September 2014: Seasonably Warm & Dry To End The Month

[djjordan]

Gonna be an interesting stretch of weather watching coming up. Hopefully everyone gets some beneficial rains in the next week. Gonna have to watch radar carefully.

[srainhoutx]

From Jeff:

Area of low pressure east of the central FL coast has been declared 92L.

Discussion:

A surface low pressure center located just north of the Bahamas and east of the east FL coast has shown little additional organization today after an explosion of thunderstorms near its center overnight and this morning. Surface pressures remain high in the area, and while both radar data from Melbourne, FL and satellite images show a well defined low level circulation, convection is not organized enough to declare the system a tropical depression. The system is drifting toward the WSW and will make landfall on the E or SE FL coast Friday into Saturday.

 

Track:

A chaotic and uncertain forecast track path exist as 92L moves WSW and then W across FL and into the SE Gulf of Mexico over the weekend. This track is in response to a building ridge of high pressure over the SE US as a result of the deep troughing over the central US which traps and moves the system westward. After 72 hours there is large model spread and very little agreement on the potential upper level steering pattern over the Gulf of Mexico and the southern US with wildly varying tracks being presented by each of the global and hurricane forecasting models. With this in mind coordinated NHC/HPC grids will bring a surface low into the SE and central Gulf by early next week and that is the extent of confidence at this time.

 

Intensity:

92L will struggle over the next 24-36 hours as strong northerly shear impacts the system and then the FL landmass. Once in the Gulf of Mexico upper level conditions appear to become more favorable for development and NHC is giving the system a 40% chance of development once in the Gulf late this weekend or early next week. Global forecast models are not overly aggressive with this system with the majority of guidance keeping the system either a tropical storm or below tropical storm status. The ECMWF keeps it an open wave as it has done so many times this summer and has usually been correct. Most of the other global models show modest development over the Gulf of Mexico.

 

Note:

For the first time this season a tropical system in the Atlantic is presenting a highly uncertain track and intensity forecast. Significant changes are likely with this system over the next 72 hours which could affect forecasts along the Gulf coast including TX next week.

Note: while there appears to be some decent model agreement on the track below, the uncertainty is larger than normal.

[Ptarmigan]

Today is the 13th anniversary of 9/11. It was a very clear and sunny day from what I remember on that tragic day. The blue skies marred by thick dust and smoke of what used to be the World Trade Center. So many lives have been lost that day.

[Katdaddy]

Rain and thunderstorm chances increase today especially over the NW portion of SE TX and then across all of SE TX down to the coast overnight and into Saturday. Some areas will likely see localized heavy rains as the weak frontal boundary drifts toward the coast and combines with the sea breeze. Tropical funnels will also be possible today along the coast. Invest 92L will need to be watched Sunday through Wednesday as it move across the GOM toward TX and LA. Currently its still disorganized. This mornings Houston-Galveston AFD sums it up quite well:

ATTENTION THEN TURNS TO THE GULF. AREA OF DISTURBED WX OFF THE EASTERN FLORIDA COASTLINE IS FCST TO CONTINUE MOVING WWD UNDER THE MID LEVEL RIDGE AND ACROSS THE GULF. MOST OF THE MODELS ARE IN DECENT AGREEMENT SHOWING THIS AXIS SOMEWHERE OFF THE TX/LA COAST MONDAY AND TUESDAY. SOME SHOW A SURFACE CIRCULATION...ABEIT NOT VERY DEVELOPED OR STRONG. NOT GONNA HYPE THIS UP...BUT DO ENCOURAGE FOLKS TO CHECK IN ON THIS OVER THE WEEKEND. WE ARE ON THE WRN PERIPHERY OF THE STEERING HIGH & IT WILL BE THE TYPICAL PEAK OF THE HURRICANE SEASON SO YA JUST NEVER KNOW.

[srainhoutx]

Morning Update from Jeff:

Slow moving cold front will bring a round of potentially heavy rainfall to the area this afternoon into early Saturday.

Early next week forecast completely dependent on track and possible development of 92L in the Gulf of Mexico.

