Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/19/18

Area Forecast Discussion
National Weather Service Denver/Boulder CO
822 PM MDT Sun Mar 18 2018 UPDATE Issued at 708 PM MDT Sun Mar 18 2018 Issued a Winter Weather Advisory for the Denver area, southern foothills, eastern Adams, and eastern Arapahoe, and Washington counties. With the earlier change over to snow expect snowfall amounts of 2-5 inches in the Denver area. Roads are being slushy in places, mainly at slightly higher elevations. As temperatures falls and with the loss of sunshine, most roads should become slushy or snow covered and be slippery this evening. UPDATE Issued at 620 PM MDT Sun Mar 18 2018 Strong spring storm will race across the region tonight. Precipitation west of I-25 has changed to snow or will shortly in the few locations it hasn`t. Nudged snowfall amounts up a little to reflect the earlier change over the snow. This puts snowfall amounts in the 2-4 inch range for the Denver area. HRRR and RAP models show the precipitation ending in the metro area around or a little before midnight. If the heavy precipitation rates linger for a few hours or if it appears snow will last a little longer may need to expand the winter weather advisories. && .SHORT TERM...(This evening through Monday) Issued at 258 PM MDT Sun Mar 18 2018 Satellite pictures are showing an oblong circulation right over the four corners at the bottom of the upper trough to our west. Convection is breaking out over the high mountains and foothills and Palmer Ridge at this time. There is a bit of lightning detected over southwestern Larimer County. The cloud shield of the system is slow to get across the CWA. Have been backing off/delaying the cloudiness on the GFE grids all day. The wind field over the plains shows mainly northeasterlies in place at this time. The 12Z models all show an upper closed low over the northeastern corner of the Texas Panhandle at 06Z and over southeastern Kansas at 12Z. I suppose it better get moving. Weakening zonal flow aloft is progged all day Monday. The strongest QG ascent is progged at 00Z late this afternoon. The system is moving quickly and by 06Z-09Z tonight downward energy is in place over the CWA; pretty strong too. The low level winds are progged to be north-northeasterly into mid evening, then more north-northwesterly for the rest of tonight. They are due northerly all day Monday. Moisture-wise, there should be plenty over the CWA tonight, and fairly deep as well. Models have quite a bit still around on Monday too. The QPF fields have measurable precipitation across all of the the CWA tonight. There is some in the high mountains all day Monday. Overall, the 12Z model runs showed a bit less precipitation than the previous runs. Will keep the current highlights going as is. Strong wind gusts will cause havoc to travelers later tonight with blowing snow. Areas under decent convection could see more precipitation and snow then is expected otherwise. Monday`s highs will be about 10-15 F below normals for the plains and foothills. .LONG TERM...(Monday night through Sunday) Issued at 238 PM MDT Sun Mar 18 2018 By Monday night, the upper level trough will push eastward bringing NW flow over the state. Conditions on the plains will be dry, but some light snow will continue in the mountains with model cross sections showing decent mid level moisture through the morning hours. Less than an inch in accumulations will be possible. Tuesday and Wednesday will see upper level ridging increasing bringing a period of dry conditions and warming temperatures. Temperatures should rebound back to above normal conditions with highs in the 60s. The next weather system will be moving onshore over the western coast by Thursday with continued ridging over the state. WAA will increase 700mb temps in the +6-7C range. This will give surface temperatures on the plains of lower 70s, the warmest day of the week. In the mountains, increased subtropical moisture from the SW ahead of the trough will bring increased chances of light rain and snow to the western slopes through the day Thursday. Thursday night into Friday and upper level shortwave combined with some CAA from the WNW will help to bring cooler temperatures and accumulating snow to the mountains Thursday night into Friday. A deep surface low over the CO/KS border will help to maintain dry conditions on the plains through Friday morning according to the GFS. The EC is slightly slower with the progression of the upper level energy that could bring a slight chance of rain to the plains by Friday afternoon. