OCTOBER: Halloween Storm: Severe Storms/Flash Flood Threat?

[Rip76]

Driving from Corpus to Houston today.

Would it be best to leave right now?

[srainhoutx]

Morning Update From Jeff:

Significant storm system to impact the area today-Halloween.

Flooding rainfall and isolated tornadoes are the main threats.

Powerful upper level storm system over the SW US this morning is starting to track eastward with strong lift beginning to spread into TX. Deep moisture advection overnight has led to the development of strong thunderstorms from College Station to Katy to Wharton this morning. Luckily these storms are moving quickly northward keeping rainfall manageable. These storms are in response to weak disturbances aloft overtop over increasing Gulf moisture levels.

Heavy Rainfall:

Moisture will continue to increase today and peak near maximum levels for this time of year on Thursday. In fact if PWS were to reach 2.3 inches this would be close to the maximum level for summertime…so there is no shortage of moisture to work with. Main focus will be on the excessive rainfall threat. Factors are in place to produce excessive rainfall including

1. Slow moving frontal boundary

2. Good upper level divergence

3. Strong moisture advection

4. Cell training

5. Maximum PW values

Expect current activity to continue for much of the day and then the main event will enter into the region tonight. Expect a solid line of heavy rainfall to develop along the frontal boundary with high potential for cell training. Where these cells line up will determine where the maximum rainfall will occur. Widespread 2-3 inches is likely with isolated amounts of 5-7 inches. With grounds already wet from previous rainfall, rainfall of this magnitude will produce some significant run-off and rises on area watersheds. Heaviest rainfall axis looks to be shifted closer to the US 59 corridor, but the entire region is at risk. Given run-off is still ongoing from upstream points from Sunday on some of the major rivers this additional heavy rainfall could push some points to action stage or even flood stage. Urban flooding will also be a concern given the potential for 2-3 inch per hour rainfall rates.

Severe Weather:

No overly concerned with the severe threat. A good amount of low level shear will be in place, but instability is lacking so not expecting widespread severe. This types of setups with a very moist air mass can produced low topped supercells that produce very heavy rainfall and isolated weak tornadoes in their rain cores. Suspect we could see 1 or 2 weak tornadoes wrapped in rain and the warnings will be very short fused. Again I stress that the main impact will be rainfall and potential flooding.

Halloween Evening:

Good news is that nearly all model guidance clears the rainfall off the coast by 700pm Thursday evening. Could still be dealing with run-off issues and high water, but it is looking likely that the rain will be over by sunset Thursday. North winds of 10-15mph and temperatures in the low to mid 60’s for any evening activities.

Weekend:

Stronger front clears the area Friday evening with a much drier and cooler air mass ushering in. Lows down into the 40’s by Sunday AM with highs in the 70’s. Starting to look like the break in the rainfall could be brief with moisture wanting to return as early as Sunday afternoon over the frontal boundary. Will likely see rainfall by early next week again as SW flow aloft and increasing Gulf moisture impacts the region.

[srainhoutx]

My good friend Wes Junker (HPC Senior Forecaster/Retired) just sent a message stating that we are seeing PW's of 3 Standard Deviations above normal for Texas and SREF 850mb moisture influx of 5 Standard Deviations above normal for October. As Jeff mentioned, this is a classic October Flood event threat and we have already seen over an inch of rain so far this morning in NW Harris County in short order. Keep a close eye on the weather today and tomorrow folks.

[Rip76]

I'm guessing yes, looks like the storms are clustering near I-10 atm.

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0753 AM CDT WED OCT 30 2013

VALID 301300Z - 311200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS LOWER MO VALLEY ACROSS
CENTRAL/SRN PLAINS TO SW TX...

