new WPC Met Watch
Posted by cypresstx on 3/28/2025, 1:11 am
| this after over a foot of rain over Harlingen area in last days per MRMS https://www.wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=91&yr=2025  Mesoscale Precipitation Discussion 0091 NWS Weather Prediction Center College Park MD 1256 AM EDT Fri Mar 28 2025 Areas affected...Lower Rio Grande Valley and Lower Texas Gulf Coast... Concerning...Heavy rainfall...Flash flooding likely Valid 280500Z - 281000Z SUMMARY...Strong MCV, providing ascent for another round of strong thunderstorms capable of 2"+/hr rates to further compound ongoing significant flash flooding across the Rio Grande Valley. Heavy rainfall likely to expand northward toward Corpus Christi urban areas over the next few hours as well, with possible flash flooding DISCUSSION...GOES-E WV shows strong vorticity center/MCV currently along the south-southwest side of the larger scale stationary upper-level low crossing over the Rio Grande into Webb county. These height-falls have once again backed the low level flow off the very moist/unstable western Gulf that had filtered across Tamaulipas and into eastern Nuevo Leon state in Mexico. CIRA LPW shows surface to boundary layer moisture nearing 1" fluxed on 30-35kts toward the flanking line, allowing for increased instability of 1000-1500 J/kg (narrow and skinny profiles) while this is leading to confluence through the ascent layer in the 850-500mb layer. CIRA LPW suggests an additional third to half inch and quarter to third of an inch in those mid-levels to support overall depth of 1.75 to near 2" along the Gulf coast. So once again, strong moisture flux convergence aided by unstable air has developed into a squall line with cells likely to increase from 1.25 to 1.5-2"/hr as the line reaches deeper moisture further east. Additionally, the southerly moist flow is expanding scattered isentropically forced cells between the exiting convective cluster and the approaching line. These more scattered cells will be a tad shallower, but with solid flux should be still prolific in rainfall capability even if more scattered/random in nature...adding .5-1" prior to the main line. This WAA appears to be trending northward toward relatively drier locations and may start to stall/flatten to southwest steering as it nears the coast across N Kenedy, Kleberg and Nueces county. Spots of 2-3" are possible across this northern area that may initiate some localized flash flooding concerns, especially near the Corpus Christi urban areas that are particularly prone to intense rates. Additionally, upper level jet diffluence remains extreme across far southeast TX and the lower Rio Grande Valley with 60-70kt speed max jet lifting northward across south Texas, while the core of the sub-tropical jet streak is fairly flat (west to east) across northeast Mexico into the Gulf. This is over 90 degrees of diffluence maintaining solid evacuation of convection as it moves eastward to areas already flooded. This should also allow for slowing of forward propagation as well as with strengthening of the low level inflow for flanking line back-building across the Lower Rio Grande Valley. Additional 3-5" totals across already flooded areas; likely to maintain flash flooding conditions with some significant flash flooding/emergency conditions to be possible with this next round. Localized totals over 10" are likely to become reality across a broader area of lower Rio Grande Valley. While it is hopeful that after this MCV/forcing wave moves through, the environment will clear out; however, there remains quite a bit of uncertainty, as south-southeasterly flow of the western Gulf is likely to be maintained through the peak of the diurnal surge after prior to day break (08-10z). Intersection with lingering outflow boundaries may still trigger additional development, but will update the MPD later this morning to address this concern. Gallina ATTN...WFO...BRO...CRP... ATTN...RFC...WGRFC...NWC... LAT...LON 28039762 27789713 27029738 26529721 25969710 25799726 25919782 26109845 26259881 26489914 26749915 27249867 27579831 |
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In this thread:
Flooding in S Texas - cypresstx, 3/28/2025, 12:53 am
- Re: new WPC Met Watch - Chris in Tampa, 3/28/2025, 7:06 am
- almost afraid to read the news - cypresstx, Yesterday, 11:15 am
- Re: almost afraid to read the news - Chris in Tampa, Today, 12:49 am... 2h 44m ago
- almost afraid to read the news - cypresstx, Yesterday, 11:15 am
- Re: new WPC Met Watch - Chris in Tampa, 3/28/2025, 7:06 am
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