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 815 PM MDT Sun Mar 18 2018 IFR and LIFR cigs and vsbys due to snow and fog exist at all Denver area air terminals as of 02z/Monday. These conditions are expected to improve first across northwest portions of the metro area such as at KBJC within the next few hours, then at KDEN by around 07z/tonight, followed by KAPA an hour or two after that. Roads and runways could become snow and/or slush covered with slowly falling temperatures, if they haven`t done so yet. However, road surfaces remain rather warm, so serious ice accumulation is not anticipated. Should see MVFR conditions at all airports by 10z tonight and VFR conditions on or before 12z/Monday with this latest storm system racing off to the east. Winds are forecast to remain northerly overnight at sustained speeds of 10-22kts, with higher gusts in the 20-30kt range prior to 07z tonight. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 AM MDT Monday for COZ035-036- 039>041-045-046-049. Winter Weather Advisory until noon MDT Monday for COZ031-033-034. && $$ UPDATE...Baker SHORT TERM...RJK LONG TERM...Bowen AVIATION...Baker
Area Forecast Discussion
National Weather Service Fort Worth TX
906 PM CDT Sun Mar 18 2018 .UPDATE... The storms that moved through North and Central Texas early this evening have either dissipated or moved to the east. The remainder of the evening will be quiet overall. However, we will see an increase in winds as a cold front translates from west to east across the region. A few showers and storms may accompany the cold front overnight, mainly across the east/northeast zones where moisture and instability will be the most abundant. Severe storms are not expected with the overnight activity. Have sent an update to the forecast to remove Severe Thunderstorm Watch 11 from all counties and remove PoPs from all but the eastern zones. No other major changes were made. 79 && .AVIATION... /Issued 659 PM CDT Sun Mar 18 2018/ /00z TAFs/ With scattered convection moving quickly east of the I-35 corridor, VFR conditions will prevail across North Central Texas - with wind becoming the primary impact Monday. A strong mid-level shortwave trough exiting the southern Rockies this evening will zip eastward into Mississippi Valley by Monday afternoon. This will create a strong, deep westerly flow regime across the region by mid-morning Monday. Westerly surface winds should increase to 20 knots sustained at the DFW-area TAF sites, gusting at times in excess of 30 knots from 16z through 00z. These winds will veer gradually to a NWly direction through the afternoon, creating some potential crosswind issues at KDFW for several hours. The gradient will be slightly weaker across Central Texas, and have backed off the wind speeds at KACT accordingly for Monday. Other than some scattered mid/high level cloudiness streaming eastward across the region tonight, VFR conditions will persist through Monday night. Bradshaw && ..SHORT TERM... /Issued 333 PM CDT Sun Mar 18 2018/ /Through Tonight/ Main concern through the short term is the potential for isolated strong/severe thunderstorms this afternoon and evening. Much uncertainty still surrounds the next ~8 hours of the forecast, largely due to the stubborn bank of low clouds that have been slow to scatter through midday. Ingredients are in place for some thunderstorms to become severe this afternoon, should they be able to develop. The uncertainties lie largely on the coverage of storms and the most favorable location for initiation. A pair of shortwave troughs are currently moving through the Southern Plains. A deep surface low resides in southeast Colorado while a more ill-defined low exists across the San Angelo/Abilene area. A surface dryline is positioned southward through the surface trough axis, and a stalled frontal zone is draped from east to west through North Texas. The warm sector bounded by these features has begun to destabilize with gradual clearing starting to take place across our western zones where temperatures have climbed into the low 80s. When combined with dewpoints in the 60s and very steep lapse rates aloft (as illustrated by the FWD 18z sounding), these conditions are yielding a narrow tongue of large SBCAPE values immediately ahead of a westward-bulging dryline. As lift increases with height falls from the nearby shortwaves along with low-level convergence near the boundaries, we should start seeing attempts at convection. Areas that have cleared immediately along the dryline may destabilize sufficiently to break the cap or eliminate it entirely, whereas areas to the east have remained capped due