May 2017: Memorial Day/End Of May Outlook

[houstonia]

Finally getting nice rain, thunder and lightness my here in southwest Houston. The dog isn't happy but I am!!

[DoctorMu]

Storms starting to explode over Ft Bend county. Appear to be strengthening as well

Impressive. mckinne63 may have gotten their wish.

[srainhoutx]

tmp_8936-mcd0258276061964.gif

MESOSCALE PRECIPITATION DISCUSSION 0258 NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 352 AM EDT MON MAY 22 2017 AREAS AFFECTED...COASTAL TEXAS CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE VALID 220752Z - 221352Z SUMMARY...AN UPTICK IN CONVECTIVE COVERAGE ACROSS PORTIONS OF COASTAL TEXAS WILL LEAD TO A FLASH FLOOD THREAT OVER THE NEXT SEVERAL HOURS. DISCUSSION...RECENT RADAR IMAGERY AND SURFACE WIND FIELDS SUGGEST THAT AN MCV HAS FORMED WITH THE SMALL THUNDERSTORM COMPLEX MOVING EAST ACROSS SOUTH TEXAS. THIS COMPLEX IS ALSO IN AN AREA OF INCREASED UPPER LEVEL DIVERGENCE ON THE NOSE OF THE SUBTROPICAL JET. AS THE MCV AND INCREASED UPPER LEVEL DIVERGENCE MOVES EAST...CONDITIONS SHOULD CONTINUE TO BECOME MORE FAVORABLE FOR CONVECTIVE DEVELOPMENT OVER PORTIONS OF SOUTHEAST TEXAS. EARLIER THIS EVENING A BOUNDARY WAS EVIDENT OFFSHORE...WITH TRAINING CONVECTION EVIDENCE OF THIS BOUNDARY. HOWEVER THIS CONVECTION HAS BEEN FORCED EASTWARD WITH TIME...AND WIND FIELDS SUGGEST THE BOUNDARY IS SLOWLY LIFTING BACK NORTH INTO THE COAST FROM CORPUS CHRISTIE TO PORT LAVACA. THE COMBINATION OF FAVORABLE UPPER DYNAMICS MOVING IN...AND INCREASED LOW LEVEL MOISTURE TRANSPORT INTO THIS BOUNDARY...WILL SET THE STAGE FOR AN INCREASE IN ROBUST CONVECTION OVER THE NEXT SEVERAL HOURS. HIGH RES MODEL RUNS ARE GENERALLY IN GOOD AGREEMENT ON THE EVOLUTION...WITH CELL MERGERS AND TRAINING CONVECTION LIKELY FROM THE MCV TOWARDS THE COASTAL FRONT. PRECIPITABLE WATER VALUES ARE RIGHT AROUND 2" PER GPS...WHICH COMBINED WITH A DEEP WARM LAYER SUPPORTS EFFICIENT RAINFALL. THUS ANTICIPATE ISOLATED TO SCATTERED 4-6" TOTALS INTO THE EARLY MORNING HOURS...WITH THE MAIN FOCUS THROUGH 12Z ALONG THE COAST IN BETWEEN CORPUS CHRISTIE AND HOUSTON. CONFIDENCE IN AN EXCESSIVE RAINFALL THREAT IS LOWER FURTHER UP THE COAST IN THE VICINITY OF HOUSTON...THUS HAVE OPTED TO NOT EXTEND THE MPD INTO THIS AREA AT THIS TIME. THIS AREA IS CURRENTLY FURTHER INTO THE MORE STABLE AIR PER RADAR IMAGERY AND SPC RAP MESOANALYSIS. HOWEVER DO ANTICIPATE THAT THE FRONT WILL SLOWLY LIFT BACK NORTH WITH TIME HERE AS WELL. JUST A QUESTION AS TO HOW FAR NORTH THE COASTAL FRONT AND BETTER INSTABILITY CAN GET NEAR HOUSTON. THIS WILL DETERMINE WHETHER THE HEAVIEST TOTALS END UP ONSHORE OR JUST OFFSHORE AS THE CONVECTION MOVES UP THE COAST EARLY THIS MORNING. WILL CONTINUE TO MONITOR THIS REGION...AND ISSUE ADDITIONAL MPDS AS NEEDED. CHENARD ATTN...WFO...CRP...EWX...HGX...

