Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/05/18

Area Forecast Discussion
National Weather Service Bismarck ND
952 PM CST Sun Mar 4 2018 .UPDATE... Issued at 942 PM CST Sun Mar 4 2018 Again, no major changes this evening. We did adjust pops/qpf for the tonight period, mostly after midnight with much lower pops/qpf west. Latest NAM and RAP keep minimal ice aloft tonight and into tomorrow morning across most all of the forecast area. However, think latest satellite and radar imagery, with surface reports indicate there is enough ice in the far north to generate snow. We used a blend of the latest NAM/RAP for ProbIce present but manually bumped up the ice in the north where we are seeing snow. This kept mainly light rain or light freezing rain/drizzle tonight most areas with snow increasing/ fzra decreasing Monday morning. As for overall snow amounts, this changed very little as we did not adjust Monday pops and this is where most of the QPF occurs. UPDATE Issued at 655 PM CST Sun Mar 4 2018 Main update was to lower pops during the evening period over the southwest. We also lowered temperatures this evening central. Otherwise no significant changes to the going forecast. Updated text products will be sent shortly. && .SHORT TERM...(This evening through Tuesday afternoon) Issued at 434 PM CST Sun Mar 4 2018 Currently, the upper level and mid level low was over eastern Montana. The surface low over eastern Colorado/western Kansas and Nebraska, with an inverted trough extending northward into eastern South Dakota and arcing back into western North Dakota. Fog and drizzle continued in the southwest, but convection with rain, freezing rain, and snow with scattered thunder developed this afternoon in an arc from Beach/Medora across north central North Dakota, into Jamestown/Fargo area. Hail was reported at Stanley, with pea sized hail in Minot. The upper low moves southeast towards eastern South Dakota by Monday afternoon. Meanwhile the surface low lifts northward into eastern South Dakota and becomes stacked with the upper low by Monday afternoon. This stacked system then moves southeast into Iowa by Tuesday morning, continuing east into the Ohio Valley by Tuesday afternoon. Weather headlines for western and central ND have been adjusted as follows: Winter Storm Warning in currently in effect from Crosby/Williston/Beach/Dickinson to Bottineau/Minot/Garrison. A Winter Storm Warning for Mandan/Bismarck to Jamestown/Ashley to Rugby begins daybreak Monday morning. A Blizzard Warning begins daybreak Monday morning for the far southwest and far south central including Slope/Bowman/Adams/Hettinger/Grant/Sioux counties. Expected snowfall map has been sent to our web page and social media, but basically has 2 to 5 inches over the far southwest, to 8 to 12 inches over the rest of western and central ND. Some locally higher amounts up to 15 inches or so are possible across central North Dakota once the snow tapers off Tuesday afternoon. The strongest northwest winds are forecast to develop in the southwest, where gusts to 50 mph are expected daytime Monday. .LONG TERM...(Tuesday night through Sunday) Issued at 434 PM CST Sun Mar 4 2018 Mainly zonal flow aloft develops after the main storm system is off to our east in the Ohio Valley and Great Lakes area. A minor shortwave in the flow may bring a slight chance of light snow Wednesday, then again Thursday, then another quick shortwave Friday night/Saturday. Expect highs in the 20s and 30s. Lows Tuesday night and Wednesday night zero to 15 above, with lows later this week in the teens. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 942 PM CST Sun Mar 4 2018 Widespread IFR/LIFR cigs and vsbys through the 00Z TAF period. Removed mention of Thunder from the TAFS this evening. Expect snow at KISN. KMOT will have a period of -ra/-fzra 00Z-02Z, then drizzle/fog through around midnight when any precip would be snow. Drizzle/fog expected at KDIK, KBIS and KJMS and KMOT through most of night and then transitioning to all snow Monday morning. Snow and Blowing snow with low visibilities will continue through the day Monday. && .BIS WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until noon CST /11 AM MST/ Tuesday for NDZ001>004-009>011-017>019-021-031>033. Blizzard Warning from 6 AM CST /5 AM MST/ Monday to 6 AM CST /5 AM MST/ Tuesday for NDZ040>045. Winter Storm Warning from 6 AM Monday to noon CST Tuesday for NDZ005-012-013-020-022-023-025-034>037-046>048-050-051. && $$ UPDATE...TWH SHORT TERM...JV LONG TERM...JV AVIATION...TWH
Area Forecast Discussion
National Weather Service Charleston SC