to the presence of widespread low clouds and substantially cooler surface temperatures. As a result, am thinking the greatest potential for convective initiation will probably be along the dryline and near the triple point intersection with the stalled front. With strong instability and 50-60 kts of deep layer shear, a supercellular storm mode is likely. If supercells can develop in this area and move eastward into the warm sector, they will be capable of surviving as elevated supercells within a capped environment with primarily a large hail threat. If some clearing/heating occurs through late afternoon farther east in the warm sector, a wind/tornado threat would also accompany storms if surface based instability exists. The weakly capped environment may actually act to enhance the severe potential if stronger isolated storms can get going. A weak cap would suppress weaker convective attempts, allowing stronger isolated supercells to progress eastward unimpeded. The above scenario is supported by the most recent runs of the HRRR and a couple other CAMs. However, on the whole, high- resolution models remain wildly inconsistent with much disagreement regarding convective initiation locations and coverage. Some models are developing practically no convection at all, which I also have to admit is a realistic scenario if enough lift/instability is not realized. The most likely scenario is probably a couple of discrete storms developing across west/northwest portions of the forecast area which will move eastward with a potential for large hail. Any convection will move east fairly quickly and exit the area by midnight or so at the latest. Overnight, the dryline/Pacific front boundary will surge eastward bringing much drier low-level air through the entire region. This will scour the low level moisture leading to a cooler Monday morning with some breezy west winds. -Stalley && .LONG TERM... /Issued 333 PM CDT Sun Mar 18 2018/ /Monday through Sunday/ A strong surface low will move east from northeastern Oklahoma into Tennessee during the day Monday. The resulting pressure gradient will lead to gusty westerly winds which will become northwesterly during the afternoon as another cold front moves through the region. Skies will be mostly sunny and highs will range from the upper 60s northwest to around 80 degrees southeast. The combination of 20 to 25 mph winds with gusts over 35 mph at times, and minimum relative humidities in the upper teens and 20s will mean critical fire weather conditions across the western parts of the forecast area with elevated fire weather conditions elsewhere. Wind speeds will be slow to decrease Monday night with northwest winds 15 to 25 mph prevailing with some gusts over 30 mph. Lows will be mostly in the 40s. An upper level ridge will build across the Rockies early to mid week and then move into the Plains late in the work week as an upper level low moves east to off the East Coast by late week. This will result in dry weather across North and Central Texas for the upcoming work week. It will be cooler Tuesday with highs in the 60s. As a surface high moves east, moderating temperatures will occur Wednesday through Friday. Highs will be in the upper 60s to mid 70s Wednesday, 70s to lower 80s Thursday, and mid 70s northeast to upper 80s west Friday. Southerly winds will increase Thursday and Friday and despite increasing humidities, elevated fire weather conditions may occur across the western counties. With the continued southerly flow and a weakening upper level ridge next weekend, there will be low chances of showers and thunderstorms along and east of I-35 Saturday and most of the region on Sunday. Warmer than normal weather will continue with highs mostly in the 80s and lows in the 60s. 58 && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 56 78 46 65 44 / 5 0 0 0 0 Waco 52 79 45 67 42 / 5 0 0 0 0 Paris 53 73 45 62 41 / 20 0 10 5 0 Denton 51 74 43 65 42 / 5 0 0 0 0 McKinney 51 74 44 63 42 / 5 0 0 0 0 Dallas 56 76 46 66 45 / 5 0 0 0 0 Terrell 53 75 45 65 41 / 10 0 0 0 0 Corsicana 55 77 46 65 43 / 5 0 0 0 0 Temple 51 78 45 69 43 / 5 0 0 0 0 Mineral Wells 50 75 41 65 40 / 0 0 0 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Monday morning through Monday evening for TXZ100-115-116-129-130-141>143-156-157. && $$ 79/66
Area Forecast Discussion
National Weather Service Jacksonville FL
