803
FXUS02 KWBC 180616
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
216 AM EDT WED MAR 18 2026
VALID 12Z SAT MAR 21 2026 - 12Z WED MAR 25 2026
...IMPRESSIVE EARLY SEASON HEAT WAVE CONTINUES ACROSS THE
SOUTHWESTERN U.S. THROUGH THE WEEKEND WITH NUMEROUS RECORDS,
GRADUALLY EASING EARLY NEXT WEEK...
..OVERVIEW
THE HIGHLY ANOMALOUS UPPER LEVEL RIDGE OVER THE SOUTHWESTERN U.S.
WILL BEGIN TO BE MORE SUPPRESSED AND A LITTLE WEAKER GOING INTO THE
WEEKEND, WITH THE EARLY SEASON HEATWAVE LIKELY PEAKING FRIDAY AND
SATURDAY. A QUASI-ZONAL UPPER FLOW PATTERN SHOULD BE IN PLACE
ACROSS MOST OF THE COUNTRY BY SUNDAY, WITH BROAD CYCLONIC FLOW
ALOFT OVER THE GREAT LAKES AND NORTHEAST. THERE SHOULD STILL BE A
BROAD UPPER TROUGH SITUATED OVER THE EASTERN U.S. THROUGH EARLY
NEXT WEEK, AND THE RIDGE MAY TRY TO BUILD BACK IN SOME ACROSS THE
DESERT SOUTHWEST BY NEXT TUESDAY/WEDNESDAY, BUT NOT TO THE SAME
LEVEL AS THIS WEEK. MORE RAIN AND MOUNTAIN SNOW IS EXPECTED TO
RETURN TO THE PACIFIC NORTHWEST BY THAT TIME AS A TROUGH BUILDS IN
FROM THE NORTHEASTERN PACIFIC.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST MODEL GUIDANCE HAS DECENT OVERALL AGREEMENT ON THE
SYNOPTIC SCALE FOR THE UPCOMING WEEKEND, WITH A DETERMINISTIC AND
AIFS MODEL BLEND USED FOR FRONTS AND PRESSURES. LOOKING AHEAD TO
EARLY NEXT WEEK, MODEL SPREAD INCREASES SUBSTANTIALLY REGARDING
INCOMING SHORTWAVE ENERGY FROM THE PACIFIC AND HOW QUICKLY THAT HAS
AN EFFECT ON THE RIDGE OVER THE SOUTHWEST. THE 12Z ECMWF APPEARED
TO BE ON THE EDGE OF THE ENSEMBLE GUIDANCE IN SHOWING A MORE
AMPLIFIED UPPER RIDGE, WHEREAS THE REMAINING MODELS AND AIFS ARE
MORE INDICATIVE OF A FLATTER RIDGE WITH A MORE DEFINED TROUGH
APPROACHING THE PACIFIC NORTHWEST. THEREFORE, THE FRONTS/PRESSURES
FORECAST WAS HEDGED CLOSER TO THE AIFS AND ECENS GUIDANCE, AND SOME
OF THE GFS AND GEFS FOR TUESDAY INTO WEDNESDAY. THE NBM APPEARED
REASONABLE FOR MOST AREAS, ALTHOUGH QPF WAS SLIGHTLY RAISED FROM
THE EASTERN OHIO VALLEY TO THE MID-ATLANTIC FOR TUESDAY GIVEN A
STRONGER SIGNAL IN OTHER GUIDANCE, AND WINDS WERE RAISED SOME
ACROSS THE WESTERN U.S. GIVEN THE MORE ENERGETIC FLOW PATTERN THAT
IS EXPECTED TO BE IN PLACE.
..WEATHER/HAZARDS HIGHLIGHTS
THE RECORD-BREAKING HEATWAVE WILL LIKELY BE REACHING ITS PEAK BY
SATURDAY ACROSS THE SOUTHWESTERN U.S. WITH A HIGHLY ANOMALOUS UPPER
RIDGE IN PLACE. THE LOWER ELEVATIONS OF ARIZONA AND EASTERN
CALIFORNIA ARE EXPECTED TO HAVE TEMPERATURES EASILY EXCEED 100
DEGREES, AND THIS WILL SET MULTIPLE ALL TIME MARCH TEMPERATURE
RECORDS. EXTREME HEAT WARNINGS ARE NOW IN EFFECT GIVEN THE
MAGNITUDE AND HOW EARLY IN THE SEASON THIS IS HAPPENING, GIVEN MANY
ARE NOT YET ACCLIMATED TO THESE CONDITIONS. WIDESPREAD HIGHS 20-30+
DEGREES ABOVE LATE MARCH AVERAGES WILL ALSO BE EXPERIENCED FROM THE
INTERMOUNTAIN WEST TO THE CENTRAL/SOUTHERN PLAINS, WITH NUMEROUS
RECORDS BROKEN HERE AS WELL. THERE WILL LIKELY BE SOME ABATEMENT IN
THE HEAT GOING INTO EARLY NEXT WEEK, ESPECIALLY FOR THE PLAINS AS
A COLD FRONT SETTLES IN FROM THE NORTH, AND A MODEST IMPROVEMENT
FOR THE SOUTHWEST ALTHOUGH STILL WELL ABOVE NORMAL.
THERE WILL LIKELY BE A BRIEF WARM-UP FOR THE EAST COAST REGION THIS
WEEKEND AHEAD OF A STRONG COLD FRONT, WITH HIGHS EXPECTED TO BE
WELL INTO THE 60S AND 70S FOR MANY AREAS. HIGHS SHOULD RETURN TO
SLIGHTLY BELOW NORMAL LEVELS BY MONDAY AND TUESDAY AS A CANADIAN
SURFACE HIGH BUILDS IN FROM THE NORTH. THERE MAY BE SOME LIGHT RAIN
AND APPALACHIAN WINTRY PRECIPITATION FROM THE EASTERN OHIO VALLEY
TO THE MID-ATLANTIC BY TUESDAY INTO WEDNESDAY AS A POTENTIAL LOW
DEVELOPS ALONG A FRONTAL BOUNDARY, BUT UNCERTAIN ON SPECIFICS.
THE ATMOSPHERIC RIVER THAT WILL BE IN PLACE ACROSS WASHINGTON STATE
LATE THIS WEEK IS EXPECTED TO WEAKEN AND MOVE INLAND ACROSS THE
NORTHERN ROCKIES BY THE WEEKEND, AND THEREFORE NO EXCESSIVE
RAINFALL RISK AREAS ARE CURRENTLY WARRANTED FOR BOTH THE DAY
4/SATURDAY AND DAY 5/SUNDAY TIME PERIODS. HOWEVER, MORE RAIN AND
MOUNTAIN SNOW IS LIKELY TO MAKE A RETURN TO THIS REGION ON TUESDAY
AS THE NEXT STORM SYSTEM FROM THE PACIFIC APPROACHES, AND MORE SNOW
FOR THE HIGHER ELEVATIONS OF THE NORTHERN ROCKIES.
HAMRICK
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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