959 PM EST Sun Mar 4 2018 ...FROST/FREEZE CONDITIONS EXPECTED INLAND EARLY MONDAY MORNING... .SYNOPSIS... High pressure will remain over the region through Monday. A cold front will move through Tuesday night, followed by high pressure. A storm system could affect the region next weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Expanded the Frost Advisory to include Inland McIntosh, Long and Tattnall Counties. Also increased the freeze duration across the Freeze Warning area to 2-4 hours and introduced a few upper 20s. Still seeing signals for a possible brief, light freeze in the Adams Run-Hollywood-Delmar Crossroads-Parkers Ferry area in far interior lower Charleston County, but this area should remain too small to justify an upgrade to a Freeze Warning for all of Charleston County. See the updated summary of frost/freeze headlines below for more specific information. A surface ridge extending south from a 1042 hPa surface high centered over Ontario will hold firm over the region tonight. A large area of cirrus moving across the Lower Mississippi Valley into the Deep South should remain to the west tonight as the 500-300 hPa geostrophic flow is forecast to become more meridional with time in response to building heights over the Central Plains. Clear skies, low dewpoints and a decoupled boundary layer will promote strong radiational cooling through daybreak. Unfortunately, it appears an early Spring frost/freeze event is likely to occur across much of Southeast South Carolina and Southeast Georgia late tonight into early Monday. Here is a summary of the various frost/freeze headlines with specific information. * A Freeze Warning remains in force for Inland Colleton- Dorchester-Inland Berkeley. Some of this area saw temperatures at or just below freezing last night prior to arrival of a secondary wind surge before daybreak. With a more radiational component expected to dominate overnight, see no reason why another round of freezing temperatures will not occur away Lakes Marion and Moultrie along with scattered to locally widespread frost. In fact, the latest H3R and RAP output suggests a few spots could drop into the upper 20s/near 30. Expect a freeze duration of 2-4 hours. * Frost Advisory remains in force for Charleston and Tidal Berkeley. The risk for frost will be highest in the more rural areas inland of Highway 17 and outside the I-16 and I-526 corridors. This includes Adams Run, Hollywood, West Ashley outside of I-526, Park West and Awendaw. It should be noted both the RAP and H3R show a pocket of freezing temperatures occurring just before sunrise in the the Adams Run-Hollywood- Delmar Crossroads-Parkers Ferry region. Areas east of Highway 17 and inside I-526 should remain warm enough to prevent scattered frost development, but patchy frost can not be ruled out in sheltered spots. Opted to keep coastal Jasper and Beaufort Counties out of the Frost Advisory for now as any impacted area from scattered frost should remain quite small (i.e. north of Gardens Corner to near Yemassee and Pocotaligo). * A Frost Advisory remains in force for inland portions of Chatham, Bryan and Liberty Counties. With the boundary layer expected to decouple and a light north drainage wind prevailing through daybreak, this should allow temperatures to drop into the mid 30s and support scattered frost development along/west of I-95, possibly as far east as I-516 and the far western parts of the city of Savannah. * Maintained the Frost Advisory as is for interior Southeast Georgia, but expanded it south to include Inland McIntosh-Long and Tattnall Counties as guidance continues to highlight mid 30s in this area. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... Monday: Mid level ridging will persist over the region while the surface ridge decays during the day. Sunshine will prevail with a few mid or high clouds possible. Winds are expected to become light and variable during the afternoon. Temps will be a bit milder over GA zones with afternoon readings ranging from the low to mid 60s north to upper 60s south. Lows Monday night will be quite tricky and dependent on both overnight cloud cover and how fast evening temps radiate before late night warm air advection begins to negate those radiational processes. We remained a bit lower than most guidance over normally cooler inland zones with lows in the low-mid 40s. Tuesday: Models remain in good agreement that a cold front will approach from the northwest, reaching the CSRA and SC Upstate late in the day. Our area will see an increase in deep layered moisture while a decent surge of 850 MB theta-e was noted on rather