956 PM EDT Sun Mar 18 2018 ...SEVERE THUNDERSTORMS POSSIBLE MONDAY AND TUESDAY... .UPDATE...A few light showers out ahead of the advancing convective complex to the west has moved eastward into the Suwannee Valley and interior SE GA this mid evening. The best instability now resides along and west of I-75 where CAPES are 1000-1500 J/kg. However, recent trends show convection waning north of the Big Bend with CIN incrementally increasing as the nocturnal hours progress. As the remnant convective activity shifts eastward the activity is expected to remain weak with shower activity being on the increase through the night-time hours shifting southward with time. The first rain shield that moves over the region tonight will have some isold convection, mainly out over the southwest part of the CWA. HRRR showes east Texas complex that will quickly move into southern Louisiana joining up with the tail end of the precipitation shield over our region diving southeastward as a MCS during the pre-dawn hours and very early daylight hours. In the wake of the MCS, there may be a meso- high setting up over the western parts of the region during the late morning and early afternoon, providing a temporary cap with daytime heating on tap, setting the stages the mid afternoon through evening as another disturbance approaches the region. Will have being making some trend up-dates particularly based on the HRRR and HRRR-X. && .AVIATION...VFR conditions will give way to MVFR conditions as precipitation shield with some isold convection moves across the region tonight. A return to VFR will be on tap between 12z and 15z as the showers move east and south of region. A second round of showers and thunderstorms are expected to develop mid/late afternoon tomorrow with some intermittent TEMO MVFR conditions with the stronger thunderstorms between 20z-24z. Light winds tonight with light south- southwinds developing during the late morning and afternoon Monday. && .MARINE...High pressure will be S and E of the waters early this week. Weak low pressure will track eastward north of the waters...maintaining southwesterly flow over the waters Monday. A stronger low will pass north of the waters Monday night and Tuesday, producing stronger southwest winds over the waters which could reach advisory criteria. A strong cold front will move across the waters late Tuesday and Tuesday night, likely associated with strong thunderstorms. Strong northwest winds are expected Wednesday and Wednesday night with some decrease Thursday, with low pressure northeast of the area and high pressure approaching from the northwest. Rip Currents: Low risk expected with offshore flow through Monday. && .PRELIMINARY POINT TEMPS/POPS... AMG 62 76 64 82 / 70 70 50 50 SSI 62 73 63 79 / 60 70 60 60 JAX 64 78 65 85 / 80 70 40 60 SGJ 62 77 66 80 / 70 70 40 70 GNV 63 80 66 81 / 90 70 40 70 OCF 62 80 67 80 / 80 90 40 70 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Cordero//McGinnis
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
1019 PM CDT Sun Mar 18 2018 .UPDATE... Issued at 1019 PM CDT Sun Mar 18 2018 Recent RAP and HRRR model trends including the 00Z NAM, point towards an increased potential for enhanced snow accumulations across central portions of the forecast area. A storm system, currently centered over southwest Kansas will move east overnight and Monday. Colder air continues to be drawn into the system with currently temperatures from the lower to mid 30s north central and the mid to upper 30s south. The potential exists for total snowfall accumulations exceeding 3 inches for areas approximately 50 miles east and west of highway 83 before the snow ends Monday evening. UPDATE Issued at 655 PM CDT Sun Mar 18 2018 Colder early evening temperatures and latest model trends indicate an earlier onset of snow along with slightly higher precipitation chances tonight. The forecast was updated according to these latest trends. && .SHORT TERM...(This evening through Monday) Issued at 253 PM CDT Sun Mar 18 2018 The main concern the next 24 hours revolves around the evolution of a winter storm that will impact the region tonight and tomorrow. Latest satellite imagery shows cloudy skies with stratus housing most of the local forecast area with cloud bases 2-4 kft across the eastern Panhandle and southwest NEB to 400-500 ft across parts of north central NEB. Regional radar display shows little in the way of returns outside of echoes moving northeastward across south central NEB and north central KS. A shortwave trough will lift out of the Four Corners late today, close off, and move into northern OK/southeastern KS overnight. Meanwhile, a strong lee-side low will develop late this afternoon in eastern CO and will evolve east to southeast KS/northeast OK by early Monday morning. While there are chances for showers developing late this