Will focus first on the incoming frontal system and then elaborate some on 92L. Surface boundary located across NCT X this morning and has stalled. Strong secondary short wave trough currently moving through the central plains is producing a band of thunderstorms north of the frontal boundary along the Red River and the lift associated with this short wave will spread southward today and develop additional thunderstorms along the actual frontal boundary by early this afternoon (roughly along a Del Rio to College Station to Lufkin line). At the same time a tropical wave over the western Gulf of Mexico is moving inland along the TX coast this morning with a surge of tropical moisture currently moving over our outer waters (60nm) and spreading toward the coast. Showers and thunderstorms will begin to develop with this surge and spread inland by mid to late morning and then collide with the southward moving boundary and thunderstorms at some point this afternoon or early evening.

Meso models suggest this collision of the northward moving activity and the frontal boundary will occur somewhere north of a line from Columbus to Lake Livingston late this afternoon or early this evening. We have seen this pattern a couple times this summer and each of these events have produced some excessive rainfall totals. With moisture streaming inland from the Gulf and PWS rising to near 2.20 inches high short term rainfall rates in the strongest storms appears likely.

Will go with widespread rainfall amounts of .5 to 1.5 inches with isolated totals of 3-4 inches possible. The greatest threat for excessive rainfall appears to be north of I-10 and much of this area is showing significant soil moisture deficits at this time so a good bit of rainfall can be handled. Do not expect any severe weather given the warm tropical profiles, but any Friday night outdoor activities (football) could be impacted by lightning.

Dry air attempts to move into the area late Saturday into Sunday and this may confine additional weekend rain chances toward the coast. This “drier” period looks short lived however as 92L and additional tropical moisture begins approaching from the E by early next week.

92L:
Radar data from West Palm Beach and Miami indicate that the area of low pressure off the E FL coast has moved inland overnight and is currently located between West Palm Beach and Fort Lauderdale and is moving WSW to SW. Deep convection has been sheared to the south side of this system across the FL Keys and extreme southern FL. No additional development is expected while the system is over FL.

92L will enter into the SE Gulf of Mexico on Saturday and continue toward the west under building mid level ridging along the US Gulf coast. Forecast track guidance overnight remain highly uncertain, but two camps appear to be starting to emerge with one camp featuring a weaker system toward the TX coast and the other camp showing a stronger system curving hard to the right over the central US Gulf coast. Both the GFS and ECMWF models show very little development with this system, and while they both agree, I am not sure they are totally correct given the fairly well defined circulation showing on radar this morning.

Upper level conditions over the Gulf of Mexico will be marginally conducive for additional development so the system bears close watch over the weekend.

Should the southern track begin to look like it is going to verify, significant forecast changes will be required along the NW Gulf coast for early/mid next week especially with marine impacts.

[srainhoutx]

Buoy and surface observations suggest a surface low has developed in the Bay of Campeche to further complicate an already challenging forecast...

[djmike]

Wow. Bay of Campeche blob? Florida Blob? Tropical Blob south Texas? .....Yup, this is going to be a busy rough next week! So much going on in the gulf! Hope we can get some beneficial rains from atleast one system!

[kayci]

I hope that's ALL we get, djmike...

[Rip76]

Wow

[JamieP]

Very interesting week ahead of us folks, I know I will check in frequently. I hope everyone is prepared since we are in the heart of hurricane season. Hoping we get some rain in our area from one of our "blobs" : )

[srainhoutx]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
944 AM CDT FRI SEP 12 2014

TXZ199-200-210>214-226-227-235>238-121700-
MONTGOMERY-LIBERTY-COLORADO-AUSTIN-WALLER-HARRIS-CHAMBERS-WHARTON-
FORT BEND-JACKSON-MATAGORDA-BRAZORIA-GALVESTON-
INCLUDING THE CITIES OF...THE WOODLANDS...CONROE...WILLIS...
LIBERTY...CLEVELAND...DAYTON...COLUMBUS...EAGLE LAKE...WEIMAR...
SEALY...BELLVILLE...HEMPSTEAD...PRAIRIE VIEW...BROOKSHIRE...
HOUSTON...PASADENA...KATY...TOMBALL...HUMBLE...WINNIE...
MONT BELVIEU...ANAHUAC...EL CAMPO...WHARTON...PIERCE...
SUGAR LAND...MISSOURI CITY...RICHMOND...ROSENBERG...EDNA...
BAY CITY...PALACIOS...PEARLAND...LAKE JACKSON...ALVIN...
ANGLETON...FREEPORT...LEAGUE CITY...TEXAS CITY...FRIENDSWOOD...
GALVESTON
944 AM CDT FRI SEP 12 2014

...ISOLATED FUNNEL CLOUDS POSSIBLE TODAY...

