AT2k Design BBS Message Area
Casually read the BBS message area using an easy to use interface. Messages are categorized exactly like they are on the BBS. You may post new messages or reply to existing messages! You are not logged in. Login here for full access privileges. |
Previous Message | Next Message | Back to General Weather-related Discussi... <-- <--- | Return to Home Page |
|
||||||
From | To | Subject | Date/Time | |||
![]() |
Mike Powell | All | HVYRAIN: Excessive Rainfa |
January 5, 2025 4:02 PM * |
||
FOUS30 KWBC 052013 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 313 PM EST Sun Jan 5 2025 Day 1 Valid 16Z Sun Jan 05 2025 - 12Z Mon Jan 06 2025 ...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS OF THE SOUTHEAST AND CENTRAL GULF COAST... ...16z update... Small adjustments were made to the broad Marginal Risk area based on guidance trends and 12z Hi-Res/HREF probability output. 12z HREF continues to show a solid high probability axis with the convective line for 1"/hr or 1"/3hr (over 90%). However, the forward speed of cells continues to quickly diminish the potential for high overall totals, as 2"/3hr values only peak at 30% in west-central MS, eventually expanding into northern MS and mainly in the 18-00z time frames. Based on the evolution from the Hi-Res CAMs, the highest potential is across this axis, with some lower signals further south and west into central LA and far SE TX though higher FFG values in that region would have lower potential of exceedance anyway. Observational trends and rapid refresh guidance from the HRRR/RAP denote the core of surface to 850mb moisture and flux is generally parallel to the approaching front and about 25-50 miles downstream. Increasing insolation and steepening lapse rates will allow for the instability axis to align with the moisture, that pre-cursory convection is likely to develop in the 15-18z time frame across SE TX into central LA, ahead of the developing convection noted in W AR/NE TX attm. Eventually, the gap between closes and streams/ascent merge for the potential for some very short-term enhancement of totals to 1-2" ranges. This axis does align with an area of recent dryness compared to locations further west over the last 7-10 days per AHPS...further diminishing the need for a Slight Risk area; though central/northeast LA into northern MS will be the area of greatest potential for any incidents of localized flash flooding concerns. Elsewhere, the warm advection across the mid-MS Valley has trended a bit northward and some of these cells may reach SE MO/W KY where grounds may have some ice in place. As such, the Marginal Risk was lifted a bit northward with this update. Equally, trends with convection across central LA into S MS and slightly slower cold front pressing eastward after 06z; has warranted a bit further trimming of the eastern side of the Marginal Risk in AL. Gallina ---Prior Discussion--- An impressive deep layer cyclone is taking shape over the central US early this morning, originating from a potent shortwave trough digging through the Central Rockies over the past couple of days. The trough is in the process of cutting off into an upper-low as it emerges from the Rockies into the central Plains. Strong DPVA in association with the trough will interact with the right- entrance region of a broad phased jet structure (~140 kt jet streak @ 250 mb over the Mid-Atlantic, and a smaller ~100 kt jet streak near the Ozarks). A substantial low-level jet (850 mb of 40-60 kts) is expected to form as a result of deep cyclogenesis, stretching from the Central Gulf Coast to the Mid-South, ushering in highly anomalous tropospheric moisture (for this time of year) with precipitable water values nearing 1.5" (between the 90th percentile and max moving average, per JAN/BNA/BMX sounding climatology). Most hi-res CAMs continue to suggest localized 1-2" totals in association with combined totals from scattered convection in the open warm sector and the following primary squall line in association with the approaching cold front, though a couple of solutions (FV3 and CMCreg) suggest localized streaks of 2-3" totals (from northeast LA through north/central MS into northwest AL). While much of these totals may occur over a relatively short period (with any flash flooding conditions more likely due to storm mode and sub-hourly rates and totals of 1-2" |
||||||
|
Previous Message | Next Message | Back to General Weather-related Discussi... <-- <--- | Return to Home Page |
![]() Execution Time: 0.0185 seconds If you experience any problems with this website or need help, contact the webmaster. VADV-PHP Copyright © 2002-2025 Steve Winn, Aspect Technologies. All Rights Reserved. Virtual Advanced Copyright © 1995-1997 Roland De Graaf. |