...SYNOPSIS...
MAIN UPPER-AIR FACTOR FOR THIS PERIOD AND BEYOND WILL BE
HIGH-AMPLITUDE SYNOPTIC TROUGH -- NOW MANIFEST AS NNE-SSW-ELONGATED
CYCLONE COVERING MUCH OF GREAT BASIN AND CENTRAL/NRN ROCKIES
REGIONS. THIS FEATURE IS FCST TO EVOLVE INTO MORE
PROGRESSIVE/OPEN-WAVE BUT STILL HIGHLY AMPLIFIED TROUGH THROUGH
PERIOD. STG BASAL SHORTWAVE TROUGH -- EVIDENT IN MOISTURE CHANNEL
IMAGERY OVER LAS REGION -- IS FCST TO PIVOT EWD ACROSS AZ
TODAY...REACHING SWRN CO...NWRN NM AND SERN AZ BY 00Z...THEN
STRENGTHENING AND ACCELERATING EWD TO SRN HIGH PLAINS BY END OF
PERIOD. MEANWHILE...COPIOUS MID-UPPER LEVEL MOISTURE CONTINUES TO
STREAM NEWD OFF WHAT IS NOW NERN PAC T.D. RAYMOND...OVER NRN MEX AND
MUCH OF TX/OK/AR/LA.

AT SFC...STG/INITIALLY QUASISTATIONARY FRONTAL ZONE EXTENDED FROM
LOW OVER NERN KS/NWRN MO REGION SWWD ACROSS S-CENTRAL KS AND NWRN OK
TO NRN TX PANHANDLE...TO ANOTHER LOW OVER SERN CO. PAC COLD FRONT
WAS EVIDENT FROM THAT LOW SWWD ACROSS CENTRAL/SRN NM. LATTER FRONT
WILL MOVE EWD ONLY SLOWLY AT FIRST...THEN BECOME BETTER-DEFINED WITH
TIME THIS EVENING AND OVERNIGHT...OVERTAKING DRYLINE FROM N-S ACROSS
SRN HIGH PLAINS. BY 12Z...FRONTAL-WAVE LOW SHOULD EVOLVE OVER NRN
OK...WITH COLD FRONT SWWD ACROSS W TX.

...CENTRAL/SRN PLAINS...LOWER MO VALLEY...
SE-NW ALIGNED BELT OF SCATTERED TSTMS...WITH ISOLATED SVR HAIL CORES
POTENTIALLY EMBEDDED WITHIN...IS MOVING NEWD ACROSS ERN NEB AND
LOWER MO VALLEY REGION. THIS ACTIVITY IS FOLLOWED BY ADDITIONAL
ELEVATED CONVECTION INCREASING IN COVERAGE/INTENSITY AS IT MOVES
NEWD OUT OF PORTIONS CENTRAL KS...ALSO N OF SFC FRONT. REF SPC
MESOSCALE DISCUSSION 1980 FOR NEAR-TERM DETAILS.

OTHERWISE...THREE RELATIVE CONCENTRATIONS OF POTENTIAL NOW ARE
APPARENT WITHIN WHAT OTHERWISE APPEARS AS POORLY
FOCUSED...CONVECTIVELY MESSY AND VERY BROAD SVR RISK AREA.

1. CORRIDOR FROM CENTRAL/SE TX INTO OK THROUGH AFTN...
THIS REGIME WILL REMAIN ASSOCIATED WITH BROAD LLJ AND RELATED
WAA/MOISTURE-TRANSPORT PROCESS...CHARACTERIZED BY WEAK INSTABILITY
BUT FAVORABLE LOW-LEVEL HODOGRAPHS AND GRADUALLY INTENSIFYING DEEP
SHEAR. EPISODES OF WIDELY SCATTERED TO SCATTERED NON-SVR TSTMS IN
CLUSTERS ALREADY HAVE BEEN OCCURRING FOR SEVERAL HOURS OVER THIS
AREA...INCREASING OVERALL IN COVERAGE. MORE DEVELOPMENT IS LIKELY
THROUGHOUT TODAY ON ITS WRN FRINGES AS
A. LLJ REPLENISHES LOW-LEVEL THETAE AWAY FROM PERSISTENT CONVECTIVE
OVERTURNING AND
B. DESPITE ABUNDANT CLOUD COVER...DIFFUSE DIABATIC HEATING YIELDS
STEADILY INCREASING SFC-BASED BUOYANCY THROUGH LATE AFTN.