[Katdaddy]

A Flash Flood Watch has been issued for the Upper TX Coast including the Houston-Galveston areas through early afternoon. 1-3" totals with higher amounts up 5" will be possible along the coast.

[srainhoutx]

Flood Advisory
National Weather Service Houston/Galveston TX
623 AM CDT MON MAY 22 2017

Fort Bend TX-Harris TX-
623 AM CDT MON MAY 22 2017

The National Weather Service in League City has issued a

* Flood Advisory for...
East central Fort Bend County in southeastern Texas...
South central Harris County in southeastern Texas...

* Until 715 AM CDT.

* At 621 AM CDT, gauge reports indicated the storm moving through
southwest Harris County toward downtown Houston is producing
rainfall amounts near 1 inch in 15 minutes. Rates this high will
run off and produce street flooding..

* Some locations that will experience flooding include...
Northeastern Sugar Land, northern Missouri City, Stafford,
Bellaire, West University Place, Hunters Creek Village, Bunker Hill
Village, Piney Point Village, Midtown Houston, Downtown Houston,
Northside / Northline, Greenway / Upper Kirby Area, Second Ward,
Greater Heights, Neartown / Montrose, Greater Eastwood, Near
Northside Houston, Greater Fifth Ward, Memorial Park and Greater
Third Ward.

[srainhoutx]

Flood Advisory
National Weather Service Houston/Galveston TX
647 AM CDT MON MAY 22 2017

Brazoria TX-Matagorda TX-
647 AM CDT MON MAY 22 2017

The National Weather Service in League City has issued a

* Flood Advisory for...
South central Brazoria County in southeastern Texas...
Central Matagorda County in southeastern Texas...

* Until 845 AM CDT.

* At 645 AM CDT, Doppler radar indicate continued heavy rain due to
showers and thunderstorms. Since 545 am...Radar estimates 3 to 5
inches has fallen along the very immediate coast and 1 to 3 inches
further inland. Minor flooding is expected in the advisory area
as the rain will continue for the next couple hours.

* Some locations that will experience flooding include...
Matagorda, Freeport, Jones Creek and Sargent.

[srainhoutx]

Flood Advisory
National Weather Service Houston/Galveston TX
652 AM CDT MON MAY 22 2017

Harris TX-
652 AM CDT MON MAY 22 2017

The National Weather Service in League City has issued a

* Flood Advisory for...
Central Harris County in southeastern Texas...

* Until 745 AM CDT.

* At 650 AM CDT, Doppler radar and rain gages indicate a
thunderstorm moving northeast out of downtown Houston toward
northeast Harris County continues to produce around 1 inch of rain
in 15 minutes. Rain rates this high will cause minor street
flooding at susceptible locations.

heavy rain due to thunderstorms. This will cause minor flooding in
the advisory area.

* Some locations that will experience flooding include...
Humble, Near Northside Houston, Greater Fifth Ward, Aldine,
Downtown Houston, Northside / Northline, Second Ward, Greater
Heights, Greater Eastwood, Fourth Ward, northeastern Memorial Park,
Greater Greenspoint, Kingwood, Spring, Bush Intercontinental
Airport, Eastex / Jensen Area, Independence Heights, Settegast,
Atascocita and Houston Gardens.

[StormOne]

Just had golf ball sized hail in Kingwood.

[don]

Wow, i had pea size hail here in the Heights.

[srainhoutx]

Thanks for the hail reports. I've passed them along to HGX.

[jasons2k]

Most of the rain is either to my south and east or north and west. I'm caught in the middle with just sprinkles.

[srainhoutx]

Flood Advisory
National Weather Service Houston/Galveston TX
842 AM CDT MON MAY 22 2017

Wharton TX-Galveston TX-Fort Bend TX-Brazoria TX-Matagorda TX-
842 AM CDT MON MAY 22 2017

The National Weather Service in League City has issued a

* Flood Advisory for...
Eastern Wharton County in southeastern Texas...
Southwestern Galveston County in southeastern Texas...
Southeastern Fort Bend County in southeastern Texas...
Brazoria County in southeastern Texas...
Northeastern Matagorda County in southeastern Texas...

* Until 1045 AM CDT.

* At 841 AM CDT, Doppler radar indicated heavy rain due to
thunderstorms. This will cause minor flooding in the advisory area.
Up to two inches of rain have already fallen.

