhile, a surface high pressure area over the eastern conus will shift eastward over the western Atlantic by noon Wednesday, setting up a return flow with low level moisture returning midweek. A weak surface low associated with the upper trough is expected to develop over the southern Mississippi River area Wednesday night, and move east as it deepens across the southeast states to 993mb by late Thursday night. The dry weather conditions across the forecast area will persist through Tuesday night, followed by increasing coverage in rain Wednesday afternoon and evening, with likely to definite categories in the forecast. This system has been trending stronger with each run, so have introduced a slight chance of thunderstorms over much of the forecast area Wednesday afternoon through Wednesday night. With the possibility of deeper convection developing with this system, widespread rainfall amounts with this system are now expected to range from 0.50 to 0.90 inch west of I-65, and from 0.90 to 1.4 inches to the east. Locally higher amounts between one to two inches are possible, mainly east of I-65. /22 LONG TERM /Friday Through Monday/...The upper level trough will eventually shift east of the area by the weekend, with the surface low lifting northward up the Appalachian Mountains. With the combination of wrap-around moisture in the wake of the system, the presence of the cold core aloft and low level lifting, kept scattered to likely light rain showers across the area Thursday and Thursday night. The light rain will come to end throughout the day Friday. Dry conditions will resume Friday night and over the weekend as high pressure builds back in from the west. /22 MARINE...Hazardous conditions for smaller marine craft by the close of the week. Surface low pressure system approaching the Mid- South late Wednesday moves slowly eastward thru the day Thursday, lifting up across the Appalachians by late Thursday and Friday while intensifying. This feature brings a strong frontal passage across the marine area late in the week as it passes by to the north. The passage of this feature and the strengthening pressure difference between the intensifying low and high pressure over east TX favors a strong west to northwest flow and much higher seas going into Thursday and Friday. Gale conditions possible over the open Gulf waters Thursday night into Friday. /10 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at:
Area Forecast Discussion
National Weather Service Pocatello ID
228 PM MST Mon Dec 17 2018 .SHORT TERM...current satellite imagery shows significant moisture in westerly winds advancing into the Washington and Oregon coast this afternoon. This will result in snow in the Idaho Central Mountains and Eastern Highlands Tuesday through noon Wednesday. Temperatures will moderate warmer with daytime snow levels Tuesday and again on Wednesday rising to 4200 to 4500 feet elevation. There is a slight chance of freezing rain developing during the morning hours around Richfield and Craters of the Moon, until surface temperatures increase above freezing from the morning lows. A mix of rain and snow is expected in the Magic Valley and Lower Snake Plain, thus limiting snow accumulations to generally less than an inch. Strong westerly winds at or just above the mountains ridge tops will contribute to blowing and drifting snow in mountain passes, especially Banner, Galena, Targhee, Raynolds, and Pine Creek Passes. Snow accumulation above 7000 feet in the Central Mountains will be around 4 to 7 inches with up to a foot on the higher peaks. For the Eastern Highlands from Swan Valley and Driggs to Macks Inn, accumulation of 4 to 6 inches is expected above 6000 feet elevation with local accumulations of up to 8 inches. A Winter Weather Advisory has been issued. A ride of high pressure begins to build in Wednesday morning. Thursday should be a generally dry day. RS .LONG TERM...Thu night through Christmas Eve. 500mb longwave is characterized by very weak flow throughout the period. The pattern changes from weak zonal to a very low amplitude trough in the center of the country. By Sun, weak ridging has moved overhead as the central US trough progresses to the Great lakes region. But with as weak as this flow is, the pattern will be dominated by the shortwave timing, which means low confidence for this period, with the potential for strong swings in the ECMWF and GFS guidance and the potential for large differences in the model solutions. Looking at details, the period starts with the upper level ridge breaking down and generating precipitation in the central Idaho mountains Thu night, on Fri spreading eastward and focusing mainly on the northern half of the forecast area. Fri night has