2. EVENING/OVERNIGHT CONVECTIVE CORRIDOR FROM SW TX TO SRN OK...
DEEP-LAYER LIFT AND SHEAR EACH WILL INCREASE...IN ENVIRONMENT
CHARACTERIZED BY RICH LOW-LEVEL MOISTURE WITH SFC DEW POINTS
COMMONLY UPPER 60S TO LOW 70S F. THIS PROCESS SHOULD HELP TO
MAINTAIN SFC-BASED EFFECTIVE INFLOW PARCELS WITH WEAK CINH...BENEATH
STEEP MIDLEVEL LAPSE RATES...IN SUPPORT OF MOSTLY CLUSTERED TO
QUASI-LINEAR CONVECTION. THOUGH UPPER-LEVEL LAPSE RATES MAY BE
MITIGATED SOMEWHAT IN PLUME OF MOISTURE FROM RAYMOND...MLCAPE/MUCAPE
IN 1500-2000 J/KG MAY BE ATTAINABLE AWAY FROM PERSISTENT/ANTECEDENT
CONVECTIVE AREAS. LLJ WILL KEEP 0-1 KM SHEAR VALUES AND HODOGRAPH
LARGE...THOUGH WEAKNESSES ABOVE THAT MAY LIMIT TOTAL LOW-LEVEL
SHEAR. STILL...CONDITIONAL TORNADO RISK IS EVIDENT ON TOP OF
WIND/HAIL THREAT...DEPENDENT LARGELY ON MAINTENANCE OF ANY EMBEDDED
OR DISCRETE SUPERCELL MODES THAT CAN DEVELOP.

3. PORTIONS SRN KS...WRN OK AND W TX TONIGHT...
AS AFOREMENTIONED SHORTWAVE TROUGH APCHS SRN HIGH
PLAINS...HEIGHT/THERMAL GRADIENTS ALOFT WILL TIGHTEN CONSIDERABLY
AND ADVANCE EWD AMIDST PRONOUNCED DCVA AND STG HEIGHT FALLS.
RIGHT-ENTRANCE REGION OF AOA 140-KT 250-MB JET STREAK WILL BE
PRESENT OVER THIS REGION...ALONG WITH LOW-LEVEL FRONTOGENETIC
FORCING. THESE PROCESSES WILL RESULT IN INCREASING DEEP SHEAR...
LAPSE RATES AND LIFT OVER WRN FRINGES OF WARM/MOIST SECTOR AFTER
DARK. BAND OF SCATTERED TO LOCALLY NUMEROUS TSTMS MAY
FORM...OFFERING SVR HAIL...OCNL DAMAGING GUSTS AND LOW BUT NONZERO
TORNADO RISK.

WHILE THOSE REGIMES REPRESENT MOST PROBABLE SOURCES OF ORGANIZED SVR
CONVECTION...PLEASE BEAR IN MIND THAT STRENGTHENING WINDS ALOFT WILL
SPREAD OVER SEASONALLY MOIST AND AT LEAST MRGLLY UNSTABLE WARM/MOIST
SECTOR ALL PERIOD LONG. AS SUCH...AT LEAST ISOLATED SVR OF ANY TYPE
CAN OCCUR IN BETWEEN...ANYWHERE OVER OUTLOOK AREA...THROUGHOUT TODAY
AND TONIGHT.

..EDWARDS/COHEN.. 10/30/2013

[unome]

TWP updated hourly at HH:46 (can also be looped) http://weather.msfc.nasa.gov/cgi-bin/ba ... _drop=show

NESDIS QPE http://weather.msfc.nasa.gov/cgi-bin/sp ... ataset=qpe

[srainhoutx]

The HPC has just updated their Excessive Rainfall Outlook for Day 1 and have shifted the Slight Risk further S and W to include the NW portion of SE Texas as well as all of Central Texas.

[srainhoutx]

The 12Z HIRES (High Resolution) NAM short term meso model is picking up on all the abundant moisture streaming NE from EPAC cyclone Raymond as well as a new tropical disturbance forming offshore of Western Mexico near Acapulco. That deep tropical moisture combined with very deep Gulf of Mexico moisture 3 standard deviations above normal with 850mb moisture influx near 5 standard deviations above normal for October suggest the Flash Flood potential may well increase during the next 24-36 hour across much of the Eastern half of the Lone Star State extending N and E into Arkansas and Louisiana.