sharp advection gradient prior to mid afternoon. Advancing rains are expected to be of convective nature but almost no elevated instability progged suggests little to no tstm risk, despite a slug of upper forcing associated with the right entrance region of a jet streak moving through the Carolinas. We think that this lack of instability and PWATs close to 1 1/4 inch will tend to keep QPF amounts below 1/2 inch and some locations may not see 1/10 inch of QPF. We timed POPs inland from mid morning inland to coastal areas in the afternoon. Since the highest rain chances should be over southern and western zones earlier in the day, we maintained highs in the mid 60s there to some 70-71 degree maxima along GA coastal zones. The cold front will push through mainly during the evening Tuesday night and then offshore after midnight. Rain chances will diminish overnight with clearing skies from west to east late. Lows will be in the mid 40s most locations. Wednesday: Post-frontal environment will be conducive to increasing offshore winds as the mixed layer deepens under mainly sunny skies. Cold air advection will be offset just a bit by the downsloping wind component with highs in the 64-68 degree range. We bumped wind speeds up and will probably continue this trend given the synoptic setup, certainly expecting a breezy day all areas. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... A broad upper trough will prevail Wednesday night through Friday while cool Canadian high pressure expands across the eastern half of the country. Dry weather and below normal temps are expected. A potent upper trough may approach next weekend while the surface high moves offshore. Temperatures should warm up considerably due to southerly low-level flow. Low pressure moving out of the Gulf could bring unsettled weather at some point next weekend. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... VFR. Extended Aviation Outlook: A cold front will sweep across the area Tuesday evening, bringing showers and possible brief flight restrictions. Gusty offshore winds are expected on Wednesday. && .MARINE... Tonight: High pressure will extend south from Canada and maintain control of the local weather. North/northeast flow will continue to subside through the night as the pressure gradient relaxes, with speeds 10-15 knots on average. Seas will take longer to diminish, so the Small Craft Advisory will continue for the Georgia offshore waters. Improving marine conditions are expected Monday and Monday night as a lighter north flow is on tap through early afternoon Monday afternoon, prior to a period of light and variable flow Monday Night. Seas will remain elevated over offshore waters where an SCA is expected to linger over GA waters 20-60 NM, although seas could briefly fall below 6 ft closer to the Gulf Stream late Monday Night or early Tuesday. On Tuesday, a southwest flow will develop ahead of a cold front but speeds should be capped below 20 kt by a stable and cool marine environment. The front will move offshore Tuesday Night with a surge of offshore flow into Wednesday Night with potential for significant jetting conditions in favored locations. SCA conditions could develop across near shore waters late Tuesday Night and persist during the Wednesday and Wednesday evening time frame. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...Frost Advisory from 3 AM to 9 AM EST Monday for GAZ087-088- 099>101-114>116-118-137-138-140. SC...Frost Advisory from 3 AM to 9 AM EST Monday for SCZ040-042-047- 050-052. Freeze Warning from 3 AM to 9 AM EST Monday for SCZ043>045. MARINE...Small Craft Advisory until 6 AM EST Friday for AMZ374. && $$
Area Forecast Discussion
National Weather Service Cheyenne WY
505 PM MST Sun Mar 4 2018 .SHORT TERM...(This evening through Tuesday night) Issued at 239 PM MST Sun Mar 4 2018 Winds are the primary challenge in the short term as we deal with a Gap wind event followed by a Bora wind event for the Panhandle Monday. Starting off today...Frontal boundary lays along the east slopes of the Laramie Range this afternoon. East of the front, we have been dealing with northeasterly upslope winds and low stratus over the Panhandle all day long. Chadron, Lusk and Alliance have been reporting ceilings below 1K feet all day. West of the front out by Arlington and Rawlins, snow is falling and winds have been up at times. Had a few gusts earlier that were strong at Halleck Ridge (110) and Herrick Lane (115) for one time gusts, but they have since eased off. Upper shortwave seen on water vapor beginning to work into Carbon County this afternoon with snow seen