
MESOSCALE PRECIPITATION DISCUSSION 0390...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
323 AM EDT SAT JUN 24 2017
CORRECTED FOR SENTENCE FRAGMENT IN THE SECOND DISCUSSION PARAGRAPH
AREAS AFFECTED...SOUTHWEST OK & PORTIONS OF NORTHERN TX
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 240610Z - 241210Z
summary... elevated convection continues to build and expand in coverage across the tx panhandle and southwest ok. hourly rain rates to 2" and local amounts to 4" are expected.
discussion... showers and thunderstorms have been forming on the northwest side of an instability pool centered south of dallas, well to the north of associated surface boundaries. the convection appears to be tapping instability at the 700 hpa level where the flow is more westerly. mucape values in the area are 1000-2000 j/kg. closer to dallas tx, thunderstorms continue to propagate southwest slowly due to a long-lived outflow boundary/convective arc which was spawned by thunderstorm activity in ia and co 24 hours ago. precipitable water values of 1.5-2" exist here per gps data. effective bulk shear of 25-50 kts is helping to organize thunderstorms. the mean 850-400 hpa winds are fairly light throughout the region, which could magnify rainfall efficiency.
hourly rain rates up to 2" are expected. mass field-wise, a mesoscale wave is expected to drop southwest with time into central tx due to the mobile outflow boundary, which should allow convection from near dallas to follow in suit. the 00z nam conest appears to have the best handle of this activity from a pattern perspective, but the guidance is unified on a signal for ~4" in this area. there is concern, based on the nam conest, that the activity could bridge across to the southwest moving convection moving across the dallas-fort worth area at this time. the expected local totals could challenge the high flash flood guidance values in this area -- the threat appears highest in
urban locations.
ROTH
ATTN...WFO...AMA...EWX...FWD...LUB...OUN...SHV...SJT...
ATTN...RFC...ABRFC...LMRFC...WGRFC...