[srainhoutx]

From Nesdis:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 10/30/13 1428Z
SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-683-1404
LATEST DATA USED: GOES-E 1415Z LP
.
LOCATION...LOUISIANA...MISSOURI...ARKANSAS...TEXAS...
LOCATION...OKLAHOMA...KANSAS...
.
ATTN WFOS...LZK...SGF...LCH...SHV...EAX...TSA...HGX...TOP...ICT...
ATTN WFOS...FWD...OUN...EWX...
ATTN RFCS...LMRFC...MBRFC...ABRFC...WGRFC...
.
EVENT... HIGH MOISTURE AND HEAVY RAINS
.
SATELLITE ANALYSIS AND TRENDS... UL LOW CURRENTLY CENTERED OVER EXTREME
SOUTHERN NEVADA SWINGING INTO WESTERN ARIZONA CLEARLY SEEN IN RGB AIRMASS
PRODUCT. MID-UL MOISTURE PLUME VISIBLE IN WV IMAGERY IS DRAWING FROM
TROPICAL DEPRESSION RAYMOND AND SPREADING ACROSS TEXAS AND THE SOUTHERN
PLAINS. ADDITIONALLY A STRONG SOUTHWESTERLY LLJ IS FEEDING TROPICAL
MOISTURE INTO THE SAME REGION WITH THE AXIS OF HIGHEST
MOISTURE CURRENTLY NOSING INTO SOUTHEASTERN OKLAHOMA/WESTERN
ARKANSAS. SATELLITE BLENDED TPW SHOWING WIDESPREAD VALUES OF 1.5" ACROSS
EAST TEXAS AND SOUTHERN OKLAHOMA AND IS EXPECTED TO CONTINUE INCREASING
TODAY. LATEST IR IMAGERY SHOWING CLOUD TOP COOLING OCCURRING ALONG THE
LL MOISTURE AXIS MOST NOTABLY IN SOUTHEAST TEXAS AND CENTRAL OKLAHOMA.
.
AN ANNOTATED SATELLITE GRAPHIC SHOWING THE HEAVY PRECIPITATION
THREAT AREA SHOULD BE AVAILABLE ON THE INTERNET ADDRESS LISTED
BELOW IN APPROXIMATELY 10-15 MINUTES.
.
SHORT TERM OUTLOOK VALID 1430-1830Z...MEDIUM CONFIDENCE FACTOR
IN SHORT TERM OUTLOOK... RAPID CLOUD TOP COOLING IN LAST FEW HOURS IN
SOUTHEAST TEXAS INCREASING IN SCALE AND STEADILY MOVING NORTHWARD INTO
NORTHEAST TEXAS/SOUTHEAST OKLAHOMA/SOUTHWEST ARKANSAS. ADDITIONAL COLD
TOP COOLING NOW OCCURRING JUST TO WEST OF COLDEST TOPS. EXPECT RAINS
TO BE PERSISTENT GIVEN LARGE COVERAGE WITH RATES OF 1.0-1.5"/HR IN
HEAVIER BURSTS. ALSO CONCERN FOR ACTIVE CONVECTION DEVELOPING ACROSS
CENTRAL/NORTHEAST OKLAHOMA. IT IS ORIENTED SOUTHWEST-NORTHEAST AND
IS TRAINING AS IT MOVES TOWARD THE NORTHEAST INTO AREAS OF LOWER
FFG IN SOUTHEAST KANSAS AND SOUTHWEST MISSOURI (WHICH RECEIVED HEAVY
RAINS YESTERDAY MORNING). EXPECT RATES ASSOCIATED WITH STRONG CELLS
TO BE 1.0-1.25"/HR. WITH ANOMALOUS MOISTURE INCREASING THROUGHOUT THE
DAY... HEAVY RAIN THREAT WILL CONTINUE AS UL LOW BEGINS TO AFFECT REGION
LATER TODAY AND TONIGHT.

[Portastorm]

The short-term NAM image you posted, srainhoutx, certainly has my attention with that convective bullseye over south central Texas. One of the local TV stations has their own computer model which is suggesting 3-6 inches for the Austin metro area. EWX is more conservative, as expected, with 1-3 inches and isolated amounts of 4-5 inches in spots.

You folks east of us will certainly get more rain than we do, but we're hoping to see some nice rains over the Highland Lakes watershed areas.

