March 2016 - Progressive Changeable Weather To End The Month

[Ounce]

0.14 inches at the Weatherbug site of Memorial & Chimney Rock, since midnight.

[srainhoutx]

MESOSCALE PRECIPITATION DISCUSSION 0059...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1151 AM EST WED MAR 09 2016

CORRECTED FOR GRAPHIC

AREAS AFFECTED...SOUTHEAST TX...WESTERN LA...SOUTHERN AR

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 091627Z - 092027Z

SUMMARY...VERY HEAVY RAINS WITH FLASH FLOODING LIKELY...

DISCUSSION...CONVECTION CONTINUES TO INCREASE IN
COVERAGE/INTENSITY ACROSS THE REGION THIS MORNING. WATER VAPOR
IMAGERY SHOWS THAT THIS CONVECTION IS FIRING IN AN AREA OF
INCREASED MID/UPEPR LEVEL MOISTURE PUSHING NORTHEAST ON THE
PERIPHERY OF THE UPEPR LOW PUSHING EAST ACROSS NORTHERN MEXICO.
THIS IS LIKELY INDICATIVE OF INCREASED SYNOPTIC FORCING ASSOCIATED
WITH SUBTLE SHORTWAVE IMPULSES AND AN INCREASING UPPER JET MAXIMUM.

MOISTURE PROFILES AREA QUITE IMPRESSIVE ACROSS THE AREA...WITH AN
ATMOSPHERIC RIVER OF MOISTURE SHOWING A DUAL CONNECTION TO BOTH
THE TROPICAL PACIFIC AND THE CARIBBEAN. PRECIPITABLE WATER VALUES
ARE ABOVE 1.75" ACROSS SOUTHERN TX AND ABOVE 1.5" ACROSS MOST OF
EAST TX INTO LA. THESE VALUES SHOULD CONTINUE TO INCREASE THROUGH
THE DAY...PUSHING ABOVE 1.75" THIS AFTERNOON ACROSS MUCH OF
EASTERN TX AND MOST OF LA. PRECIPITABLE WATER VALUES THIS HIGH ARE
AROUND OR EVEN ABOVE THE MAXIMUM VALUES SEEN THIS TIME OF YEAR ON
RECORD.

CURRENTLY ANALYZING A LOW LEVEL BOUNDARY STRETCHING FROM EAST OF
SHREVEPORT SOUTHWEST INTO SOUTHEAST TEXAS...WITH THE HEAVIEST
CONVECTION CURRENTLY FOCUSING ALONG AND SOUTHEAST OF THIS
BOUNDARY...WHERE INFLOW IS STRONGEST AND INSTABILITY IS GREATEST.
THIS BOUNDARY WILL SLOWLY MOVE EAST ACROSS SOUTH TEXAS AS THE
ASSOCIATED SURFACE LOW MOVES NORTHEAST...BUT NOT EXPECTING MUCH
MOVEMENT OF THE BOUNDARY ACROSS NORTHEAST TX INTO LA AT LEAST
THROUGH EARLY TO MID AFTERNOON. SO THE HEAVIEST RAINFALL WILL
LIKELY OCCUR FROM LA INTO SOUTHEAST TX...ALONG/SOUTH OF THIS
BOUNDARY...OVER THE NEXT SEVERAL HOURS...WITH LESS INTENSE
RAINFALL RATES TO THE NORTHWEST WHERE INFLOW AND INSTABILITY ARE
BOTH CONSIDERABLY LESS. THE FRONT HAS PUSHED THROUGH PORTIONS OF
NORTHWEST LA AND NORTHEAST TX...WHICH VERY WELL COULD MEAN THE
ADDITIONAL HEAVIEST RAINFALL INTO EARLY/MID AFTERNOON ENDS UP
FOCUSING FURTHER SOUTH ACROSS SOUTHEAST TX INTO WEST CENTRAL AND
SOUTHWEST LA. HOWEVER GIVEN THE EXCESSIVE RAINFALL THAT HAS
ALREADY FALLEN ACROSS NORTHWEST LA...AND THE POSSIBILITY THAT THE
FRONT PUSHES BACK NORTH LATER TODAY...THE FLOOD TREAT CONTINUES
THERE AS WELL.

AS FAR AS GUIDANCE GOES...THE MORE RECENT RUNS OF THE
HRRR/EXPERIMENTAL HRRR ALONG WITH THE 0Z SPCWRF AND TO A LESSER
EXTENT THE 0Z NSSL WRF ARE THE PREFERRED HIGH RESOLUTION SHORT
TERM GUIDANCE. ALTHOUGH THESE SOLUTIONS COULD STILL BE A BIT TOO
FAR NORTH WITH THE HEAVIEST AXIS. THE 0Z ARW/NMMB/NAM CONUS NEST
ARE STRUGGLING WITH THE CONVECTIVE EVOLUTION AND ARE NOT
RECOMMENDED AT THIS TIME. HOURLY TOTALS OF 1-2" AND ADDITIONAL
RAINFALL AMOUNTS AS HIGH AS 3-5" SEEM POSSIBLE OVER THE NEXT
SEVERAL HOURS ACROSS PORTIONS OF THE OUTLOOKED AREA NEAR THE
AFOREMENTIONED BOUNDARY.