DEEP TROPICAL MOISTURE WILL PRODUCE FAVORABLE CONDITIONS FOR BRIEF
FUNNEL CLOUDS TO DEVELOP ACROSS THE REGION TODAY. THE MOST LIKELY
TIME PERIOD FOR THIS ACTIVITY WILL BE THIS MORNING THROUGH EARLY
AFTERNOON.

ALTHOUGH IT IS POSSIBLE...THESE FUNNELS DO NOT TYPICALLY EXTEND TO
THE GROUND TO BECOME TORNADOES. IF YOU OBSERVE A FUNNEL...TAKE
COVER INDOORS AWAY FROM WINDOWS IF IT BEGINS TO DESCEND. REPORT
ANY FUNNEL CLOUDS TO LOCAL LAW ENFORCEMENT OR THE NATIONAL WEATHER
SERVICE.

[srainhoutx]

RECON schedule for 92L if necessary:

Code: Select all

000
NOUS42 KNHC 121444
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1045 AM EDT FRI 12 SEPTEMBER 2014
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
         VALID 13/1100Z TO 14/1100Z SEPTEMBER 2014
         TCPOD NUMBER.....14-104

I.  ATLANTIC REQUIREMENTS
    1. SUSPECT AREA (GULF OF MEXICO)
       FLIGHT ONE -- TEAL 71        FLIGHT TWO -- TEAL 72
       A. 13/1730Z                  A. 14/1130Z, 1730Z
       B. AFXXX 01HHA INVEST        B. AFXXX 0207A CYCLONE
       C. 13/1545Z                  C. 14/0945Z
       D. 26.0N 84.0W               D. 26.0N 87.5W
       E. 13/1700Z TO 13/2200Z      E. 14/11005Z TO 14/1730Z
       F. SFC TO 10,000 FT          F. SFC TO 10,000 FT

    2. OUTLOOK FOR SUCCEEDING DAY: CONTINUE 6-HRLY FIXES IF
       SYSTEM DEVELOPS AND IS A THREAT.

[Texaspirate11]

How come our NWS isn't mentioning the Blob in the BOC?

[srainhoutx]

How come our NWS isn't mentioning the Blob in the BOC?

More than likely because it is expected to remain stationary and so far the NHC has not mentioned the area of disturbed weather. We will see if they decide it is worth mentioning later today.

[BlueJay]

We are currently dry but hoping that some of the rain I see on radar will make it up our way.
Anyone getting rain yet?

[mckinne63]

I encountered a very heavy downpour on Beltway 8 in SW Houston around 10:30am, but when I got on 59S it was dry. Sugarland was looking very dark and I was hearing thunder as I ran my errands. Manged to make it home to Stafford without getting wet. Skies are looking dark but with some sun mixed in. I have heard a few rumbles of thunder. No rain yet.

[jasons2k]

It's pouring here at my dentist office along I-45 near Rayford. But it looks like the house is still dry just a few miles away...

[BlueJay]

Now I hear some lovely thunder and it seems to be getting darker outside. Nice.

[Andrew]

Both surface obs and satellite show the front/reinforcing boundary approaching the Northern counties of SE Texas. Currently the boundary is located just to the South of Waco with a NE to SW orientation. Expect this boundary to continue its southeastward movement through the evening. To the South PWs are increasing as gulf moisture continues to stream in from the BOC. We are seeing some good moisture advection at 850mb for most of the area and this should further increase storm coverage as we continue the afternoon. The "collision" of these boundaries will be key for where heaviest rain sets up. Both the Texas Tech WRF and HRRR indicate that this initial collision will be along a line from Austin to College station to Madisonville. Storm motion will be slow with storms that develop leading to possible flash flooding. Eventually, as the front progresses south, cool air will undercut most of the storms to the north killing instability. Farther south around the metro area, the HRRR is pretty bullish about keeping rain chances around through at least midnight as the front continues its southward progression. Lost of daytime heating may limit that some but with strong kinematics associated with the front and strong moisture pull from the south, I wouldn't be surprised to see storms last into the overnight hours. Hopefully those who missed out the last couple of times can see something today or tomorrow.

[BlueJay]

Nice report Andrew, thanks!
The sky has opened up here and we are enjoying a pretty good shower with some very loud thunder.