[Andrew]

Nam Hi-Res did a pretty good job at forecasting the storms over central Texas last night and if the 12z came true, there would be a very large flooding threat through SE Texas. It has a continuos stream of moisture over the area for up to 6 hours. Worrisome to see this with the moisture already in place paired with such high PW values already.

[Rip76]

Sprinkles only from CRP to Refugio.
Seeing rain up ahead though.

[unome]

NESDIS Precip Analysis ( http://www.ospo.noaa.gov/Products/atmosphere/spe/) put up an additional graphic, it won't shrink for me & it's too large to hot-link

http://www.ospo.noaa.gov/data/atmospher ... 301428.gif

[srainhoutx]

1630Z Storm Prediction Center Update:

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT WED OCT 30 2013

VALID 301630Z - 311200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLNS NEWD INTO THE
MID MS VLY/ARKLATEX...

...SYNOPSIS...
PROGRESSIVE SPLIT FLOW PATTERN WILL CONTINUE ACROSS THE LWR 48
THROUGH THU. POSITIVE-TILT UPR LOW/TROUGH NOW OVER THE RCKYS/ERN GRT
BASIN SHOULD BEGIN TO ACCELERATE ENEWD TNGT AND THU AS JET STREAK
NOW OVER THE GULF OF AK CONTINUES E INTO BC. THIS SET-UP SHOULD
DRIVE STRONG UPR VORT IN THE BASE OF THE TROUGH...NOW OVER NRN
AZ...EWD ACROSS NM TNGT AND INTO THE TX PANHANDLE/NW OK BY 12Z
THU...STRENGTHENING LARGE SCALE ASCENT OVER THE SRN HALF OF THE
PLNS.

IN THE MEAN TIME...A BROAD SWATH OF INCREASINGLY MOIST...LOW-LVL
CONFLUENT FLOW WILL PERSIST FROM THE SRN PLNS NNE INTO THE MID-MS
VLY...ALONG AND AHEAD OF COLD FRONT PRECEDING THE UPR TROUGH...AND E
OF DRY LINE/LEE TROUGH OVER THE SRN PLNS. MID-LVL LAPSE RATES ATOP
THE MOIST CORRIDOR WILL REMAIN WEAK. BUT WITH AMPLE DEEP SHEAR IN
PLACE TO SUPPORT ORGANIZED SUSTAINED STORMS...POTENTIAL FOR
POCKETS/EPISODES OF STRONG TO SVR ACTIVITY THROUGH THE PERIOD FROM A
LARGE PART OF TX E/NEWD THROUGH THE ARKLATEX INTO PARTS OF KS/MO AND
THE MID MS VLY.

...SRN PLNS NEWD INTO KS/MO/IA/IL...AND THE ARKLATEX...
AS IMPLIED ABOVE...SCTD SVR THREATS WILL BE FAIRLY WIDELY
DISTRIBUTED IN SPACE AND TIME THIS PERIOD...WITH MULTIPLE AREAS
POTENTIALLY SEEING ONE OR TWO ROUNDS OF ACTIVITY...AND WITH THE
OVERALL SVR RISK GRADUALLY INCREASING WITH TIME.

IN THE NEAR TERM...LOW-LVL WAA/MOISTURE TRANSPORT NEAR DIFFUSE W-E
WARM FRONT IN NRN MO EXPECTED TO MAINTAIN A RISK FOR ISOLD SVR
HAIL/WIND INTO THE AFTN /REF WW 549/. AS ASSOCIATED LEAD UPR IMPULSE
CONTINUES NNEWD ACROSS NEB/SD...LARGE-SCALE FORCING FOR ASCENT OVER
MO SHOULD GRADUALLY WANE. HOWEVER...WITH LLJ CONTINUING TO
STRENGTHEN AND VEER INTO THE AFTN...IT IS NOT OUT OF THE QUESTION
THAT ISOLD SVR WEATHER /MAINLY IN THE FORM OF HAIL/...COULD SPREAD
ENE INTO THE MID MS VLY.