afternoon across portions of the Sandhills attributable to amplifying low-level warm advection and marginal elevated instability, better chances occur more so mid evening on. Little change from previous forecasts regarding the atmospheric environment for this event with it still being relatively warm based on soundings. Current thinking is will see a change to mix or snow given dynamic cooling with lift/ascent and based on the wet-bulb profile evolution tonight. Of which, a rain/snow mix to snow is anticipated to have worked down as far south as the southeast-third of the local forecast area by early morning tomorrow. However, some uncertainty exist with respect to spatial extent of snow and wintry mix given thermodynamic profiles. Nonetheless snow amounts are expected to be minor attributable to character of snow and SLR. Additionally, lift continues to be somewhat shallow based on omega fields and lower- tropospheric frontogenesis. Highest expected snowfall is 2 to 3 inches across parts of the western and central Sandhills. In addition, blowing snow is not expected to be an impact given the character of the snow and with winds not expected to be strong. That said, some patchy blowing snow cannot be ruled out early tomorrow across far western NEB nonetheless. Otherwise, highs will be generally 10-15 degrees below seasonable values given linger precipitation, cloudy skies, and colder air filtering in. Highs are forecast in the mid 30s to about 40 degrees tomorrow. .LONG TERM...(Monday night through Sunday) Issued at 253 PM CDT Sun Mar 18 2018 Light snow could linger over northeastern portions (Boyd, Keya Paha, Rock, Brown, Holt, Garfield, Wheeler) of the forecast area through about midnight. Otherwise, clearing with temperatures near normal in the mid 20s Monday night into Tuesday morning. Tuesday onward...A quick short wave zips by in the northwest flow that will bring mainly cloud cover but a few sprinkles are possible across northern Nebraska. Otherwise, a ridge will set up across the Rockies with downslope or southerly flow taking over at the low to mid levels, warmer and mainly dry conditions are expected for much of the week. Stayed with the thinking of the previous forecaster in keeping temperatures on the warmer side of guidance, resulting in widespread 50s and 60s for Wed and Thu, widespread 60s to near 70 possible for Friday depending on how much the ridge is beaten down by an approaching short wave. We can`t rule out some showers along the east side of the ridge and some enhanced fire weather concerns in central and western Nebraska. For now, it looks mainly dry next Saturday with slightly cooler temperatures, back toward normal for this time of year, and breezy northwest flow. The next chance for some precipitation will be Saturday night and/or Sunday with some model disagreement, as expected, this far out. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 619 PM CDT Sun Mar 18 2018 Main aviation concerns will be IFR/lIFR ceilings along with -RA changing to SN late this evening and overnight. A storm system currently centered over south central Colorado will move east into southeast Kansas and southern Missouri by Monday afternoon. Light to moderate snow is expected across much of western Nebraska on Monday. Visibilities should mainly range from 1-3sm, except below 1sm at times from 04z-18z Monday at KVTN. Ceilings should improve to MVFR after 21z Monday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Roberg SHORT TERM...ET LONG TERM...Allen AVIATION...Roberg
Area Forecast Discussion
National Weather Service Lake Charles LA
952 PM CDT Sun Mar 18 2018 .UPDATE... Updated zones and text products for new Severe Thunderstorm Watch 12, which includes the previous watch plus Hardin County as well as most of our LA Parishes along and north of I-10 through 1 AM. Several clusters of storms have developed acrs southeast TX this evening and are now entering western LA. Recent HRRR guidance suggests this activity will continue to move east, exiting Avoyelles and Saint Landry Parishes between 05-06Z. Made some adjustments to POPs and WX for the rest of the evening and overnight to reflect increased chance of convection as well as possibility of damaging winds and large hail. Convection has maintained intensity despite the loss of daytime heating, and KLCH 00Z sounding shows ample energy (MUCAPE ~2700 J/kg) and deep layer shear available to sustain storms near severe levels this evening. Over the coastal waters, extended the Dense Fog Advisory to the current time as at least one site (KSCF) indicates vsbys less than one mile. Expect dense fog will continue to develop and become more widespread overnight, persisting until the passage of a cold front during the day Monday. 