on METARS and webcams from Rawlins to Arlington. Right now, roads look ok with no snow covered roads seen yet. For late this afternoon and evening, looking at winds to continue increasing. Craig to Casper 850/700mb height gradients increase to 70/52 mtrs respectively at 00Z and remain up near 60mtrs through the overnight hours. Would expect winds to begin increasing late this afternoon and become more widespread. Widespread 700mb winds on the GFS at 50kts this evening, so think the High WInd Warning at Arlington still has a chance of verifying. Evening shift will need to monitor the Laramie Valley out by Quealy Dome and Rock River to maybe include this zone in the warning as well. The increasing westerly winds along with the passage of the upper low will force the surface boundary east through the overnight hours with winds shifting to the northwest as this happens. 700mb temperatures fall from 0C across the southern Panhandle this afternoon to -12C by midnight tonight. 850mb winds begin to increase with the cold air advection and downward motions behind the front. By 12Z Monday, GFS winds over the Panhandle are out of the northwest at 45-50kts that continue most of the day Monday. As a result, do think the High Wind Warnings look good on timing and aerial extent and will keep them as they are. MOS guidance for most points in the Panhandle showing 36kts sustained on the GFS with about the same on the NAM. Later shifts will want to take a look at Tuesday as MOS guidance suggests another high wind event in the Panhandle, though not as strong as tomorrows event, there could still be a few places hitting 60mph on gusts. .LONG TERM...(Wednesday through Sunday) Issued at 239 PM MST Sun Mar 4 2018 A mostly dry period ahead with temperatures at or above values typical for the first half of March. Northwest flow to prevail Wednesday and Thursday as the early week system departs towards the Great Lakes & northeast. Near normal temps on Wednesday warm back above normal for Thursday and Friday. Thursday looks breezy with wind gusts in the 35-50 mph range across southeast Wyoming along and west of I-25. Flow backs to more westerly for Friday as a clipper system splits as it dives southeast into the Dakotas. At this point, impacts look minimal with a shot of snow into the SE Wyoming mountains Friday night-Saturday and perhaps a period of snow spillilng out on the plains on Saturday. This clipper system will usher in an air mass more seasonally typical in time for next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 505 PM MST Sun Mar 4 2018 HRRR depicts an area of snow showers developing south of the Black Hills and moving quickly southeast across the central and northern Nebraska Panhandle by late evening. Included a period of snow showers with vsby and cigs down to IFR Alliance to Chadron as there is some model consensus in the short term of this happening as colder air aloft moves in from the northwest creating some steeper lapse rates aloft. We also have ongoing snow showers moving through the Rawlins area this evening that will bring them down in brief periods to LIFR in visibility, however that should trend downward through the course of the overnight period. Otherwise, expect MVFR to VFR Laramie, Cheyenne, Scottsbluff and Sidney. Other main concern will be increasing wind speeds late tonight into Monday morning as subsidence kicks in and we gusts around 50 kts through Monday, especially for Cheyenne and across the Nebraska Panhandle. && .FIRE WEATHER... Issued at 245 PM MST Sun Mar 4 2018 Poor humidity along and south of a line from Pine Bluffs to Cheyenne to Laramie this afternoon as downsloping winds continue off the Laramie Range. Elsewhere, westerly winds increasing west of Laramie with fog and stratus over the northern Nebraska Panhandle. Expect winds to increase this evening into Monday as a cold front currently laying along the eastern plains into the Panhandle gets forced back east. Widespread strong wind event for the Panhandle and areas east of the Laramie Range for Monday. Elevated westerly winds are expected to continue over southeast WYoming and Nebraska Panhandle through Tuesday && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Warning from 8 AM to 8 PM MST Monday for WYZ102-108- 119. High Wind Warning until 8 PM MST Monday for WYZ106-107-110- 116>118. Winter Weather Advisory until 6 AM MST Monday for WYZ112-114. NE...High Wind Warning from 8 AM to 8 PM MST Monday for NEZ002-003- 019>021-054-055-095-096. && $$ SHORT TERM...GCC LONG TERM...CAH AVIATION...JG FIRE WEATHER...GCC
Please see the 00Z aviation forecast discussion below.