FARTHER SW...OTHER STORMS SHOULD GRADUALLY INCREASE IN NUMBER AND
INTENSITY LATER TODAY INTO TNGT FROM ERN KS SSW THROUGH WRN/CNTRL OK
INTO WRN AND NRN TX...ALONG AND AHEAD OF COLD FRONT/DRY LINE. WHILE
FORCING FOR ASCENT WILL NOT APPRECIABLY CHANGE OVER THIS REGION
THROUGH LATE TODAY...MODEST SFC HEATING OF SEASONABLY MOIST
AIR...CONFLUENT LOW-LVL FLOW...AND WEAK HEIGHT FALLS ASSOCIATED WITH
PROGRESSIVE UPR TROUGH ALL SUGGEST LIKELIHOOD FOR NUMEROUS
CLUSTERS/BANDS OF STORMS.

GIVEN STRENGTH OF WIND FIELD...AND LIKELY INCREASE IN THE FLOW
THROUGH THIS EVE...POTENTIAL WILL EXIST FOR A COMPLEX MIX OF STORM
MODES CAPABLE OF SVR HAIL...SCTD DMGG WIND GUSTS...AND PERHAPS A
COUPLE TORNADOES. THE TORNADO THREAT WILL REQUIRE THE PRESENCE OF
MESOSCALE FORCING MECHANISMS THAT ARE NOT APPARENT ATTM...BUT SOME
RISK WILL EXIST NONETHELESS. LATER TNGT AND...ESPECIALLY...EARLY
THU...STORMS SHOULD FURTHER INCREASE IN COVERAGE AND POSSIBLY
STRENGTH AS LARGE SCALE ASCENT INCREASES WITH THE EWD ACCELERATION
OF AZ/NM UPR VORT.

STILL FARTHER S...AND SE...A SEPARATE SVR THREAT MAY ARISE OVER
CNTRL AND E TX...WHERE EXISTING WIDESPREAD AREA OF LOOSELY-ORGANIZED
CONVECTION SHOULD GRADUALLY INCREASE/BECOME BETTER ORGANIZED THROUGH
THE END OF THE PERIOD. COMBINATION OF VERY MOIST ENVIRONMENT /PW AOA
2 INCHES/ WITH SUBSTANTIALLY-INCREASED 850-700 MB FLOW LATE IN
PERIOD SUGGESTS AN INCREASING RISK FOR LEWP STRUCTURES AND AN
ATTENDANT WIND/TORNADO THREAT OVER PARTS OF E TX AND PERHAPS THE
ARKLATEX TOWARD DAYBREAK.

..CORFIDI/GARNER.. 10/30/2013

[srainhoutx]

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1217 PM CDT WED OCT 30 2013

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
SAN JACINTO COUNTY IN SOUTHEAST TEXAS...
POLK COUNTY IN SOUTHEAST TEXAS...

* UNTIL 1245 PM CDT

* AT 1216 PM CDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM
WAS LOCATED OVER COLDSPRING...OR 12 MILES SOUTHWEST OF
LIVINGSTON...AND MOVING EAST AT 25 MPH. PENNY SIZE HAIL MAY ALSO
ACCOMPANY THE DAMAGING WINDS.

* LOCATIONS IMPACTED INCLUDE...
LIVINGSTON...SHEPHERD...COLDSPRING...GOODRICH...LAKE LIVINGSTON
STATE PARK...WEST LIVINGSTON AND LEGGETT.

[srainhoutx]

A quick update on the pattern that is developing as we enter into the month of November. The medium/long range operational and ensemble guidance suggests we are in a very active and wet pattern with two more heavy rainfall episodes with the continuation of a very active deep Western trough and storms systems diving into the Great Basin and eventually ejecting E into the Plains. The GFS is advertising some locations may see well in excess of a foot of rain across portions of Texas, Arkansas and Louisiana. Perhaps someone would like to start a new Topic for November since we are near the end of October.

[snowman65]

If someone does start a new topic for November, I suggest the pros only post comments that include the words STRONG, COLD, and FRONT...agreed?

[srainhoutx]

MESOSCALE DISCUSSION 1982
NWS STORM PREDICTION CENTER NORMAN OK
1245 PM CDT WED OCT 30 2013

AREAS AFFECTED...SE...CNTRL AND NRN TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 301745Z - 301915Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...A SEVERE THREAT MAY DEVELOP THIS AFTERNOON FROM SE TX
NNWWD INTO NCNTRL TX. WIND DAMAGE AND PERHAPS AN ISOLATED TORNADO
THREAT WILL BECOME POSSIBLE AS CELLS INITIATE. WW ISSUANCE MAY BE
NEEDED ESPECIALLY IF A CLUSTER OF STORMS CAN INTENSIFY AND BECOME
ORGANIZED.

