Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
453 PM EDT Wed Jun 29 2022
 
Day 2
Valid 12Z Thu Jun 30 2022 - 12Z Fri Jul 01 2022 

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF 
THE WESTERN GULF COAST...

...Western Gulf Coast into the Central Gulf Coast...

21Z update... The QPF across the western/central Gulf Coast 
continues to have an increasing trend and the new WPC QPF ranges 
from 2 to 7 inches; the bulk of the higher amounts are expected to 
fall between the Corpus Christi and Houston metros. Some of the 
CAMs are indicating rainfall rates upwards of 3 to 4 inches/hour 
which could easily exceed the 3-hr FFG of 3 to 5 inches across the 
Gulf Coast. In coordination with the local forecast offices, an 
upgrade to a Slight Risk was made.

Campbell

Low pressure system that has been spinning through the Gulf makes 
it's way onshore by this period bringing with it ample moisture 
and potential for heavy rainfall. Models have started to converge 
on the heavier QPF amounts leaking onshore through portions of 
southeast Texas. Upwards of 2-4" with some models indicating even 
higher amounts during the 24-hr period are expected. PWATS peak 
around 2.4" for the period well above the 90th percentile for this 
time of year. Steering flow is around 25-35 kts which may push 
cells along at a quicker pace, but should we see any training 
storms in the region, flooding concerns will certainly arise. 

...Southwest into the Central Great Basin...

21Z update... The Monsoonal moisture is progged to move further 
into the Plains and as such the new WPC QPF has increased. 
Convection tracking from the Front Range into Nebraska and Kansas 
may produce heavy showers with rates of 0.50 inch/hour or greater. 
The 3-hr FFG is as low as 2 inches and these rates may reach or 
exceed local FFG. The Marginal Risk was expanded eastward to 
encompass portions of southwest Nebraska and northwest Kansas.

Campbell

A plume of moisture will continue to impact the region as a moist 
southwesterly flow sets up. Precipitable water values nearing 1.4" 
will stream into an area previously hit with heavy rainfall and 
flash flooding. Much of the area sits above 98% soil moisture and 
well into 600%+ of normal precipitation over the past week. QPF 
amounts alone during this period do not overly impress, but given 
the antecedent conditions and burn scars throughout the region, 
flooding will still pose a threat going into the day 2 period. 
Portions of eastern Arizona will see rainfall during the day 1 
time period which when combined with the additional rainfall 
expected on day 2, will only prime soils even more for the 
potential for flooding. 

...Southwest Florida...

21Z update... Over the Marginal Risk area still highlights the 
locations with an elevated threat for isolated flash flooding. 
Minor reshaping of the boundary was made to reflect the latest WPC 
guidance.
Campbell

Slow moving cells pushing over more urbanized areas will bring a 
continued threat into the day 2 period for portions of southwest 
Florida. PW values peak near 2.25" well above the 90th percentile 
for this time of year. Pockets of 600+% of normal precipitation 
has been observed over the past week for areas within the Marginal 
Risk area and will be more susceptible to isolated flooding 
concerns through the period. 

Chiari




 
Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt