AP-TX--FTW-TX N Area Forecast Discussion, TX
000
FXUS64 KFWD 151103
AFDFWD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
603 AM CDT WED JUL 15 2015
.AVIATION...
VFR CONDITIONS WILL PERSIST THOUGH THE TAF PERIOD UNDER A STRONG
UPPER LEVEL RIDGE. SOUTHERLY WINDS WILL REMAIN AROUND 10 KNOTS
THROUGH THURSDAY AFTERNOON.
78.JG
&&
.PREV DISCUSSION... /ISSUED 321 AM CDT WED JUL 15 2015/
EARLY MORNING WATER VAPOR SATELLITE IMAGERY CONTINUED TO SHOW A
LARGE AREA OF HIGH PRESSURE ALOFT CENTERED OVER NORTH CENTRAL
TEXAS. THIS FEATURE IS EXPECTED TO REMAIN THE DOMINANT PLAYER IN
CONTROL OF THE LOCAL AREA WEATHER PATTERN THROUGH EARLY NEXT WEEK.
TYPICALLY UNDER A RIDGE OF HIGH PRESSURE IN THE SUMMER ACROSS THE
SOUTHERN PLAINS...THE LONGER THE RIDGE HOLDS IN PLACE...THE MORE
THE HEAT BUILDS UP. THAT HAS NOT BEEN THE CASE THUS FAR UNDER THIS
UPPER LEVEL RIDGE THAT HAS HELD STEADY FOR NEARLY A WEEK NOW. THE
PRIMARY REASON THAT THE TEMPERATURES HAVE NOT BEEN ON A SLOW AND
STEADY RISE ALL WEEK IS LIKELY DUE TO PERSISTENT SOUTHERLY FLOW
FROM THE SURFACE UP TO ABOUT 1 MILE ABOVE GROUND LEVEL (AROUND 850
MB). EVEN THOUGH IT MAY NOT FEEL COOLER ALONG THE GULF COAST THIS
TIME OF YEAR...TEMPERATURES ALONG THE GULF COAST AND OVER THE
WESTERN GULF OF MEXICO ARE TYPICALLY 10 DEGREES COOLER THAN
TEMPERATURES FARTHER INLAND DUE TO THE FACT THAT WATER DOES NOT
HEAT OR COOL AS QUICKLY AS LAND. AS A RESULT...LOW-LEVEL SOUTHERLY
FLOW REPRESENTS A WEAK COLD AIR ADVECTION PATTERN. IF OUR LOW-
LEVEL WINDS WERE SIMPLY VEERED BY 20 TO 30 DEGREES TOWARDS THE
WEST...TEMPERATURE ADVECTION WOULD BE NEUTRAL FAVORING A BUILD UP
OF HEAT UNDER OUR DOME OF HIGH PRESSURE ALOFT. AS LONG AS OUR LOW
LEVEL FLOW REMAINS MORE SOUTHERLY THAN SOUTHWESTERLY...DAILY HIGH
TEMPERATURES WILL LIKELY HOLD STEADY IN THE UPPER 90S FOR MOST
LOCATIONS.
FOR TODAY...HEAT INDEX VALUES ARE EXPECTED TO CLIMB TO AROUND 100
DEGREES FOR MOST LOCATIONS...WHICH WOULD BE A FEW DEGREES COOLER
THAN THE PAST COUPLE OF DAYS. HEAT INDICES OF 100 DEGREES ARE NOT
COOL BY ANY STRETCH...HOWEVER THERE IS REASON TO BELIEVE IT WILL
NOT FEEL QUITE AS HUMID AND SWAMPY OUTSIDE THIS AFTERNOON. 08Z/3AM
DEW POINT VALUES WERE RUNNING ABOUT 3 DEGREES LOWER/DRIER THAN
YESTERDAY AT THIS TIME. AS A RESULT...THINK THAT AFTERNOON
HUMIDITY VALUES ARE LIKELY TO BE LOWER TODAY...MAKING OUR UPPER
90S TEMPERATURES A LITTLE MORE COMFORTABLE THIS AFTERNOON.
FOR THE REMAINDER OF THE WEEK...MAINTAINED HIGHS IN THE UPPER 90S
FOR MOST LOCATIONS AS MODEL GUIDANCE SUGGESTS THAT OUR WEATHER
PATTERN WILL REMAIN FAIRLY CONSISTENT. PERSISTENT SOUTHERLY FLOW
MAY CAUSE HUMIDITY VALUES TO RISE AGAIN AS WE HEAD INTO THE
WEEKEND...SO MAX HEAT INDEX VALUES ARE LIKELY TO REMAIN IN THE
100 TO 105 DEGREE RANGE FOR THE NEXT SEVERAL DAYS. NO HEAT
ADVISORY IS PLANNED AT THIS TIME WITH HEAT INDEX VALUES EXPECTED
TO HOLD JUST BELOW 105 DEGREES.
THIS WEEKEND...MODELS CONTINUE TO STRENGTHEN THE UPPER LEVEL RIDGE
OVER THE REGION. IF THIS OCCURS...IT IS POSSIBLE FOR HIGH
TEMPERATURES TO CLIMB A FEW DEGREES...BRING HIGHS FROM THE UPPER
90S TO RIGHT AROUND OR JUST ABOVE 100 DEGREES. FOR NOW KEPT HIGHS
A DEGREE OR TWO BELOW 100 SIMPLY BECAUSE THE LOW-LEVEL WINDS DO
NOT REALLY CHANGE DIRECTION IN MODEL GUIDANCE. THE BUILD UP OF
HEAT AND THE STRENGTH OF AN UPPER LEVEL RIDGE CAN BE DEPENDENT
UPON ONE ANOTHER.
THERE IS A POSITIVE FEEDBACK LOOP IN WHICH THE UPPER RIDGE CAUSES
CLEAR SKIES WHICH ALLOWS US TO HEAT UP QUITE A BIT EACH DAY. THE
BUILD UP OF HEAT IN TURN RESULTS IN A TROPOSPHERIC RESPONSE TO
EXPAND IN THICKNESS CAUSING THE UPPER LEVEL RIDGE TO STRENGTHEN.
WHEN SOME FACTOR INTERRUPTS THIS POSITIVE FEEDBACK LOOP...I.E.
PERSISTENT WEAK LOW-LEVEL WARM AIR ADVECTION...MODELS CAN
OVERESTIMATE THE STRENGTH OF HEATING AND RIDGING ALOFT.
AT ANY RATE...IT WILL FEEL HOT EITHER WAY... IT IS REALLY JUST A
MATTER OF WILL WE FEEL HOT BECAUSE THE AIR TEMPERATURE WILL SLOWLY
CLIMB...OR BECAUSE THE HUMIDITY WILL REMAIN HIGH WHILE
TEMPERATURES REMAIN IN THE UPPER 90S? EITHER WAY...HEAT INDEX
VALUES WILL HOLD IN THE 100 TO 105 DEGREE RANGE AND ANYONE WITH
OUTDOOR PLANS SHOULD PLAN TO MITIGATE THE IMPACTS OF THE HEAT.
FOR EARLY NEXT WEEK...MODELS INDICATE THAT A STRONG SHORTWAVE
TROUGH WILL MOVE OVER THE CENTRAL PLAINS FLATTENING OUT OUR
PERSISTENT UPPER LEVEL RIDGE...AND BRINGING A WEAK COLD FRONT
SOUTH JUST ACROSS THE RED RIVER ON TUESDAY. IF THIS VERIFIES...
MONDAY WILL PROBABLY BE HOT AS LOW-LEVEL WINDS WILL VEER AROUND TO
THE SOUTHWEST OUT AHEAD OF THE COLD FRONT. WE WOULD VERY LIKELY
CLIMB ABOVE 100 DEGREES IF THE UPPER LEVEL RIDGE STARTS TO FLATTEN
OUT ON MONDAY AS A RESULT. TUESDAY AND WEDNESDAY WOULD BE A FEW
DEGREES COOLER SIMPLY DUE TO THE PRESENCE OF SOME UPPER LEVEL
CLOUDS AND WEAKER RIDGING ALOFT. IF THE FRONT ACTUALLY MOVE SOUTH
OF THE RED RIVER...SCATTERED THUNDERSTORMS WOULD LIKELY DEVELOP
TUESDAY AND POSSIBLY WEDNESDAY AFTERNOON NORTH OF INTERSTATE 20 TO
THE RED RIVER.
FOR NOW...RAISED TEMPERATURES ON MONDAY A DEGREE OR TWO...AND
PLACED SOME 10 POPS IN ACROSS THE NORTHERN CWA TUESDAY AND
WEDNESDAY AFTERNOON WITHOUT MENTIONING THUNDER IN THE FORECAST AT
THIS TIME. IF THE COLD FRONT GETS HERE...POPS WILL NEED TO BE
RAISED. DID NOT COMPLETELY BUY IN ON A COLD FRONT SINKING SOUTH OF
THE RED RIVER AT THIS TIME BECAUSE CLIMATOLOGY DICTATES THAT THIS
DOES NOT HAPPEN VERY OFTEN IN MID TO LATE JULY. ADDITIONALLY...
ONLY YESTERDAY THE CONSENSUS OF GUIDANCE WAS TO KEEP THE UPPER
LEVEL RIDGE IN PLACE AND KEEP ALL COLD FRONTS WELL NORTH INTO THE
CENTRAL PLAINS. WOULD LIKE TO SEE MORE RUN TO RUN/DAY TO DAY
CONSISTENCY OUT OF MODEL GUIDANCE BEFORE JUMPING ON A SOLUTION
THAT IS SOMEWHAT UNUSUAL FOR THIS TIME OF YEAR.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 97 77 97 78 97 / 0 0 0 0 5
WACO, TX 95 74 96 76 97 / 0 0 0 5 5
PARIS, TX 96 74 95 76 95 / 0 0 0 0 5
DENTON, TX 98 75 97 77 96 / 0 0 0 0 5
MCKINNEY, TX 96 75 96 77 96 / 0 0 0 0 5
DALLAS, TX 98 78 98 79 97 / 0 0 0 0 5
TERRELL, TX 95 75 96 76 97 / 0 0 0 0 5
CORSICANA, TX 95 74 95 76 97 / 0 0 0 5 5
TEMPLE, TX 95 74 96 75 96 / 0 0 0 5 5
MINERAL WELLS, TX 95 73 97 75 98 / 0 0 0 0 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
78
Delivered by Weather Underground Inc. Wed Jul 15 2015 7:03AM EDT