DISCUSSION...THE LATEST SFC ANALYSIS SHOWS A CORRIDOR OF LOW-LEVEL
MOISTURE EXTENDING WWD FROM THE HOUSTON AREA INTO THE TX HILL
COUNTRY AND NWD TO NEAR THE RED RIVER. THE AIRMASS IS VERY MOIST
WITH SFC DEWPOINTS RANGING FROM THE MID 70S F IN SE TX TO THE UPPER
60S F ACROSS NCNTRL TX. IN ADDITION...VISIBLE SATELLITE SHOWS BREAKS
IN THE CLOUD COVER ALONG THIS CORRIDOR WHICH HAS ENABLED SFC TEMPS
TO WARM INTO THE MID TO UPPER 70S F. THIS HAS HELPED ENHANCE
INSTABILITY WITH SBCAPE VALUES ESTIMATED IN THE 1000 TO 2000 J/KG
RANGE. CONTINUED SFC HEATING MAY ALLOW FOR THE INITIATION OF
SFC-BASED STORMS ACROSS THE MCD AREA DURING THE MID-AFTERNOON AS IS
SUPPORTED BY THE LATEST HRRR RUN AND ECMWF. ALSO...SFC WINDS ARE
BACKED TO THE SOUTHEAST ACROSS MOST OF THE MCD AREA. THIS IS HELPING
TO ENHANCE LOW-LEVEL SHEAR WHICH ALONG WITH 0-6 KM SHEAR IN THE 45
TO 50 KT RANGE....SHOULD BE ENOUGH FOR CELL ROTATION AND POSSIBLY AN
ISOLATED TORNADO THREAT. THE MOIST BOUNDARY LAYER MAY ALSO RESULT IN
A POTENTIAL FOR WET DAMAGING OUTFLOW GUSTS.

..BROYLES/CORFIDI.. 10/30/2013


ATTN...WFO...HGX...FWD...EWX...SJT...

[srainhoutx]

The HPC Excessive Rainfall forecast update is out and continues to shift the Slight Risk further S and W including most of Central, SE, E Texas and potions of Louisiana:

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
236 PM EDT WED OCT 30 2013

...VALID 18Z WED OCT 30 2013 - 00Z FRI NOV 01 2013...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 WSW FOE 25 NNE CDJ AWG 10 SE DKB IGQ 20 S BMI 40 WNW SET
30 WNW AIZ 25 E PPF 25 NNW BVO WLD 20 ENE AAO 30 WSW FOE.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 N INJ 25 SE AQR 10 ESE RKR 30 SSE HRO 10 NNE M19 30 ENE DYR
35 NW TUP 25 WSW TVR 25 NE ESF 15 SW ACP 35 ENE GLS 20 SSW BYY
10 E VCT 10 S 3T5 15 N RND 25 S 6R9 10 SSW 05F 15 N INJ.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 ENE TRL PRX 25 W MWT 25 W LZK 20 W SGT 30 SW PBF 10 N ELD
15 NNE BAD 15 ESE GGG 10 SW JSO 25 W PSN 10 NE CRS 15 ENE TRL.


...EASTERN TX/SOUTHEASTERN OK TO THE LOWER MS VALLEY...