* Some locations that will experience flooding include...
Southeastern Pearland, southwestern League City, Galveston Island
West End, southwestern Friendswood, Lake Jackson, Alvin, Angleton,
Bay City, Santa Fe, Clute, Hitchcock, Manvel, West Columbia,
Sweeny, South Texas Nuclear Plant, Richwood, Brazoria, Jones Creek,
Danbury and Iowa Colony.

[tireman4]

000
FXUS64 KHGX 221153
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
653 AM CDT Mon May 22 2017

.PREV DISCUSSION... /ISSUED 501 AM CDT Mon May 22 2017/

Forecast remains pretty much on track and made just minor tweaks
to the ongoing package.

An MCV has developed with the large cluster of precip west of
Matagorda Bay. This should continue trekking mostly eastward
today. Surface boundary situated just offshore focused some 5"+
totals overnight. The hope was it would stay there but has since
edged closer to the coast and into the Galveston Bay area.
Convergent zone appears to be setting up from roughly Liberty to
Matagorda Bay. Inflow has really ramped up offshore with sustained
25-30 knot llvl SE winds perpendicular to this zone. Hopefully
the MCV takes a more ese track in the coming hours and pulls this
boundary back offshore. But there`s considerable uncertainty and
with resident 2-2.3" PW`s, felt is was best to issue a short fused
Flash Flood Watch and re-evaluate trends in the coming hours.
Those details are in that product that`s already been sent.

Bulk of precip should be headed off to the east later in the
afternoon and early evening. With the exception of offshore
areas, most of the region should see a break in the action
tonight. Rain and isolated storm chances return Tue aftn and evng
as a cold front makes its way into the region. The remainder of
the work week should be dry in the wake of the front. Pleasant
temps on Wed will gradually modify back into the 70s/90s Thursday
and into the weekend as onshore winds resume. Next shot of rain
looks to be late Sunday or early next week with the approach of
another weak front. 47

&&

.MARINE...
Strong and gusty onshore winds will prevail today into this evening
as low-level jet develops over SE TX. Scattered showers and thunder-
storms are possible thru Tues night as a series of upper level dist-
urbances move in from the west and interacts with left-over surface
boundaries lingering over the region. Models remain on track with a
cold front moving into the coastal waters Tues...with the stronger/
deeper northerly flow not making it into the Gulf until Tues night/
Weds morning. Caution flags may be needed during this time. Onshore
winds are set to return to the area by Weds night and then strength-
ening the rest of the week. 41

&&

.AVIATION...
A very active weather pattern over SE TX this morning that is like-
ly to continue through this afternoon. Current thinking is that the
surface boundary will be lingering mainly south of I-10 through the
rest of the day, acting as a focus for the stronger storms. Will be
keeping with mostly MVFR CIGS and the mention of TSRAs for most TAF
sites south of IAH. For the sites north, going more with VCTS/VCSHs
today. Did hit these northern TAFS a bit harder with patchy fog/low
CIGS tonight/early Tues morning. 41

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 75 65 80 57 81 / 60 20 50 40 0
Houston (IAH) 77 67 82 60 83 / 90 30 40 40 0
Galveston (GLS) 81 73 82 66 81 / 90 50 30 40 0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flash Flood Watch until 1 PM CDT this afternoon for the
following zones: Brazoria...Chambers...Fort Bend...
Galveston...Harris...Jackson...Liberty...Matagorda...
Wharton.

GM...Small Craft Advisory until 5 PM CDT this afternoon for the
following zones: Coastal waters from Freeport to the
Matagorda Ship Channel out 20 NM...Coastal waters from High
Island to Freeport out 20 NM...Galveston Bay...Matagorda
Bay...Waters from Freeport to the Matagorda Ship Channel
from 20 to 60 NM...Waters from High Island to Freeport from
20 to 60 NM.

&&

$$

[DoctorMu]

Tornado Warning
TXC039-167-221530-
/O.NEW.KHGX.TO.W.0041.170522T1505Z-170522T1530Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Houston/Galveston TX
1005 AM CDT MON MAY 22 2017

The National Weather Service in League City has issued a

* Tornado Warning for...
West central Galveston County in southeastern Texas...
Northeastern Brazoria County in southeastern Texas...

* Until 1030 AM CDT.

* At 1004 AM CDT, a severe thunderstorm capable of producing a
tornado was located over Danbury, or 8 miles northeast of Angleton,
moving northeast at 20 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without
shelter. Mobile homes will be damaged or destroyed.
Damage to roofs, windows, and vehicles will occur. Tree
damage is likely.