&& .AVIATION... A few showers continue early this evening, with coverage low enough to only mention VCSH at AUS for the next few hours. Otherwise, all sites are VFR and this is expected to continue into the early evening hours. As low-level moisture increases, clouds will thicken and conditions will drop to MVFR between 03-04Z along I-35. Cigs will continue to lower overnight into early Monday morning as the low- levels continue to moisten and -DZ and BR form. Some improvement is in store mid to late morning as daytime heating increases. Low-level winds may be slow to increase through the morning hours and prefer to show a very gradual improvement at this time. A cold front will move through during the afternoon and this will help to lift cigs for early afternoon. While we do expect some convection along the front, the hi-res models struggle to develop decent coverage along the front. For now, we will not mention any convection and await the 00Z guidance. If anything, it appears AUS may be favored for storms in the 19-22Z time frame. && .PREV DISCUSSION... /ISSUED 402 PM CST Sun Mar 4 2018/ UPDATE... Increased PoPs in the eastern CWA this afternoon and early evening given radar trends currently showing a bit more coverage than initially anticipated. Also seeing a fair amount of lightning activity due to these cells tapping into over 1000 joules of MUCAPE CAPE per the RAP Mesoanalysis and strong mid-level lapse rates. These cells will likely stay elevated however due to strong capping at the 700 mb level. PREV DISCUSSION... /ISSUED 246 PM CST Sun Mar 4 2018/ SHORT TERM (Tonight through Monday Night)... Upper air analysis this morning showed a ridge over the middle of the country with the ridge axis extending northward from East Texas. Flow over South Texas was from the south-southwest. Surface winds were from the south to southeast. Dewpoint temperatures have increased 5 to 10 degrees over the last 24 hours. This warm, moist flow will keep a slight chance for rain tonight across the eastern half of our CWA. A cold front will move through the region Monday. It should reach our southern border by mid-afternoon. This will bring a line of showers and thunderstorms through the area. The best chances will be during the day Monday across eastern half moving from north to south. Better chances will shift to the southeastern part of the CWA Monday evening. LONG TERM (Tuesday through Sunday)... Low end chance POPs will linger into Tuesday along the our southern border. Drier air will move in behind the front. Low level flow will be north to east through Thursday keeping the weather dry into the middle of the week. Temperatures will climb slowly through this period. Another Pacific cold front will approach Central Texas Friday and bring slight chances for showers and thunderstorms across the eastern half of the area. This front will move through our CWA Saturday bringing an end to any rain chances. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 67 79 47 71 44 / 20 60 20 0 0 Austin Bergstrom Intl Airport 67 78 47 70 42 / 20 60 20 0 0 New Braunfels Muni Airport 67 78 49 71 44 / 20 60 20 0 0 Burnet Muni Airport 65 75 44 69 39 / 10 40 - 0 0 Del Rio Intl Airport 63 83 51 74 49 / - 0 0 0 0 Georgetown Muni Airport 66 76 44 70 40 / 20 50 10 0 0 Hondo Muni Airport 66 83 51 74 45 / 20 30 - - 0 San Marcos Muni Airport 67 78 48 71 44 / 20 60 20 0 0 La Grange - Fayette Regional 68 80 49 70 44 / 20 70 30 - 0 San Antonio Intl Airport 68 81 52 72 46 / 20 50 20 - 0 Stinson Muni Airport 68 82 54 73 48 / 20 50 20 10 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...24 Synoptic/Grids...TB3 Public Service/Data Collection...33
Area Forecast Discussion
National Weather Service Grand Forks ND
947 PM CST Sun Mar 4 2018 .UPDATE... Issued at 947 PM CST Sun Mar 4 2018 Band of precipitation currently extends from the northern Red River Valley into west central MN, right along the low level jet and good mid-level frontogenesis. Mid level lapse rates have decreased in the last few hours so thunder threat has diminished. Reports so far have been a mixed bag of sleet, snow, rain, freezing rain. Temperatures in the northern counties are most likely to be freezing both air and road, while many spots further south have stayed warmer. Think that between precip bands there will be the possibility of drizzle or freezing drizzle. The HRRR has the next round of radar detectable precip moving into our