INGREDIENTS CONTINUE TO COME TOGETHER...WITH MOST 12Z GUIDANCE
MEMBERS AGREEING...ON A SIGNIFICANT RAINFALL EVENT DEVELOPING
ACROSS THE REGION THIS AFTERNOON INTO THE OVERNIGHT HOURS IN
ASSOCIATION WITH THE AFOREMENTIONED DEEP UPPER TROUGH MOVING INTO
THE CENTRAL U.S. PWS ARE EXPECTED TO CONTINUE INCREASING THIS
AFTERNOON ACROSS EASTERN TX/OK AND THE LOWER MS VALLEY AS HI LEVEL
MOISTURE EMANATING FROM POST-TROPICAL CYCLONE RAYMOND AND LOW
LEVEL MOISTURE FROM THE WESTERN GULF CONVERGE ON THE REGION. AS
THE LOW LEVEL FLOW INCREASES TO 40+ KTS...PWS ARE EXPECTED TO
EXCEED 2 INCHES...2-3+ STANDARD DEVIATIONS ABOVE NORMAL...ACROSS
EASTERN TX/OK WESTERN AR/LA BY THIS EVENING. GOOD UPPER LEVEL
DIFFLUENCE...HEIGHT FALL...WITH AREAS OF ENHANCED DIVERGENCE
AFFORDED BY EMBEDDED WEAK SHORTWAVES...WILL CONTINUE TO SUPPORT
AREAS OF HEAVY RAINFALL AS THEY INTERACT WITH THIS DEEP MOISTURE.
CONDITIONS ARE EXPECTED TO BECOME FAVORABLE FOR TRAINING
CELLS...FURTHER RAISING THE THREAT FOR HEAVY AMOUNTS...AS THE MEAN
FLOW BECOMES PARALLEL TO THE ASSOCIATED COLD FRONT...WHICH WILL BE
SLOW TO ADVANCE EAST AS IT AWAITS A WELL-DEFINED SHORTWAVE
EMBEDDED WITHIN THE BASE OF THE TROUGH OVER THE SOUTHWEST. EXPECT
WIDESPREAD AMOUNTS OF 1-3 INCHES...WITH LOCALLY HEAVIER
AMOUNTS...ACROSS THIS REGION WITH THE HEAVIEST AMOUNTS CENTERING
AROUND THE ARKLATEX REGION WHERE A MODERATE RISK FOR EXCESSIVE HAS
BEEN INDICATED.

PEREIRA

[srainhoutx]

URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
239 PM CDT WED OCT 30 2013

AUSTIN-BRAZOS-BURLESON-COLORADO-GRIMES-HARRIS-HOUSTON-LIBERTY-
MADISON-MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-
WASHINGTON-
INCLUDING THE CITIES OF...BELLVILLE...BRENHAM...BROOKSHIRE...
BRYAN...CALDWELL...CLEVELAND...COLDSPRING...COLLEGE STATION...
COLUMBUS...CONROE...CORRIGAN...CROCKETT...DAYTON...EAGLE LAKE...
GROVETON...HEMPSTEAD...HOUSTON...HUMBLE...HUNTSVILLE...KATY...
LAKE SOMERVILLE...LIBERTY...LIVINGSTON...MADISONVILLE...
NAVASOTA...ONALASKA...PASADENA...PRAIRIE VIEW...SEALY...
SHEPHERD...THE WOODLANDS...TOMBALL...TRINITY...WEIMAR...WILLIS
239 PM CDT WED OCT 30 2013

...FLASH FLOOD WATCH IN EFFECT FROM 7 PM CDT THIS EVENING THROUGH
THURSDAY AFTERNOON...

THE NATIONAL WEATHER SERVICE IN HOUSTON/GALVESTON HAS ISSUED A

* FLASH FLOOD WATCH FOR A PORTION OF SOUTHEAST TEXAS...INCLUDING
THE FOLLOWING COUNTIES...AUSTIN...BRAZOS...BURLESON...
COLORADO...GRIMES...HARRIS...HOUSTON...LIBERTY...MADISON...
MONTGOMERY...POLK...SAN JACINTO...TRINITY...WALKER...WALLER
AND WASHINGTON.

* FROM 7 PM CDT THIS EVENING THROUGH THURSDAY AFTERNOON

* ABUNDANT MOISTURE COMBINED WITH AN UPPER LEVEL DISTURBANCE AND
ASSOCIATED COLD FRONT WILL PRODUCE THE POTENTIAL FOR FLASH
FLOODING ACROSS PORTIONS OF SOUTHEAST TEXAS.

* SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP ACROSS SOUTHEAST TEXAS TONIGHT INTO EARLY THURSDAY.
RAINFALL AMOUNTS WILL AVERAGE 2 TO 4 INCHES ACROSS THE REGION.
ISOLATED TOTALS OF UP TO 6 TO 8 INCHES ARE POSSIBLE IN
LOCATIONS WHERE TRAINING OF CELLS DEVELOPS.