textproduct: Baltimore/Washington

SYNOPSIS

A cold front will approach from the northwest on Tuesday, before moving through Tuesday night into Wednesday morning. High pressure will build into the region on Thursday and remain in control through the end of the week.

NEAR TERM /THROUGH TONIGHT/

Flood Watch has been issued for parts of the Baltimore and Washington metro areas until 11 PM for slow moving thunderstorms that could train and be capable of producing intense rainfall rates that could cause flash flooding. Careful satellite analysis shows cumulus congestus forming in between Rt 15 and I-83. Also, NUCAPS gridded data shows in this area a max of 17C 850 mb dewpoints centered across Frederick County MD into Gettysburg PA. 12Z HREF max updraft values indicate that convection could last well through the evening into the overnight hours. For this reason, Flood Watch has been issued. Threat for damaging wind gusts remains low due lack of dry air aloft.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/

A cold front will enter the area tomorrow and be focus for widespread showers and thunderstorms. Abundant moisture, strong instability, and height falls indicate the potential for a very active afternoon and evening. While the mid-level flow will be stronger suggesting faster storm motions, the low to mid-level flow will be somewhat parallel to the sfc boundary which suggests some training or repeated storms is possible. A larger Flood Watch will likely be required. Stronger flow aloft and strong instability also indicate potential for damaging wind gusts due to wet microbursts. Activity may persist well into the overnight across southern MD before exiting or dissipating early Wed.

LONG TERM /THURSDAY THROUGH MONDAY/

A weak cold front will drop through the region Thursday bringing spotty shower or thunderstorm chances to areas west of the Blue Ridge. Most locations will remain dry with seasonable temperatures in the mid to upper 80s and low 90s. The humidity will lower even further behind the front Thursday night into Friday with dewpoints dropping into the upper 50s and low 60s. The weak front will set us up for a great July 4th holiday weather wise as well as start to the holiday weekend. Highs Friday will fall back into the 80s with dewpoints in the upper 50s and low to mid 60s. Lows Friday night will fall into the upper 50s and low to mid 60s with urban locations in the upper 60s. This will make for excellent conditions for viewing fireworks displays across the region. Similar conditions are expected Saturday with highs in the mid to upper 80s to around 90 as 1020 mb high pressure sits overhead. The high will slide south and east of the area Sunday allowing a cold front to approach from the Ohio River Valley and Great Lakes region. This front will bring renewed chances for spotty showers and thunderstorms mainly west of the Blue Ridge for the end of the weekend into the start of next week. Highs Sunday and Monday will push into the upper 80s and low 90s on southwesterly return flow.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Scattered t-storms this afternoon through this evening, then widespread showers and thunderstorms Tue afternoon and evening. Potential for training t-storms Tue with potential damaging wind gusts and torrential rainfall.

VFR conditions are most likely for Wednesday through Saturday with high pressure nearby.

MARINE

SCA conditions developing late tonight across the middle and southern waters, then spreading across the rest of the waters Tue ahead and behind a cold front. T-storms may also require SMWs. SCA conditions may last into Wed morning.

SUb-SCA level winds are expected Wednesday through Saturday as high pressure builds over the region. A dry cold front will pass through the area Friday into the start of the holiday weekend.

LWX WATCHES/WARNINGS/ADVISORIES

DC...None. MD...Small Craft Advisory from 11 PM this evening to 6 AM EDT Tuesday for MDZ008. VA...None. WV...None. MARINE...Small Craft Advisory from 11 PM this evening to 6 AM EDT Tuesday for ANZ530-531-536-538-539. Small Craft Advisory until 6 AM EDT Tuesday for ANZ532>534-537- 540>543.