southern counties in the next few hours, and looking at radar returns developing over eastern SD it doesn`t seem too far out of the question. Tweaked QPF, lowering amounts a bit in the far northeastern counties where they have not seen much due to dry easterly winds, and raised them in the central counties where the first round has moved through and the next round will come in later tonight. With temperature profiles all over the place and some dry air aloft moving in at times that could nix anything coming out of good ice developing layer, the mixed precip threat will continue for much of the night, with some ice accumulations possible. Adjustments to snow amounts still seem on track to keep our warnings and advisories as they are for now. && .SHORT TERM...(This evening through Monday) Issued at 315 PM CST Sun Mar 4 2018 Convection is developing already...from portions of western ND down into southeast ND. As the low level jet kicks in tonight, this will lift from south to north. If any intense rain falls on icy, snow covered areas with poor drainage, there may be some ponding of water. The transition from rain to snow should occur late tonight into Monday...becoming heavy at times. Currently thinking the most snow will be west of the Red River, where 6 to 8 inches is possible. Less snow to the east, but there could be some mixed pcpn and wind in these areas. Blowing and drifting still looks spotty...due to the cross valley flow and need of falling snow to have. Keeping AFD abbreviated due to busy time. .LONG TERM...(Monday night through Sunday) Issued at 315 PM CST Sun Mar 4 2018 The beginning of the long term period will finally bring the end of the early week storm. By Monday night, the main surface low looks to be centered somewhere in the vicinity of northeastern South Dakota/west central Minnesota with an inverted trough back through central North Dakota. Temperatures will finally cool enough for any lingering mixed precipitation to change to all snow across the area. The low is progged to slowly slide off to the south and east throughout the day on Tuesday with precipitation gradually tapering off from north to south early in the day. Winds will gradually turn to the northeast but look to be pretty tame as the pressure gradient relaxes so any blowing of fresh snowfall should be minimal. Surface high pressure then builds into the northern Plains by midweek with northwest flow aloft. A few weak waves passing through the upper flow aren`t out of the question through the second half of the week with some minor precipitation chances. Slightly below normal temperatures look to creep closer to normal by the end of the period. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 642 PM CST Sun Mar 4 2018 Strong storm system bringing spring like weather this evening before winter returns tomorrow. Central and western TAF sites seeing some convection with thunder reported as rain showers lift northward. Low level jet has been cranking up to 50 kts so included that in the KGFK, KFAR, and KTVF sites this evening. The showers will lift northward out of the TAF sites in the next few hours, and there will be a bit of a break with only some lingering -RA or -DZ before heavier precipitation moves back in during the early morning hours. Temperatures will have fallen by then, so there could be a mixed bag of -RA, -FZRA, or -SN going on. Precip will change over to all snow by the end of the period, with visibility across the central and western TAF sites under 1SM. Winds will stay out of the east to southeast but be quite breezy, with gusts above 30 kts at times during the later half of the period. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Winter Storm Warning from 6 AM Monday to 9 AM CST Tuesday for NDZ006>008-014>016-024-026>030-038-039-049-052>054. MN...Winter Storm Warning from 6 AM Monday to 9 AM CST Tuesday for MNZ001>004-007-008-013>016-022>024-027>032-040. Winter Weather Advisory from 3 AM Monday to 9 AM CST Tuesday for MNZ005-006-009-017. && $$ UPDATE...JR SHORT TERM...Godon LONG TERM...Lee AVIATION...JR
Area Forecast Discussion
National Weather Service Pendleton OR