24 && .PREV DISCUSSION... /issued 711 PM CDT Sun Mar 18 2018/ UPDATE... Adjusted POPs/WX for early this evening as severe storms to the west of Tyler County are expected to move into the area within the next hour. Also included severe wording in grids and zones. 24 PREV DISCUSSION... /issued 600 PM CDT Sun Mar 18 2018/ DISCUSSION... 00Z Taf issuance. AVIATION... Watching isolated severe thunderstorms moving east over C TX possibly making its way over to E TX. Remnant MCV once again could ignite TSRA over C LA later this evening into the early morning hours, thus placing VCTS by 02z with tempo group for TSRA from 03-07z. Elsewhere, believe most if any convection that forms will stay north of the I-10 corridor this evening and overnight. Main issue here will be lowering ceilings to MVFR to IFR this evening, possibly reaching LIFR ceilings as well as visibilities towards 09-13z time frame for BPT/LCH/LFT/ARA. The front, with mainly drier air behind it, expected to move west to east through the region from 14-18z. DML PREV DISCUSSION... /issued 435 PM CDT Sun Mar 18 2018/ DISCUSSION... Earlier convection over East/South Central LA has push off to the east and/or dissipated, but has left a residual SFC boundary from roughly near Jasper, TX to Lafayette, LA. This boundary is expected to retreat NWD tonight as low level kinematic fields strengthen with a lead impulse ejecting NE out of OK and the approach of a more vigorous shortwave trof just east of the Four Corners. Ample instability/shear is progged to reside along/S of this boundary the rest of the afternoon and through the evening to support a conditional risk of severe TSTMS, with that primary condition being the maintenance/EWD progression of convection currently underway across E TX. Little in the way of model consensus has emerged throughout the day on this matter, though what agreement there is depicts a cluster of TSTMS moving across interior E TX and Central LA through the evening hours. Recent coord call with SPC has yielded a SVR TSTM watch for parts of interior E TX through 11 PM. Initial front associated with this shortwave trof progged to push east through the area tomorrow, ushering a much drier airmass into the region. Small rain chances along and ahead of the front through the morning, with dry and warm expected by afternoon. Real push of cooler air to arrive with the passage of a secondary front Mon night into TUE associated with upstream shortwave trof progged to dig into the SE CONUS. Cool and dry weather to prevail mid week amid high pressure at the SFC and NW flow aloft. Flattening flow aloft and returning low level southerlies will yield increasing moisture and warmer temperatures to end the week, with low end rain chances by the weekend as a front sags toward but stalls just north of the area. 13 MARINE... A light onshore flow will continue tonight as the northwest Gulf remains between low and high pressure systems. Patchy sea fog already over the nearshore coastal waters is expected to become more widespread and dense later tonight, with a dense fog advisory in effect for the nearshore waters from midnight tonight through Monday morning. Areas of fog are expected over the rest of the Gulf and the coastal lakes and bays. As an upper low advances into and through the mid Mississippi valley on Monday, a westerly flow will develop as a surface front passes through. Drier air in the wake of this front will erode any lingering marine fog. A second front will push through the coastal waters late Monday night, with moderate and gusty northwest winds expected in its wake that will persist through Tuesday. A small craft advisory may be needed during this time for some or all of the coastal waters. A southerly return flow develops Wednesday night through the remainder of the week. 13 && .PRELIMINARY POINT TEMPS/POPS... AEX 65 83 50 67 / 70 20 0 0 LCH 69 83 53 70 / 30 20 0 0 LFT 69 82 54 69 / 40 20 0 0 BPT 69 83 53 72 / 30 20 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...Dense Fog Advisory until 10 AM CDT Monday for GMZ450-452-455. && $$
Area Forecast Discussion
National Weather Service New Orleans LA
