WPC Met Watch |
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Mesoscale Precipitation Discussion: #0150 (2018) |
(Issued at 737 PM EDT TUE MAY 15 2018
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MPD Selection |
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MESOSCALE PRECIPITATION DISCUSSION 0150
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
737 PM EDT TUE MAY 15 2018
AREAS AFFECTED......EASTERN WV PANHANDLE...NORTHERN VA...DISTRICT
OF COLUMBIA...NORTHERN AND EASTERN MD...DE...SOUTHERN
NJ...SOUTHEAST PA...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 152331Z - 160431Z
SUMMARY...A QUASI-LINEAR CONVECTIVE SYSTEM (QLCS) WILL CONTINUE TO
ORGANIZE ACROSS PORTIONS OF THE MID ATLANTIC REGION THIS EVENING.
TRAINING OF CELLS WILL BECOME MORE LIKELY AS THE EVENING
PROGRESSES, WHICH WILL ENHANCE THE POTENTIAL FOR FLASH FLOODING.
DISCUSSION...AS OF 2300 UTC, A SQUALL LINE WAS BECOMING BETTER
ORGANIZED IN A PREDOMINATELY W-E FASHION ACROSS SOUTHEASTERN PA
AND NORTHERN MD SOUTH OF THE SURFACE FRONT. AT THE SAME TIME,
ADDITIONAL LINEAR, WSW-ENE ORIENTED CONVECTION WAS DEVELOPING OVER
NORTHWEST AND NORTHERN VA. RECENT HRRR RUNS SHOW BOTH LINES
MERGING EARLY THIS EVENING AS THE ACTIVITY CONTINUES TO GROW
UPSCALE, OWING TO THE ROBUST DEEP-LAYER INSTABILITY (MUCAPES ~3000
J/KG) DOWNSTREAM TOWARD THE MID ATLANTIC COAST.
ALSO FOSTERING THE MORE WIDESPREAD CONVECTIVE ORGANIZATION THIS
EVENING WILL BE THE INCREASED RIGHT-ENTRANCE REGION FORCING VIA
THE UPPER JET STREAK THAT WILL BE TRAVERSING THE NORTHEAST REGION,
WHICH WILL LEAD TO SOME DIVERGENCE ALOFT. THE MORE FAVORABLE
DYNAMICAL PROFILE, ALONG WITH THE INCREASING LOW-LEVEL INFLOW
AFTER SUNSET (30-35 KTS), WILL PROMOTE A MORE FAVORABLE
THERMODYNAMIC ENVIRONMENT LATER THIS EVENING AS THE RECENT CAM
GUIDANCE DEPICTS A DECIDED UPTICK IN MOISTURE/THETA-E TRANSPORT
INTO THE QLCS. MOREOVER, AS THE LOW-LEVEL INFLOW VEERS MORE
WESTERLY AFTER 0000 UTC, IT WILL ALIGN MORE PARALLEL TO THE MEAN
850-300 MB FLOW AND THE SURFACE BOUNDARY, WHICH WILL GREATLY
ENHANCE THE POTENTIAL FOR UPWIND PROPAGATION AND THUS CELL
TRAINING.
THE MOST RECENT HRRR MODEL RUNS SHOW PW VALUES SPIKING BETWEEN
1.75-2.00" AFTER 00Z AS THE QLCS CONTINUES TO BECOME BETTER
ORGANIZED. GIVEN THIS THERMODYNAMIC ENVIRONMENT -- WITH THE
STRONG, DEEP-LAYER INSTABILITY AND AVAILABILITY OF ANOMALOUS PW
VALUES FOR MID-MAY -- HOURLY RAINFALL RATES OF 2-2.5" WILL BE
LIKELY UNDERNEATH THE STRONGEST CELLS, WHILE LOCALIZED STORM TOTAL
RAINFALL UP TO 4" WILL BE POSSIBLE.
HURLEY
ATTN...WFO...AKQ...CTP...LWX...PHI...
ATTN...RFC...MARFC...
LAT...LON 40007549 39857487 39417452 38997461 38597492
38297544 38337634 38557692 39017792 39277839
39527830 39617806 39627764 39727714 39877635
Last Updated: 737 PM EDT TUE MAY 15 2018
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