738 PM PST Sun Mar 4 2018 .SHORT TERM...Tonight and Monday...KSEW radar and observations from Stampede Pass indicate light snow spreading over Easton, Roslyn and Cle Elum along I-90 this evening. KPQR radar shows showers moving through Trout Lake and near Glenwood. KPDT radar shows rain showers from Ione to Condon moving east as well as isolated snow showers developing in the Blue Mountains this evening. Snow showers becoming numerous overnight in the northern Blue Mountains with snow accumulations in the northern Blues of 2-4 inches by late Monday morning. The 01Z mesoscale HRRR model shows: 1. orographic rain showers developing along the WA foothills of the Blue Mountains by 8-9 pm this evening. Rain showers are expected to continue off and on through tonight into monday morning from Walla Walla to Waitsburg. Rain showers changing to snow showers before daybreak in Dayton. 2. snow showers ending in the northern Blue Mountains by around 6 AM Monday. Polan && .PREVIOUS DISCUSSION... /issued 150 PM PST Sun Mar 4 2018/ SHORT TERM...Tonight through Wednesday. No major weather concerns are anticipated during the short term. Snow showers this afternoon have been observed in our far northwest corner of the forecast area along I-90 west of Cle Elum as well as isolated snow showers along the Blue Mountains. Snow showers will increase tonight as a shortwave moves southeast across Washington and northeast Oregon. The shortwave is currently over the Olympic Peninsula. Showers will increase along the east slopes of the WA Cascades and the Blue Mountains north of Ukiah and the Wallowa Mountains. Snow accumulations of 1-3 inches are forecast for these areas tonight. The Blue Mountain Foothills north of Pilot Rock may get rain/snow mix or snow accumulations up to 1/2 inch. The remainder of the forecast area will have little to no snow tonight. After the passage of the shortwave early Monday morning, the forecast area will be under a northwest flow aloft. Snow showers on Monday will be scattered orographic mountain snow showers across eastern Washington and northeast Oregon with up to 2 inches additional accumulations. Weak high pressure will follow for dry conditions Monday night through Wednesday. Increasing heights will mean increasing temperatures, and highs on Tuesday and Wednesday will be near seasonal. That is, highs in the 40s over the mountains and in the mid 40s to mid 50s in the lower elevations. Clouds will increase across the region Wednesday afternoon ahead of the next system. Winds will also increase in the Grande Ronde Valley with gusts around 30-35 mph Wednesday afternoon. Wister LONG TERM...Wednesday night through Monday morning...Operational models are in reasonable agreement in a return to a more active weather pattern late Wednesday night through Friday night. The first system will arrive from the southwest late Wednesday night bringing at least chances for rain and mountain snow with snow levels near 4000 feet. This system will be closely followed by another disturbance arriving from the northwest Thursday evening with an additional round of lower elevation rain and higher elevation snow expected. Pressure gradients appear more substantial with the second system, especially over central Oregon where breezy to locally windy conditions are likely Thursday evening into Friday morning. Snow levels will briefly fall to 1500-2000 feet on the heels of the second system, but any lingering showers will be limited to the mountains by this time. Transitory ridging will build in for the weekend with clearing skies and lower elevation highs approaching 60 degrees by Sunday. 74 AVIATION...00Z TAFs...VFR conditions expected through the period. Approaching upper level disturbance will spread additional mid and upper level cloudiness across the area this afternoon. A combination of forcing ahead of this feature, steepening mid-level lapse rates and existing cumulus field over the mountains will result in some spotty mountain precipitation. This activity will generally not impact the terminals except at ALW and possibly PDT where a sprinkle or two may be seen during the overnight. Winds generally less than 12KTs except at PDT where occasional gusts into the low 20s will persist for the next couple hours. 74 && .PRELIMINARY POINT TEMPS/POPS... PDT 32 50 29 51 / 20 10 0 0 ALW 36 51 34 53 / 30 20 10 0 PSC 32 54 30 54 / 10 10 10 0 YKM 28 52 28 53 / 10 0 0 0 HRI 33 53 30 53 / 10 10 0 0 ELN 30 47 29 49 / 20 10 10 0 RDM 22 46 22 53 / 10 0 0 0 LGD 27 41 25 44 / 30 30 10 10 GCD 25 42 24 47 / 10 10 0 0 DLS 35 53 33 57 / 10 10 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ 99/85/74
Area Forecast Discussion...UPDATED
National Weather Service Shreveport LA