806 PM CDT Sun Mar 18 2018 .SOUNDING DISCUSSION...00z balloon went up with no problems. What it did find was a rather unstable environment still in place. There is an inversion right around 800mb and could be an issue later tonight but as of right now we remain uncapped and had a sfc based cape of 3400 J/kg with sfc LI of -8! The more impressive aspect is the thick fat cape we have in the mid and upper levels. Mid level lapse rates are around 7.2 C/km which is rather steep. At this time the sounding doesn`t show a very favorable tornadic sounding but given that there is a left over boundary just south of Slidell any storms riding or crossing that boundary could have some extra spin to them. Winds have strengthened from this mornings sounding in the mid and upper levels and there is now a dry pocket in the mid levels which could enhance the wind risk. We will do a 6z release tonight to reassess the environment. /CAB/ && .PREV DISCUSSION... /issued 719 PM CDT Sun Mar 18 2018/ UPDATE... Forecast grids and products have been updated to increase chances for convection later this evening and overnight. The last two or three runs of the HRRR has forecast a rapid increase in convection to our west this evening that moves quickly into our forecast area around midnight and across the area overnight. Considerable convection is already ongoing across portions of east and southeast Texas. 11 PREV DISCUSSION... /issued 402 PM CDT Sun Mar 18 2018/ SYNOPSIS... Latest surface analysis showed a frontal zone from south Georgia to south Mississippi to central Texas. Surface dewpoint readings of 65F were south of the frontal zones, mainly over the forecast area. Upper air analysis showed a ridge axis the Central Gulf Coast to Dakotas and short wave trough over northern New Mexico and disturbance on the front side of the wave over Arkansas and northern Louisiana. DISCUSSION... Upper level disturbance on the east side of this shortwave will pass across the lower and mid Mississippi Valley today and tonight. This has enhanced shower activity across the forecast area this afternoon. However, thunderstorm activity has been limited but coverage of showers remained across the north half of the forecast area. The short wave over northern New Mexico will track east through Monday. However, today`s impulse will scour some of the moisture east tonight. This will leave limited moisture for the next wave tomorrow. As a result, rain chances decreased a tad to 20 percent on Monday and Monday evening. Associated cold front will finally reach the forecast area Monday night into Tuesday morning as a secondary nose of the trough digs south across the central Gulf Coast. Cooler air will be quickly filtering into the area during those early morning hours. Should bottom out around the mid 50s by sunrise Tuesday. Persistent troughing to the east, northwest flow will be in place across the forecast area through much of the week. This will keep temps at to below normal during that time frame and a dry forecast through the week. A low chance of rain will be possible the next weekend. MARINE... Onshore flow to continue through tonight before becoming disrupted a bit with a frontal zone settling across the Gulf states by tomorrow morning. A surge of high pressure pushes the front into the northern Gulf late Monday night with high pressure bringing strong northerly gradient winds and building seas to the coastal waters heading into Tuesday. Small craft advisories will be needed by Tuesday morning. Winds and seas should begin to wane late Wednesday. AVIATION... Lingering convection near KGPT, KASD, KMSY, and KNEW could produce brief periods of IFR conditions through around 03z. By 06z, another round of low ceilings and fog should begin to develop at all of the terminals. Low ceilings of 500 feet or less and visibilities of less than a mile will be possible at all of the terminals between 06z and 17z tomorrow. After 17z, the passage of a frontal boundary should result in increased westerly flow and the clearing of fog and low clouds. Expect to see MVFR and VFR conditions in place after 18z. 32 DSS code: Blue. Deployed: None. Activation: None. Activities: Monitoring river flooding Decision Support Services (DSS) Code Legend Green = No weather impacts that require action. Blue = Long-fused watch, warning, or advisory in effect or high visibility event. Yellow = Heightened impacts with short-fused watch, warning or advisory issuances; radar support. Orange = High Impacts; Slight to Moderate risk severe; nearby tropical events; HazMat or other large episodes. Red = Full engagement for Moderate risk of severe and/or direct tropical threats; Events of National Significance. && .PRELIMINARY POINT TEMPS/POPS... MCB 63 83 51 63 / 50 20 10 10 BTR 64 84 52 65 / 50 20 10 0 ASD 65 82 56 66 / 50 20 10 0 MSY 67 82 58 67 / 50 20 10 0 GPT 65 79 56 68 / 50 20 10 10 PQL 65 79 57 67 / 50 20 10 10 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$