Area Forecast Discussion
Issued by NWS Houston/Galveston, TXVersions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000 FXUS64 KHGX 102356 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 556 PM CST Wed Mar 10 2021 .AVIATION [00Z TAF Issuance]... Large swath of mid/high clouds moving in from the west looks to be producing some virga at best as it moves into/across SE TX through this evening. The moderate to strong onshore flow already in place over the area will be decoupling a bit tonight, but likely staying elevated just above the surface. This should favor the development of lower CIGS (mostly MVFR) versus lower VIS overnight for most of the CWA. That is, except at the coast where patchy sea fog is beg- inning to form. While near-term models have been overly aggressive with sea fog formation the last couple of nights, will keep trends for VIS in the 4-6 mile range for now. Spotty WAA-type showers may also be something to watch for tonight, but given the very isolat- ed nature of this development, not confident enough to include its mention in any of the TAF sites at this time. 41 && .PREV DISCUSSION... /ISSUED 311 PM CST Wed Mar 10 2021/ SHORT TERM [Through Thursday]... A steady onshore wind and cloud cover should limit much of a temp drop overnight. Sided with the higher end of guidance suggestions in regards to overnight lows. More of the same on Thurs with breezy srly flow prevailing and readings topping out in the low 80s inland and upper 70s at the beaches. Can`t totally rule out a few isolated raindrops under the cap thru the period, but shallow moisture in addition to Gulf ridging will be limiting factors for anything of significance. 47 LONG TERM [Thursday Night Through Wednesday]... Temperatures on Thursday night will remain mild in the low-to-mid 60s as onshore flow continues to persist and push warm, moist air into the region. In fact, upper-level ridging will be in place through the first portion of the weekend so this is a pattern that is here to stay until Sunday. As a result, expect unseasonably warm temperatures in the afternoons with highs in the upper 70s/low 80s on Friday and Saturday. Cloud cover will remain in place as well which will limit radiational cooling overnight. Lows will be back into the mid 60s once again for Friday night and upper 50s/low 60s for Saturday night. Upstream of the upper-level ridge will be a developing and deepening upper-level trough near the Rockies. By Saturday afternoon/evening, there is model consensus on lee cyclogenesis. This area of low pressure will offer a brief pattern change on Sunday as it pushes a surface cold front through the region. Frontal timing remains a bit uncertain but the GFS and ECMWF are in pretty good agreement for FROPA on Sunday early afternoon in our northwestern counties. ECMWF is about 3 hours behind and off the coast by Sunday night. The Canadian model is just a little behind on the timing by about 3 hours or so. Now don`t get too excited about the word "cold front" as this one will not have any significantly cold air behind it. However...it will cool us down back to more seasonal temperatures with highs in the low-to-mid 70s on Sunday and Monday, and lows in the upper 40s/low 50s on Sunday night. This front will bring our next significant chance of rain though! The persistent onshore flow ahead of FROPA will keep PW values steady around 1.00"-1.25" and peaking around 1.50" just ahead of the front. With strong winds aloft in the warm sector of the low, there will be an abundance of deep-layer shear. Models are a bit uncertain on what kind of upper-level support this setup will have as the GFS shows a cyclonically curved jet streak over North TX on Sunday afternoon, while the ECMWF shows more of a straight-line jet streak with our northern counties in the right entrance region. With upper-level divergence certainly possible during this timeframe, thunderstorms will be possible as the cold front passes through. Following this front, flow aloft becomes more zonal with a slight hint of upper-level ridging returning towards the middle of next week. Offshore flow does not last for long as the front pushes back northward as a warm front by late Monday. With the returning onshore flow, clouds will filter back into the area for Tuesday and Wednesday and warmer temperatures return as well with highs in the mid-to-upper 70s for both of these days. Models diverge quite a bit towards mid-week on the timing for the next cold front. GFS and ECMWF do agree on lee cyclogenesis, but GFS is much more progressive pushing the cold front through on Wednesday afternoon. The ECMWF solution is about 18 hours behind showing the next FROPA on Thursday morning. Due to the wide range of solutions, accounted for both in the grids and have PoPs added for both Wednesday and Thursday. This front is also not expected to offer a significant cool down, but just a bump back down towards more seasonal temperatures. Batiste MARINE... Moderate onshore winds and building seas can be expected tonight and Thursday. Will hoist the SCA flags in the 20-60nm waters this evening as winds/seas build and also extend the High Rip Current risk along area beaches thru the day Thurs. Patchy sea fog remains a possibility, but should not be overly dense near the coast thru Thurs with higher wind speeds being a limiting factor. SREF indicates slightly better odds of reduced vsbys Fri night. A weak front may briefly approach or move off the coast on Sunday, but will quickly wash out. Onshore flow will then prevail into early next week. 47 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 66 82 63 81 63 / 10 0 10 20 10 Houston (IAH) 67 81 65 80 64 / 10 10 10 20 0 Galveston (GLS) 65 76 64 71 64 / 10 10 0 0 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...High Rip Current Risk through Thursday evening for the following zones: Brazoria Islands...Galveston Island and Bolivar Peninsula...Matagorda Islands. GM...Small Craft Advisory until 9 AM CST Thursday for the following zones: Waters from Freeport to Matagorda Ship Channel TX from 20 to 60 NM...Waters from High Island to Freeport TX from 20 to 60 NM. && $$
No comments:
Post a Comment