603 PM CST Sun Mar 4 2018 .AVIATION... VFR cigs over E TX//Wrn LA/SW AR early this evening will begin to gradually lower to MVFR by mid to late evening over these areas, with isolated to widely sct -SHRA possible this evening over E TX/SE OK/SW AR, near and N of a warm front that will continue to shift N into extreme NE TX and Nrn LA by late evening. However, any -SHRA are not expected to reduce vsbys much if at all, with rainfall amounts light, as it diminishes quickly from W to E across the area later tonight. MVFR cigs should eventually shift ENE into Scntrl AR affecting ELD around 08Z Monday, and across the Ern sections of Ncntrl LA affecting MLU around 12Z. Could also see areas of -RA redevelop from the SW over Deep E TX and quickly spread NE across N LA/SW AR by/after 12Z, with cigs lowering further to low MVFR, and even some brief IFR cigs possible as well before slowly lifting by mid to late morning. However, MVFR cigs should linger through the remainder of the TAF period as moisture pooling continues ahead of a cold front that will enter Wrn AR/extreme NE TX around midday, and slide SE across much of E TX/SW AR and into NW LA by mid-afternoon. Sct convection is expected to develop by 19-21Z over lower E TX/N LA along and just ahead of the front, possibly affecting LFK, SHV, and MLU before diminishing from NW to SE as drier air spills SE in wake of the fropa. Should also see MVFR/low VFR cigs quickly scatter out over extreme NE TX/portions of SW AR by mid-afternoon as well, with this trend continuing to spread farther SE across the remainder of the region during the evening in wake of the fropa and sct convection. SSE winds 5-11kts tonight will become SSW 10-15kts with gusts to 21kts over NE TX/SW AR by Monday afternoon. /15/ && .PREV DISCUSSION... /issued 345 PM CST Sun Mar 4 2018/ DISCUSSION... A progressive day with the upper level impulse working East a little ahead of schedule with decks of clouds stretching from SE OK into NE LA, but elsewhere we have some really good breaks in NE TX and portions of N LA. Rain wise an arc of light showers stretches over NE TX into N LA where returns are strongest, but still no lightning in the last almost hour. A little cell on the stateline near Springhill at 2050Z was the last strike in our area. Of course a few more isolated thunderstorms may develop as the surface warm front is now lifting in early too with low 60 dew points from Tyler to Lufkin and Nacogdoches. Models may have to play catch up after the new soundings are in, but even HRRR still develops showers this evening into the I-30 corridor where our highest pops remain at this time. The WPC has backed off of our QPF ahead of the front for early Monday and it looks as though we will continue with a high pop low QPF event as a result. So in short it is likely going to rain, just not very much which bodes well for our rivers and bayous running bankfull. The frontal timing will tap heating tomorrow with warmer temperatures streaming in behind the warm front. SPC continues a marginal risk for severe thunderstorms which may see some large hail and then bring in a wind threat for any bows or clusters that manage to develop during the heat of the day. The will be progressive ahead of the front and help limit QPF. The Southerly winds will be shifting to NW by around lunch in our Western most counties and may even shift for Lufkin and Monroe by sunset. The remainder of the work week will see high pressure of around 1020mbs build in behind the front. Then a reinforcing airmass of 1036mbs will keep to our North, but stretch down under the NW flow and arrive by midweek with just some clouds and no rain. Our next rain event will arrive late Friday and for Saturday with some improvements perhaps for Sunday. Still our total 7 day QPF is not much more than an inch plus for the East and lesser amounts in OK/TX of a tenth to half inch. Just to note the long range GFS/ECMWF models have been flipping back and forth a bit over the last couple of days for next weekend, so we should work toward better vision for the event duration with more time and subsequent runs. /24/ && .PRELIMINARY POINT TEMPS/POPS... SHV 57 75 46 67 / 30 60 20 0 MLU 54 75 47 68 / 40 60 50 10 DEQ 51 73 38 64 / 60 60 0 0 TXK 54 73 42 65 / 40 60 10 0 ELD 52 72 42 66 / 50 60 10 0 TYR 63 75 44 66 / 30 40 10 0 GGG 60 75 44 66 / 30 60 10 0 LFK 63 79 48 69 / 30 80 40 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 15