* Locations impacted include...
Southwestern League City, Alvin, Santa Fe, Hitchcock, Danbury,
Hillcrest, Liverpool and Chocolate Bayou.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

[jasons2k]

Got another 1.63". I didn't rain as long as other places, but it poured really hard for a while.

[Katdaddy]

One more active weather day is possible across S, S Central, and SE TX before a front moves across the area bringing mostly sunny and drier air which modifies by the end of the week. The next rain chances look to arrive Sunday and Memorial Day.

The SPC has a Slight Risk area for STX and Marginal Risk area for S Central and SE TX. Its possible the Slight Risk area may be expanded to include the Middle and Upper TX Coast later today. A strong disturbance arriving during peak heating this afternoon followed by the cool front tonight will likely be strong enough to break the cap resulting in thunderstorm development.

[srainhoutx]

Will need to monitor the trends this afternoon as the frontal boundary approaches during peak heating that may assist in breaking the cap this morning. I see the 06Z Texas Tech WRF is "sniffing" a potential super cell just to the West of Metro Houston this afternoon. The synoptic pattern suggests any shower and storm activity will be mesoscale driven and likely not be resolved until about 3-5 hours prior to any storm formation...if then.

[srainhoutx]

Tuesday morning briefing from Jeff:

Upper level trough responsible for the active weather recently remains over the southern plains with additional energy rotating through the mean trough across TX.

A strong upper level disturbance rotating SE across NW TX will arrive across SE TX late this afternoon and evening along with a surface cold front. Air mass over the region has stabilized somewhat after the showers and thunderstorms of Monday and the offshore movement of a surface cool front yesterday evening. However moisture remains in place over the area and daytime heating will help to increase instability values by early afternoon. The arrival of the disturbance in the increasingly NW flow aloft combined with the surface lift of the incoming cold front and an increasingly unstable air mass will likely result in the formation of strong to isolated severe thunderstorms across portions of the area this afternoon into the evening hours.

Main threat will be large hail with damaging winds and tornadoes secondary. A broken line of thunderstorms will likely affect the area from roughly 400pm around College Station to 6-8pm along US 59 and 8-11pm along the coast.

Post frontal air mass will be refreshing for late May with dewpoints well into the 50’s on Wednesday resulting in morning lows in the upper 50’s under northerly winds.

Winds return back to the south on Thursday and a rapid influx on moisture (heat and humidity) will commence Thursday and Friday where high temperatures will likely reach the lower to possibly middle 90’s.

Yet another front will slowly advance toward the area on Sunday and Monday and once again looks to stall across the region with several disturbances moving along the boundary. Threat for thunderstorms…some severe…and heavy rainfall may be back in the forecast late Sunday into early next week. This will be something to watch in the coming days as stalling boundaries with pooling moisture this time of year can result in excessive rainfall and we do not have a good track record with Memorial Day Holiday’s and weather in this area.

[srainhoutx]

Tuesday midday briefing from Jeff:

Strong heating this morning is increasing the risk for severe thunderstorms this afternoon and evening.

Low level deck has quickly eroded allowing strong surface heating to commence over the region. Already reaching expected daytime highs in some areas with rapidly building instability under a weakening capping inversion. Disturbance swinging across NW TX will reach SE TX by late afternoon along with a surface frontal boundary which will result in the formation of strong to severe thunderstorms.

Given the heating currently taking place, the threat for severe weather is increasing with the main threats being large hail and wind damage. Think the hail threat is primary given falling freezing heights this afternoon and a few very large hail reports (golfball or larger) may be possible.

[DoctorMu]

Tuesday midday briefing from Jeff:

Strong heating this morning is increasing the risk for severe thunderstorms this afternoon and evening.

Low level deck has quickly eroded allowing strong surface heating to commence over the region. Already reaching expected daytime highs in some areas with rapidly building instability under a weakening capping inversion. Disturbance swinging across NW TX will reach SE TX by late afternoon along with a surface frontal boundary which will result in the formation of strong to severe thunderstorms.

Given the heating currently taking place, the threat for severe weather is increasing with the main threats being large hail and wind damage. Think the hail threat is primary given falling freezing heights this afternoon and a few very large hail reports (golfball or larger) may be possible.

Keep your NowCasting radar up, folks!