CHENARD

ATTN...WFO...BRO...CRP...EWX...FWD...HGX...JAN...LCH...LZK...
SHV...

[jasons2k]

Look closely at the storms in NW Harris County. As the cells themselves move to the north, the mass of storms has started building the the Southeast, following the *very* slowly advancing front. If this continues, we could see the flooding really take off across metro Houston. This needs to be monitored very closely the next several hours.

Something else to watch is the mass out in the Gulf, to see if it affects the inflow of warm & unstable air from the south.

[srainhoutx]

Appears to be a bit of a surface low moving N off of the Gulf as well directly S of San Luis Pass.

[tireman4]

Larry Cosgrove, in Hockley, has reported 4 inches of rainfall at his place since midnight.

[jasons2k]

The wind at IAH shifted back to the SE.

[srainhoutx]

Just ran the dogs in the cul du sac before the rain starts. Winds have increased out of the S to SE, so the frontal boundary remains a bit N of my location in NW Harris County.

[tireman4]

I know what that means Jason, but you might want to tell our viewers...

[ticka1]

I know what that means Jason, but you might want to tell our viewers...

What does that mean?

[srainhoutx]

I know what that means Jason, but you might want to tell our viewers...

What does that mean?

We are seeing some destabilization as the front lifts back N. HGX not sure if the showers and storms moving inland off the Gulf will cut back on rainfall totals, but we are on the very dirty NE side of the upper low over Mexico pumping copious amounts of deep tropical moisture inland. In fact PW's have increased to near 2 inches.

[jasons2k]

The front was slowly advancing SE this morning. But it stalled just south of the airport and has now retreated back to the NW a bit. It means most of metro Houston will remain in the warm sector. The strongest rains should focus in the vicinity of the front and especially just to the southeast of it, or across the Houston area...

[jasons2k]

Wind just shifted back to the ESE at Hooks....

[tireman4]

Thank you Srain and Jason. Not trying to be the school marm here, just getting the Meteorology 101 out of the way.

[Snowman]

Everyone keeps saying that the heaviest rain is going to focus just to the southeast of the front, but if you look at the radar right now everything is to the north. In fact, a large portion of the area that was supposed to be the hardest hit has barely seen anything. It's interesting that the city of Houston seems to be in a safe bubble

[tireman4]

So far, yes Snowman, so far. This is ever changing, so this afternoon the shift could be southward with the front moving northward..

[srainhoutx]

Update from Jeff:

Low level surface boundary is approaching the US 59 corridor with widespread showers and thunderstorms having developed along and ahead of this feature.

Severe thunderstorm currently over north Fort Bend County will move into extreme western Harris County shortly with a hail and high wind threat. Heavy rainfall continues along and north of this boundary in a scattered nature as southerly flow on the eastern flank of the Mexican upper level low continues over the region. Storm totals in a wide band from Lake Livingston to Colorado County is averaging 2.0-4.0 inches with the greatest totals over SW and central Montgomery County.

Models like the idea of yet another upper level impulse moving northward along the western Gulf coast to fire additional heavy thunderstorms over the region this afternoon into this evening. Severe threat will be maintained south of the low level boundary mentioned above…which may attempt to lift back northward early this afternoon.

Main threat continues to be heavy rainfall and flooding, especially since grounds are now saturating and run-off is increasing. Additional rainfall amounts of 3-5 inches are possible on top of what has fallen with isolated amounts of up to 6 inches.

Rainfall Storm Totals:

[/i]

[Cromagnum]

It has rained pretty much everywhere EXCEPT for Houston which was pegged to take the brunt. I think one of the models had a (-1) in place of the (+1) in the formula...

[Snowman]

It has rained pretty much everywhere EXCEPT for Houston which was pegged to take the brunt. I think one of the models had a (-1) in place of the (+1) in the formula...

It sure does seem like that! The HRRR showed the metro area with 9-10 inches last night and not only has that area not gotten 9-10 inches, but it has been relatively untouched. I know the atmosphere is still ripe with heavy rainfall, but based on radar trends it looks like the worst of this will remain to the north. Nothing seems to be forming south of us.

[srainhoutx]

Look down towards the Brownsville Coastal waters. That's another impulse rotating around the pesky upper low. Looks like another round may develop overnight into Thursday. Frankly I am glad that Houston has been spared so far during the work day. We certainly don't need to see folks attempting to drive home in a flood.

[Ounce]

There's a line of storms in the Gulf, east of Corpus, that would appear to be headed to Bay City and points NNE. The line stretches to off the coast of Mexico and is intensifying.

edit: Dang! Srain beat me by 2 minutes.