textproduct: NWS Wilmington

WHAT HAS CHANGED

Cold frontal passage Monday will be preceded by widely scattered afternoon or early evening thunderstorms that have the potential to reach severe limits.

KEY MESSAGES

1) Isolated storms possible this evening west of -95, with a low/marginal risk for damaging wind gusts or low- end (1") severe hail with any stronger storms that manage to develop.

2) Near record warmth on Sunday as temperatures away from the coast rise into the upper 80s to near 90.

3) Potential for severe thunderstorm activity Monday afternoon or early evening.

4) Above normal temps continue Monday followed by a strong cold frontal passage late Monday. In its wake, an abrupt temperature change with at or below normal temps slated for late Monday night thru Tuesday night.

DISCUSSION

KEY MESSAGE 1: Isolated storms possible this evening west of I-95, with a low/marginal risk for damaging wind gusts or low- end (1") severe hail with any stronger storms that manage to develop.

A shortwave will cross the southern Appalachians late this afternoon, and may initiate a few storms upstream. The airmass ahead of the storms will be weakly to marginally unstable, along with 700- 500 mb lapse rates of 7C. Although moisture will be limited as dewpoints rise into the low/mid 50s through the early evening, this should be enough to sustain widely scattered/scattered coverage of thunderstorms. Any storms that do develop should weaken and dissipate after 03Z as the airmass stabilizes.

KEY MESSAGE 2: Near record warmth on Sunday as temperatures away from the coast rise into the upper 80s to near 90.

SW flow along with increasing geopotential heights across the SE will sustain the warming trend through Sunday. Guidance still points to +14C to +15C 850 mb temps by Sunday afternoon, which would support record warmth away from the coast.

Record highs data: ................... Sun Mar 22 ... Mon Mar 23 Wilmington NC......... 87 in 1907 ... 94 in 1907 Lumberton NC.......... 87 in 1948 ... 91 in 1907 N. Myrtle Beach SC.... 86 in 1995 ... 85 in 2011 Florence SC........... 87 in 1995 ... 88 in 1995

Monday should again see unusually warm temperatures, but the arrival of a front and scattered showers/t-storms during the day could limit how warm we can get. Current forecast highs Monday are 83-87 inland with upper 70s to near 80 on the coast.

KEY MESSAGE 3: Potential for severe thunderstorm activity Monday afternoon or early evening.

A strong CFP slated for late Mon that will be preceded by a threat for isolated to scattered convection. The forcing from the cold front, short wave trof passage aloft, best heating of the day (afternoon CWA wide to early evening southern portions of the CWA) will contribute to the potential for a severe thunderstorm. Decent shear thru the atm column and supportive low level lapse rates will spell mainly a damaging wind threat from those severe tstorms.

KEY MESSAGE 4: Above normal temps continue Monday followed by a strong cold frontal passage late Monday. In its wake, an abrupt temperature change with at or below normal temps slated for late Monday night thru Tuesday night.

Max temperatures ahead of the cold front Monday will again reach the 80s, not quite as high as what's forecast for Sunday. This the result of the presence of clouds and potential pcpn associated with the CFP late Monday. Normal highs run in the upper 60s to around 70.

Here comes our daily 20+ degree temperature change, with a diurnal temp change of 35 to 40 degrees from Mon highs to Mon night lows! In the wake of the FROPA, cool and breezy N to NE winds will encompass the area Mon night thru Tue. Mon and Tue night lows will dip into the 40s, a far cry from the previous Sat and Sun night lows in the upper 50s to mid 60s, with normal being in the mid 40s. Daytime highs Tue will reach around 60, now considered below normal.

AVIATION /18Z SATURDAY THROUGH WEDNESDAY/

VFR with passing mid and high clouds. Wind will remain generally west through early evening, becoming light overnight as high pressure extends from the NE Gulf across Florida. We are still maintaining a 25-30% chance of a thunderstorm or two west of I-95 late this afternoon or early evening, which, if they occur, it would be from upstream activity that advects in from the west. Given the low chance, and even lower that KFLO or KLBT would be directly impacted, will opt to leave them out of the TAF at this time.

850 mb wind speeds will increase late this evening, particularly across the Pee Dee around 03-05Z. LLWS criteria may be reached, with best chances appearing to be for KLBT, but it's marginal at this time. Will keep an eye on it for possible inclusion with 00Z forecast.

Extended Forecast...VFR to dominate. A cold front will move through Mon with the chance for isolated restrictions due to t-storms and possibly some sea fog along the coast before the front moves through. VFR then returns through Wed.

MARINE

Through Sunday night... Surface high pressure over the NE Gulf this afternoon will transition eastward across Florida tonight into Sunday. Westerly flow this afternoon will become SW Sunday afternoon, and continue SW Sunday night ahead of a cold front. The front will be crossing the Ohio River Valley late Sunday night and approaching the TN/NC border by daybreak Monday. As a result, gradient winds will gradually increase through the period, but are expected to remain below advisory levels.

Monday through Wednesday night...Tightened gradient ahead of the cold front will keep SW winds active across the local waters thru Mon afternoon. Could observe a few gusts up to 25 kt but for now SCA will not be raised, but will need to monitor future model runs that could up the SW winds by a few knots or have a more frequent 25+ kt wind gust. After the CFP, the sfc pg tightens further combined with excellent CAA, will yield strong N to NE SCA wind and sea conditions Mon night thru Tue. The gradient is expected to relax-some later Tue night thru Wed as the center of high drops to the Mid-Atlantic Coast with winds diminishing and seas slowly subsiding, lagging behind given the decent fetch that transcribed over time. Generally seas will be a function of 6 second period or less wind waves Mon with a direction change in the wind waves after the CFP Mon night into Tue that will build and exceed SCA 6+ foot thresholds into early wed. With the fetch increasing, a 7 to 8 second period NE-E fresh or pseudo swell will become dominate later Tue thru Wed.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...None. MARINE...None.