a weak trough moving through southern Idaho, but the ECMWF has more precipitation along the border with Utah. This is a large swing from the overnight guidance, just as expected. The ECMWF continues wetter with this feature for Sat, over the entire forecast area. The largest and wettest storm of the week may come as early as Sun, if the ECMWF is correct, or Sun night, if the GFS is more accurate. Christmas eve day has another storm moving in from the west, and GFS is heavier with precipitation than the ECMWF. The bottom line is that it will be wet, but just where and how intense has a high degree of uncertainty. Messick && .AVIATION...Weak winter storm continues to be very slow in its eastward progression, so have had to delay onset of low cloudiness and precipitation by at least two hours, except that it has begun briefly at KSUN, which is closed to all but commercial air traffic right now. However, those showers should be slackening during the early afternoon and conditions there should improve until a second wave of clouds and precipitation arrives during the morning on Tue, around 18/13Z or so. HRRR guidance has really lowered precipitation amounts for this afternoon and evening, so a lot of the predominating marginal VFR and IFR has been eased off until the morning hours. Biggest threat in the morning is to KSUN and KDIJ, both of which could end up closed during the morning. KIDA is also a possibility, while the worst for KPIH is some IFR due to CIG. Finally, KBYI should stay good VFR. Wind is very weak, even with an actual trough moving through. Messick && .PIH WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 5 AM Tuesday to 11 AM MST Wednesday for IDZ064-066-072-073. && $$
Area Forecast Discussion
National Weather Service Topeka KS
503 PM CST Mon Dec 17 2018 ...AVIATION UPDATE... .SHORT TERM...(This evening through Tuesday) Issued at 251 PM CST Mon Dec 17 2018 A longwave upper-level trough is centered over the High Plains with broad surface ridging extending from southern Texas into northern Minnesota. This ridging has allowed for above-normal temperatures over the CWA today. A cirrus shield should move through the area, but won`t preclude plentiful radiational cooling. With that said, low temperatures tonight should remain in the lower 30s. Tomorrow, a lead shortwave trough will move through the area and associated warm air advection will overspread the area ahead of the lee surface trough. A mid level cloud deck is expected to move through the area ahead of the shortwave, although high temperatures throughout the CWA should remain in the mid-50s. .LONG TERM...(Tuesday night through Monday) Issued at 251 PM CST Mon Dec 17 2018 Warm air advection in response to a 20-25 kt LLJ, combined with a weak surface inversion should allow for warmer temperatures Wednesday morning with lows in the upper 30s. By Wednesday, a broader mid level trough is expected to deepen into the Southern Plains. Model guidance suggests that there is a chance for precipitation on Wednesday night through Thursday morning as a cold front moves southeast across central and eastern Kansas. Limited moisture return should limit precipitation amounts to less than 0.1 inches. A cyclone to the east and a anticyclone to the west will result in a tight pressure gradient on the order of 7-10 mb across the CWA. This tight pressure gradient combined with 850 mb winds upwards of 40-50 kts will yield sustained winds of 15-20 kts with gusts up to 30 kts. Upper ridging will deamplify by Saturday afternoon and zonal flow will remain in place until another shortwave trough traverses the area by Sunday afternoon. There is a slight chance for precipitation on Sunday evening, although there is considerable model discrepancy in this event happening. Temperatures are expected to remain above normal through the period with high temperatures in the lower 50s through Thursday and in the mid to upper 40s through Monday. Low temperatures will stay in the upper 30s to lower 40s through Thursday, dropping off to the 20s for the remainder of the period. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday) Issued at 503 PM CST Mon Dec 17 2018 Models show low level moisture advection holding off until Tuesday afternoon. So with dry air in place, VFR conditions are expected to continue with only some increasing high clouds. The RAP and NAM do show a low level jet of 25KT to 30KT developing overnight across north central KS. With a steep nocturnal inversion likely, think there could be some LLWS at MHK. Winds are progged to be slightly weaker at TOP and FOE, so will just monitor for LLWS further east. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Bunker/Baerg LONG TERM...Bunker/Baerg AVIATION...Wolters